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Communications, IET

Issue 2 • Date February 2008

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Displaying Results 1 - 25 of 26
  • Editorial - Special Section on telemedicine and e-Health communication systems

    Publication Year: 2008 , Page(s): 179 - 180
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  • Implementation of an end-to-end standard-based patient monitoring solution

    Publication Year: 2008 , Page(s): 181 - 191
    Cited by:  Papers (8)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (971 KB)  

    A proof-of-concept design of a patient monitoring solution for intensive care unit environments has been presented. It is end-to-end standard-based, using ISO/IEEE 11073 (X73) in the bedside environment and EN13606 to communicate the information to an electronic healthcare record (EHR) server. At the bedside end, the system is a plug-and-play sensor network communicating with a gateway that collects medical information and sends the data to a monitoring server. The monitoring server transforms this information into an EN13606 extract to be stored on the EHR server. The system has been implemented to comply with the last X73 and EN13606 available versions and tested in a laboratory environment to demonstrate the feasibility of an end-to-end standard-based solution. View full abstract»

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  • SAPHIRE: intelligent healthcare monitoring based on semantic interoperability platform: pilot applications

    Publication Year: 2008 , Page(s): 192 - 201
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1067 KB)  

    As a response to the challenge of providing high-quality healthcare services with reasonable costs while the elderly population and the associated chronic diseases increase, SAPHIRE architecture provides an intelligent healthcare monitoring architecture. The monitoring of patients is achieved through a clinical decision support system based on clinical guidelines. SAPHIRE provides the necessary interoperability layers to access the patient's vital signs from wireless medical sensors and the electronic healthcare records of the patient in order to exploit them in the decision process seamlessly. This architecture is presented through two pilot applications: one for the bedside monitoring of cardiac patients at hospitals, and the other for homecare monitoring of the cardiac patients rehabilitated after a revascularisation therapy. View full abstract»

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  • Quality labels for e-health

    Publication Year: 2008 , Page(s): 202 - 207
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (316 KB)  

    A drug e-prescription demonstrator was created in compliance with existing legislation as well as security and privacy standards. A professional ID-card was built on a high security chip (ISTEC E4 High; EAL-5) with a Hash hardware accelerator for a digital signature placed in a single chip USB token. Commercial software products as well as development kits of the new hardware designed in the project were used to build an authentication, authorisation and electronic signature demonstrator. The degree of legal compliance was evaluated. The tested novel single chip USB token was highly efficient but limited by its 1.1 interface speed (12 Mbit/s). The chip, initialised with a banking-mask, inefficiently managed space for the health-care chain of trust. The public key and privilege management infrastructure was not able to handle health-care attributes in the appropriate extensions. Templates for role-rule privileges were not available and healthcare standards for security and privacy were not found in commercial products. The paper points out the urgent need for an e-health conformance label as well as a quality label for liability and confidence to gain users' trust. View full abstract»

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  • ZigBee-based alarm system for pervasive healthcare in rural areas

    Publication Year: 2008 , Page(s): 208 - 214
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (431 KB)  

    An alarm system suitable for pervasive healthcare in rural areas is presented. Taking advantage of ZigBee features, users can move freely around their habitual environment while enjoying constant protection. The resulting system is cost-effective, easily deployed (no wiring is needed) and the mobile device's batteries last for months. The user interface is a key issue when working with the elderly and those with disabilities. To ensure proper usability and avoid abandoning of the device, an alarm-detection procedure has been developed and contrasted with end-users. The application scenario is the isolated village of Fortanete, Spain, where the self- sustainability of the system is essential. In this environment, management of the alarm relies upon the user's relatives and neighbours to solve any problems that arise. Privacy and ethical considerations have also been addressed, as this kind of system can potentially invade the users' privacy; cognitive disabilities of the users also make it mandatory. View full abstract»

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  • Body area network for wireless patient monitoring

    Publication Year: 2008 , Page(s): 215 - 222
    Cited by:  Papers (37)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (718 KB)  

    Patient data monitoring is a key issue for health and disease management. The use of wireless sensors within a body area network (BAN) makes this task seamless and easy. A BAN system is presented, which allows the connectivity of a wide range of heterogeneous body sensors to a portable hub device that is connectable to external networks (IEEE 802.11, GPRS). This BAN is based on the use of Zigbee/IEEE 802.15.4 standard technology and off-the-shelf modules. It is currently being used at the European level for the detection and the prediction of the human physiological state in relation to wakefulness, fatigue, and stress applications in which users carrying out daily activities are monitored in an unobtrusive and comfortable way. Characterised by its low power consumption, low cost, and ability to connect a wide range of heterogeneous sensors, this system can substantially improve the performance of different services, especially those that are health related. View full abstract»

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  • Mobile e-Health monitoring: an agent-based approach

    Publication Year: 2008 , Page(s): 223 - 230
    Cited by:  Papers (13)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (527 KB)  

    An ageing population is now the leading healthcare concern of many countries in the world. Aged patients need more healthcare efforts as they present more cases of chronic illnesses involving higher healthcare costs. e-Health systems based on modern information technology are expected to play a role in alleviating this problem. Fortunately, there have been dramatic advances in healthcare technology in terms of mobility, size, speed and communication. However, the main drawbacks of currently deployed e-Health monitoring systems originate from the fact that patients are 'constrained' within smart rooms and beds fitted with monitoring devices. Such monitoring is not ubiquitous in view of the privacy, mobility and flexibility issues concerning patients. On the other hand, health monitoring products strapped to the patient's body provide no analysis or recommendations of results. A multi-agent architecture for mobile health monitoring is presented, involving a team of intelligent agents that collate patient data, reason collectively and recommend actions to patients and medical staff in a mobile environment. View full abstract»

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  • Telemedicine and tele-health services for cancer-care delivery in India

    Publication Year: 2008 , Page(s): 231 - 236
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (249 KB)  

    Noncommunicable diseases including cancer are emerging as major public health problems in India. Awareness of cancer and its management are being taken as a high priority at the national level because of the increase in the incidence of the disease in the country. Telemedicine provides expert-based health care to understaffed remote sites and advanced emergency care through modern telecommunication and information technologies. The incidence of cancer can be reduced if the people are aware of cancer and its root causes. Recently, the introduction of telemedicine in oncology plays a vital role. Telemedicine helps in prevention, early detection, a faster cure, palliative care and rehabilitation in the management of cancer. The status of telemedicine services for cancer care in Kerala, India, and how telemedicine can be an effective solution of cancer- care delivery in India are explored. View full abstract»

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  • Ubiquitous wireless telemedicine

    Publication Year: 2008 , Page(s): 237 - 254
    Cited by:  Papers (9)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (834 KB)  

    A general overview of the emerging wireless and networking technologies and their use to promote the ultimate goal of global health by means of deployment of a telemedicine paradigm is discussed. To achieve this the authors conduct a state-of-the-art study of recent wireless and medical sensor technologies in conjunction with investigation of continuously growing pressures for a better healthcare service throughout the world triggered by the growing age population, social transformations. The study reveals that in spite of available superior technological solutions the services are mostly too expensive, mostly inadequate to respond to the growing demand. Then it proposes a flagship solution of making the best use of the next generation of 'wireless computing' for building a new harmonised healthcare infrastructure for which the authors need to encourage researchers in the development of an innovative media-independent ubiquitous wireless telemedicine system for more cost effective superior quality healthcare services. View full abstract»

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  • Internally coded multicarrier frequency-hopping CDMA communication system and its performance analysis

    Publication Year: 2008 , Page(s): 255 - 265
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (387 KB)  

    A new internally coded scheme that combines frequency hopping (FH) and multicarrier (MC) code division multiple access (CDMA) techniques using a super-orthogonal encoder is proposed. In this method, the total bandwidth is partitioned into Ns2 disjoint bands and each band is also segmented into Ns1 subbands. On the basis of a super-orthogonal encoder output and a pseudorandom sequence, one of the Ns1 bands is selected. The data bit is then transmitted in the band in the form of the multicarrier FH (MC-FH) CDMA scheme, that is, Ns2 carriers are transmitted in the Ns2 subbands of the selected band. At the receiver, both hard and soft detectors are used. The performance of the proposed method in the additive white Gaussian noise (AWGN) and fading channels is evaluated. The results indicate that the proposed method outperforms the previously presented uncoded and coded MC-FH-CDMA systems, where the data are transmitted over the whole bandwidth, keeping the same bandwidth (spectral efficiency). Further, in the new method, the carriers hop in part of the total bandwidth, and hence coherent detection is more feasible. View full abstract»

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  • Comparison of direct-sequence impulse radio and direct-sequence ultra-wide bandwidth in multi-user interference

    Publication Year: 2008 , Page(s): 266 - 271
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (338 KB)  

    A new ultra-wide bandwidth communication system using both a time-hopping (TH) sequence and a direct spreading sequence, called direct-sequence impulse radio (DS-IR), has recently been proposed. An exact analysis to evaluate the bit error rate (BER) performance of this new scheme in multi-user interference (MUI) is provided. On the basis of this new analysis, ultra-wideband communication systems employing TH, direct-sequence and the newly proposed DS-IR schemes operating in MUI are accurately compared in terms of the BER. Our results indicate that DS-IR outperforms the TH binary phase-shift keying (BPSK) system. However, its performance is poorer than the performance of the conventional full-duty direct sequence BPSK system. Compared with the low-duty direct sequence BPSK system, DS-IR achieves a better error rate performance for medium and large signal-to-noise power-ratio values. View full abstract»

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  • Performance comparison of low density parity check codes using square root Kalman equalisation and orthogonal frequency division multiplexing techniques for broadband fixed wireless access systems

    Publication Year: 2008 , Page(s): 272 - 283
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (706 KB)  

    Broadband fixed wireless access (BFWA) systems enable services such as high-speed data communication, high quality voice/video conferencing and high-speed internet access in areas where a wired link is not possible. However, the BFWA channel is a slow-fading channel having deep frequency-selective fading caused by clusters of scatterers in the environment that introduce inter-symbol interference (ISI) at the receiver. Low density parity check (LDPC) codes, optimised for the single-input single-output BFWA channel, are designed using the structured balance incomplete block design method. The use of both quadrature phase shift keying (QPSK) and 16-quadrature amplitude modulation (16-QAM) are investigated theoretically. To help overcome the ISI effects of the channel, equalisation techniques are employed separately with LDPC decoding for a system employing QPSK and 16-QAM modulation schemes. The equaliser single carrier approach is then replaced with orthogonal frequency division multiplexing (OFDM) and the performance of these two approaches is evaluated in terms of bit-error rate. The simulation results show that equalisation with LDPC coding has a measurable performance gain over LDPC coding with OFDM. View full abstract»

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  • Robust end-to-end loss differentiation scheme for transport control protocol over wired/wireless networks

    Publication Year: 2008 , Page(s): 284 - 291
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (911 KB)  

    The authors propose a robust end-to-end loss differentiation scheme to identify the packet losses because of congestion for transport control protocol (TCP) connections over wired/wireless networks. The authors use the measured round trip time (RTT) values to determine whether the cause of packet loss is because of the congestion over wired path or regular bit errors over wireless paths. The classification should be as accurate as possible to achieve high throughput and maximum fairness for the TCP connections sharing the wired/wireless paths. The accuracies of previous schemes in the literature depends on varying network parameters such as RTT, buffer size, amount of cross traffic, wireless loss rate and congestion loss rate. The proposed scheme is robust in that the accuracy remains rather stable under varying network parameters. The basic idea behind the scheme is to set the threshold for the classification to be a function of the minimum RTT and the current sample RTT, so that it may automatically adapt itself to the current congestion level. When the congestion level of the path is estimated to be low, the threshold for a packet loss to be classified as a congestion loss is increased. This avoids unnecessary halving of the congestion window on packet loss because of the regular bit errors over the wireless path and hence improves the TCP throughput. When the congestion level of the path is estimated to be high, the threshold for a packet loss to be classified as the congestion loss not to miss any congestion loss is decreased and hence improves the TCP fairness. In ns 2 simulations, the proposed scheme correctly classifies the congestion losses under varying network parameters whereas the previous schemes show some dependency on subsets of parameters. View full abstract»

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  • Distributed algorithm for optimal sequence and power allocation in uplink code division multiple access systems

    Publication Year: 2008 , Page(s): 292 - 299
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (279 KB)  

    An alternative approach is presented for centralised algorithms that design optimal sequences and powers under quality of service constraints in the uplink of a code division multiple access systems. The authors propose a distributed algorithm, where each user designs its optimal codeword in such a way to transmit minimum power, based on certain feedback information sent from the base station. The authors define the user cost function, which is the user power written as a convex function of user codewords for a defined signal-to-interference plus noise ratio target. For the constrained optimisation problem, optimal codewords are designed based on feasible direction method and the optimal user powers are the minimum values of the user cost functions. For the optimal configuration, the matched filter employed at receiver will have the same performance as the minimum mean squared error filter. Even if the optimal user powers are unique, the optimal codewords do not correspond to a unique allocation, but rather to an entire class of codewords that can be related by unitary transformations. The algorithm works properly in the presence of multiple access interference with white or coloured additive noise and requires no ordering. The proposed algorithm is analysed and illustrated with numerical examples obtained from simulations. View full abstract»

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  • Iterative cancellation of clipping noise in multilevel quadrature amplitude modulation multi-carrier CDMA system

    Publication Year: 2008 , Page(s): 300 - 305
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    An iterative reconstruction method that was proposed for clipping noise cancellation in orthogonal frequency domain multiplexing (OFDM) systems is applied to multilevel quadrature amplitude modulation-based multi-carrier (MC) code division multiple access signals in downlink. The iterative method uses a known distortion function, maybe a nonlinear one such as a successive clipping and filtering process, in the iterations to give an approximation of inverse of the distortion process and then the iterative method removes distortion under a convergence condition. The authors show that MC signal with properly chosen clipping threshold satisfies convergence conditions of the iterative method. In contrast to some of the other reconstruction-based techniques, this method requires no extra bandwidth and side information and it can be implemented with reasonable complexity. Furthermore, the authors show that the proposed iterative scheme can be enhanced by using an extra frequency bandwidth. Exploiting extra bandwidth improves the performance of the reconstruction-based methods in case of using successive clipping and filtering. Simulation results will be used to demonstrate achievable bit-error-rate improvement by the proposed enhanced iterative scheme. View full abstract»

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  • On physical layer-oriented routing with power control in ad hoc wireless networks

    Publication Year: 2008 , Page(s): 306 - 319
    Cited by:  Papers (9)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (985 KB)  

    Routing in ad hoc wireless networks does not simply consist in finding a route with shortest length (as in wired networks with virtually error-free communication links), but it requires the creation of a stable and good quality communication route to avoid any unnecessary packet loss. In this paper,we discuss physical layer-oriented routing in ad hoc wireless networks, and we analyse the potential advantages of combining the use of power control (PC) with the chosen routing strategy. More precisely, we propose a modified ad hoc on-demand distance vector (MAODV) routing protocol, with and without PC, derived from the AODV-routing protocol by considering the bit error rate at the end of a multi-hop path as the metric to be minimised for route selection. In other words, we consider routing with a physical layer-oriented quality of service criterion, and we analyse the system performance in scenarios with either strong line-of-sight (LOS) or shadowed communications. Although in a scenario with strong LOS communications there are a few cases where the MAODV-PC protocol offers the best performance, in the presence of shadowed communications the proposed physical layer-oriented strategy is not attractive. View full abstract»

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  • Performance of blind channel estimation algorithms for space-frequency block coded multi-carrier code division multiple access systems

    Publication Year: 2008 , Page(s): 320 - 328
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (237 KB)  

    The problem of blind channel estimation for downlink space-frequency block coded multi-carrier code division multiple access (SFBC MC-CDMA) schemes is considered. For these schemes, the authors first develop a system model for complex modulated signals, which reduces the multichannel estimation problem to a single-input single-output problem. Then, they present an intuitive subspace-based channel estimation method along with the corresponding necessary and sufficient conditions under which the channel estimate is unique (within a complex scalar). Their studies highlight two interesting properties of SFBC MC-CDMA systems: (i) there is no antenna order ambiguity (also known as permutation ambiguity) even though only one spreading code is assigned to each user; (ii) channel identifiability is guaranteed, regardless of the channel zeros location. They also establish the unbiasedness of the channel estimates and derive closed-form expressions for the mean-square-error of the estimates as well as the corresponding Cramer-Rao bound (CRB). In the derivation of the CRB, they suggest a novel approach which assumes the knowledge of only the spreading code of desired user. This approach results in a tighter bound than the CRB derived based on the knowledge of all users' signatures. View full abstract»

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  • Integrated quality-of-service differentiation over IEEE 802.11 wireless LANs

    Publication Year: 2008 , Page(s): 329 - 335
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (515 KB)  

    The fundamental medium access control mechanism in IEEE 802.11 wireless LANs (WLANs)-distributed coordination function (DCF) only supports the best-effort service and does not support quality-of-service (QoS) differentiation. Enhanced distributed channel access (EDCA) in IEEE 802.11e supports delay differentiation. A new approach, EDCA+ , is proposed to enhance QoS over WLANs. It simultaneously achieves bandwidth, delay and jitter differentiation by distinguishing the minimum contention window, the maximum backoff stage or persistent factor and packet-loss rate differentiation by distinguishing the retry limit. Analytical models are proposed to analyse the performance of EDCA+ in terms of throughput, bandwidth, delay, jitter and packet-loss rate. Extensive simulations are also carried out to evaluate the accuracy of the proposed performance models and to compare the performance of DCF, EDCA and EDCA+. The simulation results show that EDCA+ performs better than DCF and EDCA in ensuring integrated QoS, and that the proposed analytical models are valid. View full abstract»

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  • Performance analysis of multi-homed transport protocols with network failure tolerance

    Publication Year: 2008 , Page(s): 336 - 345
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (790 KB)  

    The performance of multi-homed transport protocols tolerant of network failure is studied. It evaluates the performance of different retransmission policies combined with path failure detection thresholds, infinite or finite receive buffers for various path bandwidths, delays and loss rate conditions through stream control transmission protocol simulation. The results show that retransmission policies perform differently with different path failure detection threshold configurations. It identifies that retransmission of all data on an alternate path with the path failure detection threshold set to zero performs the best in symmetric path conditions but its performance degrades acutely in asymmetric path conditions even when the alternate path delay is shorter than the primary path delay. It illustrates that retransmission of all data on the same path with the path failure detection threshold set to one or zero gives the most stable performance in all path configurations. View full abstract»

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  • Efficient multi-user detection scheme for overloaded group-orthogonal MC-CDMA systems

    Publication Year: 2008 , Page(s): 346 - 352
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (481 KB)  

    An efficient multi-user detection scheme for overloaded MC-CDMA systems is presented. The proposed detection scheme for overloaded systems achieves the optimal performance for constant-modulus modulation schemes, for example MPSK, and provides near-optimal performance for non-constant-modulus modulation, for example M-QAM. Moreover, it has overall lower complexity than the other optimal detection algorithms, especially suitable for group-orthogonal MC-CDMA systems, where group-based technique keeps multi-user receiver size relatively small. View full abstract»

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  • Comparison between wavelet-based and Fourier-based multicarrier UWB systems

    Publication Year: 2008 , Page(s): 353 - 358
    Cited by:  Papers (10)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (301 KB)  

    The use of wavelet transform in multicarrier ultra wideband (UWB) systems is analysed and the results are compared with Fourier-based multicarrier UWB systems. It is well known that convolution in time domain is equivalent to multiplication in frequency domain; however, there is no closed-form expression in the literature for convolution's counterpart in the wavelet domain. A formula is derived to represent convolution's counterpart in the wavelet domain. Furthermore, the effects of choice and type of wavelet filters and different decomposition levels are investigated. Finally, a performance comparison of both techniques for IEEE 802.15.3a channel models using IEEE802.15.3a multiband-orthogonal frequency division multiplexing UWB specifications is provided. View full abstract»

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  • Adaptive pseudo-noise code acquisition scheme using automatic censoring for DS/SS communication in frequency-selective Rayleigh fading channel

    Publication Year: 2008 , Page(s): 359 - 365
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (314 KB)  

    An adaptive pseudo-noise code acquisition scheme based on automatic multipath signal cancellation for mobile communication systems in frequency-selective Rayleigh fading channel is proposed. The proposed system combines a serial strategy and an automatic censored cell-averaging constant false alarm rate (CFAR) detector based on ordered data variability. This system does not require any a priori information about the number of interferences caused by the presence of multipath signals in the reference channel. The mean acquisition time and the detection performances of the proposed processor are evaluated and compared with those of the conventional adaptive acquisition scheme based on fixed-censoring point detector. It is shown that the considered scheme outperforms significantly the conventional one. The effects of various channel parameters on the acquisition performance, namely the number of resolvable paths, the partial correlation length and the signal-to-noise ratio are also investigated. View full abstract»

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  • Pulse position modulated space-time trellis coding for ultra-wideband impulse radio multiple-input multiple-output communication systems

    Publication Year: 2008 , Page(s): 366 - 371
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (270 KB)  

    The design of pulse position modulated (PPM) space-time trellis codes (STTC) for ultra-wideband impulse radio (UWB-IR) multiple-input multiple-output (MIMO) communication systems over slow and fast fading multipath channels is considered. First, A probability of error analysis is carried out to derive upper bounds on pairwise symbol error probability at high and low signal-to-noise ratios (SNRs). From the upper bounds, A new distance notion is introduced and novel design criteria for optimal (in error rate performance) M-ary PPM STTC are deduced for UWB. An optimal binary-PPM STTC is designed for two transmit antennas. Finally, simulation results of the UWB-IR MIMO system, using the optimal STTC, confirm significant improvement in bit-error-rate performance over the uncoded UWB-IR single-input single-output system and also over previously proposed space-time coding scheme for UWB, at higher SNR. View full abstract»

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  • Non-coherent improved-gain diversity reception of binary orthogonal signals in Nakagami-q (Hoyt) mobile channels

    Publication Year: 2008 , Page(s): 372 - 379
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (161 KB)  

    A novel non-coherent receiver with diversity reception for binary orthogonal signals in non-identical Nakagami-g (Hoyt) fading channels (channels having arbitrary average fading powers and arbitrary fading parameters) is proposed. A closed-form expression for the average bit error probability of the proposed receiver is derived, which is given in terms of elementary functions, and can be readily evaluated numerically. In addition, the results clarify that the proposed receiver does not incur non-coherent combining loss, and at the same time, lower bounds the performance of the conventional non-coherent equal-gain combining (NC-EGC) receiver. Simulation results are provided to validate the mathematical analysis. View full abstract»

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  • Performance analysis of multipath transmission over 802.11-based multihop ad hoc networks: a cross-layer perspective

    Publication Year: 2008 , Page(s): 380 - 387
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (350 KB)  

    Data transmission in ad hoc networks involves interactions between medium access control (MAC)-layer protocols and data forwarding along network-layer paths. These interactions have been shown to have a significant impact on the performance of a system. This impact on multipath data transmission over multihop IEEE 802.11 MAC-based ad hoc networks is assessed; analysis is from a cross-layer perspective. Both MAC layer protocols and network-layer data forwarding are taken into account in the system models. The frame service time at source in a 802.11 MAC-based multipath data transmission system under unsaturated conditions is studied. Analytical models are developed for two packet generation schemes (round robin and batch) with a Poisson frame arrival process. Moreover, an analytical model is developed to investigate the throughput of a multipath transmission system in 802.11-based multihop wireless networks. Two methods are proposed to estimate the impact of cross-layer interactions on the frame service time in such a system. Two bounds of the system throughput are obtained based on these estimation methods. These models are validated by means of simulation under various scenarios. View full abstract»

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