SUMMARY Millimeter-wave (mmw) frequency bands, especially 60 GHz unlicensed band, are considered as a promising solution for gigabit short range wireless communication systems. IEEE standard 802.11ad, also known as WiGig, is standardized for the usage of the 60 GHz unlicensed band for wireless local area networks (WLANs). By using this mmw WLAN, multi-Gbps rate can be achieved to support bandwidthintensive multimedia applications. Exhaustive search along with beamforming (BF) is usually used to overcome 60 GHz channel propagation loss and accomplish data transmissions in such mmw WLANs. Because of its short range transmission with a high susceptibility to path blocking, multiple number of mmw access points (APs) should be used to fully cover a typical target environment for future high capacity multi-Gbps WLANs. Therefore, coordination among mmw APs is highly needed to overcome packet collisions resulting from un-coordinated exhaustive search BF and to increase total capacity of mmw WLANs. In this paper, we firstly give the current status of mmw WLANs with our developed WiGig AP prototype. Then, we highlight the great need for coordinated transmissions among mmw APs as a key enabler for future high capacity mmw WLANs. Two different types of coordinated mmw WLAN architecture are introduced. One is distributed antenna type architecture to realize centralized coordination, while the other is autonomous coordination with the assistance of legacy Wi-Fi signaling. Moreover, two heterogeneous network (HetNet) architectures are also introduced to efficiently extend the coordinated mmw WLANs to be used for future 5 th Generation (5G) cellular networks. key words: millimeter wave, IEEE802.11ad, coordinated mmw WLAN, 5G cellular networks, heterogeneous networks

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This paper presents a joint resource allocation and interference avoidance algorithm for uplink transmissions in a multi-cell cognitive radio network (CRN), which overlays with a multi-cell primary network (PN). We consider a primary willingness based coexistent architecture. Primary base stations will broadcast pilot signals and interference margins to the CRN for interference channel evaluation and power control. The objective of the algorithm is to maximize the sum rate of cognitive radio cells without causing unacceptable interference to primary receivers, where Lagrangian duality based technique has been utilized to solve the maximization problem and jointly allocate the subchannels and power for each user. The fairness among users is considered within the joint resource allocation to guarantee that the instantaneous rate for each user is larger than a given minimum rate. Simulation results show the efficiency of our algorithm, which has good convergent performance. Moreover, compared to the conventional schemes, the proposed algorithm can satisfy the fairness well, and also obtain a large gain on cell-edge user throughput only with a small reduction in cell sum rate.

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