Millimeter-wave communication achieves multi-Gbps data rates via highly directional beamforming to overcome pathloss and provide the desired SNR. Unfortunately, establishing communication with sufficiently narrow beamwidth to obtain the necessary link budget is a high overhead procedure in which the search space scales with device mobility and the product of the sender-receiver beam resolution. In this paper, we design, implement, and experimentally evaluate Blind Beam Steering (BBS) a novel architecture and algorithm that removes in-band overhead for directional mm-Wave link establishment. Our system architecture couples mm-Wave and legacy 2.4/5 GHz bands using out-of-band direction inference to establish (overhead-free) multi-Gbps mm-Wave communication. Further, BBS evaluates direction estimates retrieved from passively overheard 2.4/5 GHz frames to assure highest mm-Wave link quality on unobstructed direct paths. By removing in-band overhead, we leverage mm-Wave's very high throughput capabilities, beam-width scalability and provide robustness to mobility. We demonstrate that BBS achieves 97.8% accuracy estimating direction between pairing nodes using at least 5 detection band antennas. Further, BBS successfully detects unobstructed direct path conditions with an accuracy of 96.5% and reduces the IEEE 802.11ad beamforming training overhead by 81%.

In this paper, we propose "Virtual Duplex," a wireless architecture which, like Frequency Division Duplex (FDD), divides spectrum resources into two sub-bands. However, in contrast to FDD, both bands in Virtual Duplex are physically bidirectional, and transmissions are allocated to the bands according to whether they correspond to download or upload traffic. The "download data channel" carries data originating from the AP and that data's associated reversed-direction acknowledgements, and vice-versa for the "upload data channel." Thus, Virtual Duplex separates upload and download traffic at the link layer so that MAC layer Data-ACK handshakes are allocated into one of the two (physical) independent and asynchronous bi-directional channels. The spectrum division can be equal (as is typical with FDD) or weighted with a configurable bandwidth allocated to each channel to guarantee a spectrum share independent of client density. We show that the logical division and spectrum isolation between upload and download Data-ACK handshakes increases spectral efficiency, eliminates contention asymmetry and provides scalability to traffic asymmetry. Experimental and simulation results demonstrate that Virtual Duplex matches download vs. Upload throughput to demand ratio within 1% under any client density and traffic load. This matching capability offers unbounded download gains as congestion increases, minimizing and in some cases eliminating retransmissions and contention time.