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This paper focuses on the coexistence problem of multi-band orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) systems and current radio systems such as IEEE802.11a. Aiming at improving the performance of MB-OFDM UWB, we attempt to avoid interferences from IEEE802.11a systems. The cognitive radio (CR) technology is introduced to detect the distribution of co-channel interferences...
In this paper, a blind method to detect and suppress narrow-band interference (NBI) for multi-band orthogonal frequency-division multiplexing (MB-OFDM) based ultrawideband (UWB) communications is proposed. The method utilizes mean-square-error (MSE) statistics in the frequency domain to detect subcarriers damaged by NBI. Approximating the MSE statistics by a decision-feedback (DF) scheme creates a...
Ultra Wide Band (UWB) and Cognitive Radio (CR) offer radically different approaches to efficiently use the seemingly scarce spectrum in wireless communications. In this paper, we study the combined cognitive multiuser spectrum sharing and power allocation problem in the context of Multiband OFDM. A proposed gradient power allocation scheme with a target based game strategy is investigated to solve...
A novel Narrowband Interference (NBI) suppression scheme using a Soft Limiter (SLM) is proposed for a digital noncoherent receiver in Time-Hopping Pulse Position Modulation Ultra Wideband (TH-PPM-UWB) communications. The NBI suppression is carried out in the analog domain (before the digital processing) via a feedforward structure. The suitability of this NBI suppression concept is confirmed by the...
New channel estimation technique is proposed for multiband orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) systems. Several steps have been carried out to achieve this purpose. In first step, refined least square (LS) channel estimation is found out by using subspace-based narrowband interference (NBI) estimation method with prilimonary LS channel. In second step, low rank...
The area of cognitive radio has become an active research area; it promises a new paradigm in spectrum policy because it shifts the management of spectrum from being a political process at the national and world level to a set of algorithms that manage the airwaves around a more limited area. This is attractive because it allows much better spectrum reuse and spatial capacity. One of the primary requirements...
This paper presents a generalized analysis of Multiband OFDM (MB-OFDM) Ultra Wideband (UWB) communication in the presence of generic or non-specific interference sources. The interference sources are assumed to be distributed in a two-dimensional space according to a homogeneous Poisson field. An aggregate interference is formed by the asynchronous operation of these sources. To provide a generalized...
This paper considers the dynamic resource allocation in a multiuser context taking into account the quality of service (QoS) requirements for the high-rate ultra-wideband (UWB) systems. The aim of this paper is twofold. First, we exploit the effective SINR method in the multi-band WiMedia solution proposed for UWB systems. This method is based on the exploitation of the characteristics of multiple...
Spectrum awareness is the key technique for Cognitive Radio (CR). A special spectrum sensing scheme is necessary for Cognitive UWB radio (CUWB) because of its lower radio power and ultra wide bandwidth. Although CUWB transmitter and receiver could respectively detect the spectrum holes, they couldn't communicate with each other probably if they are out of the communication range or there isn't common...
Ultra-wideband (UWB) systems possess several distinct features such as very high data rate, large multipath or frequency diversity and improved ranging precision while requiring low-power low-complexity transceivers. Among the different modulation schemes, differential PSK is an attractive option because it does not require channel estimation, and hence reduces implementation complexity. This paper...
In this paper we consider the coexistence issue between OFDM-based WLANs of the 802.11a family and time-hopping ultra wideband (TH-UWB) systems. A general analytical expression is provided for the bit error rate (BER) of the OFDM transceiver operating in the presence of UWB interference and the interferences caused by the multipath propagation phenomenon on the 802.11a OFDM signal, comprising intersymbol...
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