Opportunistic Multicast Scheduling for Unicast Transmission in MIMO-OFDM System

TL;DR

This paper introduces an opportunistic multicast scheduling scheme for MIMO-OFDM WLANs that leverages content reuse and caching to improve system capacity and reduce resource usage, without needing prior channel statistics.

Contribution

It develops a low-complexity Lyapunov-based scheduling algorithm that combines unicast and multicast transmissions, aligning with IEEE 802.11 standards and enhancing user capacity.

Findings

Outperforms existing techniques by 17% to 35% in user capacity.

Effectively exploits content reuse and caching for resource efficiency.

Ensures low complexity and no need for prior channel statistics.

Abstract

We propose a multicast scheduling scheme to exploit content reuse when there is asynchronicity in user requests. A unicast transmission setup is used for content delivery, while multicast transmission is employed opportunistically to reduce wireless resource usage. We then develop a multicast scheduling scheme for the downlink multiple-input multiple output orthogonal-frequency division multiplexing system in IEEE 802.11 wireless local area network (WLAN). At each time slot, the scheduler serves the users by either unicast or multicast transmission. Out-sequence data received by a user is stored in user's cache for future use.Multicast precoding and user selection for multicast grouping are also considered and compliance with the IEEE 802.11 WLAN transmission protocol. The scheduling scheme is based on the Lyapunov optimization technique, which aims to maximize system rate. The resulting scheme has low complexity and requires no prior statistical information on the channels and queues. Furthermore, in the absence of channel error, the proposed scheme restricts the worst case of frame dropping deadline, which is useful for delivering real-time traffic. Simulation results show that our proposed algorithm outperforms existing techniques by 17 % to 35 % in term of user capacity.