Seminar on Enhanced Data Rates for GSM Evolution(EDGE)

High Speed Wireless Terms 1G- It uses analog transmission (AMPS). 2G - Uses digital transmission for voice signals. - Improved the battery life for wireless phones. -Added many features like Caller ID, text messaging and intelligent roaming. -Data is usually transported over voice channels at speeds ranging from 9.6 kbps to 14.4 kbps. 2.5G- No change in the way voice is transported, -Introduced packet data services, allowing for speeds of 20 to 40 kbps about the same speed as a dial-up service. 3G- Increases the speed of packet data transport through the network to avg. speeds above 100 kbps.

WHAT IS EDGE? It stands for Enhanced Data rates for GSM Evolution. EDGE is extended version of GPRS i.e. EGPRS. First launched in the United States in 2003 by Cingular, which is now AT&T. EDGE is a new set of GSM-bearer services that provides packet mode transmission within the GSM network & interconnects with external packet data networks. Designed to deliver multimedia applications such as streaming television, audio and video to mobile phones at speeds up to 384 Kbps, theoretically up to 473.8 kbps.

Salient Features of EDGE Compliment to 3G. Standardized by ETSI. EDGE is deployed over GPRS network. Provides Data Packet delivery service. Support for leading internet communication protocols. Billing based on volume of data transferred. Utilizes existing GSM/GPRS authentication and privacy procedures.

Evolution of EDGE/EGPRS

GPRS v/s EDGE EDGE only introduces a new modulation technique and new channel coding that can be used to transmit both packet- switched and circuit-switched voice and data services. EDGE is an add-on to GPRS and cannot work alone. And is therefore much easier to introduce than GPRS. GPRS has a greater impact on the GSM system than EDGE has. EDGE offers significantly higher throughput and capacity. EDGE can transmit three times as many bits as GPRS during the same period of time. GPRS can transfer data at rates of 115 kbps theoretically and up to 60 kbps on physical layer, whereas EDGE/EGRPS can transfer up to 473.6 kbps and 384 kbps respectively.

GPRS v/s EDGE (cont…) With EDGE, the same time slot can support more users. GPRS and EDGE have different protocols and different behaviour on the base station system side. On the core network side, GPRS and EDGE share the same packet-handling protocols and, therefore, behave in the same way. GPRS and EDGE share the same symbol rate, but the modulation bit rate differs.

EDGE Network Architecture A-bis Base Station and Tower PCU SGSN – Serving GPRS Support Node- takes care of routing, handover and IP address assignment and Performs security functions and access control. GGSN – Gateway GPRS Support Node- gateway/anchor to external networks. HLR – Home Location Register- database that contains subscriber information. VLR – Visitor Location Register- mobile station’s profiles are preserved in it. PSTN – Public Switched Telephone Network BSC – Base Station Controller GMSC – Gateway Mobile Switching Centre PCU – Packet Control Unit- Distinguishes data and voice

SGSN – Serving GPRS Support Node Delivers data packets to mobile stations & vice-versa. Detects and Registers new GPRS/EDGE MS in its serving area. Packet Routing, Transfer & Mobility Management. Authenticates and Maintains user profiles. Its location register stores location info. & user profiles.

GGSN – Gateway GPRS Support Node Interfaces GPRS backbone network with external packet data networks. Converts the EDGE packets from SGSN to the PDP (Packet Data Protocol) format. Converts PDP addresses change to GSM addresses of the destination user. Stores the current SGSN address and profile of the user in its location register.

Impact of EDGE on existing GSM/GPRS network Hardware upgrade to BSS (new transceivers in each cell). Software upgrade to BS and BSC. No change in the core network.( independent of user bits) New terminals Terminal which provides 8PSK in the uplink and downlink Terminal which provides GMSK in the uplink and 8PSK in the downlink.

EDGE channel coding & frame structure Burst N Convolution Coding Rate = 1/3 Length = 7 464 bits 1 data block Puncture Interleave Burst N+1 348 bits/ burst 1392 bits 1392 bits Burst N+2 8PSK Modulate Burst Format 156.25 symbols/slot Burst N+3 468.75 bits 348 bits 20 m-sec frame with 4 time-slots for each of 8 bearers 8 Time Slots 1 2 3 4 5 6 7 1 Time Slot = 576.92 µs Tail symbols 3 Data symbols 58 Training symbols 26 Data symbols 58 Tail symbols 3 Guard symbols 8.25 Modulation: 8PSK, 3 bits/symbol Symbol rate: 270.833 ksps Payload/burst: 348 bits Gross bit rate/time slot: 69.6 kbps - overhead = 59.2 kbps user data

Example of EDGE Time Slot Structure BCCH: Broadcast Control Channel- carries synchronization, paging and other signalling information TCH: Traffic channel- carries voice traffic data PDTCH: Packet data traffic channel- carries packet data traffic for EDGE PBCCH: Packet broadcast control channel- additional signalling for EDGE; used only if needed

8PSK Modulation in EDGE New modulation technique 8-PSK. High-level linear modulation in 200 kHz TDMA method that carries three times more information through an extended signal constellation. Constellation diagram is simply phasor diagram representing phases as angles around a circle. EDGE produces a 3-bit word for every change in carrier phase. The symbol rate is 271 kb/s. Gross bit rates per time slot is 69.2 kb/s.

EDGE Modulation, Channel Coding Scheme & Bit Rates Maximum rate [kb/s] Code Rate MCS-9 8PSK 59.2 1.0 MCS-8 54.4 0.92 MCS-7 44.8 0.76 MCS-6 29.6 0.49 MCS-5 22.4 0.37 MCS-4 GMSK 17.6 MCS-3 14.8 0.80 MCS-2 11.2 0.66 MCS-1 8.8 0.53

Types of EDGE EDGE Classic EDGE Compact Based on the EDGE standard developed by ETSI. 4/12 reuse. continuous downlinks on first 12 carriers. 2.4 MHz x2 minimum spectrum. EDGE Compact 1/3 reuse in space. Can be deployed in less than 1 MHz of spectrum . frame synchronized base stations. reuse of 4 in time for control channels. partial loading for traffic channels. discontinuous downlinks. 600 KHz x2 minimum spectrum.

EDGE Classic Multi-slot Gain Average User Throughput (kb/s) Ave. # of users per sector

Application of EDGE 30% - 50% of business to business use of internet carried out on mobile devices. IBM wireless group working on application to track employees. File transfer and document sharing for collaborative work. Corporate e-mailing. Vehicle positioning through GPS. E-banking, Online reservation, E-shoping. Pictures, Post cards, Greetings, Presentations. Video messages and video conferencing. News headlines, flight information, traffic reports, weather reports, maps etc.

EDGE Advantages Time to market GSM global scale & scope Designed for existing spectrum: 800/900/1800/1900 MHz Low risk technology evolution from GSM/GPRS GSM global scale & scope Chipsets, handsets, infrastructure and applications Lower capital investment, better vendor selection Global roaming Short-term benefits: Capacity and performance Easy implementation on a GSM/GPRS network Cost effective Increase the capacity and triples the data rate of GPRS Enabling new multimedia services

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