GSM cellular network

GSM defines function definitions and specifies the interface requirements, but there is no limitation for the hardware to be used. This approach aims to restrict the device to work with designers and operators is to be able to get from different manufacturers. GSM network is divided into three main systems: Switching System (SS), Base Station System (BSS) and Operation and Support System (OSS).

Switching system:

Switching System is responsible for call processing and subscriber related functions. The switching system comprises the following functional units:

• ·         Home Location Register (HLR)
• ·         Mobile Services Switching Center (MSC)
• ·         Visitor Location Register (VLR)
• ·         Authentication Center (AUC)
• ·         Equipment Identity Register (EUR)

Base Station System (BSS)

Base Station Controllers (BSC) and Base Transceiver Station consists of BSS performs all operations related to radio frequency.

Operation and Support System (OSS)

Operations and Maintenance Center (OMC) is connected to all devices and BSc in switching systems. OMC shape adapted to the GSM system is called Operating Support System (OSS). OSS is a functional system that allows network operators to monitor and control the network. The purpose of the OSS in a GSM network is to provide needed customer support as regional and local operations to a reasonable cost.

2G, 3G, and 4G technologies

2G:  The basic technology that 2G stands on is; Increase the capacity of the system, bring additional services (sms…), decrease the cost, manage security and increase it. This technology digitalized all the network system. As the 2G system we can name GSM (global system for mobile) and IS-95 (cdmaone).

Some QoS (Quality of services) for 2G can be listed as bellow;

• -          Physical Channel: 200kHz
• -          Data rate: 270 Kbps
• -          Modulation: 0.3 GMSK
• -          Channel rate: 270.833kbps
• -          Modulation Efficiency (b/s/Hz): 1.4
• -          Traffic Channels per Carrier: 8
• -          Multiple Access: FDD/FDMA/TDMA
• -          Divided into two standards: TDMA and CDMA
• -          Includes: GSM, Digital AMPS, CDMA, PDC(personal digital comm.) and multiple digital system

2G technology provides circuit-switched data service (9.6Kbps – 14.4Kbps) but by the 2.5 the max data rate reached (57-384 Kbps) which the normal data rate was 30 – 70 Kbps. While transferring to 3G from 2G, first transferring from 2G to 2.5G is done by GPRS (General Packet Radio Service) then by EDGE (Enhanced Data for GSM Evolution) transformation for 2.75 is performed. After these all steps transformation to 3G technology is accomplished.

Problems for 2G:

• -                Low transmission quality
• -                Spotty coverage
• -                Video not support
• -                System capacity
• -                Limited coverage area by towers
• -                Abrupt drop calls

3G:  Some QoS (Quality of services) for 3G can be listed as bellow;

• -                  Transfer voice and non-voice data
• -                   3G can deliver broadband capacity
• -                    Support greater no. of voice and data customer
• -                    It’s using standard: W-CDMA and EVDO
• -                    Less complexity and faster transmission
• -                    Speed: 384Kbps – 2Mbps
• -                    Increased spectrum efficiency – 5Mhz
• -                    High data rate

İnternational Telecommunication Unit (ITU) did not declared any information about 3G data transfer speed but for the normal users it changes between (2-14.4 Mbps) and for the moving tool it is minimum 348Kbps. 3G it providing much better security service than 2G, in addition to this it is also supports point to point security when it is possible to access to general parts of application, but this is not a property specified to 3G. 3G technology is using KASUMI block crypto instate of old technology A5 / 1 stream cipher.

Problems for 3G:

• -                  High bandwidth required
• -                  High cost of spectrum
• -                  Huge capacity

4G: Some QoS (Quality of services) for 4G can be listed as bellow;

• -                  The successor of 3G
• -                  High data rate 20 to 100 Mbps
• -                   High resolution movies, TV
• -                  4G based on IPv6 (128 bits)
• -                   Lower cost than previous generation
• -                   Faster and more reliable

By 4G it aimed to transfer data from any point of the word to another by the 100Mbps and for the multimedia it can provide high quality performance including video streaming, TV, video calls, video clips, News, Music, Sports, Chat ,GPS, Telemedicine. And for the business it promise high speed networking, VPN Access sales force, Automation Video Conferencing, Real Time Financial information.