Adaptive channel management schemes for wireless communication systems

Channel management schemes for wireless networks aim typically at minimizing the hand-off failure probability of on-going calls at the risk of blocking new calls. In a dynamically changing environment, however, such a strategy may increase the likelihood of blocking new calls, unnecessarily. To provide a 'better effort' quality of service support (QoS) to new calls, while guaranteeing a high level of QoS support for hand-off calls, this paper proposes a new class of adaptive channel management schemes. The QoS level support is achieved by dynamically adjusting a channel sharing ratio between new and hand-off calls so that the hand-off failure probability and the new call blocking probability remain below their respective predefined thresholds. Two different schemes are presented, the randomized channel assignment (rCA) scheme and the balanced channel assignment (bCA) scheme. The rCA scheme controls the system's performance so that new calls are allowed to compete randomly with hand-off calls for excess channels within a cell, without violating the QoS requirements of the hand-off calls. The bCA scheme takes a different approach and dynamically adjusts the new call admission rate, depending on which type of call, new or handoff, is currently more prevalent within a cell. This approach alleviates the channel assignment scheme from a tight dependency on the underlying traffic model and reflects the dynamically changing load within the cell. The performance of the proposed schemes is studied and compared to other channel management schemes proposed in the literature.