Pillow Talks: Bits Over Communications in WLAN

Improving the channel utilization is a significant issue to enhance the performance in WLAN. This paper presents Pillow Talks MAC (PT-MAC), a novel spectrum sharing mechanism to create an extra channel (pt-channel) for client-to-client transmission in WLAN. Obviously, The basic challenge in our proposal is how pt-channel works concurrently and transparently with AP transmissions. To address the issue, in PT-MAC, selected clients are allowed to contend for pt-channel during uplink transmissions and talk freely under the ongoing downlink transmissions. Based on advanced physical techniques, pt-channel transmitter receives and forwards the AP signals simultaneously within OFDM cyclic prefix, resulting in mixed signals are overheard by receiver in pt-channel. However, the mixed message can be recovered by pt-decoding system. Simulations and analytical results show that, PT-MAC reuses the spectrum in WLAN and achieves a throughput gain as large as 92% with similar fairness, when the ratio of downlink traffic is about 80%.