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A construction scheme of M-QAM (quaternary amplitude modulation) signals using quaternary phase-shift keying (QPSK) constellations for the orthogonal frequency division multiplexing (OFDM) has been proposed, when M= 2k and k is an even number. In this paper, we extend Rudin-Shapiro polynomials (RSP) to the generalized Rudin-Shapiro polynomials (GRSP). Based on the generalized Rudin-Shapiro polynomials...
By taking advantage of the multiple wavelength provisioning capability, WDM PON dramatically enlarges its capacity as compared to TDM PON. The capacity of a WDM PON system depends on many factors, such as the number and capacities of wavelength channels, the network architecture, the wavelength support of receivers, and the tuning ability of lasers. This paper introduces the definition of achievable...
This paper presents a low complexity receiver for downlink orthogonal frequency division multiple access (OFDMA) systems. We consider the comb-type subcarriers assignment for a resource block. Based on this arrangement, a resource block could be demultiplexed at the user equipment without performing fast Fourier transform(FFT) on one OFDMA symbol. The inter-symbol interference(ISI) resulted from multipath...
This paper presents novel single-source localization techniques for a sensor network that is capable of obtaining both direction and range estimates by considering an optimization approach. Specifically, linear programming and non-linear programming techniques are developed and compared to a classic linear least squares technique. It is shown that the proposed techniques achieve superior results to...
Medium access in ad-hoc wireless networks must be performed in a distributed fashion due to lack of coordination between nodes. Specifically, when nodes are capable of receiving more than one transmission simultaneously, the design of distributed medium-access mechanisms that efficiently exploit the receiver's capability becomes more challenging. Adaptive probabilistic medium access for ad-hoc wireless...
In this paper, we address the preamble-based channel estimation problem for orthogonal frequency-division multiplexing (OFDM) systems using multiple amplify-and-forward (AF) relays. We first establish a linear minimum mean-square-error (LMMSE) channel estimator which directly estimates the overall channels from the source to the destination. Then, based on the assumption that the channel correlations...
The growth in broadband access and increases in terminal capability have enabled us to provide large-scale multimedia services. The traditional unicast architecture cannot support such a service because the transportation from a content server to many end hosts causes the overload to a content server. Overlay multicast techniques have been proposed to solve this problem. This high-layer technology...
We propose a new family of high-rate space-time block codes called embedded orthogonal space-time (EOS) codes. The family is parameterized by the number of transmit antennas, which can be any positive integer, and by the rate, which can be as high as half the number of transmit antennas. The proposed codes are based on a new concept called embedding, whereby information symbols of a traditional space-time...
Interference cancellation (IC) techniques yielding significant capacity gains are presented in this paper for CDMA2000 lx base station receiver. In addition to performance gain from conventional IC, hybrid ARQ gain is achieved effectively without interlaced transmission or feedback on the forward link (FL). A new definition of CDMA capacity, based on equivalent load, is introduced to allow a fair...
The distribution of the received signal power ?? of a multiple-input multiple-output system, with the associated 2 ?? 2 complex Wishart matrix having n degrees of freedom, is investigated under the channel inversion power allocation scheme. Exact closed-form expressions are derived for the probability density function and the cumulative distribution function of ??. The analysis covers systems with...
This paper considers a cognitive radio network where a secondary user shares the same narrow band with a primary user for transmission. Instead of adopting the conventional interference-power/interference-temperature constraint, this paper proposes a new type of constraint for the secondary user to protect the primary transmission, which limits the maximum outage probability of the primary transmission...
A wireless MIMO link is considered in a LOS configuration with multiple SISO wireless repeaters assisting. A theoretical analysis is presented in which repeater positions are considered and sufficient conditions proposed and evaluated for maximizing the MIMO multiplexing gain. The assisting repeaters would be useful when space constraints, for example, on a building top, would prohibit the wide element...
For downlink transmission in a multiuser multiple-input multiple-output (MIMO) communication system, quantized Channel State Information (CSI) is fed back to the base station in an uplink channel of finite rate. The quantized CSI is obtained via Channel Vector Quantization (CVQ) of the so-called composite channel vector, i.e., the product of the channel matrix and an estimation of the receive filter,...
In this paper, we consider the problem of multifunctional compression with side information. The problem is how we can compress a source X so that the receiver is able to compute some deterministic functions f1 (X,Y1), ..., fm(X,Ym), where Yi, 1 ? i ? m, are available at the receiver as side information. In, Wyner and Ziv considered this problem for the special case of m = 1 and f1(X, Y1) = X and...
This paper studies the computation of postprocessing signal-to-interference plus noise ratio (SINR) for maximum likelihood detector (MLD) in multiple-input and multiple output (MIMO)-orthogonal frequency division multiplexing (OFDM) spatial multiplexing systems. We derive an effective post-MLD SINR for each spatial stream, which is computed as post minimum mean-squared error (MMSE) SINR plus gain...
In a protocol assisted switched diversity (PASD) system, the time separated repetition blocks are accumulated in order to increase decoding reliability. In this paper, we consider transmit antenna selection (TAS) protocols in a PASD system. To minimize system complexity we assume the feedback information is limited to the SNR of the current pair of antennas. We propose three TAS protocols : the random...
In this paper, a greedy sub-channel redistribution routing scheme (GSRRS) is proposed for multi-hop wireless OFDMA networks. In GSRRS, between any two neighboring nodes, different sub-channels are routed over different paths including the direct one-hop path and the two-hop path with one intermediate node. Compared to the traditional routing scheme where all the sub-channels route over the same path,...
Delay Tolerant Networks (DTNs) are able to provide communication services in challenged networks where the end-to-end path between the source and destination does not exist. In order to increase the probability of delivery, DTN routing mechanisms may require nodes in the network to store and carry messages in their local buffer and replicate many copies. When the limited buffer is consumed, choosing...
In this paper, we derive optimal pilot power allocation for OFDM systems suffering from in-phase and quadrature-phase (IQ) imbalances. Existing works in literature on IQ imbalances optimize for pilot spacings and pilot designs. However, in all these works, optimal power allocation between pilot and data symbols has not been considered. Using a lower bound on the average channel capacity as a metric,...
In this paper, we propose a distributed contention resolution algorithm for multi-packet reception slotted ALOHA systems, which is based on backlog estimation. In the algorithm, a base station broadcasts a binary-valued collision indicator and the identifications of the packets successfully received, when some of packets simultaneously transmitted collide. Then, mobile terminals (MTs) estimate the...
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