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This paper presents the use of a commercially available radio scanner for characterizing on-vehicle 2×2 Long-Term Evolution (LTE) radio Multiple-Input Multiple-Output (MIMO) antennas. The scanner measures the LTE eNodeB, i.e. the cell base station, reference signals and each channel and determines the MIMO channel matrices from which the downlink throughput can be determined. For a given LTE radio,...
In wireless community networks, backbone point-to-point links concentrate most of the traffic. Thus, these links are crucial for the overall performance of the network. Network managers have to constantly test and maintain these links to optimise their performance, but their decisions are often based upon rumours or a purely theoretical knowledge of the technologies being used. These sources of information...
The proliferation of smart devices and the resulting exponential growth in data traffic has increased the need for higher capacity wireless networks. The cellular systems industry is envisioning an increase in network capacity by a factor of 1000 over the next decade to meet this traffic demand. In addition, with the emergence of Internet of Things (IoT), billions of devices will be connected and...
This paper describes a hardware efficient linear precoder for Massive MIMO Base Stations (BSs) comprising a very large number of antennas, say, in the order of 100s, serving multiple users simultaneously. To avoid hardware demanding direct matrix inversions required for the Zero-Forcing (ZF) precoder, we use low complexity Neumann series based approximations. Furthermore, we propose a method to speed-up...
This paper proposes a novel relay selection strategy based on the feedback beamforming (BF) information for 60GHz millimeter-wave (mmWave) wireless communication systems under non-line-of-sight (NLoS) condition. First, an approach of collecting instantaneous channel state information (CSI) through overheard during BF is devised. Second, with the aim of maximizing overall network throughput capacity,...
We propose a new framework for optimizing the target secrecy rate for SISOME wiretap channels when the instantaneous capacity of the eavesdropper's channel is not available at the transmitter. In our framework we introduce the effective secrecy throughput, a new optimization metric that implicitly captures the two key features of wiretap channels, namely, reliability and secrecy. We derive target...
In order to realise the potential benefits of co-channel deployments in Heterogeneous Networks (HetNets) and achieve an efficient spectrum reuse, a joint optimisation of small cell and macrocell network operation is highly beneficial. In this paper, a novel cellular network and frequency reuse configuration for both small cells and macrocells is proposed to address inter-cell interference and handover...
Directional Medium Access Control protocols (DMACs) have been studied for decades. Since most existing DMACs assume an ideal antenna model which does not consider the minor-lobe interference, their performance cannot be guaranteed in practice. Other approaches assuming non-ideal antenna require either extra equipment or clock synchronization, making the system more complicated. It is also observed...
We are concerned with the throughput of a full-duplex (FD) MIMO network. Unlike conventional half-duplex (HD) MIMO, two wireless devices of a bidirectional FD-MIMO link have freedom of selecting which antennas/RF-chains to transmit or receive before tuning their radiation patterns to maximize the link's throughput. The freedom in configuring the function of available RF-chains, resulting in various...
The 60GHz radio technology is highly promising since it can offer multi-Gbps data rate for short range wireless communication. Recently, the idea of using wireless Ad-Hoc networks in the 60 GHz unlicensed band has begun to draw a lot of attention. This paper investigates the throughput capacity of the millimeter wave wireless Ad-Hoc networks with directional antennas when the multi-hop relay schemes...
Small cell is an attractive and promising technology for improving capacity in traffic hotspots using cell densification. We consider the traffic load balancing problem for small cells under the enhanced Local Area (eLA) architecture utilizing the flexible 3-dimensional (3D) beamforming facilitated by the adoption of the active antenna system (AAS) at base stations (BSs). Different load balancing...
Cloud radio access network (C-RAN) is a new concept of network architecture, which brings a technical revolution into the wireless communication market and leads to some kind of all new mode of the future wireless communications. In this paper the clustering algorithm based on multi-objective optimization is investigated. The proposed algorithm aims at maximizing the throughput contribution of the...
A novel transmission scheme is developed for the downlink frame of cellular networks. Each base station (BS) aims at iteratively balancing the throughput at the mobile stations (MSs) of its cell with the interference it causes at the MSs of the neighboring cells, requiring negligible coordination between the BSs. A simplified version of the scheme that neither requires iterations nor cooperation is...
Frequently, client-side wireless devices have a view of multiple WiFi access points, whether from open residential and commercial networks, corporate networks, or mesh networks. Given the increasing number of radios and antennas in today's wireless devices, residual capacity from these multiple APs could be leveraged if client devices communicate with multiple APs simultaneously. In this paper, we...
In this paper we present the impact of femtocell underlay deployment sharing same radio frequency resources with urban macro-cell in terms of throughput performance of enodeBs in the presence of inter cell interference that a femto base station environment adds to users served by enodeBs and vice versa. The performance of the two systems, one with femto base station indoor deployment for indoor users...
We study the performance of a two-tier system where a large number of small cells is deployed under a macro-cellular “umbrella”. The macro-cellular tier provides coverage and handles mobile users, while the small cell tier provides high rate locally to nomadic users. While the standard approach consists of operating the two tiers in different frequency bands, for various reasons (e.g., lack of licensed...
The increased demand on capacity in cellular networks calls for increased site density and heterogeneous networks. With unchanged mobility pattern this will increase the handover rate, the signaling load and the impact from handover on experienced user quality. An attractive solution to mitigate the handover impact is Combined Cell which combines area splitting gain with seamless mobility. In this...
This paper studies an uplink massive MIMO system that employs zero-forcing (ZF) receiver and pilot reuse. Although with infinity number of antennas it has been shown that maximum ratio combining (MRC) attains the same throughput as ZF, we find that for antenna number as large as 100, ZF attains significant throughput gain over MRC. A tight lower bound is derived for cell throughput attained by ZF,...
In this work, we present a polarized-MIMO enabled cooperation framework between multiple secondary users (SUs) and a single primary user (PU). To achieve a two-phase cooperative communication paradigm, some state-of-the-art polarization signal processing techniques, e.g., polarization zero-forcing and oblique projection polarization filtering, are introduced to address the co-channel interference...
We consider downlink multi-user MIMO transmission of a wireless system in which the base station is equipped with a large number of antennas. We propose two downlink schemes based on random beamforming and subspace tracking and show that while reducing signaling overhead, these schemes can improve the system performance compared to conventional systems with a smaller number of antennas at the base...
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