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# IET Communications

## Filter Results

Displaying Results 1 - 25 of 30
• ### Fast two-stage spectrum detector for cognitive radios in uncertain noise channels

Publication Year: 2012, Page(s):1341 - 1348
Cited by:  Papers (2)
| | PDF (407 KB)

An enormous influx of wireless services and devices coupled with inefficient usage of electromagnetic spectrum has led to an apparent scarcity of usable radio bandwidth. Cognitive radio is leading the trend for increasing the spectrum efficiency by utilising the vacancy in the radio spectrum created by absence of the licensed primary user. This paradigm shift can only take place if the means to de... View full abstract»

• ### Power saving scheme based on joint control of bufferthreshold and timer in binary exponential sleep mode

Publication Year: 2012, Page(s):1349 - 1355
Cited by:  Papers (1)
| | PDF (483 KB)

The authors propose a new power saving scheme based on a buffer-threshold and timer in wireless packet networks. In a standard sleep mode operation with a binary exponential algorithm, a mobile station (MS) can begin a wake period if it is aware of the existence of its own downlink packets during a listening interval. In a light traffic environment, this conventional standard operation consumes a ... View full abstract»

• ### Simplified maximum likelihood-based detection schemes for M-ary quadrature amplitude modulation spatial modulation

Publication Year: 2012, Page(s):1356 - 1363
Cited by:  Papers (4)
| | PDF (700 KB)

In this study, the authors propose a simplified maximum likelihood (ML)-based detection scheme for Nt×Nr M-ary quadrature amplitude modulation (M-QAM) spatial modulation (SM) that is computationally less complex than the conventional ML detection scheme. Instead of searching for the transmit antenna index and transmitted symbol pair among all possible ... View full abstract»

• ### Interference aware resource allocation in orthogonal frequency-division multiple access-based relay networks

Publication Year: 2012, Page(s):1364 - 1373
Cited by:  Papers (3)
| | PDF (776 KB)

Adaptive radio resource allocation in a cellular and multiuser orthogonal frequency-division multiple access (OFDMA)-based relay network is studied here. The authors have considered a margin adaptive optimisation problem to minimise the total transmitted power of the base and relay stations subject to the requested data rates of the users. In this study, a novel algorithm is presented for subcarri... View full abstract»

• ### Spectrum sidelobe suppression for discrete Fourier transformation-based orthogonal frequency division multiplexing using adjacent subcarriers correlative coding

Publication Year: 2012, Page(s):1374 - 1381
Cited by:  Papers (1)
| | PDF (559 KB)

The large spectrum sidelobes of orthogonal frequency division multiplexing (OFDM) signal lead to the interference with the licensed user working on the adjacent band in spectrum pooling. The power spectral leakage of discrete Fourier transformation (DFT)-based OFDM systems can be divided into two parts, in-band-out-of-subband (IBOSB) spectral leakage and out-of-band (OOB) spectral leakage. A corre... View full abstract»

• ### Quality-of-service-based interference cancellation in upstream very-high-bit-rate digital subscriber line systems

Publication Year: 2012, Page(s):1382 - 1387
| | PDF (428 KB)

Crosstalk (XT) is the main performance limiter in digital subscriber line (DSL) systems such as very-high-bit-rate digital subscriber line (VDSL) systems. In order to overcome these limitations various XT cancellation techniques have been proposed to mitigate this effect. While leading to very high performance gains, the computational complexity grows quadratically with the number of lines in a bi... View full abstract»

• ### Blind eigenvalue-based spectrum sensing for cognitive radio networks

Publication Year: 2012, Page(s):1388 - 1396
Cited by:  Papers (4)
| | PDF (1214 KB)

Spectrum sensing for cognitive radio allows a secondary user to detect spectrum holes and to opportunistically exploit this space for unlicensed communication. Blind spectrum sensing has the advantage that it does not require any knowledge of the transmitted signal, the channel or the noise-power, which are usually unknown at the receiver. In this study, the simulation and performance results fo... View full abstract»

• ### Performance measures over slowly fading multiple-input multiple-output channels using quantised and erroneous feedback

Publication Year: 2012, Page(s):1397 - 1406
| | PDF (1319 KB)

In this study, a conceptual transmission scheme that adjusts rate and power of codewords which are sent over a slowly fading channel, when quantised and possibly erroneous channel state information (CSI) is available at the transmitter, is designed. Here, the goal is to maximise data throughput or the expected data rate using a two-way training protocol and temporal power control at the transmitte... View full abstract»

• ### Adaptive power management system for mobile multimedia device

Publication Year: 2012, Page(s):1407 - 1415
| | PDF (844 KB)

Recently, methods that combine the concepts of dynamic voltage scaling (DVS) and dynamic power management (DPM) approaches have been proposed for a single task. This study proposes adaptive power management system (APMS), which utilises useful features of both DPM and DVS and an existing pattern analysis algorithm, and new break even time-based task partition scheduling (BET-BTPS). APMS splits tas... View full abstract»

• ### High-throughput turbo decoder using pipelined parallel architecture and collision-free interleaver

Publication Year: 2012, Page(s):1416 - 1424
Cited by:  Papers (3)
| | PDF (682 KB)

Novel high-throughput architecture for a turbo decoder, which has been conceived by combining the advantages of pipelining and parallel processing, is proposed. Increase in throughput has been achieved by pipelining the add compare select offset (ACSO) unit and advancing the normalisation process in the ACSO unit based on global overflow protection logic. The proposed turbo decoder also benefits f... View full abstract»

• ### Power and mobility aware routing in wireless ad hoc networks

Publication Year: 2012, Page(s):1425 - 1437
Cited by:  Papers (2)
| | PDF (838 KB)

Nodes in a wireless ad hoc network have to support routing using their limited battery power resource. The routing protocol involved should use battery power efficiently for good system performance. For systems where node location information is available, this study proposes an on-demand routing protocol for choosing a route based on maximising the minimum node battery power and minimising the to... View full abstract»

• ### Timing jitter tracking for orthogonal frequency division multiple access system in high doppler spread

Publication Year: 2012, Page(s):1438 - 1446
Cited by:  Papers (1)
| | PDF (438 KB)

In the use of orthogonal frequency division multiple access (OFDMA) in multiple access applications, symbols are transmitted in narrowband sub-channels, which are supposed to be orthogonal. However, the use of a practical oscillator, with its inherent drift because of temperature and other environmental changes, will result in clock jitter which destroys the orthogonality between subcarriers and i... View full abstract»

• ### Performance analysis of distributed resource reservation in IEEE 802.11e-based wireless networks

Publication Year: 2012, Page(s):1447 - 1455
Cited by:  Papers (2)
| | PDF (453 KB)

Guaranteeing quality of service (QoS) is one of the most critical challenges in IEEE 802.11-based wireless networks. This study proposes an analytical framework to evaluate hybrid medium access control (MAC) scheduling mechanisms with distributed resource reservation (RR), that was proposed for the IEEE 802.11e-enhanced distributed channel access protocol for guaranteeing QoS. The hybrid MAC sched... View full abstract»

• ### Performance assessment of virtual multiple-input multiple-output systems with compress-and-forward cooperation

Publication Year: 2012, Page(s):1456 - 1465
Cited by:  Papers (7)  |  Patents (2)
| | PDF (716 KB)

A cooperative virtual multiple-input multiple-output (MIMO) system using two transmit antennas that implements bit-interleaved coded modulation (BICM) transmission and compress-and-forward (CF) relay cooperation among two receiving nodes is presented here. To perform CF cooperation, we propose to use standard source-coding techniques for virtual MIMO detection, based on the analysis of its expecte... View full abstract»

• ### Approach for cluster-based spectrum sensing over band-limited reporting channels

Publication Year: 2012, Page(s):1466 - 1474
Cited by:  Papers (3)
| | PDF (705 KB)

In this study, the authors address the problem of bandwidth limitations of the reporting channels in cognitive radio (CR) networks. They propose a cluster-based spectrum-sensing approach that minimizes the bandwidth requirements by reducing the number of terminals reporting to the fusion centre to a minimal reporting set. The approach replaces the secondary base station by a local fusion centre an... View full abstract»

• ### Fair congestion control over wireless multihop networks

Publication Year: 2012, Page(s):1475 - 1482
Cited by:  Papers (2)
| | PDF (200 KB)

Over wireless multihop networks, the conventional transmission control protocol (TCP) cannot allocate the bandwidth fairly to flows. This is because flows with different locations competing for the same wireless channel may have very different perceptions on congestion in terms of packet delay and packet loss rate. In this study, the authors introduce a new window control algorithm and a new estim... View full abstract»

• ### Peak-to-average power ratio reduction in orthogonal frequency division multiplexing system using differential evolution-based partial transmit sequences scheme

Publication Year: 2012, Page(s):1483 - 1488
Cited by:  Papers (3)
| | PDF (347 KB)

A differential evolution (DE)-based partial transmit sequence (PTS) scheme for peak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) systems has been proposed. PTS techniques can improve the PAPR statistics of an OFDM signals, but the considerable computational complexity for the required search through a high-dimensional vector space is a potential prob... View full abstract»

• ### Experimental investigation of polarisation modulated free space optical communication with direct detection in a turbulence channel

Publication Year: 2012, Page(s):1489 - 1494
Cited by:  Papers (3)
| | PDF (286 KB)

Binary polarisation shift keying (BPOLSK) has been proposed to mitigate the atmospheric turbulence-induced fading in free space optical (FSO) communication systems. In this study, the Q-factors obtained for the BPOLSK-FSO system are verified in conjunction with theoretical results to confirm the validity of the proposed scheme. The analytical bit error rate (BER) for the BPOLSK and non-retu... View full abstract»

• ### Spectrum sharing in cognitive radio networks: an adaptive game approach

Publication Year: 2012, Page(s):1495 - 1501
Cited by:  Papers (2)
| | PDF (381 KB)

Throughout this study, an adaptive competitive second-price pay-to-bid sealed auction game is presented as a solution to the fairness problem of spectrum sharing among a number of users in a cognitive radio environment. First, a comparison among three main spectrum-sharing game models; optimal, cooperative and competitive game models is discussed to highlight the advantages and disadvantages of ea... View full abstract»

• ### Analysing bit-interleaved coded modulation in multiple-input multiple-output systems with channel estimation error

Publication Year: 2012, Page(s):1502 - 1510
| | PDF (457 KB)

The performance of bit-interleaved coded modulation in multiple-input multiple-output (BICM-MIMO) systems using an iterative channel estimator is analysed. In a conventional iterative channel estimator, after initialisation with the training phase, the channel estimator switches to the data phase. However, such a conventional iterative channel estimator does not always improve the performance of t... View full abstract»

• ### Max-min fairness aware joint power, subcarrier allocation and relay assignment in multicast cognitive radio

Publication Year: 2012, Page(s):1511 - 1518
Cited by:  Papers (2)
| | PDF (373 KB)

The authors presented low-complexity schemes for jointly deciding subcarrier assignment, power allocation and relay assignment (JSPARA) for multiuser non-regenerative relaying in a multigroup, multicast cognitive radio system (MMCRS). The authors considered two different optimisation problems. In one optimisation problem, the authors studied the problem of maximising the sum-rate of an MMCRS. In a... View full abstract»

• ### Outage capacity optimisation for cognitive radio networks with cooperative communications

Publication Year: 2012, Page(s):1519 - 1528
Cited by:  Papers (3)
| | PDF (625 KB)

Cognitive radio networks with cooperative communications can effectively improve spectrum efficiency and data rate. Under this network scenario, there are three possible transmission modes: direct transmission, multi-hop transmission and cooperative communication. To optimise the system performance, three issues should be carefully considered: whether or not and which relay is needed, which channe... View full abstract»

• ### Bidirectional gigabit ethernet optical wireless communications system for home access networks

Publication Year: 2012, Page(s):1529 - 1536
Cited by:  Papers (1)
| | PDF (607 KB)

The design, simulation and practical implementation for a bidirectional 1.25 Gbit/s indoor optical wireless communications system has been presented. It is a part of the European community funded hOME Gigabit Access project (OMEGA). The line-of-sight (LOS) system uses angle-diversity transceivers enabling discrete beam steering. Each transceiver uses three transmitting and receiving elements givin... View full abstract»

• ### Performance bound for generalised multilevelquadrature amplitude modulations constellations in multipath Rayleigh fading channels with imperfect channel estimation

Publication Year: 2012, Page(s):1537 - 1543
Cited by:  Papers (2)
| | PDF (486 KB)

The authors derive a lower bound on the performance of generalised multilevel quadrature amplitude modulations (M-QAM) in time-discrete multipath Rayleigh fading environments with imperfect channel estimation. The bound can be regarded as an extension of the well-known matched filter bound (MFB), taking into account the impact of imperfect channel knowledge. The analytical expressions deriv... View full abstract»

• ### Spectral efficient impulse radio-ultra-wideband transmission model in presence of pulse attenuation and timing jitter

Publication Year: 2012, Page(s):1544 - 1554
| | PDF (965 KB)

This study investigates the spectrum shaping observed in ultra-wideband (UWB) communications. An auxiliary independent signal (AIS) to limit undesired spectral lines because of periodicity or unbalanced data sources (i.e. non-uniformly distributed) and or non-symmetric data modulation schemes are introduced. Each transmitted symbol is represented by a preamble AIS pulse followed by a set of transm... View full abstract»

## Aims & Scope

IET Communications covers the theory and practice of systems, networks and applications involving line, mobile radio, satellite and optical technologies for telecommunications, and Internet and multimedia communications.

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