• Title/Summary/Keyword: Access probability

Search Result 533, Processing Time 0.027 seconds

Analysis of the performances of random access channels in multi-service multi-user OFDMA systems according to resource management schemes (다중 서비스 다중 사용자 OFDMA 시스템에서의 자원할당방식에 따른 임의접근 채널 성능 분석)

  • Koo, In-Soo;Lee, Young-Du
    • Proceedings of the KIEE Conference
    • /
    • 2007.04a
    • /
    • pp.237-239
    • /
    • 2007
  • In the paper, we analyze the performances of random access channels in multi-service multi-user OFDMA systems. The resource of the random access channels in OFDMA systems is the nubmer of available sub-channels and PN-codes. For given available sub-channels and PN-codes. we analyze the performances of the random access channels of OFDMA systems according to three resource allocation methods (resource full sharing, resource partial sharing, resource partition) in tenus of the access success probability, the blocking probability, the access delay and the throughput of each service class. Further, we find the feasible region of the access probability of each service class in which the allowable minimum access success probability, the allowable maximum blocking probability and the allowable maximum access delay are satisfied. The results also can be utilized to find proper region of the access probabilities of each service class for differentiated quality of service(QoS)s, and for the system operations.

  • PDF

Optimized Medium Access Probability for Networked Control Systems (네트워크 제어 시스템을 위한 최적화된 매체 접근 확률)

  • Park, Pangun
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.19 no.10
    • /
    • pp.2457-2464
    • /
    • 2015
  • Distributed Networked Control Systems (NCSs) through wireless networks have a tremendous potential to improve the efficiency of various control systems. In this paper, we define the State Update Interval (SUI) as the elapsed time between successful state vector reports derived from the NCSs. A simple expression of the SUI is derived to characterize the key interactions between the control and communication layers. This performance measure is used to formulate a novel optimization problem where the objective function is the probability to meet the SUI constraint and the decision parameter is the channel access probability. We prove the existence and uniqueness of the optimal channel access probability of the optimization problem. Furthermore, the optimal channel access probability for NCSs is lower than the channel access probability to maximize the throughput. Numerical results indicate that the improvement of the success probability to meet the SUI constraint using the optimal channel access probability increases as the number of nodes increases with respect to that using the channel access probability to maximize the throughput.

The Relation of CLR and Blocking Probability for CBR Traffic in the Wireless ATM Access Network

  • Lee, Ha-Cheol;Lee, Byung-Seub
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.27 no.11C
    • /
    • pp.1158-1163
    • /
    • 2002
  • In this paper it is focused on the relation between CLR (Cell Loss Ratio) and blocking probability, GoS(Grade of Services) parameters in the wireless ATM (Asynchronous Transfer Mode) access network which consists of access node and wireless channel. Traffic model of wireless ATM access network is based on the cell scale, burst scale and call connection level. The CLR equation due to buffer overflow for wireless access node is derived for CBR (Constant Bit Rate) traffic. The CLR equation due to random bit errors and burst errors for wireless channel is derived. Using the CLR equation for both access node and wireless channel, the CLR equation of wireless ATM access network is derived. The relation between access network CLR and blocking probability is analyzed for CBR traffic.

The Probability Based Ordered Media Access (IEEE 802-15.4에서 우선순위 IFS를 이용한 확률기반 매체 접근 방법)

  • Jean, Young-Ho;Kim, Jeong-Ah;Park, Hong-Seong
    • Proceedings of the KIEE Conference
    • /
    • 2006.04a
    • /
    • pp.321-323
    • /
    • 2006
  • The IEEE 802.15.4 uses a CSMA/CA algorithm on access of media. The CSMA/CA algorithm does Random Backoff before the data is transmitted to avoid collisions. The random backoff is a kind of unavoidable delays and introduces the side effect of energy consumptions. To cope with those problems we propose a new media access algorithm, the Priority Based Ordered Media Access (PBOMA) algorithm, which uses different IFSs. The PBOMA algorithm uses Sampling Rate and Beacon Interval to get a different access probability(or IFS). The access probability is higher, the IFS is shorter. Note that The transfer of urgent data uses tone signal to transmit it immediately. The proposed algorithm is expected to reduce the energy consumptions and the delay.

  • PDF

Performance Analysis of random access channels in multi-service multi-user OFDMA systems (다중 서비스 다중 사용자 OFDMA 시스템에서의 임의접근 채널 성능 분석)

  • Koo, In-Soo;Pham, Thi Hong Chau
    • Journal of Internet Computing and Services
    • /
    • v.9 no.5
    • /
    • pp.141-151
    • /
    • 2008
  • In the paper, we analyze the performance of random access channels in multi-service multi-user OFDMA systems. The resource of the random access channels in OFDMA systems are available sub-channels and PN-codes. For given available sub-channels and PN-codes,' we analyze the performance of the random access channels of OFDMA systems in terms of the access success probability, the blocking probability, the access delay and the throughput per each service class. Further, we find the feasible region of the access probability of each service class in which the allowable minimum access success probability, the allowable maximum blocking probability and the allowable maximum access delay are satisfied. The results also can be used to find proper region of the access probabilities of each service class for differentiated quality of service(QoS)s, and for the system operations in multi-service multi-user OFDMA systems.

  • PDF

The Relation of Cell Scale and Call Connection Level for the VBR Trafac in the Wireless ATM Access Transport (무선 ATM 액세스 전달구조에서 VBR 트래픽에 대한 셀 스케일과 호 접속레벨간의 관계)

  • Lee Ha-Cheol
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.30 no.9B
    • /
    • pp.596-601
    • /
    • 2005
  • In this paper it is focused on the relation between CLR(Cell Loss Ratio) and blocking probability in the wireless ATM access transport. Traffic model of wireless ATH access transport is based on the cell scale, burst scale and call connection level. The CLR due to buffer overflow for wireless access node is derived for VBR traffic. The CLR due to transmission errors for wireless channel is derived. Using the CLR for both access node and wireless channel: the CLR of wireless ATM access transport is derived. The relation between CLR and blocking probability is analyzed for VBR traffic to evaluate performance of wireless ATM access transport.

Channel Access Control Method for the CDMA Packet Service System (CDMA 패킷 서비스 시스템에서 채널 엑세스 제어 기법 연구)

  • 이강원
    • Journal of the Korean Operations Research and Management Science Society
    • /
    • v.28 no.3
    • /
    • pp.169-184
    • /
    • 2003
  • In the IS-95 packet service system, the radio channels are generally classified into the dedicated and the common traffic channels. In this paper, a common traffic channel access method is proposed for the COMA packet service system to enhance the radio resource utilization while guaranteeing QoS to the users. The proposed method is based on the permission probability for the common traffic channel user. To derive permission probability, optimization models are developed for two different QoS constraints. Approximation methods are also developed.

COGNITIVE RADIO SPECTRUM ACCESS WITH CHANNEL PARTITIONING FOR SECONDARY HANDOVER CALLS

  • Lee, Yutae
    • Journal of applied mathematics & informatics
    • /
    • v.33 no.1_2
    • /
    • pp.211-217
    • /
    • 2015
  • A dynamic spectrum access scheme with channel partitioning for secondary handover calls in cognitive radio networks is proposed to reduce forced termination probability due to spectrum handover failure. A continuous-time Markov chain method for evaluating its performance such as blocking probability, forced termination probability, and throughput is presented. Numerical and simulation results are provided to demonstrate the effectiveness of the proposed scheme with channel partitioning.

Enhanced Channel Access Estimation based Adaptive Control of Distributed Cognitive Radio Networks

  • Park, Jong-Hong;Chung, Jong-Moon
    • KSII Transactions on Internet and Information Systems (TIIS)
    • /
    • v.10 no.3
    • /
    • pp.1333-1343
    • /
    • 2016
  • Spectrum sharing in centrally controlled cognitive radio (CR) networks has been widely studied, however, research on channel access for distributively controlled individual cognitive users has not been fully characterized. This paper conducts an analysis of random channel access of cognitive users controlled in a distributed manner in a CR network. Based on the proposed estimation method, each cognitive user can estimate the current channel condition by using its own Markov-chain model and can compute its own blocking probability, collision probability, and forced termination probability. Using the proposed scheme, CR with distributed control (CR-DC), CR devices can make self-controlled decisions based on the status estimations to adaptively control its system parameters to communicate better.

Contention-based Reservation MAC Protocol for Burst Traffic in Wireless Packet Networks

  • Lim, In-Taek
    • Journal of information and communication convergence engineering
    • /
    • v.5 no.2
    • /
    • pp.93-97
    • /
    • 2007
  • In this paper, centralized access control and slot allocation algorithm is proposed for wireless networks. The proposed algorithm is characterized by the contention-based reservation. In order to reduce the collision probability of reservation request, the base station calculates and broadcasts the transmission probability of reservation requests, and the wireless terminal transmits its reservation request with the received transmission probability. The scheduler allocates the uplink data slots based on the successful reservation requests. Simulation results show that the proposed algorithms can provide high channel utilization, and furthermore, maintains constant delay performance in the heavy traffic environment.