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In order to improve the efficiency of spectrum resource usage and the capacity of wireless networks, cooperative relay techniques which utilize the vacant spectrum of primary users for secondary users' data transmission have been applied in cognitive radio networks. Considering the dynamic time-varying vacant spectrum resources and achievable rate on different channels at relay nodes (RN), the traditional...
Consider an infrastructure-based multi-band cognitive radio network (CRN) where secondary users (SUs) opportunistically access a set of sub-carriers when sensed as idle. The carrier sensing threshold which affects the access opportunities of SUs is conventionally regarded as static and treated independently from the resource allocation in the model. In this article, we study jointly the optimization...
In this article, we consider a cognitive radio (CR) communication system based on spectrum sharing schemes, where we have a secondary user (SU) link with multiple transmitting antennas and a single receiving antenna, coexisting with a primary user (PU) link with a single receiving antenna. At the SU transmitter (SU-Tx), the channel state information (CSI) of the SU link is assumed to be perfectly...
To deal with the future high demands of wireless traffic and energy consumption, one type of heterogeneous deployments is to distribute the base station antennas throughout the entire cell, which is called remote radio head (RRH). In view of radio resource management, the joint resource allocation in broadband orthogonal frequency division multiple access RRH (OFDMA-RRH) has not been thoroughly studied,...
With evolution and popularity of radio access technologies, the radio resource is becoming scarce. However, with fast-growing service demands, the future advanced wireless communication systems are expected to provide ubiquitous mobile broadband coverage to support higher data rate. Therefore, it is becoming an important problem that how to meet the greater demand with limited resources? In this situation,...
Heterogeneous network (HetNet) is a typical deployment scenario for the IMT-Advanced system whereby the macro enhanced node B (eNB) provides the wide coverage while the lower power nodes such as micro, pico, femto, and relay nodes extend the coverage/capacity for coverage hole or hotspot. This literature addresses the spatial propagation modeling for urban micro (UMi) scenario of HetNet. Due to users...
Two ultra-wideband (UWB) specifications, that is, direct-sequence (DS) UWB and multiband-orthogonal frequency division multiplexing (MB-OFDM) UWB, have been proposed as the candidates of the IEEE 802.15.3a, competing for the standard of high-speed wireless personal area networks (WPAN). Due to the withdrawal of the standardization process, the two heterogeneous UWB technologies will coexist in the...
This paper proposes a user cooperation stimulating strategy among rational users. The strategy is based on cooperative game theory and enacted in the context of cooperative relay networks. Using the pricing-based mechanism, the system is modeled initially with two nodes and a Base Station (BS). Within this framework, each node is treated as a rational decision maker. To this end, each node can decide...
Accuracy and complexity are two crucial aspects of the applicability of a channel model for wideband multiple input multiple output (MIMO) systems. For small number of antenna element pairs, correlation-based models have lower computational complexity while the geometry-based stochastic models (GBSMs) can provide more accurate modeling of real radio propagation. This paper investigates several potential...
A novel partial frequency response channel estimator is proposed for OFDMA systems. First, the partial frequency response is obtained by least square (LS) method. The conventional discrete Fourier transform (DFT) method will eliminate the noise in time domain. However, after inverse discrete Fourier transform (IDFT) of partial frequency response, the channel impulse response will leak to all taps...
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