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In GERAN networks, Multiple Users Reusing One Single timeslot (MUROS) promises to enhance the cell capacity through pairing of two or more users onto a single timeslot. So far no work has been done on the basis on which the different users would be paired. The criteria used for the pairing decision to pair two or more users is critical for MUROS as this will eventually decide the actual gains due...
Single-Carrier Frequency Division Multiple Access (SC-FDMA) has been selected as the uplink transmission scheme in the 3GPP Long Term Evolution standard. SC-FDMA is a form of Single-Carrier Frequency Domain Equalization (SCFDE) with flexibility in its resource allocation. In this paper we investigate the performance of SC-FDMA with Frequency-Domain Linear Equalization (FD-LE) with optimized transmit...
In this paper we investigate channel state information (CSI) feedback strategy for a basestation (BS) scheduling multiple users for data transmissions in the downlink. For the purpose of fair provisioning of service among users with possibly heterogeneous channel statistics, we adopt scheduling algorithms based on scores: specifically the maximum quantile (MQ) scheduling is used as one of such schedulers...
A Hybrid ARQ (HARQ) scheme employing a flexible amplify and forward (AF) relaying is considered for a cooperative relay channel. Two phase types with flexible length: one phase for relay reception and another phase for relay forwarding are assumed to accommodate half duplex relaying. We assume two types of encoding: repetition coding (RC) and unconstrained coding (UC). The outage performance of the...
Current cellular systems suffer from co-channel interference, when simultaneous transmissions in other cells use the same physical resources. Schemes involving cooperation between Base Stations (BS) are currently discussed for further releases of the 3GPP Long Term Evolution (LTE) system as a promising method to mitigate co-channel interference for users located at cell-edge. The BS cooperation approach...
In this paper, performance of Transmit Antenna Selection / Maximal Ratio Combining (TAS / MRC) in two hop Amplify-and-Forward (AF) relay system is analyzed over frequency non-selective and slowly Rayleigh fading channel. In the system, all nodes are equipped with multiple antennas; TAS is employed at the source and relay for transmission, MRC is employed at the relay and destination for reception...
This paper concentrates on characterizing energy, latency and capacity trade-offs in multi-hop wireless ad-hoc networks. Therefore, a multiobjective framework is proposed to derive the Pareto-optimal set of solutions with respect to these three criteria. The work presented in this paper assumes a linear network where transmission powers and relay positions are optimization variables. We study the...
This paper considers the network coded relay protocol utilized in the cellular systems. The time division multiple access (TDMA) based opportunistic network coded cooperation(TDMA-ONCC) scheme, whose central idea is to perform the opportunistic network coded cooperation based on the observed instantaneous channel qualities of source-to-relay and relay-to-destination links, is researched. Performances...
Distributed beamforming has the great potential of performance improvement in wireless networks while the carrier synchronization overhead will reduce its performance gain. In this paper the effects of carrier synchronization on link throughput of distributed beamforming is studied. The expressions of the frequency and initial phase used by each cooperative node are derived for the existing round-trip...
Opportunistic scheduling for wireless network coding (OWNC) combines the strategies of opportunistic scheduling and network coding. This paper applies two variants of OWNC on a two-user OFDMA system. Symbol-based OWNC decides a strategy from sum rate of the whole OFDM symbol. Subcarrier-based OWNC decides a strategy from the capacity on a subcarrier level. Novel algorithms are derived for power allocation...
In wireless networks, designing transmission schemes adapting to time varying channel conditions is key to achieve better spectral efficiency. The design of such schemes for multi-hop wireless networks requires coordination among nodes in the network, which is achieved through feedback between nodes. Spectral efficiency can be improved for such networks by designing transmission schemes with limited...
In this paper, multiple-input multiple-output (MIMO) transmit beamforming (TB) systems under the consideration of nonlinear high-power amplifiers (HPAs) are investigated. The optimal beamforming scheme, with the optimal beamforming weight vector and combining vector, is proposed for MIMO systems with HPA nonlinearity. The performance of the proposed MIMO beamforming scheme in the presence of HPA nonlinearity...
In this paper indoor wireless Infrared (IR) technology for healthcare monitoring is studied. Monitoring provides a continuous and reliable vital sign measurement to secure patient staying in the hospital. Considering that patient moving is inevitable, we focus on a mobile IR channel based on diffuse propagation. A model of mobile channel is developed through the study of statistical distributions...
The IEEE 802.11 standard conformant wireless communication stations have multi-rate transmission capability. To achieve greater communication efficiency, multi-rate capable stations use rate-adaptation to select appropriate transmission rate according to variations in the channel quality. This paper proposes a novel rate-adaptation scheme where the decision of rate selection relies on the mutual feedback...
This paper presents a link adaptation strategy for non-binary LDPC code over a time-variant frequency-selective channel. The algorithm is based first on the adoption of waterfilling technique to wisely adapt the transmitted power. It is shown that as long as best subchannels are identified with the waterfilling algorithm, an equal power distribution can be applied with performance comparable to the...
Vandermonde-subspace frequency division multiplexing (VFDM) is a technique for interference cancellation in overlay networks that allows a secondary network to operate simultaneously with a primary network, on the same frequency band. VFDM can be applied to block transmission systems with a guard time (or cyclic prefix) over frequency selective channels. It achieves zero interference towards the primary...
In this paper, we consider spectrum sensing of DVB-T signals in different fading environments. We compare state-of-the-art detectors including detectors based on pilot subcarriers, as well as detectors for general OFDM signals that exploit the correlation structure incurred by the cyclic prefix. Energy detection is also included for comparison. We show numerically that the choice of detector depends...
Machine-to-Machine (M2M), an emerging communications paradigm, is a facilitator of data flows between machines used, e.g., in mission-critical applications. Focusing in this paper on embedded multihop M2M implementations with myopic routing, a prime design aim is to jointly minimize energy expenditure and the end-to-end delay whilst not jeopardizing the network's operational reliability. We thus evaluate...
In multiple-input multiple-output (MIMO) broadcast channel, the lattice-reduction-aided (LRA) precoder is the modified zero-forcing beamforming (ZFBF) scheme which perturbs data symbols to reduce the transmit power. In this paper, we propose the optimal user group selection (UGS) scheme for the LRA-precoder to maximize the sum-rate in MIMO broadcast systems. We derive the approximated sum-rate of...
This paper addresses joint power control and link scheduling problem in Spatial-reuse Time Division Multiple Access (STDMA) networks with consecutive transmission constraint, where multiple links should be scheduled in a number of consecutive time slots. By multi-link management with power control and scheduling, the network can provide lower transmission latency or support more users. In this paper,...
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