IET Communications

The automatic recognition of the modulation format of a detected signal, the intermediate step between signal detection and demodulation, is a major task of an intelligent receiver, with various civilian and military applications. Obviously, with no knowledge of the transmitted data and many unknown parameters at the receiver, such as the signal power, carrier frequency and phase offsets, timing i... View full abstract»

A method for automatic classification of composite FM/PM speech signals is proposed here. The method classifies a number of intercepted signals into FM or PM, provided that each signal is either speech FM or PM. The signals are transmitted through flat fading channels and contaminated with white Gaussian noise. A linear array consisting of several sensors is constructed to intercept these signal. ... View full abstract»

Use of IEEE 802.11 wireless local area networks (WLANs) as an extension to existing wired networks, offering both mobility and portability in a residential or office environment, is growing at an unprecedented rate. One of the critical limitations of current WLANs is the limited energy storage of mobile devices, and the design of energy-efficient protocols for WLANs has therefore become an area of... View full abstract»

The fact that ad hoc networks are required to support mobility of individual network nodes results in problems arising when routing data. These problems include route loss, poor longevity of established routes and asymmetric communications links. Mobility of nodes also increases the control traffic overhead and affects the performance of the protocol. Mobility can, however, be exploited to improve... View full abstract»

Control phase plays a critical role in the performance of time-division multiple access (TDMA)-based networks. Within cluster-based wireless sensor networks, a nimble and adaptive control phase algorithm called NACPA to control the control phase of TDMA-based medium access control (MAC) in cluster-based sensor networks is proposed. This algorithm takes advantage of the wireless sensor hardware fea... View full abstract»

This communication discusses implementation aspects of a novel, fast iterative tap amplitude and delay estimation (ITADE) technique for RAKE receivers required for the downlink in the universal mobile telecommunications system (UMTS) frequency domain duplex (FDD) mode wideband code division multiple access (WCDMA). The Texas Instruments TMS320C6416 digital signal processor (DSP), operating at 720 ... View full abstract»

The performance of a time hopping combined with pulse position modulation ultra wide band system with a nonlinear receiver using an adaptive filter and a soft-limiter in the presence of narrowband interference has been considered. This system brings a significant performance improvement compared with the system that uses an adaptive filter and a linear receiver, particularly in the case of high-in... View full abstract»

An improved discrete Fourier transform (DFT)-based channel estimation for orthogonal frequency division multiplexing systems is proposed. Conventional DFT-based channel estimations improve the performance by suppressing time domain noise. However, they potentially require information on channel impulse responses and may also result in mean-square error (MSE) floor due to incorrect channel informat... View full abstract»

The performance of binary phase shift keying in a Weibull fading environment is analysed in the presence of cochannel interference (CCI) in terms of the bit error rate (BER). We derive an exact expression for the BER in this case on the basis of a characteristic function approach. Furthermore, since it is difficult to obtain the distribution of the CCI and because of the complexity of the obtained... View full abstract»

The first complete measurement of the Chinese Internet topology at the autonomous systems (AS) level based on traceroute data probed from servers of major ISPs in mainland China is presented. Both the Chinese Internet AS graph and the global Internet AS graph can be accurately reproduced by the positive-feedback preference model with the same parameters. This result suggests that the Chinese Inter... View full abstract»

A statistical characterisation of a small-scale fading mobile radio channel is presented and a fading simulator for the simulation of multiple input-multiple output multicarrier systems is introduced. The derivation of the equivalent lowpass channel as a function of time, transmit and receive antenna positions and subcarrier frequency, leads to a tapped delay-line model with time, space and freque... View full abstract»

A new time-hopping ultrawideband (TH-UWB) CDMA scheme for indoor wireless communications is presented. In the proposed method, the duration of each bit is divided into Ns1 frames, each one containing Ns2 subframes. Two pseudorandom sequences are assigned to each user. During each bit interval, based on the output of a super-orthogonal encoder and the user's first dedicated ps... View full abstract»

A priority-based CDMA system with variable code reservation periods for supporting multiple traffic types is presented. For the purpose of evaluation we build mathematical models for analysing two subsystems with different types of multimedia traffic. Two performance measures, the average packet dropping probability and the average packet transmission delay, are derived from the models based on eq... View full abstract»

List decoding is a novel method for decoding Reed-Solomon (RS) codes that generates a list of candidate transmitted messages instead of one unique message as with conventional algebraic decoding, making it possible to correct more errors. The Guruswami-Sudan (GS) algorithm is the most efficient list decoding algorithm for RS codes. Until recently only a few papers in the literature suggested pract... View full abstract»

Under the signal-strength-based power control scheme, the effect of various microcell cluster locations on the uplink average signal-to-interference ratio (also called carrier-to-interference ratio, or CIR) is studied for the hierarchical code-division multiple-access cellular system with attenuators applied to each microcell base station. On the basis of the interference statistics analysis, the ... View full abstract»

A general and simple differential modulation scheme that can be applied to both partial-diversity quasi-orthogonal space-time block codes and full-diversity quasi-orthogonal space-time block codes is reported. A new class of quasi-orthogonal coding structures is presented for various number of transmit antennas. Differential encoding and decoding can be simplified to differential Alamouti codes by... View full abstract»

Radio resource management in wireless data networks is different from that of voice networks. This is mostly due to the different quality of service that users perceive for different signal to interference ratios. The reference system used here is HIPERLAN type 2, which has both a link adaptation (LA) mechanism, that is the ability to adapt data rates to channel quality and a power control mechani... View full abstract»

The paper develops a new method for estimating and correcting the carrier frequency offsets (CFO) of orthogonal frequency division multiple access (OFDMA) systems at the uplink receiver. Multiple CFO of the different users in the OFDMA system may violate the orthogonality among subcarriers and induce inter-carrier interference (ICI) and inter-user interference (IUI). The IUI provides some extra ch... View full abstract»

A signal attenuation difference of arrival (SADOA) scheme is proposed to combine with the time difference of arrival (TDOA) method for mobile location estimation. On the basis of ratio of distances between the mobile and base stations derived from differences of signal attenuations, each SADOA measurement yields a circle on which the mobile may lie. Meanwhile, each TDOA measurement defines a hyper... View full abstract»

Presents an erratum for the paper by Barbero and Thompson (IET Commun., vol.1, no.1, p.122-30, 2007). View full abstract»