Corlayer: A transparent link correlation layer for energy efficient broadcast

Wireless communication essentially occurs in a broadcast medium with concurrent receptions. Recent works [34,41] have shown clear evidence that wireless links are not independent and that trans- missions from a transmitter to multiple receivers are correlated, a phenomenon that has profound implications for the performance of network protocols such as broadcast, multi-cast, opportunistic forwarding and network coding. In this paper, we show how link correlation can significantly impact broadcast. We present the de- sign and implementation of CorLayer, a general supporting layer for energy efficient reliable broadcast that carefully blacklists cer- Tain poorly correlated wireless links. This method uses only one- hop information, which makes it work in a fully distributed manner and introduces minimal communication overhead. The highlight of our work is CorLayer's broad applicability and effectiveness. Our system effort is indeed significant. We integrate CorLayer transpar- ently with sixteen state-of-the-art broadcast protocols specified in thirteen publications [1, 3, 18, 19, 23, 25-27, 32, 36, 38-40] on three physical testbeds running TelosB, MICAz, and GreenOrbs nodes, respectively. The experimental results show that CorLayer remark- Ably improves energy efficiency across a wide spectrum of broad- cast protocols and that the total number of packet transmissions can be reduced consistently by 47% on average.