# IET Communications

## Filter Results

Displaying Results 1 - 17 of 17
• ### Geographic hole-bypassing forwarding protocol for wireless sensor networks

Publication Year: 2011, Page(s):737 - 744
Cited by:  Papers (4)
| | PDF (463 KB)

The authors propose a new geographic hole-bypassing forwarding (HBF) protocol to address the hole diffusion problem in wireless sensor networks (WSNs). To support efficient hole-bypassing, the HBF protocol models a hole using a virtual circle whose radius is adjustable within a certain range and is calculated on a per-packet basis. The information associated with the virtual circle will be used, i... View full abstract»

• ### Optimal M-amplitude shift keying/quadrature amplitude shift keying with non-equal symbol probabilities

Publication Year: 2011, Page(s):745 - 752
Cited by:  Papers (3)
| | PDF (375 KB)

In this study the authors derive a formula to compute the optimal signal constellation, bit error probabilities and decision thresholds for M-ASK (amplitude shift keying) with non-equal symbol probabilities. The resulting signal constellation is not equally spaced. The authors demonstrate the importance of assigning lower energy signals to symbols with higher probabilities. The authors show... View full abstract»

• ### Enhanced buffer management policy that utilises message properties for delay-tolerant networks

Publication Year: 2011, Page(s):753 - 759
Cited by:  Papers (5)
| | PDF (483 KB)

A delay-tolerant network is a network designed so that temporary or intermittent communication problems and limitations have the least possible adverse impact. Two major issues should be considered to achieve data delivery in such challenging networking environments: a routing strategy for the network and a buffer management policy for each node in the network. The routing strategy determines whic... View full abstract»

• ### Cooperative relay broadcast channels with partial causal channel state information

Publication Year: 2011, Page(s):760 - 774
| | PDF (648 KB)

The authors consider partially and fully cooperative state-dependent relay broadcast channels (RBCs), where partial channel state information (CSI) is available at the nodes causally. First, the authors derive an achievable rate region for general discrete memoryless partially cooperative RBC (PC-RBC) with partial causal CSI, by exploiting superposition coding at the source, decode-and-forward... View full abstract»

• ### Improving the performance of power-aware multi-rate IEEE 802.11 in multihop wireless networks

Publication Year: 2011, Page(s):775 - 788
Cited by:  Papers (1)
| | PDF (678 KB)

In multihop, multi-rate wireless networks, simultaneous transmissions can interfere with one another to impair the transmission quality and prevent correct frame reception. Achieving high network performance (e.g. throughout and energy consumption) in such networks therefore requires a balance between the spectrum spatial reuse and the transmission quality. To achieve this trade-off, a decentralis... View full abstract»

• ### Time-multiplexed single front-end multiple-input multiple-output receivers with preserved diversity gain

Publication Year: 2011, Page(s):789 - 796
Cited by:  Papers (4)
| | PDF (836 KB)

A design technique to realise a low-complexity multiple-input multiple-output (MIMO) receiver using a time-multiplexed single front-end receiver is introduced. The architecture uses a simple front-end receiver where it delivers radio frequency signals to baseband section. The theory behind this architecture is analysed and the diversity gain of the proposed receiver is investigated. This simple MI... View full abstract»

• ### Optimal SNR-based selection relaying scheme with M-ary modulations in cooperative wireless networks

Publication Year: 2011, Page(s):797 - 810
Cited by:  Papers (2)
| | PDF (1333 KB)

Error propagation from the relay to the destination is a major drawback of digital relaying protocols that substantially diminishes the cooperative diversity gain of the system. Appropriately designed selection relaying schemes can effectively mitigate this phenomenon and improve the diversity order, especially when the source-relay channel state information (CSI) is not available at the destinati... View full abstract»

• ### Outage threshold extraction for maximising the capacity of wireless ad hoc networks

Publication Year: 2011, Page(s):811 - 818
Cited by:  Papers (3)
| | PDF (603 KB)

In this article, the authors develop an analytical closed-form expression for the outage capacity of a wireless ad hoc network. First, a series of practical modulation schemes including binary phase shift keying (BPSK) and quadrature amplitude modulation (QAM) are considered. Then, a proper formulation for the total network capacity is presented based on the cumulative distribution functi... View full abstract»

• ### Incoherent spatial diversity combining scheme for spread spectrum

Publication Year: 2011, Page(s):819 - 826
| | PDF (419 KB)

There are applications in spread spectrum channels where spatial diversity is required to mitigate fading. The spreading gain in such channels is often limited to reduce the chances of a nearby interferer being in-band. With modest spreading gains the signal bandwidth may be less than the coherence bandwidth. In such cases receiver-based multi-path diversity is not feasible, and spatial diversity ... View full abstract»

• ### Performance analysis of multiple input single output systems using transmit beamforming and antenna selection with delayed channel state information at the transmitter

Publication Year: 2011, Page(s):827 - 834
Cited by:  Papers (1)
| | PDF (299 KB)

The authors consider a multiple input single output (MISO) system in which both transmit beamforming and antenna selection (AS) are implemented using delayed channel state information (CSI) at the transmitter (CSIT). The performance of the system has been analysed for three different AS schemes wherein two out of N antennas are selected at the transmitter. The authors have derived closed-fo... View full abstract»

• ### Waveform distortion performance evaluation using practical antennas in deterministic multipath impulse radio channels

Publication Year: 2011, Page(s):835 - 843
| | PDF (817 KB)

As a potential future technology, impulse radio is a promising new reliable data transmission method for time-sensitive applications. However, owing to the complex nature of ultra-wideband (UWB) channels used in practice, there are many design problems that remain to be resolved. This study looks into some UWB channels classified as waveform distortion for which the authors present an implementati... View full abstract»

• ### Accurate multiple-input multiple-output fading channel simulator using a compact and highthroughput reconfigurable architecture

Publication Year: 2011, Page(s):844 - 852
Cited by:  Papers (5)
| | PDF (888 KB)

This article presents an ultra-compact and high-throughput reconfigurable fading channel simulator that supports a relatively large number of propagation paths. To closely reflect actual radio channels, the authors used a recently improved Rayleigh and Ricean fading channel model based on the sum-of-sinusoids technique. The improved model is optimised for hardware compactness. To achieve a fast fa... View full abstract»

• ### Reduced feedback selective cluster index scheduling with user pre-selection for next-generation multi-input multi-output orthogonal frequency division multiple access syste

Publication Year: 2011, Page(s):853 - 863
| | PDF (961 KB)

The joint use of opportunistic scheduling and orthogonal frequency division multiple access (OFDMA) provide significant gains in environments of low mobility and scatter for which channel variations are low. The downside of opportunistic scheduling in multicarrier systems such as OFDMA, lies in the substantial uplink overhead required to feed back by the mobile stations (MSs) describing users' ins... View full abstract»

• ### Effects of optical communication receiver circuits on Q and BER estimation accuracy

Publication Year: 2011, Page(s):864 - 871
| | PDF (812 KB)

Q factor and bit error rate (BER) estimation based on synchronous and asynchronous sampling have been established as an important method for performance monitoring in optical networks. This study presents a simple model that estimates Q and BER from experimental data using curve fitting under the Gaussian assumption. The model improves estimation accuracy by optimising the receiver a... View full abstract»

• ### Multi-branch decode-and-forward cooperative diversity networks performance analysis over Nakagami-m fading channels

Publication Year: 2011, Page(s):872 - 878
Cited by:  Papers (13)
| | PDF (374 KB)

In this study, the performances analysis of cooperative-diversity networks using adaptive decode-and-forward (DF) relaying over independent non-identical flat Nakagami-m fading channels is investigated. The authors derive exact and approximate closed-form expressions for the error probability, outage probability and average channel capacity, and analyse their dependence on the channel param... View full abstract»

• ### Advantages of identity certificate segregation in P2PSIP systems

Publication Year: 2011, Page(s):879 - 889
Cited by:  Papers (2)
| | PDF (971 KB)

The security of RELOAD, a protocol developed by the IETF for session initiation protocol (SIP) communications over peer-to-peer (P2P) networks, is based on each user's possession of a public key certificate that links her identity (username) with the identity of her device (nodeID) and a public key. In this study, the authors will analyse a flaw in its design related to the joint certification of ... View full abstract»

• ### Analysis and modelling of interference in bluetooth device discovery

Publication Year: 2011, Page(s):890 - 900
Cited by:  Papers (1)
| | PDF (1285 KB)

During Bluetooth device discovery process, nodes enter inquiry substate to discover other nodes within the range by periodically sending inquiry packets on a predetermined frequency partition of hop frequencies used by neighbouring piconets. Intuitively, potential collisions will occur between inquiry packets and packets exchanged between piconet nodes during connection state, which lead to degrad... 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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