Traditional Call Admission Control (CAC) schemes only consider call-level performance and are mainly designed for circuit-switched wireless network. Since future wireless communications will become packet-switched systems, the packet-level features could be explored to improve the system performance. This is especially true when the TCP-type of elastic applications are running over such packet-switched wireless networks, as the elasticity of TCP applications has more tolerance toward the throughput/delay variation than non-elastic traffic does. In order to efficiently utilize the system resource from an admission control perspective, we propose a TCP-aware CAC scheme to regulate the packet-level dynamics of TCP flows. We analyze the system performance under realistic scenarios in which (i) the call holding time for non-elastic traffic like voice is independent of system states and (ii) the call holding time for TCP type of traffic depends on the system state, i. e., on the TCP flow’s transmission rate. Extensive simulations are presented under different scenarios to show that the proposed scheme can effectively improve the system performance in terms of call blocking probability, call-level throughput (call/min) and link utilization, in accordance with our theoretical results.

This paper addresses the problem of maximizing the protocol capacity of 802.11e networks, under the assumption that each access category (AC) has the same packet length. We prove that the maximal protocol capacity can be achieved at an optimal operating point with the medium idle probability of e−√2/T*c, where T*c is the duration of collision time in terms of slot unit. Our results indicate that the optimal operating point is independent of the number of stations and throughput ratio among ACs, which means the proposed analytical results still hold even when throughput ratio and station number are time-varying. Further, we show that the maximal protocol capacity can be achieved in saturated cases by properly choosing the protocol parameters. We present a parameter configuration algorithm to achieve both efficient channel utilization and proportional fairness in IEEE 802.11e EDCA networks. Extensive simulation and analytical results are presented to verify the proposed ideas.

For TCP/AQM systems, the issue of buffer sizing has recently received much attention. The classical rule-of-thumb suggests O(N) buffer size to ensure full link utilization when N TCP flows share a bottleneck link of capacity O(N), while recent empirical study shows the buffer of size O(√N) is enough to yield high utilization (say, 95%) for large N. However, these results are all limited to the drop-tail scheme and there has been no systematic modeling framework for any buffer sizing between O(√N) and O(N). In this paper, we study the limiting behavior of a TCP/AQM system for an intermediate buffer sizing of O(Nγ) (0.5 ≤γ< 1). We develop a stochastic model in a discrete-time setting to characterize the system dynamics and then show that we can have 100% link utilization and zero packet loss probability for a large number of flows when the buffer size is chosen anywhere between O(√N) and O(N). Our model is general enough to cover any queue-based AQM scheme with ECN marking (including the drop-tail) and various generalized AIMD (Additive-Increase-Multiplicative-Decrease) algorithms for each TCP flow. We also provide arguments showing that the discrete-time based modeling can effectively capture all the essential system dynamics under our choice of scaling (0.5 ≤γ< 1) for buffer size as well as AQM parameters.

Channel allocation was extensively investigated in the framework of cellular networks, but it was rarely studied in the wireless ad-hoc networks, especially in the multi-hop ad-hoc networks. In this paper, we study the competitive multi-radio channel allocation problem in multi-hop wireless networks in detail. We model the channel allocation problem as a static cooperative game, in which some players collaborate to achieve high date rate. We propose the min-max coalition-proof Nash equilibrium (MMCPNE) channel allocation scheme in the game, which aims to max the achieved date rates of communication links. We analyze the existence of MMCPNE and prove the necessary conditions for MMCPNE. Furthermore, we propose several algorithms that enable the selfish players to converge to MMCPNE. Simulation results show that MMCPNE outperforms CPNE and NE schemes in terms of achieved data rates of the multi-hop links due to cooperation gain.