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This paper proposes a novel beam aggregation scheme for millimeter wave (mm-Wave) system under hybrid beamforming architecture, assuming one user equipment (UE) equipped with multiple antenna panels receives distinct beams from multiple transmission points (TPs) simultaneously. Further, system framework including channel state information (CSI) feedback scheme and scheduling algorithm is investigated...
Ambient backscatter is a new technology that utilizes existing wireless signals of other communication systems to enable small devices to communicate with each other. One key problem for ambient backscatter is that if it will result in interference on existing communication systems. We investigate this problem in this paper. Specifically, we build up the theoretical system model for the ambient backscatter...
A general inner bound is given for the discrete memoryless broadcast channel with an arbitrary number of users and general message sets, a setting that accounts for the most general form of concurrent groupcasting, with up to exponentially many messages intended for any set of subsets of receivers. Achievability is based on superposition coding and rate-splitting, where each receiver jointly decodes...
This work evaluates interference mitigation mechanisms to enable the operation of self-organizing hybrid terrestrial-satellite networks with aggressive frequency reuse between terrestrial and also satellite links. The objective is to take advantage of the improved capacity and resilience to congestion of such networks while assuring and efficient use of the spectrum. In particular, single- and multi-user...
Large-scale MU-MIMO is a promising technology to scale network capacity and the capacity gain grows linearly with the numbers of antennas and users in theory. However, its practical deployment faces three critical challenges in the state-of-the-art WLANs: i) the demand of a large number of expensive RF chains; ii) the linear growth of feedback overheads with the number of antennas; iii) the lack of...
In this paper, a new spectrum sharing model referred to as riding on the primary (RoP) is proposed for wireless- powered IoT devices with ambient backscatter communication capabilities. The key idea of RoP is that the secondary transmitter harvests energy from the primary signal, then modulates its information bits to the primary signal, and reflects the modulated signal to the secondary receiver...
IoT wireless connectivity often presents a lossy and error prone radio link layer between the wireless edge device and the wireless base station. Data transacted over the radio link layer often uses TCP, which provides programmatic error mitigation elements, e.g., loss of and out-of-order packet detection, combined with ACK/NACK from far end to trigger packet retransmission. In the use case of subscription...
This paper examines design of mixed-timescale hybrid precoding with vector perturbation (VP) to achieve minimum mean square errors (MMSE) for multi-user massive multiple-input multiple-output (MIMO) systems. In particular, equipped with the perfect effective channel state information (CSI)-based MMSE-VP solution at the baseband, we derive partial CSI-based linear radio frequency (RF) precoding as...
Cellular heterogeneous networks (HetNets) with densely deployed small cells can effectively boost network capacity. The co-channel interference and the prominent energy consumption are two crucial issues in HetNets which need to be addressed. Taking the traffic variations into account, in this paper, the performances of HetNets with joint further-enhanced inter-cell interference coordination (FeICIC)...
A throughput analysis is conducted for a large scale peer-to-peer wireless network whose devices are capable of operating in both full- and half-duplex modes, using the tools of stochastic geometry. Each device selects its operating duplex mode based on the distance to its partner node. In both duplex modes, the energy consumption and the hardware configurations of the nodes are made equivalent for...
In ambient backscatter communications (Am-BC), a backscatter device can harvest power from ambient RF signals and modulate its information symbols over the ambient carriers without using complex RF transmitter. Conventional receiver design for AmBC focuses on tackling the direct link interference from the RF source. In this paper, a novel receiver, which is called cooperative receiver, is proposed...
In this paper, we focus on the millimeter-wave multi-user multiple-input-multiple-output (mmWave MU-MIMO) systems and propose a low-complexity hybrid precoding and combining design, which is applicable to both fully-connected structures and sub-connected structures. Based on the channel knowledge of each user, the analog combiner for each user is independently designed based on the singular value...
Judiciously setting the base station transmit power that matches its deployment environment is a key problem in ultra dense networks and heterogeneous in-building cellular deployments. A unique characteristic of this problem is the tradeoff between sufficient indoor coverage and limited outdoor leakage, which has to be met without explicit knowledge of the environment. In this paper, we address the...
Coherent detection requires exact knowledge of the channel state information, which is often a challenging task in demanding practical applications. Based on this, non-coherent detection of differentially modulated signals can be considered as an alternative method. The present paper investigates the effects of in-phase/quadrature-phase imbalance (IQI), which are known to degrade the performance of...
An interference monitoring station is presented which detects, characterises and logs interference events. The system operates autonomously and continuously over multiple global navigation satellite system (GNSS) bands. With a bandwidth of up to 80 MHz, input resolution of 8 bit an overall data rate of approximately 1.3 Gbit/s can be supported. The interference detection is carried out in real-time,...
Wireless virtualization is an emerging approach to enhance the spectrum utilization by sharing wireless resources such as RF spectrum and wireless infrastructures of different networks through slicing. In this paper, we investigate RF spectrum sharing for virtual wireless networks where wireless resources for virtual networks shrink and grow based on their availability and the demands from the users...
We consider an energy harvesting (EH) based cooperative relaying network, where two half-duplex relays can alternatively forward source data to the destination. The power-splitting technique is implemented at each relay. That is, part of the received source signal and inter-relay interference is allocated for the EH, while the remaining part is used for the information decoding (ID). The inter-relay...
In this work, we study the effect of energy harvesting in a cognitive shared access network with delay constraints on the primary user. We model the distribution of secondary nodes by a homogeneous Poisson point process (PPP), while the primary user is located at fixed location. The secondary users are assumed to have always packets to transmit whilst the primary transmitter has bursty traffic. We...
Carrier aggregation supports an increased total bandwidth, data rate and utilization of available fragmented spectrum, where the latter is a core component of next generation Wi-Fi and Cellular networks, including 5G. Wireless communications receivers with intra-band non-contiguous CA, employing conventional complex mixers and base-band circuitry, are desirable, however risks of VCO injection pulling...
We consider the problem of designing hybrid analog-digital beamformers in a downlink multi-user large-scale MIMO system. The objective is to minimize the total transmit power, while fulfilling SINR targets of all users. A dual virtual uplink problem is formulated for the original downlink problem based on the uplink-downlink duality theory, in order to decouple the digital beamformers in the constraints...
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