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In this paper, a reduced-complexity multiple-input multiple-output (MIMO) detector for the Bell Labs Layered Space-Time Architecture (BLAST) is described. It incorporates the idea of set partitioning in the tree search to reduce the number of multiplications and comparisons. An algorithm that adapts the number of partitions based on the channel conditions is also proposed to achieve a better tradeoff...
A new oversampled orthogonal frequency division multiplexing (OFDM) system operating in doubly selective fading environment is proposed in this paper. The oversampled OFDM structure employs oversampling in time domain and linear signal processing in frequency domain. The time-frequency processing enables a two dimensional Doppler-frequency grid that allows each data symbol be transmitted at multiple...
The detection of MIMO signals presents a formidable computation challenge due to the inherent complexity incurred by matrix-type wireless fading channels. To reduce the hardware cost, linear MIMO detection algorithms can be used instead of non-linear space-time processing. Conventionally, adaptive linear algorithms such as RLS and LMS are treated separately in implementation from matrix inversion...
Sums of fading envelopes arise in several wireless communications applications, such as equal-gain combining, outage probability, signal detection, etc. In this paper, based on the intricate task of evaluating the exact statistics of such sums, accurate approximations for the outage probability of equal-gain receivers subject to arbitrary independent cochannel interferers are proposed. In our analysis,...
In this paper we present a novel systematic approach for inference of missing observations in environmental monitoring wireless sensor networks (WSNs). This capability is important in that it enables sensor networks to effectively estimate the missing data when observation is incomplete to address two critical challenges in WSNs: (1) how to achieve sensor node failure tolerant and robust data collection...
Majority of characterization studies on Vehicular Networks are based on simulations that assume little network errors and consistent signal strength. Existing VANET experiments, on the other hand, focus mostly on single-hop communication. In this paper, we present the results of an extensive measurement campaign involving up to six vehicles and evaluating the performance of IEEE 802.11 in different...
In this paper, we propose a method for realistic mobility aware information gathering in disaster areas. In the proposed method, a disaster area is divided into a grid, and each node's safety information is held in its pre-defined home grid cells, and it can be referred by sending a query to mobile nodes in its home cells. In this paper, we propose an autonomous adaptable protocol so that it can adapt...
Because wireless channel condition is time-varying, the allocated bandwidth is usually not fixed. Therefore, it is a challenge to guarantee QoS, especially for bandwidth- consuming and delay-sensitive multimedia applications. In this paper, we propose a cross-layer mechanism to improve the quality of H.264 video when encountering short-term bandwidth fluctuations over IEEE 802.11e wireless networks...
With the advance of various wireless access technologies, the demand for a mobile user equipped with multiple air interfaces simultaneously executing diverse applications emerged. In such network environment, per- application mobility management is a key to allow each application of an end user device to dynamically and fully take advantage of the most suitable access technology. In this paper, we...
Multihoming and mobility in IPv6 are usually considered as two disjoints concepts. This has lead to the development of the two protocols family separately. However, the new IPv6 terminals are most of the time mobile and are equipped with multiple interfaces. Thus, we need to adopt a new vision toward multihoming and mobility and propose new solutions to manage both of them. In this paper, we focus...
Churning of mobile users from one service provider to another is expected to become a common feature when the mobile users have freedom to choose the best wireless service. This churning behavior impacts both the technical and the economical aspects of wireless network design. In this paper, we model the churning behavior of wireless service users by using the theory of evolutionary game. We consider...
4G supports various types of services. The coverage of high-speed data service is smaller than that of low-speed data service, which make the high-speed data service users occur dropping before reaching the handover area. In order to solve the problem, this paper proposes A Coverage-based Handover Algorithm for High-speed Data Service (CBH), which extends the coverage of high-speed data service by...
In this paper, we present a new policy for admitting voice over IP (VoIP) sessions over wireless networks. Our proposed policy receives the admission information advertised by the VoIP gateway on the wired network, and uses it to decide whether a new VoIP session can be admitted or not. The proposed policy can be easily integrated with the current call admission control algorithms used in wireless...
A throughput-maximization call admission control (CAC) policy is proposed for CDMA beamforming systems in which the QoS requirements in both physical and network layers can be guaranteed. While the existing cross-layer CAC policies rely on a separate reduced-outage-probability (ROP) algorithm to guarantee the physical layer QoS requirement, which adds to system complexity and reduces spectral efficiency,...
To overcome the disadvantage in traditional manual configuration method for WLANs, such as the high configuration and maintenance cost and low efficiency of system performance, we propose the plug-and-play (PnP) of multi-mode APs that APs auto-configure themselves based on the network environment. In order to implement the PnP, the Multi-mode AP must obtain its neighboring APs' configuration and environment...
Consider a bidimensional domain S sube Rfr2 and throw two statistically independent uniform poisson point processes with constant densities equal to PL and PNL, respectively. The first point process identifies the spatial distribution of a set of nodes which has information about their position, hereafter denoted as L-nodes, while the other one is used to model the spatial distribution of nodes which...
Single frequency networks (SFN) broadcast is an efficient method to provide broadcast services in cellular networks. How to select broadcast services by the SFN operation to trade off between the occupied bandwidth and the SFN performance including spectrum efficiency and broadcast service continuity is a new problem. To the best of our knowledge no solutions have been proposed to solve this problem...
In next generation networks, technological advancements lead a trend towards offering guaranteed services. ISPs are eager to support subscribers' requirements by offering SLAs across domains. This paper considers the interaction between ISPs under deregulatory environment. In order to capture a freedom of the policy selection, path-classification scheme is proposed to group paths into a few choices...
In ad hoc position-location networks, location information is obtained through the sequential estimation of node locations. An unlocalized node can estimate its location based on range and location estimates of nearby localized (";anchor";) nodes, and subsequently provide range and location information to other unlocalized nodes in its vicinity. In such distributed location-estimation scenarios,...
Beyond 3G and 4G wireless promise 'always best connected' as well as new high-rate wireless networks. Since costly earlier generation networks are still useful, load sharing between integrated wireless networks becomes feasible. Studies have shown that load shared networks using common radio resource management (CRRM) techniques are beneficial - with circuit-oriented sessions. Since wireless networks...
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