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, 2011
"... Frequency synthesis for cognitive multi-radio Synthèse de fréquence dans une architecture multi-radio cognitive Thèse dirigée par: ..."
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Frequency synthesis for cognitive multi-radio Synthèse de fréquence dans une architecture multi-radio cognitive Thèse dirigée par:
Table 1. Mobile WiMAX channel profiles defined by the WiMAX Forum.
, 2010
"... 1 From the standard and regulations to front-end specifications 1.1 Regulations characteristics The WiMAX standard includes two sub-standards. The first standard is the 802.16a or Fixed WiMAX and the second standard is the 802.16e or Mobile WiMAX. We focus here only on the Mobile WiMAX. The basic ra ..."
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1 From the standard and regulations to front-end specifications 1.1 Regulations characteristics The WiMAX standard includes two sub-standards. The first standard is the 802.16a or Fixed WiMAX and the second standard is the 802.16e or Mobile WiMAX. We focus here only on the Mobile WiMAX. The basic radio channel features are summarized in the Table 1.
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"... Analysis and mitigation of phase noise and sampling jitter in OFDM radio receivers ville syrja¤la ¤ and mikko valkama This article addresses the analysis and digital signal processing (DSP)-based mitigation of phase noise and sampling clock jitter in orthogonal frequency division multiplexing (OFDM) ..."
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Analysis and mitigation of phase noise and sampling jitter in OFDM radio receivers ville syrja¤la ¤ and mikko valkama This article addresses the analysis and digital signal processing (DSP)-based mitigation of phase noise and sampling clock jitter in orthogonal frequency division multiplexing (OFDM) radios. In the phase noise studies, the basic direct-conversion receiver architecture case is assumed with noisy downconverting oscillator. In the sampling jitter case, on the other hand, the so-called direct-radio-frequency-sampling receiver architecture is deployed utilizing bandpass sub-sampling principle. The basis for the DSP-based impairment mitigation techniques is first formed using analytical receiver modeling with incom-ing OFDM waveform, where the effects of both oscillator phase noise and sampling clock jitter are mapped to certain type subcarrier cross-talk and distortion compared to ideal receiver case. Then iterative detection principles and interpolation tech-niques are developed to essentially estimate and cancel the subcarrier distortion. Also some related practical aspects, like channel estimation, are addressed. The performance of the proposed mitigation techniques is analyzed and verified with extensive computer simulations. In the simulations, realistic phase-locked-loop-based oscillator models are used for phase noise and sampling clock jitter. In addition, different received signal conditions like plain additive white Gaussian noise channel and extended ITU-R Vehicular A multipath channel are considered for practical purposes. Altogether the obtained results indicate that the effects of oscillator and sampling clock instabilities can be efficiently reduced using the developed signal processing techniques.
1-4244-2589-1/09/$20.00 ©2009 IEEE. Phase Noise Modelling and Mitigation Techniques in OFDM Communications Systems
"... Abstract—This paper addresses the analysis and mitigation of the signal distortion caused by oscillator phase noise (PN) in OFDM communications systems. Two new PN mitigation techniques are proposed, especially targeted for reducing the intercarrier interference (ICI) effects due to PN. The first pr ..."
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Abstract—This paper addresses the analysis and mitigation of the signal distortion caused by oscillator phase noise (PN) in OFDM communications systems. Two new PN mitigation techniques are proposed, especially targeted for reducing the intercarrier interference (ICI) effects due to PN. The first proposed method is a fairly simple one, stemming from the idea of linearly interpolating between two consecutive common phase error (CPE) estimates to obtain a linearized estimate of the time-varying phase characteristics. The second technique, in turn, is an extension to the existing state-of-the-art ICI estimation methods. Here the idea is to use an additional interpolation stage to improve the phase estimation performance around the boundaries of two consecutive OFDM symbols. The paper also verifies the performance improvement of these new PN estimation techniques by comparing them to the existing state-of-the-art techniques using extensive computer simulations. To emphasize practicality, the simulations are carried out in 3GPP-LTE downlink –like system context, covering both additive white Gaussian noise (AWGN) and extended ITU-R Vehicular A multipath channel types. Index Terms—phase noise; OFDM; common phase error; intercarrier interference; LTE
Abstract — Orthogonal Frequency Division Multiplexing
"... System are better suited to the today’s generation 3G networks and upcoming 4G networks in terms of bandwidth efficiency due to overlapping of frequency bands, high speed data transfer due to parallel data transfer, maintaining high quality of wireless link even under multipath conditions due to low ..."
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System are better suited to the today’s generation 3G networks and upcoming 4G networks in terms of bandwidth efficiency due to overlapping of frequency bands, high speed data transfer due to parallel data transfer, maintaining high quality of wireless link even under multipath conditions due to low symbol rate it minimizes ISI effects. The application of channel codes like convolution codes further reduces the Bit Error Rate and improves the link reliability. Although OFDM systems shows superior performance over single carrier and FDM system but there is one disadvantage that is the over sensitivity to Phase noise of the local oscillator which hinders the orthogonality of the sub carriers and increases inter carrier interference. OFDM system performance is degraded due to phase noise. Accordingly going deep into the various parameters of the OFDM system it was observed that Phase Locked Loop (PLL) could better control the phase noise problem in comparison to free running oscillator. It is deployed at the downlink side of incoming signal received from Antenna generating its own local frequency slightly higher than the incoming frequency to generate IF signal (after mixing the incoming and the local frequency) for further processing. Accordingly to examine closely the other aspects of PLL in relation to Free Running Local Oscillator
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"... Abstract — In this paper, simulation and analysis of phase noise distortion in radio frequency (RF) transceiver of Wireless Local Area Network (WLAN) bridge system are presented. It is focused on the oscillator in RF transmitter and RF receiver in the transceiver. The effect of phase noise on the co ..."
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Abstract — In this paper, simulation and analysis of phase noise distortion in radio frequency (RF) transceiver of Wireless Local Area Network (WLAN) bridge system are presented. It is focused on the oscillator in RF transmitter and RF receiver in the transceiver. The effect of phase noise on the constellation error of RF transmitter and the receiver sensitivity of RF receiver is analysed based on IEEE 802.11a standard. By this way, these analyses can be applied in early stage of oscillator design for RF transceiver of IEEE 802.11a WLAN system. RF behavioural models and Agilent Ptolemy simulator are used in Advanced Design System (ADS) software to perform simulation of constellation error and receiver sensitivity. As a result, it is found that the phase noise of oscillator should not be higher than-120 dbc/Hz at 1 MHz offset in order to optimise the receiver sensitivity and also to minimising constellation error in RF transceiver of IEEE 802.11a standard. Index Terms—Phase noise, transceiver, transmitter, receiver,
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"... All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately. ..."
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All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
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"... In this paper, we present a new inter-carrier interference (ICI) self-cancellation scheme — namely, ISC scheme — for orthogonal frequency-division multiplexing systems to reduce the ICI generated from phase noise (PHN) and residual frequency offset (RFO). The proposed scheme comprises a new ICI canc ..."
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In this paper, we present a new inter-carrier interference (ICI) self-cancellation scheme — namely, ISC scheme — for orthogonal frequency-division multiplexing systems to reduce the ICI generated from phase noise (PHN) and residual frequency offset (RFO). The proposed scheme comprises a new ICI cancellation mapping (ICM) scheme at the transmitter and an appropriate method of combining the received signals at the receiver. In the proposed scheme, the transmitted signal is transformed into a real signal through the new ICM using the real property of the transmitted signal; the fast-varying PHN and RFO are estimated and compensated. Therefore, the ICI caused by fast-varying PHN and RFO is significantly suppressed. We also derive the carrier-to-interference power ratio (CIR) of the proposed scheme by using the symmetric conjugate property of the ICI weighting function and then compare it with those of conventional schemes. Through simulation results, we show that the proposed ISC scheme has a higher CIR and better bit error rate performance than the conventional schemes.
