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erage can be achieved in existing cell plans,a TDMA system with 95% voice coverageis used as reference. With this reference, theresults are valid fot the downlink. EDGEperformance is analyzed assuming the samecattier output power as in the reference system.Additionally, within EGPRS, the sameaverage power is assumed for GMSK and8PSK. For TDMA, the requirement is anE b /N 0 of 15.7 dB. Thus, this is the valuefound at the 5% percentile of E b /N 0 distributionsin the cell. When the 8PSK EDGEmodulation scheme is introduced, the E b /N 0distributions diminish due to the highergross bit rate. Assuming the same carrieroutput power, the difference in E b /N 0 forEDGE compared to that of standard TDMAmodulations is calculated asFigure 12CDF of user throughput per timeslot for COMPACT, 1/3 frequency-reuse pattern with 5 to30 users per sector.Figure 1310% percentile of packet throughput per timeslot versus spectral efficiency for Classicand COMPACT.where RTDMA an^ REDGE are tne gross ratesof standard TDMA and EDGE, respective-ly-The coverage simulations result in E b /N 0distributions. From these original distributions,we can calculate distributions for8PSK. Additionally, we can determine theblock error-rate performance of differentmodulation and coding schemes from theradio-link-level simulations for the downlinkwith noise but without interference(E b /N 0 ). The results do not include antennadiversity; similarly, body loss is neglectedfor packet-data traffic. Given the performanceresults derived from the block-errorrate, we can transform the E b /N 0 distributioninto a packet-bit-rate distribution,using an E b /N 0 curve, which is similar to theC/I curve in Figure 5.Assuming a system with 95% TDMAvoice coverage, then EDGE coverage is excellent(Figure 14). Approximately 95% ofthe users obtain a packet bit rate that exceeds120 kbit/s using 7 TS. Existing sitescan thus be reused with excellent performance.Even better coverage can be achievedby employing smart antennas or antennadiversitytechniques.""" 1Terminal capabilitiesGPRS and EGPRS terminals can supportdifferent modes of operation. For example,the GSM/GPRS standard for pure 200 kHzuse specifies class B and class C modes of operation.In the class B mode of operation, amobile terminal can be attached to GPRSand other GSM services simultaneously, but78 Ericsson Review No. 2,2000