HSDPA Performance in Live Networks

The first HSDPA (high-speed downlink packet access) networks have been recently deployed for operational use. We evaluate and compare live HSDPA operational network performance from the end-user perspective, especially related to voice over IP and Web browsing applications. We compare goodput performance with user datagram protocol (UDP) and transmission control protocol (TCP) in both wideband code division multiple access (WCDMA) and HSDPA. We also address one-way delay measurements to show how up- and downlink asymmetry affects delay and jitter. We found that HSDPA and WCDMA goodput correlate well with the advertised maximum performance values. However, with small payload sizes HSDPA does not bring a substantial improvement over TCP. With UDP the situation is clearly better except with payload sizes commonly used by VoIP. We verify that HSDPA delay is substantially smaller than with WCDMA, as well as the occurrence of delay spikes caused by link level retransmissions. We found that despite 2 ms time division in HSDPA, the main jitter level is at 10 ms. The results can be exploited by operators and equipment manufacturers for service optimisation.