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Max-utility subcarrier allocation for heterogeneous services in wireless OFDM system
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作者 CHEN Zi-xiong SUN Kai +1 位作者 YUAN Jun WANG Ying 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 2009年第1期51-57,共7页
In future wireless network, one user will require multiple homogeneous or heterogeneous services simultaneously. Then, the scheduling algorithm is not only responsible for assigning a resource block to different users... In future wireless network, one user will require multiple homogeneous or heterogeneous services simultaneously. Then, the scheduling algorithm is not only responsible for assigning a resource block to different users but also sharing the assigned resource block among multiple services for one user. Most of the traditional scheduling algorithms are designed to serve one service per user, and cannot be applied directly to this scenario because of the fairness criterion. This article focuses on adaptive resource allocation for multiple services per user at the downlink of orthogonal frequency division multiplexing (OFDM) based system. This article addresses this integrative resource scheduling problem based on utility function. First, the optimal algorithm for dynamic subcarrier allocation and share is deduced for homogeneous best-effort service system. Then the algorithm is extended to heterogeneous services system by classifying the delay sensitive service according to the head-of-line packet delay. The design goal is to maximize aggregate utility function to exploit multiuser diversity gain to the greatest extent even as guaranteeing quality of service (QoS) for delay sensitive service. 展开更多
关键词 heterogeneous service multiuser diversity radio resource scheduling utility function
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A tour-based analysis of travel mode choice accounting for regional transit service
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作者 丁川 林姚宇 +2 位作者 谢秉磊 朱晓雨 Sabyasachee Mishra 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第1期402-408,共7页
The aim of this work is to explore the impact of regional transit service on tour-based commuter travel behavior by using the Bayesian hierarchical multinomial logit model, accounting for the spatial heterogeneity of ... The aim of this work is to explore the impact of regional transit service on tour-based commuter travel behavior by using the Bayesian hierarchical multinomial logit model, accounting for the spatial heterogeneity of the people living in the same area.With two indicators, accessibility and connectivity measured at the zone level, the regional transit service is captured and then related to the travel mode choice behavior. The sample data are selected from Washington-Baltimore Household Travel Survey in 2007,including all the trips from home to workplace in morning hours in Baltimore city. Traditional multinomial logit model using Bayesian approach is also estimated. A comparison of the two different models shows that ignoring the spatial context can lead to a misspecification of the effects of the regional transit service on travel behavior. The results reveal that improving transit service at regional level can be effective in reducing auto use for commuters after controlling for socio-demographics and travel-related factors.This work provides insights for interpreting tour-based commuter travel behavior by using recently developed methodological approaches. The results of this work will be helpful for engineers, urban planners, and transit operators to decide the needs to improve regional transit service and spatial location efficiently. 展开更多
关键词 transit service travel mode choice spatial heterogeneity Bayesian hierarchical model transit accessibility transit connectivity tour
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Jitter analysis of real-time services in IEEE 802.15.4 WSNs and wired IP concatenated networks
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作者 Na Fei Chi Xuefen +1 位作者 Dong Wen Yu Haifeng 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 2016年第4期1-8,共8页
It is challenging and significant to explore the impacts of non-real-time services on real-time services from the perspective of jitter. Most of current researches on jitter made too many mathematical hypotheses on ne... It is challenging and significant to explore the impacts of non-real-time services on real-time services from the perspective of jitter. Most of current researches on jitter made too many mathematical hypotheses on networks and traffic. This paper puts forward a tandem queuing model to characterize the real communication scenario where heterogeneous services are served by IEEE 802.15.4 wireless sensor networks(WSNs), and then the packets served successfully are fed to Internet protocol(IP) networks. By analyzing the contention access processes in IEEE 802.15.4 WSNs, the authors derive the departure processes of the two types of services, i.e., the arrival processes of IP networks. The IP network is modeled as a queuing system, in which the real-time service is forwarded accompanied by the non-real-time service. Investigating the jitter of real-time services is intractable. Therefore, this paper abstracts this problem as a dynamic queuing system evolving on a dynamic time interval. Referring the transient analysis method(TAM), this paper obtains the queue length in a random time interval which is scaled by the arrival of real-time services. Queue length evolution is closely connected with the jitter. Benefiting from the derivation in probability generation domain, the jitter of real-time services is obtained. 展开更多
关键词 jitter heterogeneous M2M services transient analysis IEEE 802.15.4 WSNs IP networks
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