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Wireless Communications, IEEE Transactions on

Issue 6 • Date June 2012

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Displaying Results 1 - 25 of 45
  • Table of contents

    Publication Year: 2012 , Page(s): c1 - c4
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  • [Staff list]

    Publication Year: 2012 , Page(s): c2
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  • Performance Analysis of Cooperative Time Hopping UWB Systems with Multi-User Interference

    Publication Year: 2012 , Page(s): 1969 - 1975
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (161 KB) |  | HTML iconHTML  

    In this letter, we propose an analytical model to study the performance of cooperative links for time hopping ultra wideband (UWB) systems under two relay models: amplify-and-forward (AF) and decode-and-forward (DF). The effects of multi-user interference (MUI) are considered when deriving closed-form expressions for outage probability and average bit error probability (BEP) over single-path model. Simulation results show that the presented analytical model can accurately predict the link performance. View full abstract»

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  • Rice Factor Estimation from the Channel Phase

    Publication Year: 2012 , Page(s): 1976 - 1980
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (146 KB) |  | HTML iconHTML  

    A Rice factor (K) estimator is described which uses simple operations on the phase of the well-defined Rice channel. Multiple receive channels, such as used in MIMO communications, enable spatial sampling which enhances the accuracy. For an example configuration of four uncorrelated receive antennas with a ten wavelength linear trajectory in isotropic scattering, the estimator works well for small to medium K (i.e., K ≲ 7). Limitations of the estimator include an assumption of isotropic scattering and that the angle-of-arrival of the dominant component is fixed and cannot be perpendicular to the mobile trajectory. View full abstract»

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  • Ambiguity Mitigating Technique for Cosine-Phased Binary Offset Carrier Signal

    Publication Year: 2012 , Page(s): 1981 - 1984
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (214 KB) |  | HTML iconHTML  

    This letter focuses on mitigating ambiguity for cosine-phased binary offset carrier (BOC) modulated signals which are used in the global navigation satellite system (GNSS). The main idea is to use the cross-correlation function (CCF) of the received cosine-phased BOC signal with the specifically designed local auxiliary signal to counterbalance the undesired side peaks of the received BOC autocorrelation function (ACF), the final correlation function has only two small positive side peaks which can be rectified by combing with the classical bump jump (BJ) technique easily. The modulated symbol of the local auxiliary signal is derived and simulations show that at the cost of some degradation of detection probability in the acquisition phase the proposed method is better than the traditional BJ method in mitigating the ambiguity for cosine-phased BOC signals, especially when the subcarrier frequency is high and even under multipath interference. View full abstract»

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  • Outage Probability and Power Allocation of Two-Way Amplify-and-Forward Relaying with Channel Estimation Errors

    Publication Year: 2012 , Page(s): 1985 - 1990
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (209 KB) |  | HTML iconHTML  

    We consider a two-way amplify-and-forward (AF) relaying system consisting of two source nodes and a half-duplex relay. We assume that the source nodes are equipped with the linear minimum mean squared error (LMMSE) channel estimators. We investigate the effect of uncertainty due to channel estimation error on the system outage probability, considering the imposed bandwidth and energy costs of channel estimation. For a fixed transmission block length and a total transmit power constraint, we provide a compact-form expression for the system outage probability upper bound and we explore the optimal number of training symbols, the optimal power allocation between data and training, and the optimal power allotment between the two users and the relay, such that this bound is minimized. Our numerical results show that channel estimation error does not limit the performance in high signal-to-noise ratio (SNR). Also, the optimal power allocation between data and training and between the users and the relay provides a significant SNR improvement, compared with the suboptimal schemes, including fixed power allocation. The optimization gain increases as the relay moves away from the middle point. View full abstract»

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  • A Dynamic Offloading Algorithm for Mobile Computing

    Publication Year: 2012 , Page(s): 1991 - 1995
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (455 KB) |  | HTML iconHTML  

    Offloading is an effective method for extending the lifetime of handheld mobile devices by executing some components of applications remotely (e.g., on the server in a data center or in a cloud). In this article, to achieve energy saving while satisfying given application execution time requirement, we present a dynamic offloading algorithm, which is based on Lyapunov optimization. The algorithm has low complexity to solve the offloading problem (i.e., to determine which software components to execute remotely given available wireless network connectivity). Performance evaluation shows that the proposed algorithm saves more energy than the existing algorithm while meeting the requirement of application execution time. View full abstract»

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  • Coordinated Spatial Multiplexing with Orthogonalized Channels for Multiuser MIMO Downlink Systems

    Publication Year: 2012 , Page(s): 1996 - 2001
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (157 KB) |  | HTML iconHTML  

    In this paper, we propose a new coordinated spatial multiplexing algorithm for multiuser multiple-input multiple-output (MIMO) downlink systems. Unlike other conventional coordination methods, our scheme exploits orthogonalized effective channels to yield the transmit precoding and receive combining matrices without requiring an iterative operation. In order to determine each row of the effective channels, a greedy type successive process is utilized. Simulation results show that the performance of our proposed scheme is very close to the conventional iterative scheme with significantly reduced complexity. Also, our method achieves a 3 dB performance gain over the conventional non-iterative scheme. View full abstract»

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  • Resource Allocation for Two-Way AF Relaying with Receive Channel Knowledge

    Publication Year: 2012 , Page(s): 2002 - 2007
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (355 KB) |  | HTML iconHTML  

    The resource allocation problem for two sources communicating via an amplify-forward relay is studied from an outage perspective. Analog network coding is considered for half-duplex nodes with perfect receiver-side channel knowledge. Under a sum power constraint, an optimal power allocation that minimizes an approximate outage probability is derived and shown to improve the performance upto 4.77 dB. A cut-set bound is also optimized to serve as a comparison reference. When such a power allocation is not feasible, two novel resource- optimized schemes, which exploit conventional one-way relaying, are proposed to reduce the outage at low multiplexing gains1. View full abstract»

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  • Simplified Power Allocation Scheme for Cognitive Multi-Node Relay Networks

    Publication Year: 2012 , Page(s): 2008 - 2012
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (211 KB) |  | HTML iconHTML  

    The simplified optimization problem is considered since the power allocation (PA) problem is the nonconvex optimization problem in cognitive multi-node relay networks, which has the interference on the primary user and the maximum transmission power constraint. The maximum transmission power constraint is guaranteed after we obtained the closed-form solution of the simplified optimization problem which has only the interference constraint on the primary user. The proposed PA method with much lower complexity performs close to the suboptimal PA method using interior point method. View full abstract»

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  • Reduced-Rate OFDM Transmission for Inter-Subchannel Interference Self-Cancellation over High-Mobility Fading Channels

    Publication Year: 2012 , Page(s): 2013 - 2023
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (868 KB) |  | HTML iconHTML  

    In this paper, we develop a general reduced-rate orthogonal frequency division multiplexing (OFDM) transmission scheme for inter-subchannel interference (ICI) self-cancellation over high-mobility fading channels. Via transmit and receive processing, we transform the original OFDM system into an equivalent one with fewer subcarriers. By reducing transmission rate, we are able to design a transmitted signal structure with inherent ICI self-cancellation capability without requiring the instantaneous channel state information. We develop a general structure of transmit and receive processing matrices so that all equivalent subchannels in the transformed OFDM system have the same average signal-to-interference ratio (SIR). For the developed structure, we further optimize the transmit and the receive processing coefficients to maximize the SIR based on channel statistics. Numerical and simulation results demonstrate that the developed reduced-rate OFDM transmission achieves an SIR gain of around 5 dB over the existing ICI self-cancellation schemes and significantly reduces the error floor at the receiver. View full abstract»

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  • Throughput Analysis of Opportunistic Access Strategies in Hybrid Underlay—Overlay Cognitive Radio Networks

    Publication Year: 2012 , Page(s): 2024 - 2035
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (509 KB) |  | HTML iconHTML  

    In cognitive radio networks, it is important to effectively use the under-utilized spectrum resources without affecting the primary users. In an underlay system, secondary users are allowed to share the channel simultaneously with primary users (with the restriction on interference level) but not in an overlay system. In this article, we consider a system where a secondary user can switch between overlay and underlay modes of operation in order to improve its throughput with limited sensing capability (i.e. sensing only one channel at a time). The results based on Markov chain analysis are satisfactorily verified using Monte-Carlo simulation. It is found that proper selection of transmission mode can provide greater improvement in throughput for a secondary user. The mode selection depends on the transition characteristics of primary users and the throughput ratio between the two modes of operation. View full abstract»

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  • Optimization of MAC Frame Structure for Opportunistic Spectrum Access

    Publication Year: 2012 , Page(s): 2036 - 2045
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (411 KB) |  | HTML iconHTML  

    Sensing-throughput tradeoff is involved in opportunistic spectrum access (OSA). At the physical layer it's expressed as the tradeoff between false alarm and misdetection, while at the MAC layer it's between maximizing the throughput of secondary users and reducing collisions with primary users. To balance both tradeoffs together drives the optimization of MAC frame structure for OSA. Since channel handoff results in a time overhead for MAC frame, it's first researched by modeling OSA dynamics in the paper. Three handoff cases and their probabilities are deduced, which lead to three application scenarios of MAC frame. Thus the throughput model of secondary network involving channel handoff is proposed. By balancing the misdetection and false alarm probabilities and maximizing the throughput of secondary network subject to the sensing quality and collision avoidance constraints, the optimal sensing time and frame duration are deduced as closed forms. The characteristics of the optimal MAC frame structure are researched as well. Theoretical and simulated results disclose the impacts of channel handoff and spectrum sensing on MAC frame structure and the achievable throughput of secondary network, which provide an insight for OSA design and improvement. View full abstract»

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  • Adaptive Access Mechanism with Optimal Contention Window Based on Node Number Estimation Using Multiple Thresholds

    Publication Year: 2012 , Page(s): 2046 - 2055
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (603 KB) |  | HTML iconHTML  

    How to improve the short-term fairness and increase the aggregated throughput simultaneously is a major problem in WLANs, yet has not been solved satisfactorily in previous work, especially in the situation that network loads vary significantly. To improve the performance in saturation state, we propose a novel access mechanism that sets an optimal Contention Window (CW) for all nodes in the network. By introducing a new parameter of CW Index (CWI), we present a linear CW adjustment rule based on the active node number and then develop an estimation algorithm of node number with three thresholds. Compared to previous algorithms, the new algorithm predicts the future node number based on the current network status, thus minimizes the fluctuating effect of idle slot intervals observed at each process. Moreover, it can identify the dense degree of idle slot intervals and track the changes of the accurate node number quickly. By selecting the optimal CWI adaptively, the maximum aggregated throughput keeps basically a constant despite the variation of the number of nodes. Meanwhile, by eliminating multiple transmission attempts of the same node, the short-term fairness is improved significantly. To evaluate the mechanism, we derive closed-form expressions for the network performance. The simulation results demonstrate the validity and good scalability of the proposed access mechanism. View full abstract»

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  • Optimum Sensor Density in Distortion-Tolerant Wireless Sensor Networks

    Publication Year: 2012 , Page(s): 2056 - 2064
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (323 KB) |  | HTML iconHTML  

    The optimum sensor node density for one- and two-dimensional (1-D and 2-D) wireless sensor networks (WSNs) with spatial source correlation is studied in this paper. The WSN attempts to reconstruct a spatially correlated signal field by collecting the location-dependent measurements from the distributed sensor nodes. The WSN is designed to minimize the mean square error (MSE) distortion between the original and the reconstructed signals under the constraint of a fixed power per unit area. The impacts of node density and spatial data correlation on the network performance are investigated for both small networks with finite number of nodes, and large networks with infinite area, infinite number of nodes, but finite node density through asymptotic analysis. The interactions among the various network parameters and their impacts on the system performance are quantitatively identified with exact analytical expressions, many of which are in closed-forms. The results provide guidelines on the design of practical WSNs. View full abstract»

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  • Interference Analysis and Mitigation for Cognitive-Empowered Femtocells Through Stochastic Dual Control

    Publication Year: 2012 , Page(s): 2065 - 2075
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1479 KB) |  | HTML iconHTML  

    This paper provides an extensive analysis on interferences due to different interfering sources within cognitive-empowered femtocell (CEF) networks. Based on the interference analysis and formulations, a stochastic dual control (SDC) approach is introduced for dynamic sensing coordination, aiming to achieving efficient interference mitigation without involving global and centralized control efforts. Simulation results show that the proposed SDC approach can effectively reduce interferences under highly dynamic environments within CEF networks when compared with other spectrum sensing strategies. View full abstract»

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  • Energy Efficiency of Cooperative Relaying over a Wireless Link

    Publication Year: 2012 , Page(s): 2076 - 2083
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (179 KB) |  | HTML iconHTML  

    Cooperation enhances the performance of wireless networks with fading channels. In this paper, we develop joint physical and network layer cooperative techniques in a simple network composed of a single source, a relay, and a destination, and focus on energy consumption as the performance criterion. Two transmission schemes are used at the network layer: (i) Simple Automatic Repeat Request (ARQ) and (ii) Random Network Coding (RNC). We also consider the use of Alamouti Space-time codes at the physical layer. For each of the proposed cooperative schemes, we consider the energy consumed per successfully delivered packet, and then find the optimal power values used by the source and the relay that minimize the energy consumed. Finally, we use the obtained optimal power values to compute the minimum stable throughput achieved at the source. Our results show that cooperation using Random Network Coding combined with Alamouti Coding at the physical layer achieves the best performance among the proposed schemes. View full abstract»

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  • A Practical Joint Network-Channel Coding Scheme for Reliable Communication in Wireless Networks

    Publication Year: 2012 , Page(s): 2084 - 2094
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (828 KB) |  | HTML iconHTML  

    In this paper, we propose a practical scheme, Non-Binary Joint Network-Channel Coding (NB-JNCC), for reliable multi-path multi-hop communication in arbitrary large-scale wireless networks. NB-JNCC seamlessly couples channel coding and network coding to effectively combat the detrimental effect of fading of wireless channels. Specifically, NB-JNCC combines non-binary irregular low-density parity-check (LDPC) channel coding and random linear network coding through iterative joint decoding, which helps to fully exploit the spatial diversity and redundancy residing in both channel codes and network codes. In addition, since it operates over a high order Galois field, NB-JNCC can be directly combined with high order modulation without the need of any bit-to-symbol conversion nor its inverse. Through both analysis and simulation, we demonstrate the significant performance improvement of NB-JNCC over other schemes. View full abstract»

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  • Geographic Transmission with Optimized Relaying (GATOR) for the Uplink in Mesh Networks

    Publication Year: 2012 , Page(s): 2095 - 2105
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (711 KB) |  | HTML iconHTML  

    We consider communication in the uplink of a wireless mesh or sensor network. A group of mobile radios or sensors (“nodes”) have information to transmit to one or more access points (APs). When the channels from the nodes to the APs suffer from fading, direct transmissions to the APs may have a high failure probability, and packets may need to be relayed through other nodes. In conventional routing, the relay is preselected, and hence fading may cause a high failure probability at the router. Geographic approaches can improve performance through opportunistic reception, in which a relay is selected from those nodes that receive the packet correctly and move it toward the AP. Existing geographic transmission schemes use an ad hoc design for the protocol that selects the relay node. In this paper, we propose Geographic Transmission with Optimized Relaying (GATOR), which provides a mathematical design for relay selection in a time-slotted geographic communication scheme. For path-loss exponent two, the relay selection scheme simplifies to depend on circular regions around the destination. Simulation results show that GATOR provides better performance than direct transmission, routing, and other geographic transmission schemes, especially when the signal-to-noise ratios are low and APs are sparse. View full abstract»

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  • PKC Based Broadcast Authentication using Signature Amortization for WSNs

    Publication Year: 2012 , Page(s): 2106 - 2115
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (556 KB) |  | HTML iconHTML  

    Public Key Cryptography (PKC) is widely used for broadcast authentication. Intensive use of PKC for broadcast authentication, however, is thought to be expensive to resource constrained sensor nodes. In this paper, we propose a novel PKC based broadcast authentication scheme using signature amortization for Wireless Sensor Networks (WSNs). The proposed scheme exploits only one Elliptic Curve Digital Signature Algorithm (ECDSA) signature to authenticate all broadcast messages. Thus, the overhead for the signature is amortized over all broadcast messages. Besides low overhead, the proposed scheme retains high security that is as strong as conventional PKC based broadcast authentication schemes. Moreover, the proposed scheme can achieve immediate authentication and does not require time synchronization. For the implementation of the proposed scheme, an efficient public key distribution protocol is also presented in this paper. Experimental results of a testbed show that the overhead for authenticating a broadcast message is reduced significantly. View full abstract»

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  • Sparsity Order Estimation and its Application in Compressive Spectrum Sensing for Cognitive Radios

    Publication Year: 2012 , Page(s): 2116 - 2125
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (434 KB) |  | HTML iconHTML  

    Compressive sampling techniques can effectively reduce the acquisition costs of high-dimensional signals by utilizing the fact that typical signals of interest are often sparse in a certain domain. For compressive samplers, the number of samples Mr needed to reconstruct a sparse signal is determined by the actual sparsity order Snz of the signal, which can be much smaller than the signal dimension N. However, Snz is often unknown or dynamically varying in practice, and the practical sampling rate has to be chosen conservatively according to an upper bound Smax of the actual sparsity order in lieu of Snz, which can be unnecessarily high. To circumvent such wastage of the sampling resources, this paper introduces the concept of sparsity order estimation, which aims to accurately acquire Snz prior to sparse signal recovery, by using a very small number of samples Me less than Mr. A statistical learning methodology is used to quantify the gap between Mr and Me in a closed form via data fitting, which offers useful design guideline for compressive samplers. It is shown that Me ≥ 1.2Snz log(N/Snz + 2) + 3 for a broad range of sampling matrices. Capitalizing on this gap, this paper also develops a two-step compressive spectrum sensing algorithm for wideband cognitive radios as an illustrative application. The first step quickly estimates the actual sparsity order of the wide spectrum of interest using a small number of samples, and the second step adjusts the total number of collected samples according to the estimated signal sparsity order. By doing so, the overall sampling cost can be minimized adaptively, without degrading the sensing performance. View full abstract»

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  • Cooperative OFDM Relaying for Opportunistic Spectrum Sharing: Protocol Design and Resource Allocation

    Publication Year: 2012 , Page(s): 2126 - 2135
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (619 KB) |  | HTML iconHTML  

    In this paper, we propose an opportunistic spectrum sharing protocol that exploits the situation when the primary system is incapable of supporting its target transmission rate. Specifically, the secondary system tries to help the primary system to achieve its target rate via two-phase cooperative OFDM relaying, where the secondary system acts as an amplify-and-forward relay for the primary system by allocating a fraction of its subcarriers to forward the primary signal. At the same time, the secondary system uses the remaining subcarriers to transmit its own signal, and thus gaining opportunistic spectrum access. As a part of the protocol, if the primary system finds that outage will occur even when the secondary system serves as a pure relay, the primary system will cease transmission and the secondary system will be granted access to the primary spectrum. We study the joint optimization of the set of subcarriers used for cooperation, subcarrier pairing, and subcarrier power allocation such that the transmission rate of the secondary system is maximized, while helping the primary system, as a higher priority, to achieve its target rate. Simulation results demonstrate the performance of the proposed spectrum sharing protocol as well as the win-win solution for the primary and secondary systems. View full abstract»

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  • Ergodic Transmission Capacity of Wireless Ad Hoc Networks with Interference Management

    Publication Year: 2012 , Page(s): 2136 - 2147
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (468 KB) |  | HTML iconHTML  

    Most work on wireless network throughput ignores the temporal correlation inherent to wireless channels because it degrades tractability. To better model and quantify the temporal variations of wireless network throughput, this paper introduces a metric termed ergodic transmission capacity (ETC), which includes spatial and temporal ergodicity. All transmitters in the network form a homogeneous Poisson point process and all channels are modeled by a finite state Markov chain. The bounds on outage probability and ETC are characterized, and their scaling behaviors for a sparse and dense network are discussed. From these results, we show that the ETC can be characterized by the inner product of the channel-state related vector and the invariant probability vector of the Markov chain. This indicates that distributed channel-aware scheduling (DCAS) does not always increase ETC. Finally, we look at outage probability with interference management from a stochastic geometry point of view. The improved bounds on outage probability and ETC due to interference management are characterized and they provide some useful insights on how to effectively manage interference in sparse and dense networks. View full abstract»

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  • Delay and Throughput Oriented Continuous Spectrum Sensing Schemes in Cognitive Radio Networks

    Publication Year: 2012 , Page(s): 2148 - 2159
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (511 KB) |  | HTML iconHTML  

    Periodic spectrum sensing over the entire primary user (PU) band always interrupts the secondary user (SU) data transmission in the sensing interval, which may degrade the quality of service of the SU. To alleviate this problem, we divide the PU band into two subbands, one for opportunistic SU data transmission, and the other for continuous spectrum sensing. Based on the PU band division, we propose a delay oriented continuous spectrum sensing (DO-CSS) scheme for delay sensitive SU services. In the DO-CSS scheme, the average SU transmission delay is reduced by selecting the proper bandwidth for spectrum sensing within each frame. Since different SUs may have different requirements on their quality of services, we further propose a throughput oriented continuous spectrum sensing (TO-CSS) scheme. In the TO-CSS scheme, the achievable average SU throughput is maximized by choosing the optimal sensing bandwidth within multiple adjacent frames. Both theoretical analyses and simulation results show that compared with the conventional periodical spectrum sensing scheme, the average transmission delay of the SU is reduced without degradation in the maximum achievable throughput by using the proposed DO-CSS scheme, and both the delay performance and achievable SU throughput are further improved by using the proposed TO-CSS scheme. View full abstract»

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  • Switched-Based Interference Reduction Scheme for Open-Access Overlaid Cellular Networks

    Publication Year: 2012 , Page(s): 2160 - 2172
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (469 KB) |  | HTML iconHTML  

    Femtocells have been proposed to enhance the spatial coverage and system capacity of existing cellular networks. However, this technology may result in significant performance loss due to the increase in co-channel interference, particularly when coordination between access points is infeasible. This paper targets interference management in such overlaid networks. It is assumed that the femtocells employ the open-access strategy to reduce cross-tier interference, and can share resources concurrently. It is also assumed that each end user (EU) can access one channel at a time, and transfer limited feedback. To reduce the effect of co-tier interference in the absence of the desired EU channel state information (CSI) at the serving access point as well as coordination between active access points, a switched scheme based on the interference levels associated with available channels is proposed. Through the analysis, the scheme modes of operation in under-loaded and over-loaded channels are studied, from which the statistics of the resulting interference power are quantified. The impact of the proposed scheme on the received desired power is thoroughly discussed. In addition, the effect of the switching threshold on the achieved performance of the desired EU is investigated. The results clarify that the proposed scheme can improve the performance while reducing the number of examined channels and feedback load. View full abstract»

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The IEEE Transactions on Wireless Communications publishes high-quality manuscripts on advances in the state-of-the-art of wireless communications.

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Editor-in-Chief
Jeff Andrews
Cullen Trust for Higher Education Endowed Professor of Engineering