Network/hardware cross-layer evaluation for ROHC and packet aggregation on wireless mesh networks

This paper proposes a profile-based network and hardware co-simulation method to investigate the overall performance and real-timing characteristics of a wireless mesh network (WMN) affected by hardware capabilities, speed and complexity. For the sophisticated algorithms to be assisted by a hardware realization, we adopt the RObust Header Compression (ROHC) and packet aggregation that provide high and reliable data transmission over unstable wireless links, which is proven in the preliminary works. To verify the hardware support needs to get the benefit of the two algorithms, we measure the ROHC processing time from Intel Pentium 4 and RouterBOARD, and identify the deterioration of sensor throughput and successful voice calls under various NS-2 simulation scenarios. The co-simulation method integrates the network level simulator, NS-2 and hardware level simulator, SystemC. In this approach, we first insert the modules of ROHC and packet aggregation algorithms into the network simulator hierarchy, and measure the packet arrival times. Then, the corresponding hardware architecture is designed by SystemC for profiling the hardware delay appeared in encoding and decoding packets. The hardware is suitably designed to reduce the complexity and make a sufficient speedup in the packet processing. Finally, the traced hardware delays are applied into the network level simulator to extract real-timing WMN behaviors changed by the hardware operations in each mesh router.