Introduction to algorithms
Cross Layer Design for IEEE 802.11 WLANs: Joint Rate Control and Packet Scheduling
LCN '05 Proceedings of the The IEEE Conference on Local Computer Networks 30th Anniversary
Combinatorial Reverse Auction based Scheduling in Multi-Rate Wireless Systems
IEEE Transactions on Computers
IEEE 802.11n: enhancements for higher throughput in wireless LANs
IEEE Wireless Communications
IEEE 802.11n MAC frame aggregation mechanisms for next-generation high-throughput WLANs
IEEE Wireless Communications
A high-performance MIMO OFDM wireless LAN
IEEE Communications Magazine
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Frame aggregation is a MAC-layer technology proposed in 802.11n WLAN. The base station can serve two or more users in one frame simultaneously, which can improve MAC-layer efficiency by reducing the transmission time for preamble and frame headers, and the random backoff period for successive frame transmissions. This fact enables us to design a more QoS-aware scheduler from the MAC layer. In this paper, we first formulate the scheduling problem with frame aggregation into a knapsack problem that is shown NP hard. Then we propose a simple approximation algorithm (LUUF) based on the unit urgency concept. Our analysis shows that the complexity of LUUF is O(nlogn) and it achieves an approximation ratio of F^'/F"m"a"x. We then show that in practice the complexity can be further reduced to O(n) and the approximation ratio can be made very near to 1, which makes LUUF a promising candidate for wireless systems that support frame aggregation. We also conduct simulations comparing LUUF with the widely used Round-Robin scheduler and find that LUUF can significantly improve the quality of service for various numbers of users and different maximum aggregation frame sizes.