Timo Halonen

Performance of adaptive multirate (AMR) voice in GSM and WCDMA

This paper studies the performance of adaptive multirate (AMR) voice service in GSM and WCDMA radio networks. The AMR voice codec and its utilization in GSM and WCDMA radio networks are first introduced. The effect of AMR to GSM and WCDMA spectral efficiency is evaluated. It is shown that AMR can improve GSM spectral efficiency 100-150% compared to the enhanced full rate (EFR) codec. AMR further allows the utilization of half-rate codec improving the hardware efficiency in GSM. In WCDMA networks, the AMR allows to make a trade-off between voice capacity and AMR bit rate. The paper also presents the future evolution of AMR voice coding for further enhancements of spectral efficiency and voice quality. The source based rate adaptation is shown to improve the AMR spectral efficiency up to 25%. The wideband AMR will bring improved audio quality for the wireless and fixed network.

Comparison of networks with different frequency reuses, DTX, and power control using the effective frequency load approach

Networks with different reuses, with and without DTX are compared by using the effective frequency load concept (EFL). EFL makes it possible to compare networks under different circumstances, like for example different weekdays or networks using different configurations. The simulations results show that networks using high frequency reuse factors give the best quality, while the gain from DTX is higher than the gain from power control. Both features can be combined to get an even higher gain. Field trial results show the same tendencies.

Capacity increase in mixed networks with EGPRS downlink power control

The progressive introduction of packet switched (PS) services in GSM networks involves interference control techniques that preserve the quality of speech communications. downlink power control (DLPC) for (E)GPRS reduces considerably the interference introduced by PS and notably increasing the system capacity Regina Rodriguez et al. (2002). The effect of this feature must be taken into account for network dimensioning purposes. This article presents a mathematical study about the equivalences that can be established in terms of interference between Erlang/spl I.bar/PS and Erlang/spl I.bar/CS in mixed environments when the downlink power control (DLPC) is applied to GPRS and EGPRS services.