Packet Size Optimization for Goodput Enhancement of Multi-Rate Wireless Networks

In this paper, we propose a link adaptation scheme to adapt the packet size as a crucial system parameter for quality of service (QoS) provisioning in multi-rate wireless networks. The link adaptation scheme combines adaptive modulation and coding (AMC) at the physical layer with type-II hybrid automatic repeat request (HARQ) at the data link layer in a cross-layer fashion. We then study the goodput performance of the proposed link adaptation scheme at the medium access control (MAC) layer. We show that there exists an optimal packet size to achieve the maximum goodput in transmitting messages over transport layer sessions. Based on this observation, we provide an efficient and effective algorithm to search the optimal packet size. Finally, we propose a link adaptation architecture, through which the proposed link adaptation scheme can adapt packet sizes to instantaneous channel conditions to fulfill committed QoS in higher layers. Numerical results show that the system adopting the proposed optimal packet sizes has superior goodput performance over the systems using fixed packet sizes.