Optimal power scheduling in 802.11n wireless networks for real‐time services

Abstract

The growing popularity of mobile devices in our daily life demands higher throughput of wireless networks. The new communication standard 802.11n has significantly improved throughput because of the use of advanced technologies such as the multiple-input multiple-output communication technique. Because mobile devices are usually battery-operated, power efficiency is critical; on the other hand, delay performance can be improved by transmitting at high power. To address the conflicting requirement of power saving and small delay, power scheduling is needed. In the past, many approaches to power scheduling have been proposed for real-time applications, but few of them have considered complicated modes of channel state information(CSI) in multiple-input multiple-output. In this paper, we study this and classify the CSI into four types, namely, constant, slow fading, fast fading, and unknown. For known CSI, we propose an optimal algorithm for power scheduling. For unknown CSI, we propose an approximate algorithm based on some heuristics. To improve resource utilization, a stochastic delay-bound method is proposed for fast-fading condition. Simulation results demonstrate that the performance achieved by the optimal and heuristic algorithms agrees well with the analysis.

An Efficient Fixed Rate Transmission Scheme Over Delay-Constrained Wireless Fading Channels

“…For example, at packet drop rate of 10 −3 , the gap between FRT with S = 30 and JQLA is only 0.5 dB. Note that this is where JQLA realizes nearly 10 dB power gain over time domain waterfilling algorithm (WF) as reported in [7,10]. Secondly, the packet rate S should be larger than λ to realize the near JQLA performance.…”

“…w(n) is normally distributed with zero mean and unit variance. The transmitter consists of three parts: the link layer, physical layer and the resource scheduler [3,7,10]. At the link layer, we assume the data source is stable and data packets arrive at a constant rate of λ packets per channel.…”

“…A buffer is placed at the link layer to coordinate the arrived data packets, and a scheduler is in charge of controlling the data departure according to the buffered data length and the channel state information (CSI) [3]. In the literature, numerous previous works studied the scheduler design problems in link-PHY models with various channel fading assumptions [2][3][4], performance measures [5,6] and multiple antennas [8][9][10]. However, most of these works assume the buffer is with infinite length which is invalid in practice.…”