Vincent K. N. Lau

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It is now well known that employing channel adaptive signaling in wireless communication systems can yield large improvements in almost any performance metric. Unfortunately, many kinds of channel adaptive techniques have been deemed impractical in the past because of the problem of obtaining channel knowledge at the transmitter. The transmitter in many(More)
Microwave power transfer (MPT) delivers energy wirelessly from stations called power beacons (PBs) to mobile devices by microwave radiation. This provides mobiles practically infinite battery lives and eliminates the need of power cords and chargers. To enable MPT for mobile recharging, this paper proposes a new network architecture that overlays an uplink(More)
In this paper, we propose a combined adaptive power control and beamforming framework for optimizing multiple-input/multiple-output (MIMO) link capacity in the presence of feedback-link capacity constraint. The feedback1 is assumed to be noiseless and causal with a feedback capacity constraint in terms of maximum number of feedback bits per fading block. We(More)
Spectrum sharing between wireless networks improves the usage efficiency of radio spectrums. This paper addresses spectrum sharing between a cellular uplink and a mobile ad hoc networks. These networks use either all uplink frequency subchannels or their disjoint subsets, called spectrum underlay and spectrum overlay, respectively. Given these methods, the(More)
To fully utilize the spatial multiplexing gains or array gains of massive MIMO, the channel state information must be obtained at the transmitter side (CSIT). However, conventional CSIT estimation approaches are not suitable for FDD massive MIMO systems because of the overwhelming training and feedback overhead. In this paper, we consider multi-user massive(More)
By employing spatial multiplexing, Multiple-Input Multiple-Output (MIMO) wireless antenna systems provide increases in capacity without the need for additional spectrum or power. Zero-Forcing (ZF) detection is a simple and effective technique for retrieving multiple transmitted data streams at the receiver. However the detection requires knowledge of the(More)
As a promising paradigm for fifth generation (5G) wireless communication systems, cloud radio access networks (C-RANs) have been shown to reduce both capital and operating expenditures, as well as to provide high spectral efficiency (SE) and energy efficiency (EE). The fronthaul in such networks, defined as the transmission link between a baseband unit(More)
Cognitive radio technology facilitates spectrum reuse and alleviates spectrum crunch. One fundamental problem in cognitive radio is to avoid the interference caused by other communication systems sharing the same frequency band. However, spectrum sensing cannot guarantee accurate detection of the interference in many practical situations. Hence, it is(More)
In network MIMO systems, channel state information is required at the transmitter side to multiplex users in the spatial domain. Since perfect channel knowledge is difficult to obtain in practice, limited feedback is a widely accepted solution. The dynamic number of cooperating BSs and heterogeneous path loss effects of network MIMO systems pose new(More)