The expansion of Cognitive Radio (CR) was first impacted by the advent of Software Defined Radio (SDR). SDR provides the reconfigurability needed to switch from one standard to another. In this context and because it will reduce the size of the software to be downloaded, parameterization is an active research topic and appears as a keystone of SDR. Thereby, this paper points out an Extended Reconfigurable Linear Feedback Shift Register Based (ER-LFSR) structure, which can realizes several front rank operations of multi mode CR transceivers. Focused on OFDM based Air Interfaces, the selected approach was to define a range of operations applying like-looking structures. In so doing, we specify two parameterizable structures to fulfill functions such as Pseudo Random Sequence Generators, Scrambling, Convolutive Coding, Cyclic coding, Reed-Solomon Coding or Reed-Solomon decoding.
{"title":"Extended Reconfigurable Linear FeedBack Shift Register Operators for Software Defined Radio","authors":"Laurent Alaus, D. Noguet, Jacques Palicot","doi":"10.1109/ISSSTA.2008.132","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.132","url":null,"abstract":"The expansion of Cognitive Radio (CR) was first impacted by the advent of Software Defined Radio (SDR). SDR provides the reconfigurability needed to switch from one standard to another. In this context and because it will reduce the size of the software to be downloaded, parameterization is an active research topic and appears as a keystone of SDR. Thereby, this paper points out an Extended Reconfigurable Linear Feedback Shift Register Based (ER-LFSR) structure, which can realizes several front rank operations of multi mode CR transceivers. Focused on OFDM based Air Interfaces, the selected approach was to define a range of operations applying like-looking structures. In so doing, we specify two parameterizable structures to fulfill functions such as Pseudo Random Sequence Generators, Scrambling, Convolutive Coding, Cyclic coding, Reed-Solomon Coding or Reed-Solomon decoding.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129224052","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}
Relaying is expected to play an important role in the design of next generation cellular networks. Integrating multihop communications with the infrastructure-based design of cellular networks results in a new wireless architecture known as multihop based cellular network (MBCN). Studies performed so far on MBCNs mainly assume the use of omnidirectional antennas at relay stations. In this work, we investigate the use of advanced antenna configurations at fixed relay stations in CDMA-based MBCNs. The considered advanced antenna configurations include directional antennas and various adaptive antenna arrays. A new interference reduction factor is derived and studied in terms of overall system performance. Analytical results accompanied by Monte-Carlo simulation results demonstrate that with proper selection of advanced antennas at fixed relay stations, significant performance gains can be achieved.
{"title":"Advanced Antenna Configurations for the Downlink of Multihop Based Cellular Networks","authors":"I. Abdel Nabi, Z. Dawy","doi":"10.1109/ISSSTA.2008.147","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.147","url":null,"abstract":"Relaying is expected to play an important role in the design of next generation cellular networks. Integrating multihop communications with the infrastructure-based design of cellular networks results in a new wireless architecture known as multihop based cellular network (MBCN). Studies performed so far on MBCNs mainly assume the use of omnidirectional antennas at relay stations. In this work, we investigate the use of advanced antenna configurations at fixed relay stations in CDMA-based MBCNs. The considered advanced antenna configurations include directional antennas and various adaptive antenna arrays. A new interference reduction factor is derived and studied in terms of overall system performance. Analytical results accompanied by Monte-Carlo simulation results demonstrate that with proper selection of advanced antennas at fixed relay stations, significant performance gains can be achieved.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121081043","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}
In the wireless local area network (WLAN) standard IEEE 802.11b, complementary code keying (CCK) modulation has been adopted for the high data rate transmission mode, which can be considered as a special type of spread spectrum modulation with data-dependent spreading. In this paper, complexity reduction for block reduced-state sequence estimation (bRSSE), tailored for CCK transmission over frequency-selective channels, is considered. A trellis diagram for the chip phases of the codewords fully describes the CCK code properties. Subset trellises are derived from the full CCK trellis diagram based on set partitioning of the multidimensional CCK code set. The CCK subset trellises connect consecutive bRSSE states in order to form a compound trellis. The Viterbi algorithm (VA) with per-survivor processing is applied to the compound trellis to take the inter-chip interference into account. Inter-codeword interference is also accounted for by state-dependent decision feedback. The resulting scheme is denoted as bRSSE-pS and has a significantly lower complexity than bRSSE with brute-force search. By introducing a sphere constraint on the overall decoding trellis (SC-bRSSE-pS), the complexity of bRSSE-pS can be further reduced. Omitting states in the CCK subset trellises that violate the sphere constraint, edges that emanate from such states can be pruned, and the average number of metric calculations per CCK trellis segment can be reduced. Simulation results show that the performance of bRSSE-pS and SC-bRSSE-pS, respectively, is essentially equivalent to that of bRSSE with brute-force search, while complexity is significantly reduced.
{"title":"Sphere Constrained Block RSSE with Per-Survivor Intra-Block Processing for CCK Transmission","authors":"C. Jonietz, W. Gerstacker, R. Schober","doi":"10.1109/ISSSTA.2008.53","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.53","url":null,"abstract":"In the wireless local area network (WLAN) standard IEEE 802.11b, complementary code keying (CCK) modulation has been adopted for the high data rate transmission mode, which can be considered as a special type of spread spectrum modulation with data-dependent spreading. In this paper, complexity reduction for block reduced-state sequence estimation (bRSSE), tailored for CCK transmission over frequency-selective channels, is considered. A trellis diagram for the chip phases of the codewords fully describes the CCK code properties. Subset trellises are derived from the full CCK trellis diagram based on set partitioning of the multidimensional CCK code set. The CCK subset trellises connect consecutive bRSSE states in order to form a compound trellis. The Viterbi algorithm (VA) with per-survivor processing is applied to the compound trellis to take the inter-chip interference into account. Inter-codeword interference is also accounted for by state-dependent decision feedback. The resulting scheme is denoted as bRSSE-pS and has a significantly lower complexity than bRSSE with brute-force search. By introducing a sphere constraint on the overall decoding trellis (SC-bRSSE-pS), the complexity of bRSSE-pS can be further reduced. Omitting states in the CCK subset trellises that violate the sphere constraint, edges that emanate from such states can be pruned, and the average number of metric calculations per CCK trellis segment can be reduced. Simulation results show that the performance of bRSSE-pS and SC-bRSSE-pS, respectively, is essentially equivalent to that of bRSSE with brute-force search, while complexity is significantly reduced.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124018263","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}
We consider a multicell multiple-input-multiple-output (MIMO) orthogonal-frequency-division-multiple-access (OFDMA) scenario conforming to the 3GPP long term evolution (LTE) recommendation. Scheduling policies proposed for interference mitigation in LTE rely on a pseudo-random permutation of the subcarriers (interference randomization) or on a centrally coordinated reuse of the OFDMA bandwidth (interference coordination). For both the approaches, this paper investigates the performance of a multiple antenna communication over a Rayleigh fading multipath channels. An analytical model is derived to assess the average bit error probability for frequency-selective (correlated) channels with either stationary or nonstationary (due to subcarrier permutation) multicell interference. Simulation results corroborate the proposed analytical model for different traffic conditions and propagation scenarios.
{"title":"Interference Mitigation in Multicell LTE Systems: Performance over Correlated Fading Channels","authors":"D. Molteni, Monica Nicoli","doi":"10.1109/ISSSTA.2008.32","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.32","url":null,"abstract":"We consider a multicell multiple-input-multiple-output (MIMO) orthogonal-frequency-division-multiple-access (OFDMA) scenario conforming to the 3GPP long term evolution (LTE) recommendation. Scheduling policies proposed for interference mitigation in LTE rely on a pseudo-random permutation of the subcarriers (interference randomization) or on a centrally coordinated reuse of the OFDMA bandwidth (interference coordination). For both the approaches, this paper investigates the performance of a multiple antenna communication over a Rayleigh fading multipath channels. An analytical model is derived to assess the average bit error probability for frequency-selective (correlated) channels with either stationary or nonstationary (due to subcarrier permutation) multicell interference. Simulation results corroborate the proposed analytical model for different traffic conditions and propagation scenarios.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"53 18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123179636","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}
Code division multiple access (CDMA) schemes and combination of CDMA with OFDM have been considered as attractive multiple access schemes in the second-generation (2G), third-generation (3G) and future broadband wireless systems. In this paper, we studied the performance of DS-CDMA signals with quasi-orthogonal codes namely balanced gold codes and m-sequences in presence of timing synchronization error. The synchronization error considered is smaller than the chip duration. We evaluate the maximum synchronization error that can be tolerated so that complete error-free despreading is guaranteed for the two quasi-orthogonal codes in the absence of additive white Gaussian noise and channel impairments. This provides insight in the synchronization demands for QS-CDMA systems. Also system capacity (the total bit rate which can be transmitted) subject to this synchronization error has been calculated for the two codes. It has been found that m-sequence provide maximum tolerable synchronization error and system capacity as compared to balanced gold code. We have also presented the BER analysis for QS-CDMA. The BER performance of the two quasi-orthogonal sequences at different values of synchronization error is also studied. Monte-Carlo simulations have been carried out to verify analysis with the simulation results.
{"title":"BER Analysis of Quasi-Orthogonal Codes in Quasi-Synchronous CDMA Communication","authors":"S. Jos, P. Kumar, S. Chakrabarti","doi":"10.1109/ISSSTA.2008.105","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.105","url":null,"abstract":"Code division multiple access (CDMA) schemes and combination of CDMA with OFDM have been considered as attractive multiple access schemes in the second-generation (2G), third-generation (3G) and future broadband wireless systems. In this paper, we studied the performance of DS-CDMA signals with quasi-orthogonal codes namely balanced gold codes and m-sequences in presence of timing synchronization error. The synchronization error considered is smaller than the chip duration. We evaluate the maximum synchronization error that can be tolerated so that complete error-free despreading is guaranteed for the two quasi-orthogonal codes in the absence of additive white Gaussian noise and channel impairments. This provides insight in the synchronization demands for QS-CDMA systems. Also system capacity (the total bit rate which can be transmitted) subject to this synchronization error has been calculated for the two codes. It has been found that m-sequence provide maximum tolerable synchronization error and system capacity as compared to balanced gold code. We have also presented the BER analysis for QS-CDMA. The BER performance of the two quasi-orthogonal sequences at different values of synchronization error is also studied. Monte-Carlo simulations have been carried out to verify analysis with the simulation results.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115709791","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}
In multiuser downlink, the use of multiple antennas at the base station and user terminals leads to a great increase in the system throughput. However, this increase is only achieved with proper transmission techniques which schedule the best set of users and distribute resources according to each user's channel condition. In this paper, a multiuser MIMO-OFDM technique based on partial CSI is presented for broadcast channels, which achieves a greatly increased system throughput. In the proposed scheme, the base station schedules transmission to a subset of users and allocates data streams on each antenna and subcarrier to users based on their received partial CSI. A combination of eigenmode transmission and zero-forcing (ZF) receiver processing is used to separate spatial layers on each subcarrier. The results show the proposed scheme's advantage over limited feedback linear ZF receiver processing and frequency division multiplexing (FDM). The feedback overhead of the proposed scheme over realistic channels is significantly reduced compared to the case where only ZF receiver processing is adopted on each subcarrier.
{"title":"Efficient Transmission Technique for MIMO-OFDM Broadcast Channels with Limited Feedback","authors":"M. Eslami, W. Krzymień","doi":"10.1109/ISSSTA.2008.49","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.49","url":null,"abstract":"In multiuser downlink, the use of multiple antennas at the base station and user terminals leads to a great increase in the system throughput. However, this increase is only achieved with proper transmission techniques which schedule the best set of users and distribute resources according to each user's channel condition. In this paper, a multiuser MIMO-OFDM technique based on partial CSI is presented for broadcast channels, which achieves a greatly increased system throughput. In the proposed scheme, the base station schedules transmission to a subset of users and allocates data streams on each antenna and subcarrier to users based on their received partial CSI. A combination of eigenmode transmission and zero-forcing (ZF) receiver processing is used to separate spatial layers on each subcarrier. The results show the proposed scheme's advantage over limited feedback linear ZF receiver processing and frequency division multiplexing (FDM). The feedback overhead of the proposed scheme over realistic channels is significantly reduced compared to the case where only ZF receiver processing is adopted on each subcarrier.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130986109","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}
J. George, A. Chamarti, A. Ng'oma, D. Thelen, M. Sauer
Remote positioning of the ultra wide band (UWB) wireless technology based ranging systems using the radio over multimode fiber (RoMMF) technology is investigated here. The ranging accuracy of such a system with various fiber lengths is studied. Another aspect of the study involves the evaluation of the impact of a coexistent in-band wireless local area network (WLAN) signal (802.11a) on the accuracy of UWB ranging capabilities. The impact of a co-existent UWB signal on 802.11a WLAN performance is also evaluated using error vector magnitude (EVM) measurements.
{"title":"Accuracy of UWB Ranging over Multimode Fiber With and Without In-Band WLAN Interference","authors":"J. George, A. Chamarti, A. Ng'oma, D. Thelen, M. Sauer","doi":"10.1109/ISSSTA.2008.62","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.62","url":null,"abstract":"Remote positioning of the ultra wide band (UWB) wireless technology based ranging systems using the radio over multimode fiber (RoMMF) technology is investigated here. The ranging accuracy of such a system with various fiber lengths is studied. Another aspect of the study involves the evaluation of the impact of a coexistent in-band wireless local area network (WLAN) signal (802.11a) on the accuracy of UWB ranging capabilities. The impact of a co-existent UWB signal on 802.11a WLAN performance is also evaluated using error vector magnitude (EVM) measurements.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126706066","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}
Sekwon Kim, Jaewoon Kim, Youngjin Park, Soonwoo Lee, Y. Shin
We propose a selective signal combining scheme to effectively improve bit error rate (BER) performance of noncoherent ultra wide band (UWB) systems utilizing binary pulse position modulation (2PPM) based on impulse radio. First, to effectively combine multipath components at the noncoherent UWB receiver, the proposed scheme preserves the energies during the pulse width interval for the received UWB signals. Next, it calculates the approximate signal-to-noise ratio (SNR) by comparing the difference in signal energies during the pulse width interval. Finally, the proposed scheme selectively combines the preserved signal energies in order of the estimated SNR, and then performs signal detection. Hence, the proposed scheme provides effective signal combining which is proper for noncoherent 2PPM UWB receivers, thereby significantly improving BER performance compared to conventional noncoherent UWB receivers.
{"title":"A Selective Signal Combining Scheme for Noncoherent UWB Systems","authors":"Sekwon Kim, Jaewoon Kim, Youngjin Park, Soonwoo Lee, Y. Shin","doi":"10.1109/ISSSTA.2008.63","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.63","url":null,"abstract":"We propose a selective signal combining scheme to effectively improve bit error rate (BER) performance of noncoherent ultra wide band (UWB) systems utilizing binary pulse position modulation (2PPM) based on impulse radio. First, to effectively combine multipath components at the noncoherent UWB receiver, the proposed scheme preserves the energies during the pulse width interval for the received UWB signals. Next, it calculates the approximate signal-to-noise ratio (SNR) by comparing the difference in signal energies during the pulse width interval. Finally, the proposed scheme selectively combines the preserved signal energies in order of the estimated SNR, and then performs signal detection. Hence, the proposed scheme provides effective signal combining which is proper for noncoherent 2PPM UWB receivers, thereby significantly improving BER performance compared to conventional noncoherent UWB receivers.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114245631","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}
3GPP is in the process of defining the Long-Term Evolution (LTE) for 3G radio access in order to maintain the future competitiveness for 3G technology. In this paper, we consider packet scheduling for the 3GPP LTE downlink in a multiuser OFDMA environment. The quality of service (QoS) concept proposed for LTE is a realization of Diffserv for 3GPP access networks, where each QoS class is associated with a policy profile. Our main goal is to design 3GPP LTE scheduler within this Diffserv context under realistic traffic models such as file transfer and web browsing. Our obtained results show that the associated Diffserv polices can enforced and hence provide an effective way of dividing bandwidth between QoS classes. We further show possible benefits of having service-dependent scheduling algorithms.
{"title":"Scheduling Algorithms for 3GPP Long-Term Evolution Systems: From a Quality of Service Perspective","authors":"M. Gidlund, Jean-Christophe Laneri","doi":"10.1109/ISSSTA.2008.28","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.28","url":null,"abstract":"3GPP is in the process of defining the Long-Term Evolution (LTE) for 3G radio access in order to maintain the future competitiveness for 3G technology. In this paper, we consider packet scheduling for the 3GPP LTE downlink in a multiuser OFDMA environment. The quality of service (QoS) concept proposed for LTE is a realization of Diffserv for 3GPP access networks, where each QoS class is associated with a policy profile. Our main goal is to design 3GPP LTE scheduler within this Diffserv context under realistic traffic models such as file transfer and web browsing. Our obtained results show that the associated Diffserv polices can enforced and hence provide an effective way of dividing bandwidth between QoS classes. We further show possible benefits of having service-dependent scheduling algorithms.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"107 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122422584","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}
Overloading is a technique to accommodate more number of users than the spreading factor N. This is a bandwidth efficient scheme to increase the number users in a fixed bandwidth. One of the efficient schemes to overload a CDMA system is to use two sets of orthogonal signal waveforms (O/O). The first set is assigned to the N users and the second set is assigned to the additional M users. An iterative multistage detection (IMSD) technique is used to cancel interference between the two sets of users. The interference cancellation receiver uses hard decisions (HDIC) or soft decisions (SDIC) to estimate the interference. In this paper, the BER performance of s-O/O overloading scheme using Walsh-Hadamard (WH) orthogonal codes is evaluated with SDIC receiver on a Rayleigh fading channel. It is observed that this scheme provides the channel overloading of 33% at a BER of 0.0005, with an SNR degradation of about 1 dB as compared to single user performance on a Rayleigh fading channel with real scrambling. With complex scrambling, overloading performance increases significantly to 75%. This is a significant amount of overloading on a Rayleigh fading channel.
{"title":"Overloading Performance of OCDMA/OCDMA Scheme for Cellular DS-CDMA System on Rayleigh Fading Channel","authors":"Preetam Kumar, S. Jos, S. Chakrabarti","doi":"10.1109/ISSSTA.2008.106","DOIUrl":"https://doi.org/10.1109/ISSSTA.2008.106","url":null,"abstract":"Overloading is a technique to accommodate more number of users than the spreading factor N. This is a bandwidth efficient scheme to increase the number users in a fixed bandwidth. One of the efficient schemes to overload a CDMA system is to use two sets of orthogonal signal waveforms (O/O). The first set is assigned to the N users and the second set is assigned to the additional M users. An iterative multistage detection (IMSD) technique is used to cancel interference between the two sets of users. The interference cancellation receiver uses hard decisions (HDIC) or soft decisions (SDIC) to estimate the interference. In this paper, the BER performance of s-O/O overloading scheme using Walsh-Hadamard (WH) orthogonal codes is evaluated with SDIC receiver on a Rayleigh fading channel. It is observed that this scheme provides the channel overloading of 33% at a BER of 0.0005, with an SNR degradation of about 1 dB as compared to single user performance on a Rayleigh fading channel with real scrambling. With complex scrambling, overloading performance increases significantly to 75%. This is a significant amount of overloading on a Rayleigh fading channel.","PeriodicalId":334589,"journal":{"name":"2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122810560","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：