The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring.最新文献

{"title":"Limitations in spectral efficiency of a rate-adaptive MIMO system utilizing pilot-aided channel prediction","authors":"B. Holter, G. Oien, K. Hole, H. Holm","doi":"10.1109/VETECS.2003.1207547","DOIUrl":"https://doi.org/10.1109/VETECS.2003.1207547","url":null,"abstract":"A performance analysis of an adaptive modulation (ACM) system operating on a multiple-input multiple-output (MIMO) channel with uncorrelated Rayleigh fading subchannels is presented. Rate adaptation is based on periodically transmitted channel state information (CSI) back to the transmitter, providing information about the channel signal-to-noise ratio (CSNR) as predicted by the receiver. Transmit diversity is utilized by employing space-time block coding (STBC) at the transmitter.","PeriodicalId":272763,"journal":{"name":"The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring.","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131146385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reliable wireless multicast using fast low-density codes","authors":"J. Chung, Sungeun Kim, J. Copeland","doi":"10.1109/VETECS.2003.1207821","DOIUrl":"https://doi.org/10.1109/VETECS.2003.1207821","url":null,"abstract":"Recently, there has been the high demand for one-to-many reliable multicast distribution under wireless environments. The characteristics of multicast protocol combined with the inherent wireless channel impairment make the network performance drastically degrade as the group size or packet loss rate increases. Although the conventional Reed-Solomon FEC (forward error correction)-based scheme can mitigate problems such as NACK implosion and exposure, its computational complexity makes itself inappropriate for software implementation in resource-limited wireless device. We studied efficient wireless multicast protocol using low-density erasure codes known as tornado FEC and furthermore improved the encoding and decoding speed of tornado FEC by our novel interleaving technique without degrading its overall performance. We call new codes homogeneous tornado FEC (HTF). Our protocol scheme aims at a multicast bulk data distribution in wireless local area networks such as IEEE 802.11.","PeriodicalId":272763,"journal":{"name":"The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring.","volume":"05 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130692571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Variable-rate OFDM systems with selective antenna diversity and adaptive modulation","authors":"M. Torabi, M. Soleymani","doi":"10.1109/VETECS.2003.1207605","DOIUrl":"https://doi.org/10.1109/VETECS.2003.1207605","url":null,"abstract":"In this article, a new scheme consisting of a combination of adaptive modulation, orthogonal frequency division multiplexing (OFDM), high order space-frequency block coding (SFBC), and antenna selection is presented. The proposed scheme, exploits the benefits of space-frequency block codes, OFDM and adaptive modulation to provide high quality of transmission for wireless communications over frequency selective fading channels. We examine the spectral efficiency and coding gain advantages of the proposed system. It is shown that antenna selection with adaptive modulation can greatly improve the performance of the conventional SFBC-OFDM systems.","PeriodicalId":272763,"journal":{"name":"The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring.","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132926955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An improved 2-dimensional pilot-symbols assisted channel estimation in OFDM systems","authors":"Z. Jianhua, Zhang Ping","doi":"10.1109/VETECS.2003.1207091","DOIUrl":"https://doi.org/10.1109/VETECS.2003.1207091","url":null,"abstract":"In orthogonal frequency division multiplexing (OFDM) systems, the pilot-symbols (PS) are utilized to provide an accurate estimation of the channel response. Based on the channel response of PS, 2-dimensional Wiener filtering can provide the optimal channel estimation. However, for the shortage of PS the bit error rate (BER) performance of the side subcarriers obviously worse than that of the other subcarriers. In this paper the periodical character of the discrete time-frequency channel response in frequency domain is observed and the new frequency autocorrelation function (acf) with the periodical property is derived. Then it is applied to obtain the new coefficients of the Wiener filtering. Through the simulation it is verified that the 2-dimensional Wiener filtering based on the periodical frequency acf can efficiently enhance the accuracy of the channel estimation at side subcarriers and it is more accurate optimal PS assisted channel estimation scheme in discrete OFDM systems.","PeriodicalId":272763,"journal":{"name":"The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring.","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133490626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterisation of the time-dependent urban MIMO channel in FDD communication systems","authors":"J. Maurer, C. Waldschmidt, T. Kayser, W. Wiesbeck","doi":"10.1109/VETECS.2003.1207601","DOIUrl":"https://doi.org/10.1109/VETECS.2003.1207601","url":null,"abstract":"The influence of the time dependent urban transmission channel on MIMO systems is investigated in this paper. Exploiting the full potential of MIMO systems requires the knowledge of the transmission channel matrix at the transmitter and the receiver. Channel estimation is therefore necessary. It has to be performed continuously as the transmission channel changes over time. In real communications systems it is only possible to update the channel state information in certain time intervals. During these intervals the estimated channel matrix is assumed to be constant. The difference between the real channel and the estimated one leads to non-orthogonal channels in the MIMO system. The result is inter-sub-channel interference (ISCI). The ISCI is considered as a Gaussian noise random process, which is added to the common thermal noise. Due to the increased total noise power of the resulting channel, the capacity decreases. Furthermore, a sub-channel transmission gain degradation (STGD) occurs caused by the non-orthogonal sub-channels. This results in an additional capacity loss. The dependency of ISCI and STGD on the update time interval is investigated. The considerations are based on simulations of the transmission channel in an urban environment. In order to attain realistic results, a 3D ray-tracing tool is used. An FDD communication system is assumed.","PeriodicalId":272763,"journal":{"name":"The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring.","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133674697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A unit with functions of spectrum monitoring, self-excitation detection and isolation degree test for wireless relay station","authors":"Sujian Zhao, Xin Su, Chu Zhang, Yan Yao","doi":"10.1109/VETECS.2003.1207082","DOIUrl":"https://doi.org/10.1109/VETECS.2003.1207082","url":null,"abstract":"This paper proposes a practical plan for a unit with functions of spectrum monitoring, self-excitation detection and isolation degree test, which is suitable for current wireless relay station. Its design principles, signal processing algorithms and simulation results are given. This design plan leaves room for future functional extension, and does not perform large modifications to the original structure of the relay station.","PeriodicalId":272763,"journal":{"name":"The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring.","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134620382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Variable spreading factor-OFCDM with two dimensional spreading that prioritizes time domain spreading for forward link broadband wireless access","authors":"N. Maeda, Y. Kishiyama, H. Atarashi, M. Sawahashi","doi":"10.1109/VETECS.2003.1207516","DOIUrl":"https://doi.org/10.1109/VETECS.2003.1207516","url":null,"abstract":"This paper proposes the optimum design for adaptively controlling the spreading factor in orthogonal frequency and code division multiplexing (OFCDM) with two-dimensional spreading according to the cell configuration, channel load, and propagation channel conditions, assuming the adaptive modulation and channel coding (AMC) scheme employing QPSK and 16QAM data modulation. Furthermore, we propose a two-dimensional channelization code assignment scheme to achieve skillfully orthogonal multiplexing of multiple physical channels. Computer simulation results elucidate that bit-interleaving in the frequency domain is superior to chip-interleaving especially for a full channel load because bit-interleaving exhibits a large randomization effect of burst errors, while still maintaining code orthogonality. In time domain spreading, the optimum spreading factor, except for an extremely high mobility case such as for the fading maximum Doppler frequency f/sub D/ = 1500 Hz, becomes SF/sub Time/ = 16, and it should be decreased to SF/sub Time/ = 8 for such a very fast fading environment using 16QAM modulation. When the channel load is light such as C/sub mux//SF = 0.25 (C/sub mux/ and SF denote the number of multiplexed codes and total spreading factor, respectively), the required average received signal energy per symbol-to-background noise power spectrum density ratio (E/sub s//N/sub 0/) is reduced as the spreading factor in the frequency domain is increased up to say SF/sub Freq/ = 32 for QPSK and 16QAM modulation, respectively (Note that, nevertheless, 16QAm modulation under such a lighter channel load condition is replaced by QPSK modulation together with two fold the channel load as 16QAM to achieve the same information bit rate). Meanwhile, when the channel load is close to full such as when C/sub mux//SF = 0.94, the optimum spreading factor in the frequency domain is SF/sub Freq/ = 1 for 16QAM modulation and SF/sub Freq/ = 1 to 8 for QPSK modulation according to the delay spread. Consequently, by setting several combinations of spreading factors in the time and frequency domains, the near maximum link capacity is achieved both in cellular and hot-spot cell configurations assuming various channel conditions.","PeriodicalId":272763,"journal":{"name":"The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring.","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115439742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Uplink and downlink SIR analysis for base station placement","authors":"Joseph K. L. Wong, M. Neve, K. Sowerby","doi":"10.1109/VETECS.2003.1207513","DOIUrl":"https://doi.org/10.1109/VETECS.2003.1207513","url":null,"abstract":"Most published work relating to base station placement focuses on desired signal coverage in outdoor wireless systems. However, this approach may not be adequate for future indoor wireless CDMA systems since the systems are interference-limited. In this paper, we present a method for solving the base station placement problem using binary integer programming (BIP). This formulation incorporates coverage, transmitter power and both the uplink and downlink signal-to-interference-ratios into the optimisation process. It is shown that both the uplink and downlink signal-to-interference-ratios should be considered when planning indoor wireless CDMA systems.","PeriodicalId":272763,"journal":{"name":"The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring.","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115639856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design alternatives for IP in vehicles","authors":"C. Maihofer, M. Bechler","doi":"10.1109/VETECS.2003.1207130","DOIUrl":"https://doi.org/10.1109/VETECS.2003.1207130","url":null,"abstract":"For most network technologies, researchers and engineers already have developed mechanisms to run IP on top of the natively supported protocols. Such network technologies include for example IEEE 802, IEEE 1394 networks, or Bluetooth. In the automotive domain other network technologies like CAN and MOST are in use and new ad hoc networks for car-to-car communication are currently being developed. This paper presents and discusses generic approaches for implementing IP in intra-vehicular networks. The discussion includes the criteria whether standard software can be used or customized software has to be developed, the resulting efficiency regarding the message overhead, the fault tolerance of an approach and finally their efficient support for mobile nodes.","PeriodicalId":272763,"journal":{"name":"The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring.","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124173682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simple iterative chip-by-chip multiuser detection for CDMA systems","authors":"Lihai Liu, W. K. Leung, L. Ping","doi":"10.1109/VETECS.2003.1207209","DOIUrl":"https://doi.org/10.1109/VETECS.2003.1207209","url":null,"abstract":"This paper examines several low-cost iterative chip-by-chip multiuser detection algorithms for chip-interleaved code-division multiple-access (CDMA) systems in multipath and multiple antenna environments. The complexities (per user) of these algorithms are very low and increase either linearly or quadratically with path number. It is shown that a system employing a rate-1/2 16-state convolutional code and a length-8 spreading sequence can support more than 100 users with two receive antennas.","PeriodicalId":272763,"journal":{"name":"The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring.","volume":"292 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124203656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}