mance Measurements As usual, performance measurements involve drive tests, reports from the network manage- ment system (NMS), and network planning tools. However, the focus will be on throughput in an EDGE network, and the key areas of performance measurement will therefore be at the air interface and the Abis interface. For the air interface, the interest will be on capacity, coverage and quality; while for the Abis interface it will be on the variation of throughput with respect to modulation and coding schemes. One such example of performance based on accessibility, retainability, quality (ARQ) and peak traffic is shown in Figure 6.8. Accessibility_BTS/Accessibility (BTS level) Retainability_BTS/Retainability (BTS level) DL_Quality/DL_Quality 70.00 60.00 100.00 50.00 95.00 40.00 90.00 30.00 85.00 20.00 80.00 10.00 75.00 70.00 Figure 6.8 Test results (ARQ and peak traffic: BTS As stated in earlier chapters, performance indicators like the ability of mobile stations to get access to the cell (accessibility), DCR (retainability), call quality in the downlink (DL-quality), etc., need to be measured. Figure 6.9 shows an example of BTS performance measuements. Accessibility Retainability BTS ID (BTS level) (BTS level) UL_Quality DL_Quality TCH Erlang 04/06/03 98.61 99.05 92.73 72.01 04/07/03 98.21 96.49 91.35 91.23 04/08/03 66.18 100.00 99.11 99.33 04/09/03 100.00 95.62 Figure 6.9 BTS performance measurements Measurement of the Abis throughput capacity with respect to the coding schemes used by mobile subscribers will be critical in adjusting the boundaries of the dynamic pool. The example in Figure 6.10 shows the variation of the pool with respect to modulation and coding schemes. Performance of an EDGE network will usually be in terms of the underlying GPRS network. The achieved mean throughput values and delay values in an EDGE network are EDGE: NETWORK PLANNING AND OPTIMISATION Coding Schemes Figure 6.10 MCS versus throughput better than for the GPRS network, even when the load is higher. The measurement infor-