Cross-Layer Distributed Diversity for Heterogeneous Wireless Networks

In this paper, we introduce a cross-layer diversity framework for multi-air interface wireless communication devices. As an initial step, we focus on devices, of the cellular phones type, that have both longrange relatively low-rate communication air-interface (e.g., GSM) and short-range high-rate communication air-interface (e.g., IEEE802.11). The devices can cooperate through the energy-efficient high-rate interface to improve the performance of the long-range interface. Within this framework we propose a distributed signal-combining technique that accounts for the limited bandwidth of the short-range communication: Threshold Maximum Ratio Combining. We analytically derive the probability distribution function of the signal to noise ratio (SNR) of the combined signals as a function of the number of involved devices and show that significant improvement of the SNR is achievable which translates into a reduction of the overall system outage probability.