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Date 25-27 June 2012

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Displaying Results 1 - 25 of 37
  • [Copyright notice]

    Page(s): 1
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    Freely Available from IEEE
  • Program

    Page(s): 1 - 5
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    Freely Available from IEEE
  • An AEAD cryptographic framework and TinyAEAD construct for secure WSN communication

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (739 KB) |  | HTML iconHTML  

    A new cryptographic framework called Joint Cypher Mode (JCM) is introduced. JCM provides an authenticated-encryption with associated data (AEAD) cryptographic service in packet-based communication protocols. JCM is utilised to design a resourceful block cipher-based, light-weight construct named TinyAEAD. TinyAEAD is benchmarked in comparison with standardised block cipher-based AEAD schemes, used in contemporary wireless sensor network (WSN) communication protocols. Results of the software simulation benchmark indicate that, TinyAEAD exhibits advantageous performance regarding processing latency, processing throughput and processing efficiency for practical WSN communicated data frame lengths. View full abstract»

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  • Secure multipath routing in wireless multihop networks based on erasure channel modeling

    Page(s): 6 - 10
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (143 KB) |  | HTML iconHTML  

    Multipath routing can offer various advantages for wireless multihop networks. Among these advantages, in this paper, we focus on secure multipath routing using the notion of the information-theoretic security. The rate allocation problem for multipath routing is considered to maximize the throughput from a source node to a destination node with information-theoretic security constraints as a linear optimization problem. We also perform an asymptotic analysis to see whether or not multipath routing (with equal rate allocation) could be secure in terms of the information-theoretic security point of view. View full abstract»

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  • Investigating the impact of message size and broadcast frequency on hybrid data dissemination protocol for VANETs

    Page(s): 11 - 15
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (684 KB) |  | HTML iconHTML  

    Delivering data with maximum efficiency to a widest possible reach is critical for most VANET applications. Multi-hop and store-and-forward are two mutually exclusive categories of ad hoc broadcast protocols that are used to disseminate data. Both these schemes have their strengths but also have weaknesses. In previous work, we proposed a novel hybrid protocol that capitalizes on the strengths and mitigates the weaknesses of these two categories. We evaluated the performance of our hybrid protocol by varying aggregation ratio, density, and the broadcast zone radius and got promising results. As an extension to our previous work, in this paper we investigate the behavior and performance of our proposed hybrid data dissemination protocol by varying the data message size and frequency of the broadcast messages. We use simulation to study the performance of the proposed hybrid protocol in comparison to pure store-and-forward and pure multi-hop broadcast protocols. Our results demonstrate that the hybrid protocol is effective in both the urban and highway mobility scenarios showing better latency than pure store-and-forward and less data sent than pure-multi-hop broadcast schemes. View full abstract»

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  • A general distributed consensus algorithm for wireless sensor networks

    Page(s): 16 - 21
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1524 KB) |  | HTML iconHTML  

    In wireless sensor networks, distributed consensus algorithms can be employed for distributed detection. Each sensor node can compute its log-likelihood ratio (LLR) from local observations for a target event and using an iterative distributed algorithm, the average of sensors' LLRs can be available to all the sensor nodes. While the average of sensors' LLRs allows each sensor node to make a final decision as a decision statistic for an overall detection problem with all sensors' LLRs, it may be desirable if all sensors' LLRs or local observations, which form a full information vector and denoted by x, could be available to each sensor for other purposes more than the detection of a target event In this paper, we show that each sensor can have not only the average of local observations, but also full information vector, x, (or its estimate) using a well-known iterative distributed algorithm. We extend the proposed approach to estimate x when x is sparse based on the notion of compressed sensing. View full abstract»

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  • Efficient middleware for user-friendly wireless sensor network integrated development environment

    Page(s): 22 - 28
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB) |  | HTML iconHTML  

    Wireless sensor networks (WSNs) have played an important role in widespread applicable domains. However, the programming and reprogramming processes in WSNs are complicate, this results from the diverse software and hardware platforms in WSNs, the constraint memory and energy resources on sensor nodes as well as the unstable wireless transmission process, etc. Thus, it's significant to design and implement an efficient user-friendly integrated development environment (IDE) for the WSN users. Several related mechanisms have been implemented, such as script language machines, dynamic linking mechanism, embedded Java virtual machine. But these methods are not suitable for the high resource-constraint sensor nodes. In this paper, a middleware named EMIDE is implemented for providing a user-friendly WSN IDE. This middleware simplifies the user programming process and improves the reprogramming performance by separating the application part from the low-level system one. Moreover, it provides sufficient functionalities for the application development and has low requirements to the memory and energy resources. To evaluate the performances of EMIDE, it is compared with Embedded Java Virtual Machine (simpleRTJ) and Contiki dynamic linking mechanisms in terms of resources consumption, application code size and execution efficiency. The obtained results show that EMIDE is an efficient method to provide a user-friendly WSN IDE, even on the high resource-constraint sensor nodes. View full abstract»

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  • Linear precoding in coordinated multicell systems with amplify-and-forward relaying

    Page(s): 29 - 33
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (169 KB)  

    The paper studies the linear precoding problem in coordinated multicell MIMO half-duplex amplify-and-forward (AF) relay-aided systems. Based on the idea of the Blahut-Arimoto algorithm, an iterative algorithm is proposed to obtain a suboptimal solution of the non-convex weighted sum rate maximizing problem. The proposed method involves the following three steps in each iteration: updating the posterior conditional probability using the closed-form solution, updating the source precoding matrices through solving a simple quadratically constrained quadratic program (QCQP) problem and updating the relay precoding matrices one by one by an efficient bisection search method. This algorithm increases the weighted sum rate monotonically in each iteration until convergence. Simulation results are presented to demonstrate the effectiveness of our method. View full abstract»

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  • On OFDM-based cognitive radio spectrum sharing systems with random access

    Page(s): 34 - 38
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (142 KB) |  | HTML iconHTML  

    The performance of an orthogonal frequency-division multiplexing (OFDM)-based spectrum sharing communication system that assumes random access and no information about the primary user's (PU) channel occupation information is studied. Also, no cooperation, information exchange overhead, or subcarrier allocation mechanism between the secondary users (SUs) is assumed. SUs randomly access the subcarriers of the primary network and collide with the PUs' subcarriers with a certain probability. To maintain the quality of service (QoS) requirement of PUs, the interference that SUs causes onto PUs is controlled by adjusting SUs transmit power below a predefined threshold, termed interference temperature. Herein paper, the average capacity of SU with subcarrier collisions is employed as performance measure to investigate the proposed random access scheme. Bounds and scaling laws of average capacity with respect to the number of SUs', PUs' and available subcarriers are derived, and corroborated by computer simulations. View full abstract»

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  • Sensing-throughput tradeoff in a cognitive radio under outage constraints over non-identical fast fading Rayleigh channels

    Page(s): 39 - 43
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (164 KB) |  | HTML iconHTML  

    Sensing-throughput tradeoff under outage constraints has been studied before by assuming that sensing channels are independent and identically distributed (i.i.d). However, the plausible and reasonable assumption is that the sensing channels are independent but not necessarily identically distributed (i.n.i.d). In this work, we derive a closed form expression for the false alarm probability of cooperative spectrum sensing using an energy detector under outage constraints. This false alarm probability relies upon a new threshold which takes into account an outage constraint on the probability of detection due to the i.n.i.d slow and fast fading Rayleigh channels. The results showed that the throughput still improves as the number of secondary users increases over i.n.i.d Rayleigh fading channels. In addition, the throughput degrades dramatically as we move from fast fading to slow fading ones. View full abstract»

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  • Multiobjective cooperative spectrum sensing in cognitive radio using cat swarm optimization

    Page(s): 44 - 48
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (116 KB) |  | HTML iconHTML  

    Cognitive radio has emerged as a potential solution to the problem of spectrum scarcity. Cooperative spectrum sensing exploits the spatial diversity between cognitive radios for reliable detection of primary users' signals. The selection of weight and decision threshold for each cognitive radio can be formulated as a constrained multiobjective optimization problem where probabilities of false alarm and detection are the two conflicting objectives. This paper uses multiobjective cat swarm optimization in the field of cooperative spectrum sensing. The simulation results show that our proposed approach performs better in terms of efficient computation and quality of nondom-inating solutions. View full abstract»

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  • Statistical analysis of optimal distributed detection fusion rule in wireless sensor networks

    Page(s): 49 - 53
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB) |  | HTML iconHTML  

    The problem of optimal distributed detection in wireless sensor networks (WSNs) is revisited. The optimal fusion rule (OFR) of the local detection decisions is derived under the general case of unknown sensor nodes location and number. The OFR is usually used as a benchmark for comparison with other suboptimal fusion rules. However its performance is difficult to characterize due to the complexity of finding its probability distribution under both, null and alternative hypothesis. In this paper, this issue is addressed by instrumenting stochastic geometry to model the distributed detection system in WSNs. Under this framework, we are able to derive an insightful form of the characteristic function of the OFR. Furthermore, the first and second moments of OFR are accurately computed. Equipped with those moments, the OFR distribution is approximated by a Gamma and Gaussian distributions via moment matching method. Simulation results shows that the Gamma distribution fits the OFR distribution to high extent when compared with Gaussian distribution. View full abstract»

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  • Optimal placement in hybrid VANETs-sensors networks

    Page(s): 54 - 57
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (211 KB) |  | HTML iconHTML  

    In this paper, we consider the total road coverage problem in hybrid VANET-Sensor networks. Our proposal aims to determine the optimal deployment of networked sensors and RSUs, along the sides of the road, that ensures complete road coverage while minimizing the total network cost and maintaining connectivity between sensors and RSUs. The problem is NP-Complete as it can be considered as a 2-dimentional critical grid coverage problem which was proved to be NP-Complete by ke et al [17]. We propose a new mathematical linear programming formulation to optimally solve the problem. Computational experiments are performed on randomly generated data. The results show that the proposed linear model, using cplex, is able to provide an appropriate placement solution, for both RSUs and sensors, in a small and medium size networks. View full abstract»

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  • Scalability evaluation of two network simulation tools for Vehicular Ad hoc Networks

    Page(s): 58 - 63
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (164 KB) |  | HTML iconHTML  

    Vehicular Ad hoc Networks (VANETs) are becoming very important since they bring many new features to road transportation (e.g., safety, entertainment, location-based advertisements) and can significantly assist passengers and drivers in their journey. Due to the high cost of experimentation, simulation is a crucial, alternative approach to validate new algorithms and protocols for VANETs. Some analytical comparisons of simulation tools have been proposed, but are mainly focused on: learning curve, configuration, supported protocols, type of license, documentation, graphical support, intended area of use, etc. That is, not much research has been done on performance and scalability in VANETs, which is rapidly gaining importance due to the increasing number of vehicles on our roads. In this paper we present a comparative study of two well-known simulation tools, JiST/SWANS and OMNet++/INETMANET, with an emphasis in scalability (overall time for simulation and memory consumption) with the aim of guiding researchers in their selection of an adequate tool for large simulation scenarios in VANETs. View full abstract»

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  • Modeling and characterization of multi-rate direct sequence CDMA system using dynamic resource allocation scheme

    Page(s): 64 - 68
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (125 KB) |  | HTML iconHTML  

    In this paper the resource allocation problem in multirate direct-sequence code division multiple access (DS-CDMA) has been discussed. A spectral efficiency maximization algorithm for a CDMA system comprising of variable bit rate (VBR) groups has been proposed here. The developed algorithm is capable to utilize the available radio resources efficiently to maximize the spectral efficiency of the system. The power of each group is dynamically controlled to minimize the cell interference thereby enhancing the system capacity. A mathematical model is also developed to estimate the effect of voice activity factor and antenna sectorization on dynamic resource allocation. The proposed model shows significant improvement in bandwidth utilization. The Bit Error Rate (BER) performance of the above model is also measured in presence of Gaussian Noise and Rayleigh fading. View full abstract»

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  • Radio resource allocation schemes for relay assisted OFDMA dynamic spectrum allocation systems

    Page(s): 69 - 73
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (139 KB) |  | HTML iconHTML  

    In this paper, we investigate the downlink radio resource allocation in underlay relay assisted OFDMA spectrum sharing system. Our main objective is to maximize the secondary service sum rate. Two cases are presented to manage the impact of secondary service activity on the primary network through radio resource allocation. In the first (second) case we assume that the channel distribution information (CDI) (the channel side information (CSI)) for the channel between the secondary transmitter and primary receiver is available at the secondary base station (BS). Simulation studies are also conducted to compare the performance of the two above mentioned cases which indicate that in case of uncertain CSI, it is more efficient to use CDI and let the collision probability be managed through corresponding optimized radio resource allocation. An interesting advantage for this approach is eliminating the need to have feedback signalling between primary and secondary systems. View full abstract»

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  • Resource management mechanism for femtocell enterprise networks

    Page(s): 74 - 78
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (218 KB) |  | HTML iconHTML  

    The LTE femtocell network is an emerging technology for deploying the next generation of wireless networks. One of the most important issues in this new concept is radio resource management such as interference reduction and packet scheduling. This paper proposes a cognitive approach based on modified version of exponential (EXP-rule) and maximum-largest weighted delay first (M-LWDF) scheduling algorithms for long term evolution (LTE) femto-networks. System performance can be improved by adapting to users' needs and memberships inside the network. View full abstract»

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  • Distributed joint source-channel coding for relay systems exploiting spatial and temporal correlations

    Page(s): 79 - 84
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB) |  | HTML iconHTML  

    In this paper, we propose a distributed joint source-channel coding (DJSCC) strategy to exploit spatial and temporal correlations simultaneously for transmitting binary Markov sources in a one-way relay system. The relay only extract and forward the source message to the destination, which implies imperfect decoding at the relay. The probability of errors occurring in the source-relay link can be regarded as spatial correlation between source and relay nodes. This spatial correlation can be estimated at the destination node and utilized in the iterative processing. In addition, the knowledge about the temporal correlation of the Markov source is also utilized at the destination. A modified version of the BCJR algorithm is derived to exploit the temporal correlation. Furthermore, extrinsic information transfer (EXIT) chart analysis is performed to investigate convergence property of the proposed technique with the aim of the suitable code design. Simulation results for bit error rate (BER) performance and EXIT chart analysis show that, by exploiting the spatial and temporal correlations simultaneously, our proposed technique achieves significant performance gain, compared with the case where the correlation knowledge is not fully used. View full abstract»

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  • Rate and distortion modeling for real-time MGS coding and adaptation

    Page(s): 85 - 89
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (325 KB) |  | HTML iconHTML  

    Scalable Video Coding (SVC) is the extension of the Advanced Video Coding standard (H.264/AVC) providing video compression with spatial, temporal and quality scalability. Scalability can be exploited in order to provide a better video quality for the end user in video transmission over wireless networks. In this paper we develop a parametric Rate Distortion (R-D) model for Medium Grain Scalability (MGS) SVC depending only on two indexes describing the spatial and temporal complexity of video sequences. The two indexes can be easily obtained from the original raw video, thus enabling real time video adaptation for transmission over channels with variable bandwidth such as wireless channels. The results from simulations show that the use of the proposed model for rate adaptation of multiple-videos sharing a common channel results in an end user video quality comparable to that obtained by using a more accurate non-real time rate distortion model. View full abstract»

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  • A combined scheme of LDPC-STBC for image transmission in asynchronous cooperative MIMO systems

    Page(s): 90 - 94
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (166 KB) |  | HTML iconHTML  

    This paper presents a novel coding system which can reduce the error rate and improve the image transmission performance in the asynchronous cooperative MIMO systems. We propose a combined coder of LDPC-STBC with guard intervals for Set Partitioning in Hierarchical Trees (SPIHT) coded image transmission. The linear dispersion structure is employed to accommodate the cooperative wireless communication network in the dynamic topology of structure, as well as achieving higher throughput than conventional space time codes based on orthogonal designs. The LDPC encoder without girth-4 and the STBC encoder with guard intervals are introduced respectively. The experiment results show that the combined scheme can be the good error correcting codes and achieve better BER performance in the asynchronous cooperative communication. The combined scheme can improve the quality of the reconstructed image in the PSNR values and SPIHT coded image transmission in the asynchronous cooperative MIMO systems. View full abstract»

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  • Is multicast useful in health care monitoring systems?

    Page(s): 95 - 99
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (116 KB) |  | HTML iconHTML  

    Health care monitoring is a technique for early detection of many symptoms and illness. As a step forward to ubiquitous monitoring, wireless sensor networks could be a solution for health care monitoring. However, wireless sensor networks do not support heavy load because they have limited energy, short transmission range, low throughput and small memory storage. This paper uses multicast protocols to reduce the network load. We tested some multicast and unicast routing protocols under a mixed mobility model for health care using the NS-2 simulator in wireless sensor networks. Our simulation results show that the On-Demand Multicast Routing Protocol (ODMR) performs better than other routing protocols in terms of Packet Delivery Ratio (PDR) and Normalized routing overhead. View full abstract»

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  • A local enhancement process to improve fairness and throughput in femtocell networks

    Page(s): 100 - 104
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (142 KB) |  | HTML iconHTML  

    Spectrum efficiency and energy efficiency are the two formal rivals in telecommunication networks. Decreasing cell size in a cellular network is the only way to improve both and femtocell is the most recent technology to this end. Plug-and-play and non-coordinated distribution of femtocells yield some technical challenges. Providing fairness between femtocell base stations (FBSs) is one of the most critical one. In this paper, we propose a local enhancement process as a resource allocation optimization algorithm to improve fairness and throughput in femtocell networks. Different from previous approaches, either centralized or distributed, we are advocating the use of local optimizations where FBSs cooperatively achieve better fairness compared to state-of-the-art fairness algorithms without any aggregated throughput loss. Simulation results show that the proposed local enhancement process improves the fairness and throughput in femtocell networks. View full abstract»

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  • Channel estimation for transmit diversity in time domain synchronous OFDM systems

    Page(s): 105 - 109
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (130 KB) |  | HTML iconHTML  

    As the key technology of the international Digital Television Terrestrial Broadcasting (DTTB) standard called Digital Terrestrial Multimedia Broadcast (DTMB), time domain synchronous OFDM (TDS-OFDM) differs from classical cyclic prefix OFDM (CP-OFDM) by replacing CP with known pseudorandom noise (PN) sequence. Channel estimation is an essential component of single-antenna TDS-OFDM systems due to the interference problem over multipath channels, and the time-domain received PN sequence is used to accomplish this task. However, when transmit diversity is applied to TDS-OFDM, PN sequences passing through different channels will mix together at the receiver, so the conventional PN-based channel estimation is invalid any more due to more complex interferences. To realize transmit diversity for TDS-OFDM, the space-time-frequency (STF) orthogonal training sequence design and the corresponding space-frequency and space-time channel estimation methods over time-varying and frequency-selective channels are proposed in this paper. The feasibility of the proposed scheme is validated by the simulation results, which also demonstrate that the bit error rate (BER) performance close to the ideal channel state information case could be achieved as well. View full abstract»

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  • Enhancing MC-CDMA system using rotated quasi-orthogonal STBC in wireless channels

    Page(s): 110 - 114
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (138 KB) |  | HTML iconHTML  

    Due to the increasing demand on wireless technologies, many researches are trying to find a way to support a continually growing number of users and services which consume bandwidth. Multi-carrier with code division multiple access (MC-CDMA) is a promising candidate for mobile radio systems. On the other hand, Space Time Block Code (STBC) as a spatial diversity multi input multi output technique (MIMO) increases the bit rate without consuming additional bandwidth. The proposed model is to enhance MIMO MC-CDMA system using rotated quasi-orthogonal STBC (QOSTBC) to achieve full diversity and rate one code in case of four transmitter antennas in a quasi static Rayleigh fading channel to design an efficient system. View full abstract»

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  • Differential distributed quasi-orthogonal space-time-frequency coding

    Page(s): 115 - 120
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (179 KB) |  | HTML iconHTML  

    We propose differential distributed quasi-orthogonal space-time-frequency coding (DQSTFC) to cater for broadband cooperative networks operating in scenarios where channel state information (CSI) acquisition is impractical. Our differential DQSTFC scheme combines the concept of differential modulation, space-time-frequency (STF) mapping and quasi-orthogonal coding in cooperative networks. From this, we develop a scheme that exploits the achievable diversity gain in the spatial, temporal and frequency dimensions, and guarantees full code rate in non-coherent broadband cooperative networks. Different from existing STF schemes where full code rate is only achievable for cooperative networks with two relay nodes, and unlike other STF schemes that assume coherent signal recovery, our differential DQSTFC scheme is able to guarantee full code rate for cooperative networks with more than two relay nodes while guaranteeing non-coherent signal recovery. We first introduce our STF mapping scheme, we then show how the quasi-orthogonal codewords are constructed from a special choice of signal sets such that full code-rate signals are obtained. Then we present the full differential encoding and decoding setup for cooperative networks with four relay nodes. Unlike other works where the quasi-static channel assumption is adopted for long symbol periods, we show that performance degradation can be reduced when the quasi-static channel assumption is adopted only across adjacent symbols. Simulation results show that our scheme is robust against time-selective and frequency-selective fading compared to other related schemes. View full abstract»

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