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Robust, efficient and low complexity design methodologies for high speed multi-band orthogonal frequency division multiplexing ultra-wideband (MB-OFDM UWB) is presented. The proposed design is implemented in 0.13μm CMOS technology with the core area of 2.66mm × 0.94mm. Operating at 132MHz clock frequency, the estimated power consumption is 170mW.
Traditional OFDM based transmission system uses Cyclic Prefix (CP) in an OFDM symbol in order to maintain orthogonality of transmission. Present days' Ultra-Wideband (UWB) systems use Multi-Band OFDM (MB-OFDM) techniques for transmission in application like Wireless Personal Area Network (WPAN). UWB based systems are power limited by the regulation of FCC. CP introduces correlation in the transmitted...
The Fourth generation (4G) wireless networks are expected to afford high data rate transmission of multimedia services such as wireless video, wireless Internet access and mobile computing. Orthogonal frequency division multiplexing (OFDM) is an effective technique for the future 4G communications because of its great immunity to impulse noise and intersymbol interference. Ultra wide band (UWB) wireless...
The emerging technology of cooperative communication has been intensively examined in the recent years. However, few investigate its combination with the Multi-band (MB) OFDM physical layer. In the paper, we propose a cooperative MB-ODFM communication with efficiently grouped relays under multipath channel. Taking advantage of the multiple bands together with the grouped relays, the proposed zero-padding...
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...
The detector proposed in this paper tries to address the challenge of low signal-to-noise ratio signal detection in low-complexity MB-OFDM UWB receivers. The idea is to exploit the 128-point FFT of the UWB receiver to carry out frequency-domain energy detection. The main advantage of the proposed detector is that it only requires a memory buffer the size of the UWB receiver FFT, which makes it lighter...
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...
OFDM-based systems are sensitive to phase distortion. Although the carrier frequency offset (CFO) can be coarsely corrected in time domain, the residual CFO, the sampling frequency offset and other phase noises will still lead to system performance degradation. Therefore, using fine phase tracking in frequency domain is necessary to guarantee the receiver performance. In this paper, an efficient and...
Considering the potential interference of ultra-wideband (UWB) on narrowband communication systems, this paper studies coexistence issue between UWB with both impulse radio (IR) and multiband (MB) modulation and IEEE802.11n system, using physical layer modelling strategy. According to the physical characteristics of UWB and the victim system, entire physical layer models are set up. Based on the requirements...
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 analyzes the I/Q imbalance effect of direct-conversion receiver in wide-band wireless communication system and sets up frequency-selective I/Q imbalance model for ultra-wide band system. We design a new training sequence based on extra phase rotation and propose an estimation algorithm using diversity message introduced by I/Q imbalance during the demodulation process. Theoretical analysis...
In a multiple-input multiple-output (MIMO) multi-band orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) system, coherent detection where the channel state information (CSI) is assumed to be exactly known at the receiver requires the transmission of a large number of symbols for channel estimation, thus reducing the bandwidth efficiency. This paper examines the use of unitary...
This paper presents the interference of ultra wide-band (UWB) sensor applied in Korea into wireless broad-band (WiBro) system based on orthogonal frequency division multiplexing (OFDM) using frequency of 2.3 GHz. The minimum coupling loss (MCL) method and spectrum engineering advanced Monte Carlo analysis tool (SEAMCAT) are used to evaluate the interference effects of UWB sensor on WiBro. The required...
The European Commission has recently adopted specific power spectral density masks for Ultra Wideband devices, with detect and avoid capabilities, for coexistence with licensed standards. Under these regulations, a novel approach for analysing the Ultra Wideband interference effects on the WiMax downlink is provided in this paper. The maximum permissible interference level, as well as the signal-to-interference...
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 proposes a new I/Q imbalance estimation algorithm for multiband orthogonal frequency division multiplexing (MB-OFDM) based ultra-wideband (UWB) systems. The proposed algorithm is highly effective for the UWB channels with strong frequency selectivity in the presence of carrier frequency offset (CFO). In order to estimate I/Q imbalance, the 2nd-order moments of received signal are analyzed,...
In this paper a low-power multi-gigabit single-chip transceiver is demonstrated in 90 nm CMOS operating in the worldwide allocated 7.2 GHz - 8.5 GHz ultra-wideband frequency spectrum. The transceiver operates as an MB-OFDM compatible front-end as well as a single-carrier modulator/demodulator with an integrated BPSK baseband modem. An embedded pulse shaping filter enables transmission of 2.4 Gbps...
Ultra wideband (UWB) technology has been shown to possess several characteristics that are required for the next generation wireless personal area network (WPAN) applications: simple implementation, high data rate, coexistence with existing systems. This paper presents performance evaluations of the multiband OFDM (MB-OFDM) UWB system based on simulations using indoor UWB channel measurements collected...
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