It is the old adage of supply and demand. The commodity is bit rate capacity, often called bandwidth by IT people. Certainly, the demand is there and probably doubling every one to two years. In the supply chain the bits, now in great quantities, must be transported in some manner. The other requirement is that they be directed to or accepted from a user. What we are talking about is information represented by bits. The only transport that can handle these great quantities is an optical link. At every node in the
optical network the stream of bits must be returned to the electrical domain for switching/routing. The goal is an all-optical network without the laborious return to the electrical domain at switching nodes except at the input–output points. Optical links are presently carrying 10 Gbits/s per bit stream per wavelength.
With dense wavelength division multiplexing (DWDM) a single fiber can carry 8, 16, 32, 40, 80, 160, or 320 wavelengths. Within some years of the publication of this book, we will have 40 Gbits/s per bit stream and a single fiber will support in that same time frame 320 wavelengths or more. If each wavelength carries
40 Gbits/s, then a single fiber will have the capacity to carry 40 × 160 Gbits/s or 6400 Gbits/s.
As seen from the network provider, a major drawback in fiber networking technology is the costly requirement for repeated conversions from the optical domain to the electrical domain and back again, called OEO, at every regeneration point and for periodic signal monitoring along the line. Amplifiers replacing regenerative repeaters where the add–drop function is not necessary have improved the cost situation somewhat. When optical switching without OEO is employed in the network, the requirement for regenerative repeaters (regens) in the network will be vastly reduced.
In the PSTN, fiber networks are primarily based on SONET and SDH infrastructures. In such cases the cost of regenerating optical signals can be very expensive, especially when it requires full SONET or SDH termination equipment at every ADM regeneration point. It has been found that even in these relatively
homogeneous all-SONET environments, optical layer management can be a key factor in maintaining system integrity. Present optical networks, unfortunately, require OEO conversion for effective network management.
Even at locations along the fiber line where full conversion is not necessary, partial conversion at key points can be vitally important for monitoring to assure circuit quality. At amplifier locations as in conversion signal points, active signal monitoring capabilities should be included. This will require optical signal splitting and optical-to-electrical conversion of some portion of the light signal. The move toward direct deployment of gigabit ethernet (GbE) over the MAN WAN is a factor that may help to temporarily mitigate some of the push for all-optical switching because the cost of interface equipment for GbE fiber transport
links is significantly less than for a SONET or SDH link. We see it as highly unlikely that GbE could completely replace SONET/SDH in the foreseeable future for anything other than very limited environments. However, the real-world impact of GbE deployment is likely to be increased traffic heterogeneity
that will further drive the need for effective optical-layer management. The ultimate goal behind DWDM deployment is the provision of more bit rate capacity. As a corollary then, MANs and WANs in the real world require optimization of the use of each wavelength’s bit rate capacity. With the PSTN,
where long-haul links traverse the network core, this goal of optimized utilization has typically been accomplished by pre-grooming all traffic such that uniform groups of signals can be efficiently transported long distances with a minimum of intervening decision points along the way. However, for traffic traveling nearer
the edge of the transport network, new-generation equipment needs to provide a higher level of traffic monitoring and grooming capabilities within the optical domain to achieve a balance of flexibility, performance, and capacity utilization. We would argue that in most cases it would make little economic and practical
sense to invest in DWDM and then map GbE connections across individual wavelength carriers on a one-to-one basis. Therefore, the push for aggregation of multiple connections can very quickly lead to a mix of heterogeneous non concatenated traffic traveling within a shared wavelength with a multitude of
different end-point destinations. The goal of the industry is to make the network all-optical except at each
edge transition point. This point will be on a user’s premises. By transition we mean the conversion of light to equivalent electrical information expressed as 1s and 0s. This chapter’s objective is to describe various steps to be taken toward what may now be called the “all-optical” network, its topology, and routing/switching
in the optical domain.

The following is a list of new technology and radical approaches to make an all-optical network a reality:
a. Optical switching
b. Advanced wavelength demultiplexing and multiplexing
c. Tunable filters
d. Stabilized lasers
e. New approaches to modulation
f. Improved optical amplifiers with flat gain characteristics
g. New and larger optical cross-connects (OXCs)
h. Optical add–drop multiplexers (OADMs)
i. Signaling techniques in the light domain

2.1 Derived Technology Applications
The semiconductor optical amplifier (SOA) is one of the most promising technologies for optical networks. By integrating the amplifier functionality into the semiconductor material, the same basic component can perform many different applications. SOAs can perform switching and routing roles in an integrated
functionality within the semiconductor material. Other important elements of an all-optical network are space switches, wavelength converters, and wavelength selectors, all of which can be fabricated from SOAs.
The new-generation managed optical network is moving toward a distributed switching model in which lambda (λ) switches with intelligent Layer 1 cross connect capability are distributed at various points along the network border. This concept is illustrated in Figure 20.1. Such an architecture provides seamless
and efficient Layer 1 management of heterogeneous traffic types throughout the network, without sacrificing performance or flexibility in either the core or edge environments. This global distributed-switching architecture is equally adaptable to using dedicated wavelengths packed with homogeneous traffic for long-haul point-to-point transport or for flexibly managing heterogeneous traffic on dynamically
allocated short-haul wavelengths. With cross-connects along the edge of the network cloud, there is an emerging need for supporting a managed optical layer within a distributed optical switching
environment. This outlines the crux of the matter and presents significant opportunities and challenges for both the semiconductor level and module-level developers and manufacturers. To achieve the required performance requirements, next-generation cross-connects need to be closer to the network by providing
Layer 1 switching as opposed to the present traditional Layer 2 switching.
There will be two cross-point designs: asynchronous and synchronous. The higher-speed asynchronous cross-points enable heterogeneous MAN implementations to efficiently support different types of native-mode traffic within the same ring. In long-haul networks, there will be innovative uses of synchronousswitching
cross-points which will provide the necessary performance requirements. These switches are seen as more of a time–space–time switch rather than the more rudimentary space switch. These new-generation synchronous crosspoints will incorporate Layer 1 grooming capabilities that can selectively switch SONET (or SDH) or any other TDM (time-division multiplex) signals between any combination of inputs and outputs.
It is expected that these optical Layer 1 switching capabilities will use highspeed
synchronous ICs. This next-generation synchronous cross-point switch will offer the capability to selectively groom out and switch and STS-1 (STM-1) from within STS-48 (STM-16) or STS-192 (STM-64) bit streams. These devices will provide complete flexibility for provisioning IC-level managed optical crossconnects from any STS-1 input to any STS-1 output. Non-SONET traffic mapped to STS-N-equivalent containers and protocol-independent wrapped traffic can be switched within the same cross-connects. These high-density, high-speed grooming switches are deployed along the edge
of the switching network cloud. They can optimize capacity utilization whileefficiently making Layer 1 access decisions to partition out traffic to outlying internet protocol, GbE, ATM, fiber channel, or other Layer 2 switches. Localized Layer 2 functions such as routing and policy management are appropriately handled
by the outlying switches while Layer 1 access switches provide high-speed performance IC-level switching/grooming of DWDM wavelengths [1].

Today’s data networks typically have four layers:
• IP for carrying applications
• ATM for traffic engineering
• SONET/SDH for transport
• DWDM for capacity
This architecture has been slow to scale, making it ineffective for photon networks. Multilayering architectures typically suffer from the lowest common denominator effect where any one layer can limit the scalability of the other three layers and the entire network.
4.1 Two-Layer Networks Are Emerging
For the optical network developer, an absolute prerequisite for success is the ability to scale the network and deliver bit rate capacity where a customer needs it. Limitations of the existing network infrastructure are hindering movement to this service-delivery business model. It is the general belief in the industry that
a new network foundation is required. This network foundation is seen as one that will easily adapt to support rapid change, growth, and highly responsive service delivery. What is needed is an intelligent, dynamic, photonic transport layer deployed in support of the service layer.
The photonic-network model divides the network into two domains: service and optical transport. The new architecture is seen as combining the benefits of
photonic switching with advances in DWDM technology. It delivers a multigigabit bit rate capacity and provides wavelength-level traffic-engineered network interfaces to the service platforms. The service platform includes routers, ATM switches, and SONET/SDH add–drop multiplexers, which are redeployed from
the transport layer to the service layer. The service layer is seen as relying completely on the photonic transport layer for the delivery of the necessary bit rate capacity where and when it is needed to peer nodes or to network elements (NEs). The bit rate capacity is provisioned in wavelength granularity rather than in PDH TDM granularities. We expect exponential growth rate of the fiber network; to meet these requirements, rapid provisioning is an integral part of the new architecture. While the first implementations of this model will support error detection, fault isolation, and restoration via SONET, these functions will gradually move
to the optical layer.

KongZhong Corporation(KONG) Chaina Analyst on Telecom

KongZhong Corporation, through its subsidiaries, provides wireless interactive entertainment, media and community services to mobile phone users in the People’s Republic of China. The company also engages in the development, marketing, and distribution of consumer wireless value-added services.
The company’s wholly-owned subsidiaries include KongZhong Beijing, KongZhong China and Beijing Anjian Xingye.
The company provides interactive entertainment, media and community services to mobile phone users through 2G technology platforms, including SMS, IVR and CRBT, and through 2.5G technology platforms, including WAP, MMS and Java, which offer higher quality graphics, richer content and interactivity than 2G wireless services.
The company operates its wireless value-added services through Beijing AirInbox Information Technologies Co., Ltd (Beijing AirInbox), Beijing Boya Wuji Technologies Co., Ltd., (Beijing Boya Wuji), Beijing Wireless Interactive Network Technologies Co., Ltd (Beijing WINT), Wuhan Chengxitong Information Technology Company Limited (Wuhan Chengxitong) and Beijing Xinrui Network Technology Company Limited (BJXR).
The company provides wireless value-added services on each of the wireless access protocol (WAP), multimedia messaging services (MMS) and Java technology platforms. In addition, the Company provides wireless value-added services on the networks of China Unicom, China Telecom and China Netcom, China’s other telecommunications operators.
The Company offers a range of services that users can access directly from their mobile phones, including by choosing an icon embedded in select models of handsets, or from a mobile operator’s portal or Website.
Wireless Value-Added Services
The company’s services are organized in three categories, consisting of:
Interactive Entertainment: The company offers a range of interactive entertainment services, including mobile games, karaoke, electronic books and mobile phone personalization features, such as ringtones, wallpaper, icons, clocks and calendars. The company provides its interactive entertainment services through its technology platforms. Mobile phone users download on demand or subscribe for regular downloads of its interactive entertainment services, although most of its mobile games are offered on a single-transaction basis.
Mobile Games: The company focuses on offering mobile games based on 2.5G platforms including WAP and Java. In 2005, the company developed mobile games product development team to develop and publish 2.5G mobile games and also acquired Tianjin Mammoth, a mobile games developer. As of December 31, 2006, the company had a library of approximately 100 internally developed mobile game titles. The company's internally developed mobile on-line game e 3-Kingdom was named Most Popular Mobile Networking Game at the 2006 China Joy Best Games Contest.
Pictures and Logos: Mobile phone users can download pictures and logos to personalize the background of their mobile phone screens. Such pictures include cartoons, pets and scenic photos.
Polyphonic Ringtones: The company's ringtones enable a mobile phone user to personalize their ringtones using the melodies of their favorite songs or special sound effects.
Media: Users can download its media content on either a single-transaction basis or a monthly subscription basis. Media content covers international and domestic news, entertainment, sports, fashion, lifestyle and other special interest areas.
News: The company offers international and domestic news, delivered in a format easy for the reader to peruse. The company's WAP version enables users to search for news that interests them.
Entertainment: The company's entertainment magazine focuses on high-profile celebrities and includes star biographies, interviews and photos.
Sports: The company's sports magazine features sports news, game scores and information about sports stars.
Community: Users can engage in community-oriented activities such as interactive chatting, message boards, dating and networking. Users might access the company's community services on a monthly subscription basis or single-transaction basis.
Chat: The company offers various chat services. For instance, the company has a virtual reality game that allows mobile phone users to choose the lifestyle they dream of and interact with the city’s other inhabitants/players.
Dating: The company offers dating mobile services. The company has a mobile chat and dating service available on WAP and MMS that allows users to utilize the improved features of 2.5G technology to choose their chatting partners from a selection of pictures taken with users’ mobile phone cameras. The company also offers a WAP-based dating service designed to simulate a campus environment tailored for students.
Photo Albums: The company's photo albums allow mobile users to post and arrange their photos taken with their mobile handsets into albums accessible via their handsets. Utilizing the WAP technology platform, mobile users can access photo albums in a similar to accessing photo albums on the Internet.
Wireless Internet Business
The company has developed a wireless Internet site that customers can visit from their mobile phones through their WAP browser while using 2.5G mobile networks. The company's wireless Internet site is independent of the telecommunications operators’ portals, including China Mobile’s Monternet portal. Through Kong.net, the company offers news, community services, games and other interactive media and entertainment services to its customers free of charge. The company also sells advertising space on Kong.net in the form of text-link, banner and button advertisements.
The company has signed cooperation agreements with approximately 50 content providers including Beijing Mapabc, a digital map provider, SouFun.com, a real estate portal, and Hexun.com, an on-line financial news provider, to include selected content from these providers on Kong.net.
Technology Platforms
2.5G Wireless Standard Services
The company delivers its 2.5G services primarily to users of mobile phones that either are based on the global system for mobile communication, or GSM, standard and utilize general packet radio service, or GPRS, technology or are based on the code-division multiple access, or CDMA, standard and utilize CDMA 1x technology, in both cases through the WAP, MMS and Java technology platforms.
Wireless Application Protocol (WAP): WAP allows users to browse content on their mobile phones so that users can request and receive information in a manner similar to accessing information on Internet web sites using personal computers. The company provides its WAP services primarily over China Mobile’s GPRS networks. The company's WAP services allow users to download color and animated pictures, logos and wallpaper, interactive mobile games, customized ringtones and other Internet content. In 2006, China Mobile selected the company to provide services on two of China Mobile’s nine premium WAP channels, the game channel and the music channel, for an initial period of six months.
Multimedia Messaging Services (MMS): MMS is a messaging service that the company delivers approximately GPRS networks and that, in China, allows up to 50 kilobytes of data to be transmitted in a single message, compared to 140 bytes of data via SMS. The company's monthly subscription services automatically send information to users’ mobile phones, and include news, beauty, celebrity photographs and special collectible items. The company's services that can be downloaded on a single-transaction basis include pictures, screensavers, ringtones and special sound effects.
Java: Java technology allows mobile phone users to play interactive and networked mobile games, perform karaoke and download applications, such as screensavers and clocks, to customize their mobile phone settings.
2G Wireless Standard
The company delivers its 2G services primarily through the SMS, IVR and CRBT technology platforms.
Short Messaging Services (SMS): SMS is the basic form of mobile messaging service, and is supported by substantially all mobile phone models sold. Users can receive the company's products and services, which include news, jokes, weather forecasts and short stories, through their mobile phones on a subscription or single-transaction basis.
Interactive Voice Response (IVR): Interactive voice response services allow users to access voice content from their mobile phones, including music, chat, foreign-language instruction and novels.
Color Ring Back Tone (CRBT): Color ring back tones allow a mobile phone user to customize the sound that callers hear when ringing the user’s mobile phone. The company offers various entertaining content, including pre-recorded messages, movie dialogues and soundtracks and a range of classical and popular music.
Strategic Relationships
The company has established cooperation arrangements with telecommunications operators, mobile handset manufacturers, content providers and other business partners to produce, promote and market its services. The company provides its wireless value-added services mainly pursuant to cooperation agreements through China Mobile’s Monternet network. The company also has provided its wireless value-added services through China Unicom’s Uni-Info mobile network and each of China Netcom’s and China Telecom’s Personal Handyphone Systems, or PHS systems, which are based on fixed-line networks. In addition, the company cooperates with various China’s mobile handset manufacturers, which make select handset models with a wireless value-added services icon in the handset’s menu that enables users to access its services directly. The company pays service fees to the telecommunications operators, mobile handset manufacturers, mobile handset distributors, content providers and other partners, where relevant.
Mobile Handset Manufacturers
The company has established distribution arrangements with mobile handset manufacturers, including Motorola, Samsung, Amoi, Lenovo, Sony Ericsson and other major domestic and international handset manufacturers. The company pre-load into the menu of certain mobile handsets its WAP icons and MMS, SMS, JAVA and IVR short codes, which enable customers to access its wireless value-added services. The company has distribution arrangements with 41 mobile handset manufacturers.
Content Providers
The company licenses news content from the Xinhua News Agency, China News Service, www.qianlong.com and China Foto Press, and licenses music content from EMI Group Hong Kong Ltd., Sony BMG Music Entertainment (Asia) Inc. and Avex Asia Limited. It has entered into license agreements with Namco Limited, Gameloft, The Walt Disney Company and Superscape Ltd. to provide their games to mobile phone users in China.
2.5G Wireless Standard Services
The company's competitors in the 2.5G wireless value-added services market in China include Internet portals, such as Sina Corporation, Sohu.com Inc., NetEase.com Inc. and TOM Online Inc., as well as providers focused on wireless value-added services, such as Hurray! Solutions Limited and Linktone Limited.
2G Wireless Standard Services
The company's competitors in this market include Internet portals, such as Sina Corporation, Sohu.com Inc., Netease.com Inc. and TOM Online Inc., and providers focused on wireless value-added services, such as Tencent Technology Limited and Linktone Limited.
The company was founded as Communication Over The Air, Inc. in 2002 and changed its name to KongZhong Corporation in 2004.

History of Mobile Phone/2.5G Network

In the history of communications technology, Martin Cooper pioneered the cellular telephony technology and that is why he was considered as “the father of mobile telephony”. Mr. Cooper introduced the 1st mobile in 1973 in USA while working for the famous Motorola company, but it was not until 1979 when the first commercial cellular system was introduced in Tokyo, Japan by NTT. It was in 1981 when the Nordic countries introduced a mobile system similar to Advanced Mobile Phone System (AMPS). Side by side in 1983, United States adopted the rules for creating the first commercial cellular system that was put into operation for the first time in the city of Chicago. This step by US served as a starting point for the spread of mobile technology in several countries around the world. This system was then used as an alternative to conventional wireless telephony. The latest mobile technology was widely accepted by all the countries and within a few years, there were millions of people who began using this system. After this, there began the need to develop and implement other forms of multiple access channels and transform the analog signal to digital in order to make space for more and more users that were increasing at a rapid rate. Now in order to separate one from other stage, mobile telephony has been characterized by having different generations namely 1G, 2G, 2.5G, 3G and now 4G and 5G. I have already described 1G, 2G, and 3G in my previous hub, Cell Phone Generations - Advantage of 3G network over 1G and 2G but in between the generation of 2G and 3G, there was a generation which I forgot to mention and that was 2.5G which is very important for the understanding of mobile phone generations so here it is:
Second And A Half Generation of Mobile Phones (2.5G Network)
In the past, many telecommunication service providers moved to 2.5G networks before entering into 3G networks. It is already understood that 2.5G technology was much more advanced and faster than 1G and 2G and at the same time, it was much cheaper to upgrade to 3G from 2.5G. The 2.5 generation of mobile phones offered extended features and additional capacity that was more than 2G networks.  These new features were High Speed Circuit Switched or HSCSD, General Packet Radio System or GPRS, EDGE or Enhanced Data Rates for Global Evolution, IS- and IS-136B 95Bm. The European and U.S network carriers moved to 2.5G in 2001 while Japan got straight from 2G to 3G in 2001. Every transformation from 1G to 2G, 2G to 2.5G, and 2.5G to 3G networks helped in communicating better and better.
What's inside a mobile phone?
A mobile phone is an electronic device with intricate designs and processes millions of calculations per second to compress and decompress the voice stream. If you will disassemble a mobile phone, you will be able to find the following parts:
  • One integrated circuit containing the brain of your cell phone.
  • One antenna
  • One LCD or liquid crystal display
  • One small keyboard
  • One microphone
  • One speaker
  • One battery
So the above were some details on brief history of mobile phones, introduction of 2.5G Network or second and a half generation of mobile phones plus a small part on what's inside a cell phone or mobile phone.

The evolutioanary road for the indian Telecom network

The wireless tele-density in India has now reached 48% and is showing no signs of slowing down. The number of wireless users will only go up as the penetration moves farther into the rural hinterland. In these times Communication Service Providers (CSPs) are faced with a multitude of different competing technologies, frameworks and paradigms. On the telecom network side there is the 2G, 2.5G, 3G & 4G. To add to the confusion there is a lot of buzz around Cloud technology, Virtualization, SaaS, femtocells etc., to name a few. With the juggernaut of technological development proceeding at a relentless pace Senior Management in Telcos, Service Providers the world over are faced with a bewildering choice of technology to choose from while trying to maintain the spending at sustainable levels. For a developing economy like India the path forward for Telcos and CSP is to gradually evolve from the current 2.5G service to the faster 3G services without trying to rush to 4G. The focus of CSPs and Operators should be in customer retention and maintaining customer loyalty. The drive should be in increasing the customer base by enhancing the customer experience rather than jumping onto the 4G bandwagon. 4G technology for example LTE and WiMAX make perfect sense in countries like US or Japan where smart phones are within the reach of a larger set of the populace. In India smartphones, when they come, will be the sole preserve of high flying executives and the urban elite. The larger population in India would tend to use more of the VAS services like mobile payment, e-ticketing rather than downloading video through their mobile phones. In US, it is rumored that iPhones with their data hungry applications almost brought a major network to its knees. This is primarily due to popularity and affordability of these smart phones in countries like the US. Hence it makes perfect sense for Network Providers in the US to upgrade their network infrastructure to handle the increasing demand for data hungry applications. Hence the move to LTE or WiMAX would be a logical move in countries like US. In our nation the thrust of Service Providers should be to promote customer loyalty by offering differentiated Value Added Service (VAS) service. Also the CSPs should try to increase the network coverage so that the frustration of lost or dropped calls is minimal. The Service Providers should try to attract new users by offering an enhanced customer experience through special Value Added Services (VAS). This becomes all the more important with the impending move to Mobile Number Portability (MNP). Once MNP is in the network many subscribers will switch to Service Providers who offer better services and have more reliable network coverage.
Another area where the Service Providers should focus on is in creating App Stores like iPhone which has spawned an entire industry in the US. Mobile App s from app stores besides providing entertainment and differentiation can also be a very good money spinner. While the economy continues to flounder the world over the Service Providers should try to reduce their Capacity Expenditure (Capex) and their Operating Expenditure (Opex) through the adoption of Software-as – Service (SaaS) for their OSS/BSS systems. Cloud technology besides reducing the Total Cost of Ownership (TCO) for Network Providers can be quite economical in the long run. It is quite possible that prior to migrating to the Cloud all aspects of security should be thoroughly investigated by the Network Providers and critical decisions as to which areas of their OSS/BSS they would like to migrate to the Cloud. While a move to leapfrog to 4G from 2G may not be required, it is imperative that with the entry of smartphones like iPhone 3GS, Nexus One and Droid into India the CSPs should be in a position to handle increasing bandwidth requirements. Some techniques to handle the issue of data hungry smartphones are to offload data traffic to Wi-Fi networks or femtocells. Besides, professionals these days use dongles with their laptops to check email, browse and download documents. All these put a strain on the network and offloading data traffic to femtocells & Wi-Fi have been the chosen as the solution by leading Network Providers in the US.
So the road to gradual evolution of the network for the Network Operators, Service Providers are
1. Evolve to 3G Services from 2G/2.5G.
2. Create app stores to promote customer retention & loyalty and offer differentiated VAS services
3. Improve network coverage uniformly and enhance the customer experience through specialized App stores
4. Migrate some of the OSS/BSS functionality to the cloud or use SaaS after investigating the applications of the enterprise that can move to the cloud
5. Offload data traffic to Wi-Fi networks or femtocells.

3G (Third generation of mobile telephony)

3G refers to the third generation of mobile telephony (that is, cellular) technology. The third generation, as the name suggests, follows two earlier generations.
The first generation (1G) began in the early 80's with commercial deployment of Advanced Mobile Phone Service (AMPS) cellular networks. Early AMPS networks used Frequency Division Multiplexing Access (FDMA) to carry analog voice over channels in the 800 MHz frequency band.
The second generation (2G) emerged in the 90's when mobile operators deployed two competing digital voice standards. In North America, some operators adopted IS-95, which used Code Division Multiple Access (CDMA) to multiplex up to 64 calls per channel in the 800 MHz band. Across the world, many operators adopted the Global System for Mobile communication (GSM) standard, which used Time Division Multiple Access (TDMA) to multiplex up to 8 calls per channel in the 900 and 1800 MHz bands.
The International Telecommunications Union (ITU) defined the third generation (3G) of mobile telephony standards IMT-2000 to facilitate growth, increase bandwidth, and support more diverse applications. For example, GSM could deliver not only voice, but also circuit-switched data at speeds up to 14.4 Kbps. But to support mobile multimedia applications, 3G had to deliver packet-switched data with better spectral efficiency, at far greater speeds.
However, to get from 2G to 3G, mobile operators had make "evolutionary" upgrades to existing networks while simultaneously planning their "revolutionary" new mobile broadband networks. This lead to the establishment of two distinct 3G families: 3GPP and 3GPP2.
The 3rd Generation Partnership Project (3GPP) was formed in 1998 to foster deployment of 3G networks that descended from GSM. 3GPP technologies evolved as follows.
• General Packet Radio Service (GPRS) offered speeds up to 114 Kbps.
• Enhanced Data Rates for Global Evolution (EDGE) reached up to 384 Kbps.
• UMTS Wideband CDMA (WCDMA) offered downlink speeds up to 1.92 Mbps.
• High Speed Downlink Packet Access (HSDPA) boosted the downlink to 14Mbps.
• LTE Evolved UMTS Terrestrial Radio Access (E-UTRA) is aiming for 100 Mbps.

GPRS deployments began in 2000, followed by EDGE in 2003. While these technologies are defined by IMT-2000, they are sometimes called "2.5G" because they did not offer multi-megabit data rates. EDGE has now been superceded by HSDPA (and its uplink partner HSUPA). According to the 3GPP, there were 166 HSDPA networks in 75 countries at the end of 2007. The next step for GSM operators: LTE E-UTRA, based on specifications completed in late 2008.
A second organization, the 3rd Generation Partnership Project 2 (3GPP2) -- was formed to help North American and Asian operators using CDMA2000 transition to 3G. 3GPP2 technologies evolved as follows.

• One Times Radio Transmission Technology (1xRTT) offered speeds up to 144 Kbps.
• Evolution Data Optimized (EV-DO) increased downlink speeds up to 2.4 Mbps.
• EV-DO Rev. A boosted downlink peak speed to 3.1 Mbps and reduced latency.
• EV-DO Rev. B can use 2 to 15 channels, with each downlink peaking at 4.9 Mbps.
• Ultra Mobile Broadband (UMB) was slated to reach 288 Mbps on the downlink.

1xRTT became available in 2002, followed by commercial EV-DO Rev. 0 in 2004. Here again, 1xRTT is referred to as "2.5G" because it served as a transitional step to EV-DO. EV-DO standards were extended twice . Revision A services emerged in 2006 and are now being succeeded by products that use Revision B to increase data rates by transmitting over multiple channels. The 3GPP2's next-generation technology, UMB, may not catch on, as many CDMA operators are now planning to evolve to LTE instead.
In fact, LTE and UMB are often called 4G (fourth generation) technologies because they increase downlink speeds an order of magnitude. This label is a bit premature because what constitutes "4G" has not yet been standardized. The ITU is currently considering candidate technologies for inclusion in the 4G IMT-Advanced standard, including LTE, UMB, and WiMAX II. Goals for 4G include data rates of least 100 Mbps, use of OFDMA transmission, and packet-switched delivery of IP-based voice, data, and streaming multimedia.

Based on the International Telecommunications Union standards, the 3G network is the third generation of mobile networking and telecommunications. It features a wider range of services and advances network capacity over the previous 2G network. The 3G network also increases the rate of information transfer known as spectral efficiency. Telephony has received a wider area and more range, while video and broadband wireless data transfers have also been positively affected. These criteria are identified as the IMT-2000 standard.
A 3G network provides for download speeds of 14.4 megabits per second and upload speeds of 5.8 megabits per second. The minimum speed for a stationary user is 2 megabits per second. A user in a moving vehicle can expect 348 kilobits per second.

U Mobile Ropes In China's ZTE To Extend Mobile Network
KUALA LUMPUR, March 15 (Bernama) -- U Mobile Sdn Bhd and ZTE Corporation of China today signed an agreement which will see the local 3G mobile service operator extending its 42 Mbps network in the Klang Valley, Negeri Sembilan and the northern region by the second half of 2011.

The three-year deal also provides for the installation of LTE (long term evolution) platforms in line with the plan to bring 100 Mbps wireless network across key cities in Malaysia.

Present at the signing ceremony here were Information Communication and Culture Minister Datuk Seri Utama Dr Rais Yatim and Chinese Ambassador to Malaysia Chai Xi.

"In view of this strategic partnership, U Mobile is seen to be taking the way forward in providing the latest wireless technology for the country.

"Within the next 12 months, one should see an upgrade of U Mobile's 42 Mbps to 84 Mbps capability. A user's internet experience is likely to be ten times faster than the current rate," the companies said in a joint statement on Tuesday.

It also said that LTE technology in Malaysia would utilise 2.6 Gigahertz band and at the moment, final award of spectrum was still pending.

"Commercial launch is largely depending on the spectrum award timing by the Malaysian Communications and Multimedia Commission, and the availability of devices," it said.

Meanwhile, U Mobile chief executive officer Dr Kaizad Heerjee said his company aimed to roll out additionally 2,000 to 3,000 mobile base stations across Malaysia in the next 12 to 18 months.

Currently, it has more than 1,000 mobile base stations installed covering the Klang Valley, Seremban, Ipoh, Penang and Johor Baharu.
 Chinese telecom equipment maker Huawei Technologies has announced that it has signed a USD100 million contract with the New Zealand-based mobile network 2degrees to help the company upgrade its network over the next two years.
Eric Hertz, chief executive officer of 2degrees, said that the investment will ensure the company's network is ready to handle the requirement of the fourth-generation smartphones. It is learned that 2degrees already provides its customers with nationwide 2G and 3G mobile services via its own network and commercial roaming.
Hertz said that they are conscious that they need to build networks that deliver on tomorrow's speed and capacity demands, so being able to upgrade to 4G via a software activation rather than a network rebuild is especially important.
Winning the deal following a competitive process, Huawei will provide a turn-key project solution to meet 2degrees' development requirement. Arthur Zhang, Huawei New Zealand CEO, said that the fact that 2degrees has chosen Huawei as its partner for the building of phase two of its network marks a vote of confidence in Huawei's technology and its ability to build a world-class network for 2degrees' customers.

An interview with Zeng Xuezhong, Senior Vice President of ZTE Corporation

P&T/EXPO COMM CHINA 2010, to be held in Beijing this October, will be the most influential ICT event this year. The theme of the EXPO is tri-network convergence, and topics such as TD/LTE/4G evolution, green telecom, and Internet of Things will be discussed. In the lead up to the event, journalist Zhao Lili interviewed Zeng Xuezhong, Senior Vice President of ZTE Corporation, to find out how ZTE is working with Chinese operators to develop a new industrial chain in a new industrial environment.

Journalist: 2009 saw the birth of 3G in China, and the country’s three major operators have been involved in 3G network deployment and operation ever since. What role has ZTE played in China’s 3G deployment? And how will ZTE establish strategic partnerships with these operators to develop their networks to LTE?
Zeng: In 2009, China’s Ministry of Industry and Information Technology issued 3G licenses to China Mobile (TD-SCDMA), China Unicom (WCDMA), and China Telecom (CDMA). This marked the formal entry of China into the 3G era, and for the first time, placed Chinese telecom vendors on an even footing with foreign competitors. ZTE is not only a key participant in China’s 3G network construction, but also an advocate for 3G industry development and technological innovation.
According to a report released by iSuppli in January 2010, ZTE holds the largest share in China’s 3G market. In the TD-SCDMA sector, ZTE has been a strategic partner of China Mobile throughout its TD network construction—from the phase one and two network trials in 2007 and 2008 to the large-scale phase three commercialization in 2009. ZTE has played a key role in China Mobile’s technical innovation, industrialization, network deployment, and service delivery.
ZTE has also become the industry leader in CDMA, holding the largest market share in China since 2007.  Close cooperation was established with China Telecom after it was awarded a CDMA license, and ZTE infrastructure equipment has now been deployed in 27 provinces throughout the country. ZTE helped China Telecom build approximately 60% of its local CDMA networks at the prefecture level, and undertook most of its 3G network planning, construction, and maintenance.
ZTE has also been a key supplier to China Unicom since the company started WCDMA network deployment in 2009. ZTE’s market share increased during phase two, phase three, and phase four of China Unicom’s WCDMA project. The largest share was clinched in phase four of the project, which covered 20 provinces and 108 cities. Leveraging its implementation efficiency and service capability, ZTE became the leader in fast project completion. Moreover, network tests were passed with excellent results. All this demonstrates ZTE’s comprehensive strength in the WCDMA field.
Operators worldwide are closely monitoring the evolution of 3G to LTE, and some are even initiating the process. ZTE is devoted to LTE research and development, and is continually increasing its strategic funding in both FDD and TDD. We have applied for more than 1,700 LTE patents, and own basic patents of the LTE standard. With a quality product portfolio and a growth strategy that is prudent and sustainable, ZTE is ranked among the Top 3 players in terms of LTE strength by research firm Garnet.
ZTE offers sophisticated services for TD-SCDMA, CDMA2000, and WCDMA, working with operators to develop the whole industrial chain. We are highly recognized by operators for our innovation mechanism, long-term strategies, and enhanced brand image. Chinese telecom vendors are certainly capable of competing with global telecom giants. The 3G era is a turning point for China’s telecom industry and is of far-reaching significance.

J: The theme of P&T/EXPO COMM CHINA 2010 is tri-network convergence, and the Chinese government has put in place support policies to speed up this process. What changes will happen in China’s telecom industry, and what challenges and opportunities will this present to equipment vendors?
Zeng: In January 2010, the State Council passed a general proposal for speeding up the convergence of telecommunications, broadcast TV, and Internet networks. This proposal will alter the whole industry, not only driving the growth of telecommunications, broadcast TV, and Internet businesses in China, but also presenting opportunities and challenges to all parties in the industrial chain.
Tri-network convergence will change the competition pattern of China’s telecommunications industry.  For equipment vendors, it will lead to increasing demands for equipment because of network construction and upgrade requirements. More importantly, as telecom operators transform into service providers, equipment vendors will also transform from simple equipment suppliers to end-to-end full-service solution providers. The group of three major operators in China will expand to include CATV operators. These new operators will have diversified business models and will challenge traditional operators with their control over TV content and broadcasting rights. Both telecom and CATV operators will have to innovate and explore new areas of business to gain a competitive advantage, and this will create new market and cooperative opportunities. Demand for triple play services will grow, and emerging multimedia services such as position shift TV (PSTV), interactive TV, high definition video, mobile monitoring, and mobile TV, will be widely sought after. Moreover, with the current bandwidth restrictions for broadband services, telecom operators will be compelled to increase network access bandwidth and to widely deploy FTTH networks. Likewise, because cable networks are incapable of bidirectional transmission, CATV operators will be compelled to restructure their networks as digital two-way systems.
Changes brought about by tri-network convergence will present opportunities and challenges for equipment vendors, but the opportunities are greater than the challenges. The entire industrial chain will be reshuffled. Infrastructure equipment vendors, service equipment vendors, OSS providers, high-end integrated terminal suppliers, and content and service providers will become the market’s focus of attention. With the most complete range of infrastructure, service, OSS, and terminal equipment, ZTE has much experience in integrated broadcasting and control platforms, interactive and converged services, transmission, IP, fixed-line networks, and service software. Drawing on the advantages of our products and end-to-end network solutions, ZTE will continue to be a key player in tri-network convergence, and will further improve its ability to rapidly respond to operator needs.

J: Green technology, carbon reduction, and energy conservation are of paramount importance in today’s telecommunications industry. What requirements are implied by these issues and how will equipment vendors and operators adapt to such requirements? Specifically, what is ZTE doing to minimize negative environmental impact?
Zeng: Green products, carbon reduction, and energy conservation are now integrally linked to the sustainable development of telecom enterprises, and represent a revolution in values, concepts, production modes, and lifestyles. In a recent government work report, Premier Wen Jiabao stated that the global financial crisis was giving rise to a technological and industrial revolution, and that great efforts should be made in developing emerging strategic industries including new energies, new materials, information networks, and high-end manufacturing. The ICT industry is vitally important in promoting a low-carbon economy.
Telecom vendors and operators must play an active role in a new low-carbon economy, and are obliged to promote healthier, more sustainable telecom models. To create green, innovative networks, and to drive sustainable development across the industry, ZTE has incorporated energy conservation and environmental protection into its technological innovation, product R&D, and manufacturing.
We have been active in drafting international standards, and have established a complete green operation and evaluation system incorporating product research, implementation, supervision, and management. Environmental protection is at the forefront of our product design, testing, and manufacturing, and this helps reduce TCO while improving profitability. Green packing, transportation, installation, and operation and maintenance are implemented as part of our logistics and project delivery. Moreover, we provide unified all-IP platforms, IMS core networks, IP service engines, multi-mode BSCs, and renewable energy sources for network evolution and convergence. Power consumption of base stations can be reduced by 30% or more over a 24 hour period, which translates into savings of up to 6,300kWh per site each year. Reducing power consumption of base stations implies limiting the use of auxiliary devices associated with power supply, cooling, and maintenance. When combined with new energy resources such as solar or wind, power savings of around 50% are achievable. These efforts are examples of how ZTE is developing green, low-carbon, and energy-saving products.

J: Driven by new service demands, new business models and new technologies such as Cloud Computing, Internet of Things, and mobile Internet have emerged and are being enthusiastically promoted within the industry. How will vendors and operators change their supply and demand relationships to cope with new forms of competition?
Zeng: The emergence of Cloud Computing, Internet of Things, and mobile Internet has driven operator demands for new products, industrial convergence, and business innovation.
Increasingly, equipment vendors are being asked to not only provide upgrade solutions for products and platforms, but also to develop new products. They must meet network requirements in a new industrial environment.
Today, the telecom industry is converging with IT, entertainment, Internet, and even traditional logistics,  and this trend inevitably presents challenges and opportunities to all parties in the industrial chain.  Traditional telecom enterprises, however, may have little knowledge of other fields. Providing operators with new products and technologies is not the only role played by telecom vendors; they must also work with operators to explore future technological trends, network development, and business models. As well as helping operators increase efficiency and profitability, vendors will become long-term strategic partners in the joint exploration of new market opportunities.
With the widespread deployment of 3G networks throughout China, operators have transformed into full-service providers. 3G service operation has become a primary focus, and mobile Internet strategies have been put forth. Since the first half of 2009, ZTE has been helping China Telecom build its software stores and this year won a project to build China Unicom’s software store. ZTE is working hard to enhance its service innovation, and is partnering with operators to offer high quality feature-rich 3G services.

J: Finally, what are the future plans of ZTE in China?
Zeng: China is a very important market for ZTE. In the coming years, we intend to continue helping domestic operators explore opportunities and to maintain our own high speed growth. Drawing on our strength in integrated solutions, quality project delivery, and technological innovation, we will cooperate with our partners to satisfy requirements for mobile broadband, to thoroughly enhance service quality, and to contribute to the country’s industrialization and information building.
On the whole, ZTE will enhance its ability to deliver integrated solutions and resources, and will seek to improve its competitive strategies, product planning and deployment, and market behaviors to provide operators with a full range of products and services. Although rooted in China, ZTE is stepping forward to world-class excellence by further improving operational efficiency and developing its global strategy.

TeliaSonera and Ncell bring 3G high speed communication to Mount Everest area

TeliaSonera today announced that its subsidiary in Nepal, Ncell, has successfully launched 3G services in the Mount Everest area. By the end of 2011 Ncell will provide mobile coverage to over 90 percent of the people in Nepal.
"This is a great milestone for mobile communications, and strong evidence of TeliaSonera’s pioneering role in this industry that is truly changing the lives of billions of people”, said Lars Nyberg, President and CEO of TeliaSonera.
“We are very proud to announce the world’s highest mobile data service as we launch 3G services in the Mount Everest area in the Khumbu valley. From its perch on the world’s tallest mountain, 3G high speed internet will bring faster, more affordable telecommunication services to the people living in the Khumbu Valley, trekkers, and climbers alike”, he continued.
Located at an altitude of 5,200 meter the highest 3G base station enables locals, climbers and trekkers to surf the web, send video clips and e-mails, as well as to call friends and family back home – all at far cheaper rates than the average satellite phone. Everest base camp just came a little closer.
3G grows subscriber base
Through the expanding 3G network, Ncell will also provide affordable services to the entire population of Nepal. Mobile penetration is still low, but rapidly rising. This trend is being driven largely by investments TeliaSonera and others are making in modern telecom infrastructure. When TeliaSonera entered Nepal in 2008, mobile penetration was around 15 percent, and by the end of the third quarter this year it was already over 30% percent. Ncell already boasts 3.7 million subscribers and the advent of the 3G network is expected to boost this subscriber base.
At a press conference held today in Kathmandu, Lars Nyberg, President and CEO, Tero Kivisaari, President of Business Area Eurasia and Pasi Koistinen, CEO of Ncell, also unveiled plans for future TeliaSonera investments in Nepal. TeliaSonera has decided to increase the pace of investment for 2011 and spend over 100 M USD. This will ensure mobile coverage to over 90% of the population with affordable telecom services that contribute to the economic and social development of the country, as well as 3G coverage in all major cities and other densely populated areas.
Click here to see the Finn Veikka Gustafsson, one of the few in the world to have climbed all the world’s highest mountains without bottled oxygen, talk about the importance and possibilities of the new 3G services in the Mount Everest basecamp


1.1 Background
Mobile radio communications dates back to Marconi. For a time it was the principal application of radio. This was ship-to-shore and ship-to-ship communications. The pioneer in this was the Marconi Company of the United Kingdom. It spread to land vehicles and aircraft in the 1920s. Since 1980, mobile radio communication has taken on a more personal flavor.
Cellular radio systems have extended the telephone network to the car, to the pedestrian, and even into the home and office. A new and widely used term in our vocabulary is personal communications. It is becoming the universal tether. No matter where we go, on land, at sea, and in the air, we can have near instantaneous
two-way communications by voice, data, and facsimile. At some time it will encompass video.
Personal radio terminals are becoming smaller. There is the potential of becoming wristwatch size. However, the human interface requires input–output devices that have optimum usefulness. A wristwatch-size keyboard or keypad is rather difficult to operate. A hard-copy printer requires some minimum practical dimensions,
and so forth. A new name has entered our vocabulary, wireless. The British have been using the term since Marconi. It is relatively new in North America, and with a different flavor in meaning. I think we can define wireless as a telecommunication method that does not require wires to communicate. From our perspective, wireless and radio are synonymous.
Reference 28 states that there were 1 billion (1 × 109) by the end of 2002;
and Reference 27 expects there to be 3 billion (3 × 109) traditional telephone and wireless users in the world by the year 2010. It is our opinion that this latter estimate may be on the low side.
1.2 Scope and Objective
This chapter presents an overview of “personal communications” or what many call wireless. Much of the discussion deals with cellular radio and wireless LANs (WLANs), and it extends this thinking inside of buildings. The coverage most necessarily includes propagation for the several environments, propagation
impairments, and methods to mitigate these impairments, access techniques, bandwidth limitations, and ways around this problem. It will cover several mobile radio standards and compare a number of existing and planned systems. The chapter objective is to provide an appreciation of mobile/personal communications.
Space limitations force us to confine our discussion to what might be loosely called “land mobile systems.”
Cellular radio systems connect a mobile terminal to another user, usually through the PSTN. The “other user” most commonly is a telephone subscriber of the PSTN. However, the other user may be another mobile terminal. Most of the connectivity is extending POTS to mobile users. Data and facsimile services are
in various stages of implementation (see Chapter 13, Section 6). Some of the terms used in this section have a strictly North American flavor. The heart of the system for a specific serving area is the mobile telephone switching office (MTSO). The MTSO is connected by a trunk group to a nearby telephone exchange providing an interface to, and connectivity with, the PSTN. The area to be served by a cellular geographic serving area (CGSA) is divided into small geographic cells which ideally are hexagonal. Cells are initially laid out with centers spaced about 4 to 8 miles (6.4 to 12.8 km) apart. The basic system components are the cell sites, the MTSO, and mobile units. These mobile units may be hand-held or vehicle-mounted terminals.
Each cell has a radio facility housed in a building or shelter. The facility’s radio equipment can connect and control any mobile unit within the cell’s responsible geographic area. Radio transmitters located at the cell site have a maximum effective radiated power (ERP∗) of 100 watts. Combiners are used to connect multiple transmitters to a common antenna on a radio tower, usually between 50 and 300 ft (15 and 92 m) high. Companion receivers use a separate antenna system mounted on the same tower. The receive antennas are often arranged in a space-diversity configuration.
The MTSO provides switching and control functions for a group of cell sites.
A method of connectivity is required between the MTSO and the cell site facilities.
The MTSO is an electronic switch and carries out a fairly complex group of processing functions to control communications to and from mobile units as they move between cells as well as to make connections with the PSTN. Besides making connectivity with the public network, the MTSO controls cell site activities
and mobile actions through command and control data channels. The connectivity between cell sites and the MTSO is often via DS1 on wire pairs or on microwave facilities, the latter being the most common.
A typical cellular mobile unit consists of a control unit, a radio transceiver, and an antenna. The control unit has a telephone handset, a push button keypad to enter commands into the cellular/telephone network, and audio and visual indications for customer alerting and call progress. The transceiver permits full
duplex transmission and reception between a mobile and cell sites. Its ERP is nominally 6 watts. The unit is usually vehicle-mounted. Hand-held terminals combine all functions into one small package that can be easily held in one hand. The ERP of a hand-held is a nominal 0.6 watts. It seems that this package
is being made smaller and smaller.
In North America, cellular communication is assigned a 25-MHz band between 824 and 849 MHz for mobile unit-to-base transmission and a similar band between 869 and 894 MHz for transmission from base to mobile. The original North American cellular radio systems was called AMPS (advanced mobile telephone
system). The original system description was contained in an entire issue
Bell System Technical Journal (BSTJ) of January 1979. The present AMPS is based on 30-kHz channel spacing using frequency modulation. The peak deviation is 12 kHz. The cellular bands are each split into two to permit competition.
Thus only 12.5 MHz is allocated to one cellular operator for each direction of transmission. With 30-kHz spacing, this yields 416 channels. However, nominally 21 channels are used for control purposes, with the remaining 395 channel available for cellular end-users.
Common practice with AMPS is to assign 10 to 50 channel frequencies to each cell for mobile traffic. Of course, the number of frequencies used depends on the expected traffic load and the blocking probability. Radiated power from a cell site is kept at a relatively low level with just enough antenna height to
cover the cell area. This permits frequency reuse of these same channels in nonadjacent cells in the same CGSA with little or no co-channel interference. A well-coordinated frequency reuse plan enables tens of thousands of simultaneous calls over a CGSA. Here four channel frequency groups are assigned in a way that avoids the same frequency set used in adjacent cells. If there were uniform terrain contours, this plan could be applied directly.
However, real terrain conditions dictate further geographic separation of cells that use the same frequency set. Reuse plans with 7 or 12 sets of channel frequencies provide more physical separation and are often used depending on the shape of the antenna pattern employed.
With user growth in a particular CGSA, cells may become overloaded. This means that grade of service objectives are not being met due to higher than planned traffic levels during the busy hour (BH). In these cases, congested cells can be subdivided into small cells, each with its own base station,
 These smaller cells use lower transmitter power and antennas with less height, thus permitting greater frequency reuse.

    An important issue in wireless communication systems is multiple random access: communication links can be activated at any moment while several links can be active simultaneously. As multi-access and random-access are properties mainly determined by the chosen data-communication technique it is important to keep these requirements in mind from the very beginning. Three possible concepts to realize a multi-access communication system are in use:
  1. FDMA  
    Frequency Division Multiple Access, commonly used in conventional telephone systems: every user gets a certain frequency band assigned and can use this part of the spectrum to perform its communication. If only a small number of users is active, not the whole resource (frequency-spectrum) is used. Assignment of the channels can be done centrally or by carrier-sensing in a mobile. The latter possibility enables random-access.
  2. TDMA  
    Time Division Multiple Access, applied nowadays in mobile phone systems: every user is assigned a (set of) time-slots. Transmission of data is only possible during this time-slot, after that the transmitter has to wait until it gets another time-slot. Synchronization of all users is an important issue in this concept. Consequently, there must be a central unit (base-station) that controls the synchronization and the assignment of time-slots. This means that this technique is difficult to apply in random-access systems.
  3. CDMA  
    Code Division Multiple Access (Spread Spectrum). A unique code is assigned to each user. This code is used to ``code'' the data message. As codes are selected for low cross-correlation properties, all users can transmit simultaneously in the same frequency channel while a receiver is still capable of recovering the desired signal. Synchronization between links is not strictly required and so random-access is possible. A practical application at the moment is the cellular-cdma phone system IS-95   [Qua92].
Combinations are also possible, the popular European cellular phone systems dect   and gsm   for instance use a combination of tdmaand fdma. There a single transmission-cell is defined by a combination of a frequency channel and a time-slot.
From the above list it is clear that both fdmaand cdma are candidate transmission techniques to enable multiple random access. There are however a number of reasons for choosing cdma over fdma. The first alternative provides [Sch94, SOSL85a, Dix84]:
  •   Interference limited operation. In all situations the whole frequency-spectrum is used. As a result the more active users are present, the higher the interference level will be.
  • Privacy due to unknown codes. The applied codes are - in principle - unknown to a hostile user. This means that it is hardly possible to detect the message of another user.
  • Applying spread spectrum implies the reduction of multi-path effects. By using a wide frequency-band, the influence of narrow-band fades is reduced.
  • Random access possibilities. Users can start their transmission at any arbitrary time (no infrastructure required).
  • Good anti-jamming performance. Small-band interference is reduced as explained in the next section.
These were the reasons for selecting cdma as multi-access technique in the non-cellular target communication system. As this choice has a large impact on further design stages, the next section provides an introduction to cdma-techniques.



In a switched telephone network, signaling conveys the intelligence needed for one subscriber to interconnect with any other in that network. Signaling tells the switch that a subscriber desires service and then gives the local switch the data necessary to identify the required distant subscriber and hence to route the call
properly. It also provides supervision of the call along its path. Signaling also gives the subscriber certain status information, such as dial tone, busy tone (busy
back), and ringing. Metering pulses for call charging may also be considered a form of signaling.
There are several classifications of signaling:
1. General.
a. Subscriber signaling.
b. Interswitch signaling.
2. Functional.
a. Audible–visual (call progress and alerting).
b. Supervisory.
c. Address signaling.
 It should he appreciated that on many telephone calls, more than one switch is involved in call routing. Therefore switches must interchange information among switches in fully automatic service. Address information is provided between modern switching machines by  interregnum signaling, and the supervisory function is provided by line signaling. The audible–visual category of signaling
functions inform the calling . The alerting function informs the called subscriber of a call waiting or an extended “off-hook” condition of his or her handset. Signaling information can be conveyed by a number of means from subscriber to switch or between (and among) switches. Signaling information can be transmitted by means such as
• Duration of pulses (pulse duration bears a specific meaning)
• Combination of pulses
• Frequency of signal
• Combination of frequencies
• Presence or absence of a signal
• Binary code
• For dc systems, the direction or level of transmitted current
Supervisory signaling provides information on line or circuit condition and indicates whether a circuit is in use or idle. It informs the switch and interconnecting trunk circuits whether a calling party is “off hook” or “on hook” or whether a called party is “off hook” or “on hook.” The meaning and importance of the terms
“on hook” and “off hook” were detailed in Chapter 1, Section 2. The assumption is that a telephone in the network can have one of two states: busy or idle. Idle, of course, is represented by the “on-hook” condition.
The reader must appreciate that supervisory information–status must be maintained end to end on every telephone call. It is necessary to know when a calling subscriber lifts his/her telephone off hook, thereby requesting service. It is equally important that we know when the called subscriber answers (i.e.,
lifts her telephone off hook), because that is when we may start metering the call to establish charges. It is also important to know when the called and calling subscribers return their telephones to the on-hook condition. Charges stop, and the intervening trunks comprising the talk path as well as the switching points
are then rendered idle for use by another pair of subscribers. During the period of occupancy of a talk path end to end, we must know that this particular path is busy (is occupied) so that no other call attempt can seize it. Dialing of a subscriber line is merely interruption of the subscriber loop’s off-hook condition, often called “make and break.” The “make” is a current flow condition (or off hook), and the “break” is the no-current condition (or on hook). How do we know the difference between supervisory and dialing? Primarily by duration—the on-hook interval of a dial pulse is relatively short and is distinguishable from an on-hook disconnect signal (subscriber hangs up), which is transmitted in the same direction for a longer duration. Thus the switch is sensitized to duration to distinguish between supervisory and dialing of a subscriber loop.
2.1 E and M Signaling
Probably the most common form of trunk supervision is E and M signaling, particularly with multiplex equipment (Chapters 5 and 8). Yet it only becomes true E and M signaling where the trunk interfaces with the switch (see Figure 4.3). E-lead and M-lead signaling systems are semantically derived from historical designation of signaling leads on circuit drawings covering these systems. Historically, the E and M signaling interface provides two leads between the switch and what we may call trunk-signaling equipment (signaling interface). One lead is called the “E-lead,” which carries signals to the switching equipment.
3.1 General
Up to this point we have reviewed the most employed means of supervisory trunk signaling (or line signaling). Direct-current signaling, such as reverse-battery signaling, has notable limits on distance because it cannot be applied directly to multiplex systems (Chapters 5 and 8) and is limited on metallic pairs due to the IR drop of the lines involved. Direct-current trunk signaling is addressed in Section 10.
There are many ways to extend these limits, but from a cost-effectiveness standpoint there is a limit that we cannot afford to exceed. On trunks exceeding dc capabilities, some form of ac signaling will be used. Traditionally, ac signaling systems are divided into three categories: low-frequency, in-band, and out-band
(out-of-band) systems. Each of these can derive the four E and M signaling states.
3.2 Low-Frequency AC Signaling Systems
An ac signaling system operating below the limits of the conventional voice channel (i.e., <300 Hz) are termed low frequency. Low-frequency signaling systems are one-frequency systems, typically 50 Hz, 80 Hz, 135 Hz, or 200 Hz. It is impossible to operate such systems over carrier-derived channels because of the excessive distortion and band limitation introduced. Thus low frequency signaling is limited to metallic-pair transmission systems. Even on these systems, cumulative distortion limits circuit length. A maximum of two
repeaters may be used, and, depending on the type of circuit (open wire, aerial cable, or buried cable) and wire gauge, a rough rule of thumb is a distance limit of 80–100 km.
3.3 In-Band Signaling In-band signaling refers to signaling systems using an audio tone, or tones inside
the conventional voice channel, to convey signaling information. In-band signaling is broken down into three categories: (1) one frequency (SF or single frequency), (2) two frequency (2VF), and (3) multi frequency (MF). As the term implies, in-band signaling is where signaling is carried out directly in the voice
channel. As the reader is aware, the conventional voice channel as defined by the CCITT occupies the band of frequencies from 300 Hz to 3400 Hz. Single frequency and two-frequency signaling systems utilize the 2000- to 3000-Hz portion, where less speech energy is concentrated.
3.3.1 Single-Frequency Signaling. Single-frequency signaling is used almost exclusively for supervision. In some locations it is used still for interregister signaling, but the practice is diminishing in favor of more versatile
methods such as MF signaling. The most commonly used frequency is 2600 Hz, particularly in North America. On two-wire trunks, 2600 Hz is used in one direction and 2400 Hz is used in the other.
3.3.2 Two-Frequency Signaling. Two-frequency signaling is used for both supervision (line signaling) and address signaling. We often associate SF and 2VF supervisory signaling systems with carrier (FDM) operation. Of course, when we discuss such types of line signaling (supervision), we know that the term “idle”
refers to the on-hook condition while “busy” refers to the off-hook condition.
Thus, for such types of line signaling that are governed by audio tones of which SF and 2VF are typical, we have the conditions of “tone on when idle” and “tone on when busy.” The discussion holds equally well for in-band and out-of-band signaling methods. However, for in-band signaling, supervision is by necessity
tone-on idle; otherwise subscribers would have an annoying 2600-Hz tone on throughout the call.
A major problem with in-band signaling is the possibility of “talk-down,” which refers to the premature activation or deactivation of supervisory equipment by an inadvertent sequence of voice tones through the normal use of the channel. Such tones could simulate the SF tone, forcing a channel dropout (i.e.,
the supervisory equipment would return the channel to the idle state). Chances of simulating a 2VF tone set are much less likely. To avoid the possibility of talk down on SF circuits, a time-delay circuit or slot filters to bypass signaling tones may be used. Such filters do offer some degradation to speech unless they are
switched out during conversation. The tones must be switched out if the circuit is going to be used for data transmission [7].
It becomes apparent why some administrations and telephone companies have turned to the use of 2VF supervision, or out-of-band signaling for that matter. For example, a typical 2VF line signaling arrangement is the CCITT No. 5 code, where f1 (one of the two VF frequencies) is 2400 Hz and f2 is 2600 Hz. 2VF signaling is also used widely for address signaling (see Section 4.1 of this chapter) .
3.4 Out-of-Band Signaling
With out-of-band signaling, supervisory information is transmitted out of band (i.e., above 3400 Hz). In all cases it is a single-frequency system. Some out-of band systems use “tone on when idle,” indicating the on-hook condition, whereas others use “tone off.” The advantage of out-of-band signaling is that either system, tone on or tone off, may be used when idle. Talk-down cannot occur because all supervisory information is passed out of band, away from the speech-information portion of the channel.
The preferred CCITT out-of-band frequency is 3825 Hz, whereas 3700 Hz is commonly used in the United States. It also must be kept in mind that out-of band signaling is used exclusively on carrier systems, not on wire trunks. On the wire side, inside an exchange, its application is E and M signaling. In other
words, out-of-band signaling is one method of extending E and M signaling over a carrier system.
In the short run, out-of-band signaling is attractive in terms of both economy and design. One drawback is that when channel patching is required, signaling leads have to be patched as well. In the long run, the signaling equipment required may indeed make out-of-band signaling even more costly because of the extra
supervisory signaling equipment and signaling lead extensions required at each end and at each time that the carrier (FDM) equipment demodulates to voice.
The major advantage of out-of-band signaling is that continuous supervision is provided, whether tone on or tone off, during the entire telephone conversation.
Address signaling originates as dialed digits (or activated push buttons) from a calling subscriber, whose local switch accepts these digits and, using that information, directs the telephone call to the desired distant subscriber.

An important factor to be considered in switching system design that directly affects both signaling and customer satisfaction is post dialing delay. This is the amount of time it takes after the calling subscriber completes dialing until ring back is received. Ring-back is a backward signal to the calling subscriber telling
her that her dialed number is ringing. Postdialing delay must be made as short as possible.
Another important consideration is register occupancy time for call setup as the setup proceeds from originating exchange to terminating exchange. Call-setup equipment, that equipment used to establish a speech path through a switch and to select the proper outgoing trunk, is expensive. By reducing register occupancy
per call, we may be able to reduce the number of registers (and markers) per switch, thus saving money.
Link-by-link and end-to-end signaling each affect register occupancy and post dialing delay, each differently. Of course, we are considering calls involving one or more tandem exchanges in a call setup, because this situation usually occurs on long-distance or toll calls. Link-by-link signaling may be defined as a signaling
system where all interregister address information must be transferred to the subsequent exchange in the call-setup routing. Once this information is received at this exchange, the preceding exchange control unit (register) releases. This same operation is carried on from the originating exchange through each tandem
(transit) exchange to the terminating exchange of the call. The R-1 system is an
example of link-by-link signaling.
End-to-end signaling abbreviates the process such that tandem (transit) exchanges receive only the minimum information necessary to route the call. For instance, the last four digits of a seven-digit telephone number need be exchanged only between the originating exchange (e.g., the calling subscriber’s local exchange or the first toll exchange in the call setup) and the terminating exchange in the call setup. With this type of signaling, fewer digits are required to be sent (and acknowledged) for the overall call-setup sequence. Thus the
signaling process may be carried out much more rapidly, decreasing post dialing delay. Intervening exchanges on the call route work much less, handling only the digits necessary to pass the call to the next exchange in the sequence

Wide Area Network

A wide area network (WAN) is a computer network that covers a broad area (i.e., any network whose communications links cross metropolitan, regional, or national boundaries).[1] This is in contrast with personal area networks (PANs), local area networks (LANs), campus area networks (CANs), or metropolitan area networks (MANs) which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively.

Design options

WANs are used to connect LANs and other types of networks together, so that users and computers in one location can communicate with users and computers in other locations. Many WANs are built for one particular organization and are private. Others, built by Internet service providers, provide connections from an organization's LAN to the Internet. WANs are often built using leased lines. At each end of the leased line, a router connects to the LAN on one side and a hub within the WAN on the other. Leased lines can be very expensive. Instead of using leased lines, WANs can also be built using less costly circuit switching or packet switching methods. Network protocols including TCP/IP deliver transport and addressing functions. Protocols including Packet over SONET/SDH, MPLS, ATM and Frame relay are often used by service providers to deliver the links that are used in WANs. X.25 was an important early WAN protocol, and is often considered to be the "grandfather" of Frame Relay as many of the underlying protocols and functions of X.25 are still in use today (with upgrades) by Frame Relay.
Academic research into wide area networks can be broken down into three areas: Mathematical models, network emulation and network simulation.
Performance improvements are sometimes delivered via WAFS or WAN optimization.

Connection technology options

There are also several ways to connect NonStop S-series servers to WANs, including via the ServerNet Wide Area Network (SWAN) or SWAN 2, 3, 4, 5, 6, 7, 8, 9, 10 concentrators, which provides WAN client connectivity to servers that have Ethernet ports and appropriate communications software. You can also use the Asynchronous Wide Area Network (AWAN) access server, which offers economical asynchronous-only WAN access. Several options are available for WAN connectivity:

Transmission rates usually range from 1200 bit/s to 24 Mbit/s, although some connections such as ATM and Leased lines can reach speeds greater than 156 Mbit/s. Typical communication links used in WANs are telephone lines, microwave links & satellite channels.
Recently with the proliferation of low cost of Internet connectivity many companies and organizations have turned to VPN to interconnect their networks, creating a WAN in that way. Companies such as Cisco, New Edge Networks and Check Point offer solutions to create VPN networks.