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We consider a spectrum sharing protocol in which a secondary system operates on the same spectrum as a primary system, without adversely affecting the rate of the primary system. The protocol comprises of a two-phase transmission. In the first phase, the primary transmitter transmits a primary signal to the primary receiver, which is also received at the secondary transmitter and receiver. The secondary...
A fair distributed channel, route, and power control algorithm for multi-hop radio networks is proposed in the present paper. Since adaptive channel and route control algorithms that maximize the total throughput allocate more resources to links with good quality, there will be a large difference in throughput among communication links, and thus these algorithms are not necessarily fair. In order...
This paper proposes enabling technologies and strategies for radio resource management (RRM) in decentralized heterogeneous wireless networks. To cope with dynamic variation of user signals' bandwidth in the decentralized RRM, dynamic spectrum control (DSC) is applied to flexibly utilize spot-wise available spectra. Spectrum clipping is further applied as a bandwidth adjustment technique to fit the...
To cope with limited spectrum resources, inefficient spectrum usage and overcrowded wireless communication, the Federal Communications Commission's (FCC) has introduced a new way to manage RF resources: the interference temperature model. With this model the key point is to let unlicensed users use licensed frequencies, provided they can quantify and bound their interference toward the primary license...
This paper studies interference channels with security constraints. The existence of an external eavesdropper in a two-user interference channel is assumed, where the network users would like to secure their messages from the external eavesdropper. The cooperative binning and channel prefixing scheme is proposed for this system model which allows users to cooperatively add randomness to the channel...
Currently a number of 802.11 based standards support multiple rates at physical layer and recently 802.11 MAC protocols have been modified to make use of these multiple rates. Two such mechanisms, opportunistic auto rate (OAR) and receiver based auto rate (RBAR) have shown to improve throughput performance of wireless LANs as well as infrastructure-less wireless networks. However these protocols are...
Wireless sensor network (WSN) applications demand ultra low power devices. Digital Ultra Wideband (UWB) transceiver can be used as the communication module in a WSN due it its potential for location tracking, ranging and low data rate communication. Current digital UWB receiver architecture incorporates heavy parallelism, which significantly increases power consumption, especially during the acquisition...
We present an effective method of collision recovery for orthogonal frequency division multiplexing (OFDM)-based communications. For the OFDM system, the modulated message data can be demodulated using the partial time-domain OFDM symbol. Therefore, the partial time-domain symbol can be adopted to reconstruct the whole OFDM time-domain symbol with estimated channel information. This property can be...
In this paper we investigate the performance of the Parity Bit selected Multicarrier Direct Sequence Spread Spectrum (PB-MC-DS-SS) system using Log Likelihood Ratio (LLR). In this system information bits are convolutionally encoded prior to being used in the parity bit selected MC-DS-SS system. Reliability of the detected bits in the receiver is calculated in the form of LLRs and then used as the...
This work explores theoretically the unique aspects of different signal processing stages in a Multi-Band (MB) Orthogonal Frequency Division Multiplexing (OFDM) based system in realistic Ultra-Wideband (UWB) channel. In the process of analysis, it emphasizes the significant aspects of signal processing steps in UWB receiver design comparing a narrow-band system. The analysis preliminary considers...
In this paper, we extend the well-known model for Gaussian Cellular Multiple Access Channel originally presented by Wyner and later extended by Somekh et al. with fading. The extension to the model, incorporates the distance dependent path loss (maintaining a close relevance to path loss values in real world cellular systems) experienced by the users distributed in a planar cellular array. The density...
The evolution of air interfaces for 4G wireless systems often appears as an OFDM-CDMA battle which OFDM is going to win. This paper reviews this point of view and highlights some other features of this evolution. The paper presents a novel multicode DS-CDMA scheme which has the same advantages as OFDMA over frequency selective channels: good performance with low complexity one-tap receiver. Actually,...
The increasing demand for radio spectrum along with inefficient usage of the licensed bands has led the regulatory bodies to consider opening up the under-utilized licensed frequency bands for dynamic access by unlicensed users. Such dynamic spectrum access is envisioned to resolve the spectrum scarcity by allowing unlicensed users to opportunistically utilize the white spaces across the licensed...
Cognitive wireless system encompass the notion of intelligent network elements and terminals working together to utilize resources in a far more efficient way. The focus of this paper is on the introduction of cognitive functionalities to mobile terminals to enhance their resilience and to assist the optimized selection and auto-configuration of protocols. To fulfill these objectives, we introduce...
We consider SINR maximizing receivers based on the concept of chip-level filtering and symbol level equalization for WCDMA downlink. In this contribution we propose a new class of receivers based on channel sparsifying linear pre-processing at chip-rate followed by time-varying symbol level equalizers. Due to a sparse structure imposed on the channel (i.e. sparsification) by a chip level pre-equalizer...
The introduction of the upcoming GERAN evolution feature package in current GSM/EDGE deployments offers operators significant boost in network capacity and mobile data users UMTS/HSPA like high speed packet data services along with competitive latency. Intelligent radio resource management supports novel dual-carrier capable mobile stations by dynamic configuration of GPRS/EDGE packet data channels...
A distributed power, channel, and route selection scheme for multi-hop radio networks is proposed by extending multichannel asynchronous distributed pricing (MADP) algorithm, which is a power and channel selection scheme for single-hop radio networks. MADP algorithm achieves suboptimal system throughput in single-hop radio networks, however, since MADP algorithm allocates more resources to links with...
The combination of user multiplexing and data encoding within Ultra Wideband systems has been proposed to improve bit error performance. Relative to conventional binary coding, this technique has shown to reduce error rates in scarcely populated systems. Where non-binary turbo coding modulates data to form an integer sequence, a random mapping is generally applied to develop a time hopping sequence...
We propose an improved beamforming matrix compression by givens rotation with the use of variable feedback rate. The variable feedback rate means that the number of bits used to represent the quantized beamforming matrix is based on the value of the matrix. Compared with the fixed feedback rate scheme, the proposed method has better performance without additional feedback bandwidth.
In this paper, a distributed power-aware medium access control (MAC) algorithm for ad hoc wireless networks is presented. The algorithm is developed based on proposing a power-aware MAC game which is analyzed in the game theory framework. The aim is to adjust each active link persistence probability and power by maximizing a defined local link payoff function. The payoff function is such that its...
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