Pub Date : 2001-11-25DOI: 10.1109/GLOCOM.2001.966199
D. Wei, N. Ansari, Jianguo Chen
Scheduling algorithms are implemented in high-speed switches to provision quality-of-service guarantees in both cell-based and packet-based networks. Being able to guarantee end-to-end delay and fairness, timestamp-based fair queuing algorithms have received much attention in the past few years. In timestamp-based fair queuing algorithms, the size of timestamp and period determines the supportable rates in terms of the range and accuracy. Furthermore, it also determines the scheduler's memory in terms of access bandwidth and storage space. An efficient expression can reduce the size of the timestamp and period without compromising the supportable rate range and the accuracy. In this paper, we propose a compressed and dynamic-range-based expression of the timestamp and period, which can be readily implemented in hardware for both high-speed packet-based and cell-based schedulers. As compared to fixed-point and floating-point number expression, when the size is fixed, the proposed expression has a better accuracy. Regarding to efficiency and relative error consistency, it even better than our earlier proposal.
{"title":"A compressed and dynamic-range-based expression of timestamp and period for timestamp-based schedulers","authors":"D. Wei, N. Ansari, Jianguo Chen","doi":"10.1109/GLOCOM.2001.966199","DOIUrl":"https://doi.org/10.1109/GLOCOM.2001.966199","url":null,"abstract":"Scheduling algorithms are implemented in high-speed switches to provision quality-of-service guarantees in both cell-based and packet-based networks. Being able to guarantee end-to-end delay and fairness, timestamp-based fair queuing algorithms have received much attention in the past few years. In timestamp-based fair queuing algorithms, the size of timestamp and period determines the supportable rates in terms of the range and accuracy. Furthermore, it also determines the scheduler's memory in terms of access bandwidth and storage space. An efficient expression can reduce the size of the timestamp and period without compromising the supportable rate range and the accuracy. In this paper, we propose a compressed and dynamic-range-based expression of the timestamp and period, which can be readily implemented in hardware for both high-speed packet-based and cell-based schedulers. As compared to fixed-point and floating-point number expression, when the size is fixed, the proposed expression has a better accuracy. Regarding to efficiency and relative error consistency, it even better than our earlier proposal.","PeriodicalId":346622,"journal":{"name":"GLOBECOM'01. IEEE Global Telecommunications Conference (Cat. No.01CH37270)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122757645","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}
Pub Date : 2001-11-25DOI: 10.1109/GLOCOM.2001.965521
Jie Luo, K. Pattipati, P. Willett, F. Hasegawa
A probabilistic data association (PDA) method is proposed in this paper for multiuser detection over synchronous code division multiple access (CDMA) communication channels. PDA models the undecided user signals as binary random variables. By approximating the interuser interference (IUI) as Gaussian noise with an appropriately elevated covariance matrix, the probability associated with each user signal is iteratively updated. Computer simulations show that the system usually converges within 3-4 iterations, and the resulting probability of error is very close to that of the optimal maximum likelihood (ML) detector. Further modifications are also presented to significantly reduce the computational cost.
{"title":"A PDA approach to CDMA multiuser detection","authors":"Jie Luo, K. Pattipati, P. Willett, F. Hasegawa","doi":"10.1109/GLOCOM.2001.965521","DOIUrl":"https://doi.org/10.1109/GLOCOM.2001.965521","url":null,"abstract":"A probabilistic data association (PDA) method is proposed in this paper for multiuser detection over synchronous code division multiple access (CDMA) communication channels. PDA models the undecided user signals as binary random variables. By approximating the interuser interference (IUI) as Gaussian noise with an appropriately elevated covariance matrix, the probability associated with each user signal is iteratively updated. Computer simulations show that the system usually converges within 3-4 iterations, and the resulting probability of error is very close to that of the optimal maximum likelihood (ML) detector. Further modifications are also presented to significantly reduce the computational cost.","PeriodicalId":346622,"journal":{"name":"GLOBECOM'01. IEEE Global Telecommunications Conference (Cat. No.01CH37270)","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114186614","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}
Pub Date : 2001-11-25DOI: 10.1109/GLOCOM.2001.965700
Z. Yin, K. Chung, Mohan J. Kumar
A novel multiple access protocol, called DAMMA, is proposed for efficient handling of heterogenous traffic encountered in emerging wireless multimedia communications. To minimise contention collisions, DAMMA adopts random time slot selection in addition to the adaptive procedure for maintaining sufficient time slots available for contention. With DAMMA, time slots are selectively allocated to traffic of different service classes and priority levels to meet the diverse QoS requirements. Computer simulation results indicate that DAMMA can significantly enhance the throughput performance of data traffic. Under a given condition, the DAMMA protocol can achieve a maximum throughput of 91%, which compares well with 70% for the master-slave dynamic rate access (MSDRA) protocol adopted in the General Radio Packet Service (GPRS) system.
{"title":"A dynamic adaptive multiple access protocol for wireless integrated communications","authors":"Z. Yin, K. Chung, Mohan J. Kumar","doi":"10.1109/GLOCOM.2001.965700","DOIUrl":"https://doi.org/10.1109/GLOCOM.2001.965700","url":null,"abstract":"A novel multiple access protocol, called DAMMA, is proposed for efficient handling of heterogenous traffic encountered in emerging wireless multimedia communications. To minimise contention collisions, DAMMA adopts random time slot selection in addition to the adaptive procedure for maintaining sufficient time slots available for contention. With DAMMA, time slots are selectively allocated to traffic of different service classes and priority levels to meet the diverse QoS requirements. Computer simulation results indicate that DAMMA can significantly enhance the throughput performance of data traffic. Under a given condition, the DAMMA protocol can achieve a maximum throughput of 91%, which compares well with 70% for the master-slave dynamic rate access (MSDRA) protocol adopted in the General Radio Packet Service (GPRS) system.","PeriodicalId":346622,"journal":{"name":"GLOBECOM'01. IEEE Global Telecommunications Conference (Cat. No.01CH37270)","volume":"292 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114268324","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}
Pub Date : 2001-11-25DOI: 10.1109/GLOCOM.2001.966299
T. Yu, J. Kwun, H. Jeon, D. Hong, C. Kang
In this paper, a noncoherent adaptive code acquisition scheme is proposed by combining an adaptive filter with a differential detector. The carrier phase offset in the PN signal component of the filter input is removed by a differential detector. The probabilities for detection and false alarm are derived, and the mean acquisition time is evaluated under AWGN channel. The performance of the proposed system is compared with the conventional system using a matched filter. Simulation results show that the proposed system has a good performance under overall channel conditions, especially at low SNR. And the proposed system outperforms the matched filter by 4-6 dB under AWGN channel for 16 taps, as measured by the mean acquisition time.
{"title":"Noncoherent adaptive code synchronization for DS/CDMA systems","authors":"T. Yu, J. Kwun, H. Jeon, D. Hong, C. Kang","doi":"10.1109/GLOCOM.2001.966299","DOIUrl":"https://doi.org/10.1109/GLOCOM.2001.966299","url":null,"abstract":"In this paper, a noncoherent adaptive code acquisition scheme is proposed by combining an adaptive filter with a differential detector. The carrier phase offset in the PN signal component of the filter input is removed by a differential detector. The probabilities for detection and false alarm are derived, and the mean acquisition time is evaluated under AWGN channel. The performance of the proposed system is compared with the conventional system using a matched filter. Simulation results show that the proposed system has a good performance under overall channel conditions, especially at low SNR. And the proposed system outperforms the matched filter by 4-6 dB under AWGN channel for 16 taps, as measured by the mean acquisition time.","PeriodicalId":346622,"journal":{"name":"GLOBECOM'01. IEEE Global Telecommunications Conference (Cat. No.01CH37270)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121979334","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}
Pub Date : 2001-11-25DOI: 10.1109/GLOCOM.2001.965990
M. Eriksson, D. Turina, H. Arslan, K. Balachandran, Jung-Fu Cheng
The GSM/EDGE Radio Access Network (GERAN) is presently being evolved as a full complement to the 3G UMTS network. One part of this evolution is the introduction of efficient support of real-time packet data and alignment to the UNITS Core Network. Another part will introduce performance-enhancing features aimed at improving spectral efficiency, peak and average user-throughput and capacity. One such enhancement being considered is the use of Higher Level Modulations to enhance the user peak rate in the GERAN, in much the same way as the data rate for GPRS was enhanced with the 8PSK modulation in EDGE. By introducing new coding schemes based on QAM the maximum bit rate per time slot could be increased up to 88.8 kbit/s. This paper explains the GERAN concept and investigates possible system level gains, from both spectrum efficiency and perceived user quality perspective, with Higher Level Modulation in GERAN.
{"title":"System performance with higher level modulation in the GSM/EDGE radio access network","authors":"M. Eriksson, D. Turina, H. Arslan, K. Balachandran, Jung-Fu Cheng","doi":"10.1109/GLOCOM.2001.965990","DOIUrl":"https://doi.org/10.1109/GLOCOM.2001.965990","url":null,"abstract":"The GSM/EDGE Radio Access Network (GERAN) is presently being evolved as a full complement to the 3G UMTS network. One part of this evolution is the introduction of efficient support of real-time packet data and alignment to the UNITS Core Network. Another part will introduce performance-enhancing features aimed at improving spectral efficiency, peak and average user-throughput and capacity. One such enhancement being considered is the use of Higher Level Modulations to enhance the user peak rate in the GERAN, in much the same way as the data rate for GPRS was enhanced with the 8PSK modulation in EDGE. By introducing new coding schemes based on QAM the maximum bit rate per time slot could be increased up to 88.8 kbit/s. This paper explains the GERAN concept and investigates possible system level gains, from both spectrum efficiency and perceived user quality perspective, with Higher Level Modulation in GERAN.","PeriodicalId":346622,"journal":{"name":"GLOBECOM'01. IEEE Global Telecommunications Conference (Cat. No.01CH37270)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116620447","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}
Pub Date : 2001-11-25DOI: 10.1109/GLOCOM.2001.965182
I. Koutsopoulos, L. Tassiulas
Wireless broadband access is becoming increasingly popular in the telecommunications market due to the projected demand for high data-rate connections. Given the inherent volatility of the wireless channel, the accurate estimation of channel conditions and the adoption of sophisticated adaptation techniques is required, so that transmission parameters are selected based on link quality, and user throughput is maximized. We consider a simple wireless link monitoring method, which is based on counting positive and negative acknowledgments (ACKs and NACKs), and we investigate the class of adaptation policies that correspond to this method. The policy that maximizes the long-term throughput efficiency of a user is shown to be of threshold type. Due to inherent difficulties in realization of this policy, a suboptimal heuristic method to perform link adaptation is provided. Our results indicate a considerable improvement in link throughput under such adaptive techniques.
{"title":"Link adaptation policies for wireless broadband networks","authors":"I. Koutsopoulos, L. Tassiulas","doi":"10.1109/GLOCOM.2001.965182","DOIUrl":"https://doi.org/10.1109/GLOCOM.2001.965182","url":null,"abstract":"Wireless broadband access is becoming increasingly popular in the telecommunications market due to the projected demand for high data-rate connections. Given the inherent volatility of the wireless channel, the accurate estimation of channel conditions and the adoption of sophisticated adaptation techniques is required, so that transmission parameters are selected based on link quality, and user throughput is maximized. We consider a simple wireless link monitoring method, which is based on counting positive and negative acknowledgments (ACKs and NACKs), and we investigate the class of adaptation policies that correspond to this method. The policy that maximizes the long-term throughput efficiency of a user is shown to be of threshold type. Due to inherent difficulties in realization of this policy, a suboptimal heuristic method to perform link adaptation is provided. Our results indicate a considerable improvement in link throughput under such adaptive techniques.","PeriodicalId":346622,"journal":{"name":"GLOBECOM'01. IEEE Global Telecommunications Conference (Cat. No.01CH37270)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129782790","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}
Pub Date : 2001-11-25DOI: 10.1109/GLOCOM.2001.965674
Young Gil Kim, S. Kim
We propose a new generalized selection combining (GSC) scheme that selects m diversity branches out of L (/spl ges/m) diversity branches based on the magnitude of the log-likelihood ratio (LLR), which, for BPSK signals, is proportional to the product of the fading amplitude and the matched filter output. The proposed GSC is shown to provide a significant power gain over the conventional GSC which selects diversity branches based on signal-to-noise ratio. The proposed GSC scheme for m=3 is found to be only 0.3 dB inferior to the maximal ratio combining scheme (m=L), when L=8, in a Rayleigh fading channel.
{"title":"New generalized selection combining for BPSK signals in Rayleigh fading channels","authors":"Young Gil Kim, S. Kim","doi":"10.1109/GLOCOM.2001.965674","DOIUrl":"https://doi.org/10.1109/GLOCOM.2001.965674","url":null,"abstract":"We propose a new generalized selection combining (GSC) scheme that selects m diversity branches out of L (/spl ges/m) diversity branches based on the magnitude of the log-likelihood ratio (LLR), which, for BPSK signals, is proportional to the product of the fading amplitude and the matched filter output. The proposed GSC is shown to provide a significant power gain over the conventional GSC which selects diversity branches based on signal-to-noise ratio. The proposed GSC scheme for m=3 is found to be only 0.3 dB inferior to the maximal ratio combining scheme (m=L), when L=8, in a Rayleigh fading channel.","PeriodicalId":346622,"journal":{"name":"GLOBECOM'01. IEEE Global Telecommunications Conference (Cat. No.01CH37270)","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128230903","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}
Pub Date : 2001-11-25DOI: 10.1109/GLOCOM.2001.965139
Yaohui Liu, P. Diniz, T. Laakso
A recursive least square (RLS) based complex adaptive notch filter (ANF) using the Steiglitz-McBride (SM) method is proposed to suppress the radio frequency interference (RFI) in very-high-speed digital subscriber line (VDSL) systems. The proposed RLS-SM ANF converges fast and requires less computational complexity than the existing direct form constrained ANF using a recursive prediction error (RPE) algorithm. The proposed algorithm is specially advantageous when dealing with multiple RFI's.
{"title":"Adaptive Steiglitz-McBride notch filter design for radio interference suppression in VDSL systems","authors":"Yaohui Liu, P. Diniz, T. Laakso","doi":"10.1109/GLOCOM.2001.965139","DOIUrl":"https://doi.org/10.1109/GLOCOM.2001.965139","url":null,"abstract":"A recursive least square (RLS) based complex adaptive notch filter (ANF) using the Steiglitz-McBride (SM) method is proposed to suppress the radio frequency interference (RFI) in very-high-speed digital subscriber line (VDSL) systems. The proposed RLS-SM ANF converges fast and requires less computational complexity than the existing direct form constrained ANF using a recursive prediction error (RPE) algorithm. The proposed algorithm is specially advantageous when dealing with multiple RFI's.","PeriodicalId":346622,"journal":{"name":"GLOBECOM'01. IEEE Global Telecommunications Conference (Cat. No.01CH37270)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128319438","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}
Pub Date : 2001-11-25DOI: 10.1109/GLOCOM.2001.966003
Yong Li, J. Moon
Transmitter diversity and coding techniques can be used in high data-rate wireless communications with orthogonal frequency division multiplexing (OFDM) to improve the performance. In this paper, we propose the use of QAM modulations with the constellation size larger than the currently used modulations in HYPERLAN/2, in order to achieve higher spectrum efficiency and data rate. To compensate for the performance loss associated with an extended constellation, we apply the low-density parity check (LDPC) code and introduce transmitter/receiver diversity to the HYPERLAN/2 system. We observe that the LDPC code shows better fading-resistant and error-correcting capabilities than the convolutional code, and the performance loss is completely compensated with the use of diversity techniques.
{"title":"Increasing data rates through iterative coding and antenna diversity in OFDM-based wireless communication","authors":"Yong Li, J. Moon","doi":"10.1109/GLOCOM.2001.966003","DOIUrl":"https://doi.org/10.1109/GLOCOM.2001.966003","url":null,"abstract":"Transmitter diversity and coding techniques can be used in high data-rate wireless communications with orthogonal frequency division multiplexing (OFDM) to improve the performance. In this paper, we propose the use of QAM modulations with the constellation size larger than the currently used modulations in HYPERLAN/2, in order to achieve higher spectrum efficiency and data rate. To compensate for the performance loss associated with an extended constellation, we apply the low-density parity check (LDPC) code and introduce transmitter/receiver diversity to the HYPERLAN/2 system. We observe that the LDPC code shows better fading-resistant and error-correcting capabilities than the convolutional code, and the performance loss is completely compensated with the use of diversity techniques.","PeriodicalId":346622,"journal":{"name":"GLOBECOM'01. IEEE Global Telecommunications Conference (Cat. No.01CH37270)","volume":"543 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128384443","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}
Pub Date : 2001-11-25DOI: 10.1109/GLOCOM.2001.966235
S. Bhatnagar, B. Vickers
Providing strict bandwidth guarantees to packet flows in the Internet is an inherently challenging task. It requires signaling mechanisms, policing mechanisms, accurate and rapid accounting of network resources and call admission control. We present a novel protocol that provides bandwidth guarantees to Internet packet flows. This protocol, called the edge-assisted quality of service (EQOS) protocol, requires modifications to only a subset of an administrative domain's routers, namely the edge routers on the domain's periphery. Legacy routers within the core of the domain require no modifications. Our protocol maintains a high network utilization by dynamic sharing of bandwidth between the reserved and best effort flows. We present the results of several simulation experiments showing that EQOS is able to provide bandwidth guarantees to competing flows.
{"title":"Providing quality of service guarantees using only edge routers","authors":"S. Bhatnagar, B. Vickers","doi":"10.1109/GLOCOM.2001.966235","DOIUrl":"https://doi.org/10.1109/GLOCOM.2001.966235","url":null,"abstract":"Providing strict bandwidth guarantees to packet flows in the Internet is an inherently challenging task. It requires signaling mechanisms, policing mechanisms, accurate and rapid accounting of network resources and call admission control. We present a novel protocol that provides bandwidth guarantees to Internet packet flows. This protocol, called the edge-assisted quality of service (EQOS) protocol, requires modifications to only a subset of an administrative domain's routers, namely the edge routers on the domain's periphery. Legacy routers within the core of the domain require no modifications. Our protocol maintains a high network utilization by dynamic sharing of bandwidth between the reserved and best effort flows. We present the results of several simulation experiments showing that EQOS is able to provide bandwidth guarantees to competing flows.","PeriodicalId":346622,"journal":{"name":"GLOBECOM'01. IEEE Global Telecommunications Conference (Cat. No.01CH37270)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129140577","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}
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