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Free-space optical communication (FSOC) systems will be an important part of future networking infrastructures. With the growth in demand from users - both commercial and military - and the scarcity of available RF spectrum, FSOC has the potential to offer a solution. FSOC capacity can easily reach 10psilas Gbps or more over useful ranges. However, the ability to construct an FSOC network has many...
In this paper, options for providing seamless service delivery to mobile terminals via heterogeneous radio access networks are considered. Despite its current popularity, the Mobile IP solution for mobility management of mobile hosts is discounted due to problems associated with introducing the required network infrastructure and poor handover performance. Rather, the solution described here comprises...
In this paper, we propose a robust STBC transmission scheme to combat the timing synchronization errors over frequency-selective multiple-access channels. First, the equivalent channel model in the presence of timing synchronization errors is derived and we find that the synchronization errors result in an equivalent channel model with larger number of correlated channel taps. Based on this correlated...
For multiple-input multiple-output (MIMO) systems, space-time bit-interleaved coded modulation (ST-BICM) using iterative detection has been recognized as a method for achieving near-capacity performance. However, the a posteriori probability detector required for the conventional ST-BICM receiver is not amenable to practical implementation for high-rate MIMO due to its exponential complexity in rate...
A principal factor in sensor network design is energy efficiency. In this work, we propose to extend the lifetime of sensor networks using appropriate choice of sensor node distribution. The key idea of our scheme is to deploy more nodes in areas of extensive energy usage. Using this scheme of sensor node distribution, we use probabilistic angular routing to route data packets from the sensor nodes...
Li and Xia have recently investigated the design of space-time codes that achieve full spatial diversity for asynchronous cooperative communications. They show that certain of the binary space-time trellis codes derived from the Hammons-El Gamal stacking construction are delay tolerant and can be used in the multilevel code constructions by Lu and Kumar to produce delay tolerant space-time codes for...
In this paper userspsila short-term delay and throughput fundamental properties under basic opportunistic scheduling policies, required to support high throughput wireless communication systems with integrated multimedia services, are studied. Among the objectives of this work is to determine at what extent opportunistic scheduling policies can be used to support real-time services in addition to...
A scheme that exploits the broadcast nature of the wireless communication in order to achieve multicast content delivery is presented in this paper. As opposed to broadcasting, this method enables the clients to determine on-line the delivered content, and thus preserves the advantages of an individual service. On the other hand, a multicast content delivery is much more efficient than a unicast content...
We propose a more accurate method to analyze multilevel frequency-shift-keying frequency-hopping code-division multiple-access (MFSK/FH-CDMA) wireless communication systems using ldquoone-hitrdquo FH patterns, instead of random FH patterns. By also removing the over-optimistic symbol-synchronous assumption, the new method provides a more realistic performance analysis as the MFSK modulation may result...
Orthogonal frequency division multiplexing (OFDM) is the modulation scheme of choice for digital video broadcasting-handheld (DVB-H), which is required to operate under high mobility conditions resulting in significant Inter-carrier Interference (ICI). To mitigate ICI, several cancellation schemes have been proposed but they require reliable channel information at the receiver which is quite challenging...
Some communication applications, like multimedia, deliver data of different importance classes allowing unequal error protection (UEP) levels. In this paper, a multiple-input multiple-output (MIMO) system using orthogonal frequency division multiplexing (OFDM) is considered with a new UEP bit-loading algorithm based on the non-UEP algorithm by Chow, Cioffi, and Bingham. In the proposed bit-loading...
In recent years, organizations have been shifting focus to their core business competencies, and reducing total cost of ownership (TCO) associated with training and management of their IT infrastructure. In the same motif, organizations are establishing security and survivability frameworks as an integral part of their business strategy so as to provide an acceptable quality-of-service for their clients...
Expected growth in use and implementation of wireless sensor networks (WSNs) in different environments and for different applications creates new security challenges. In WSNs, a malicious node may initiate incorrect path information, change the contents of data packets, and even hijack one or more genuine network nodes. As the network reliability completely depends on individual nodespsila presence...
This work studies the performance of a data-driven reduced rank scheme for rapid timing acquisition in multiple access communications. Our results show that when only a limited amount of preamble bits are available, instead of the true second-order statistics (SOS), the reduced rank scheme provides reliable timing information. Exploiting the structure of the multiple access interference, the data...
This paper proposes a fast forward medium access control protocol (FFMAC) for quality-of-service (QoS) guarantee in multihop IEEE 802.11s wireless mesh networks with multiple channels. To the best of our knowledge, the proposed protocol is the first one which considers the multihop and multichannel issues simultaneously. It provides higher priority for real-time applications, while remaining the distributed...
In this paper we present an algorithm, based on power management of access points (AP), to reduce congestion in wireless local area networks (WLANs). The algorithm finds the most congested access point (MCAP) and adjusts its transmitted power in discrete steps and determines the optimal userspsila assignment such that an optimal load distribution is achieved. Results show that the algorithm is capable...
As opposed to prime factor type algorithms, the only requirement made by parallel cyclic convolution techniques based on block pseudocirculant matrices is that the convolution length be composite. Highly composite lengths, in particular, give a larger variety of implementation choices. In this paper we offer an introduction to new mathematical constructs, the super block pseudocirculant matrix, and...
A new construction of a full-diversity full-rate space-time block code (FDFR-STBC) is presented in this paper. The design is for 2 transmit antennas and 2 time slots. The code outperforms the previous FDFR-STBC codes in [3], [4], [5], [6] for 1 receive antenna. We reduce the decoding complexity by exploiting the algebraic structure of the code and using the hybrid maximum-likelihood interference cancellation...
Three applications in wireless networks where model-free stochastic learning is applicable, are discussed. The learning based optimization problems are formulated and simulation results are presented. Some open issues are also discussed.
A method to measure and compensate PMD to all orders is proposed and demonstrated. It measures the phase spectrum via spectral interference and compensates the phase changes by imposing opposite phase onto the signal with a pulse shaper.
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