A call quality performance measure for handoff algorithms

This paper proposes a new approach for performance evaluation and comparison between existing handoff algorithms taking into consideration signal levels, call dropping, and handoff cost. Using the new approach, existing handoff algorithms are then compared in terms of signal quality and number of handoffs required to achieve a desired overall signal quality. We also provide in this paper a method to estimate handoff cost and to optimize handoff sequences for retrial (where repeated call attempts are made after a call is lost) and non-retrial models based on the proposed approach. We observe that the Threshold with Hysteresis method performs better than other known methods including the one used in the GSM standard. Our results indicate that the Threshold with 4 dB Hysteresis method performs well for urban areas although with a high dropping probability, whereas the Threshold with 6 dB Hysteresis method suits for suburban areas with a low dropping probability. We find that handoff sequences obtained by existing handoff methods are less efficient than the optimal handoff sequence given in the paper by a margin of 29-45% for retrial model, and by 34-77% for non-retrial model. The paper also suggests some specific parameter values to improve the performance of currently used handoff methods based on our findings. © 2010 John Wiley & Sons, Ltd.