The Experts below are selected from a list of 1593 Experts worldwide ranked by ideXlab platform
Eun-chan Park - One of the best experts on this subject based on the ideXlab platform.
-
TCP-aware bidirectional Bandwidth allocation in IEEE 802.16 networks
Wireless Networks, 2010Co-Authors: Eun-chan ParkAbstract:In this paper, we propose a bidirectional Bandwidth-allocation mechanism to improve TCP performance in the IEEE 802.16 broadband wireless access networks. By coupling the Bandwidth allocation for uplink and downlink connections, the proposed mechanism increases the throughput of the downlink TCP flow and it enhances the efficiency of uplink Bandwidth allocation for the TCP acknowledgment (ACK). According to the IEEE 802.16 standard, when serving a downlink TCP flow, the transmission of the uplink ACK, which is performed over a separate unidirectional connection, incurs additional Bandwidth-Request/allocation delay. Thus, it increases the round trip time of the downlink TCP flow and results in the decrease of throughput accordingly. First, we derive an analytical model to investigate the effect of the uplink Bandwidth-Request/allocation delay on the downlink TCP throughput. Second, we propose a simple, yet effective, bidirectional Bandwidth-allocation scheme that combines proactive Bandwidth allocation with piggyback Bandwidth Request . The proposed scheme reduces unnecessary Bandwidth-Request delay and the relevant signaling overhead due to proactive allocation; meanwhile, it maintains high efficiency of uplink Bandwidth usage by using piggyback Request. Moreover, our proposed scheme is quite simple and practical; it can be simply implemented in the base station without requiring any modification in the subscriber stations or resorting to any cross-layer signaling mechanisms. The simulation results ascertain that the proposed approach significantly increases the downlink TCP throughput and the uplink Bandwidth efficiency.
-
QSHINE - Enhanced Bandwidth Allocation for TCP Flows in WiMAX Networks
Lecture Notes of the Institute for Computer Sciences Social Informatics and Telecommunications Engineering, 2009Co-Authors: Eun-chan Park, Chunyu HuAbstract:In this paper, we propose a bidirectional Bandwidth-allocation mechanism to improve TCP performance in the IEEE 802.16 WiMAX networks. According to the IEEE 802.16 standard, when serving a downlink TCP flow, the transmission of the uplink ACK, which is performed over a separate unidirectional connection, incurs additional Bandwidth-Request/allocation delay. Thus, it increases the round trip time of the downlink TCP flow and results in the decrease of throughput accordingly. First, we derive an analytical model to investigate the effect of the uplink Bandwidth-Request/allocation delay on the downlink TCP throughput. Second, we propose a simple, yet effective, bidirectional Bandwidth-allocation mechanism that couples the Bandwidth allocation for uplink and downlink connections by using either proactive Bandwidth allocation or piggyback Bandwidth Request. The proposed scheme reduces unnecessary Bandwidth-Request delay and the relevant signaling overhead due to proactive allocation; meanwhile, it maintains high efficiency of uplink Bandwidth usage by using piggyback Request. Moreover, our proposed scheme is quite simple and practical; it can be simply implemented in the base station without requiring any modification in the subscriber stations or resorting to any cross-layer signaling mechanisms. The simulation results ascertain that the proposed approach significantly increases the downlink TCP throughput and the uplink Bandwidth efficiency.
-
Efficient Uplink Bandwidth Request with Delay Regulation for Real-Time Service in Mobile WiMAX Networks
IEEE Transactions on Mobile Computing, 2009Co-Authors: Eun-chan ParkAbstract:The emerging broadband wireless access technology based on IEEE 802.16 is one of the most promising solutions to provide ubiquitous wireless access to the broadband service at low cost. This paper proposes an efficient uplink Bandwidth Request-allocation algorithm for real-time services in Mobile WiMAX networks based on IEEE 802.16e. In order to minimize Bandwidth wastage without degrading quality of service (QoS), we introduce a notion of target delay and propose dual feedback architecture. The proposed algorithm calculates the amount of Bandwidth Request such that the delay is regulated around the desired level to minimize delay violation and delay jitter for real-time services. Also, it can increase utilization of wireless channel by making use of dual feedback, where the Bandwidth Request is adjusted based on the information about the backlogged amount of traffic in the queue and the rate mismatch between packet arrival and service rates. Due to the target delay and dual feedback, the proposed scheme can control delay and allocate Bandwidth efficiently while satisfying QoS requirement. The stability of the proposed algorithm is analyzed from a control-theoretic viewpoint, and a simple design guideline is derived based on this analysis. By implementing the algorithm in OPNET simulator, its performance is evaluated in terms of queue regulation, optimal Bandwidth allocation, delay controllability, and robustness to traffic characteristics.
-
PIMRC - Bidirectional Bandwidth allocation for TCP performance enhancement in mobile WiMAX networks
2008 IEEE 19th International Symposium on Personal Indoor and Mobile Radio Communications, 2008Co-Authors: Eun-chan ParkAbstract:We propose a virtual bidirectional connection for efficient Bandwidth allocation to downlink TCP data and uplink acknowledgment (ACK) in mobile WiMAX networks based on IEEE 802.16. We observed that, in serving a downlink TCP flow, the standard Bandwidth-Request/allocation mechanism inevitably results in additional delay to transmit uplink TCP ACK, which increases round trip time of downlink TCP flow and decreases its throughput accordingly. To resolve this problem, we propose a hybrid approach combining proactive Bandwidth allocation with piggyback Bandwidth Request. The proposed framework removes the unnecessary Bandwidth-Request delay, and also decreases signaling overhead involved in the Bandwidth-Request. Simulation results show that this approach significantly increases downlink TCP throughput and uplink Bandwidth efficiency.
-
Dynamic Bandwidth Request-Allocation Algorithm for Real-Time Services in IEEE 802.16 Broadband Wireless Access Networks
IEEE INFOCOM 2008 - The 27th Conference on Computer Communications, 2008Co-Authors: Eun-chan ParkAbstract:The emerging broadband wireless access (BWA) technology based on IEEE 802.16 is one of the most promising solutions to provide ubiquitous wireless access to the broadband service at low cost. This paper proposes an efficient uplink Bandwidth Request-allocation algorithm for variable-rate realtime services in IEEE 802.16 BWA networks. In order to minimize Bandwidth wastage without degrading quality of service (QoS), we introduce a notion of target delay and propose dual feedback architecture. The proposed algorithm calculates the amount of Bandwidth Request such that the delay is regulated around the desired level to minimize delay violation and delay jitter for real-time services. Also, it can maximize utilization of wireless channel by making use of dual feedback, where the Bandwidth Request is adjusted based on the information about the backlogged amount of traffic in the queue and the rate mismatch between packet arrival and service rates. Due to the dual feedback architecture, the proposed scheme responds quickly to the variation of traffic load and is robust to the change of network condition. We analyze the stability of the proposed algorithm from a control-theoretic viewpoint and derive a simple design guideline based on the analysis. By implementing the algorithm in OPNET simulator, we evaluate its performance in terms of queue regulation, optimal Bandwidth allocation, delay controllability, and robustness to traffic characteristics.
Bong Dae Choi - One of the best experts on this subject based on the ideXlab platform.
-
delay analysis and optimization of Bandwidth Request under unicast polling in ieee 802 16e over gilbert elliot error channel
IEICE Transactions on Communications, 2009Co-Authors: Eunju Hwang, Frank Roijers, Bong Dae ChoiAbstract:In the centralized polling mode in IEEE 802.16e, a base station (BS) polls mobile stations (MSs) for Bandwidth reservation in one of three polling modes; unicast, multicast, or broadcast pollings. In unicast polling, the BS polls each individual MS to allow to transmit a Bandwidth Request packet. This paper presents an analytical model for the unicast polling of Bandwidth Request in IEEE 802.16e networks over Gilbert-Elliot error channel. We derive the probability distribution for the delay of Bandwidth Requests due to wireless transmission errors and find the loss probability of Request packets due to finite retransmission attempts. By using the delay distribution and the loss probability, we optimize the number of polling slots within a frame and the maximum retransmission number while satisfying QoS on the total loss probability which combines two losses: packet loss due to the excess of maximum retransmission and delay outage loss due to the maximum tolerable delay bound. In addition, we obtain the utilization of polling slots, which is defined as the ratio of the number of polling slots used for the MS's successful transmission to the total number of polling slots used by the MS over a long run time. Analysis results are shown to well match with simulation results. Numerical results give examples of the optimal number of polling slots within a frame and the optimal maximum retransmission number depending on delay bounds, the number of MSs and the channel conditions. Copyright © 2009 The Institute of Electronics, Information and Communication Engineers.
-
Delay Analysis of Bandwidth Request in Truncated Binary Exponential Backoff Mechanism over Error-Free/Error-Prone Channels in IEEE 802.16e
2008 16th Interntional Workshop on Quality of Service, 2008Co-Authors: Eunju Hwang, Andrey Lyakhov, Bong Dae ChoiAbstract:We investigate the delay of the Bandwidth Request under the truncated binary exponential backoff (TBEB) mechanism in the IEEE 802.16e, considering error-free/error- prone wireless channels. We derive the distribution of delay of Bandwidth Request packets in the TBEB by an analytic method on the assumption of Bernoulli Request arrival process and error-free channel conditions, and extend the analytic results to the error-prone channel condition where the Request transmissions have error with i.i.d. By numerical analysis we can find the optimal number of transmission opportunities for transmitting Bandwidth Requests of the TBEB satisfying QoS on delay bound and loss bound.
-
delay analysis of Bandwidth Request in truncated binary exponential backoff mechanism over error free error prone channels in ieee 802 16e
International Workshop on Quality of Service, 2008Co-Authors: Eunju Hwang, Andrey Lyakhov, Bong Dae ChoiAbstract:We investigate the delay of the Bandwidth Request under the truncated binary exponential backoff (TBEB) mechanism in the IEEE 802.16e, considering error-free/error- prone wireless channels. We derive the distribution of delay of Bandwidth Request packets in the TBEB by an analytic method on the assumption of Bernoulli Request arrival process and error-free channel conditions, and extend the analytic results to the error-prone channel condition where the Request transmissions have error with i.i.d. By numerical analysis we can find the optimal number of transmission opportunities for transmitting Bandwidth Requests of the TBEB satisfying QoS on delay bound and loss bound.
-
IWQoS - Delay Analysis of Bandwidth Request in Truncated Binary Exponential Backoff Mechanism over Error-Free/Error-Prone Channels in IEEE 802.16e
2008 16th Interntional Workshop on Quality of Service, 2008Co-Authors: Eunju Hwang, Andrey Lyakhov, Bong Dae ChoiAbstract:We investigate the delay of the Bandwidth Request under the truncated binary exponential backoff (TBEB) mechanism in the IEEE 802.16e, considering error-free/error- prone wireless channels. We derive the distribution of delay of Bandwidth Request packets in the TBEB by an analytic method on the assumption of Bernoulli Request arrival process and error-free channel conditions, and extend the analytic results to the error-prone channel condition where the Request transmissions have error with i.i.d. By numerical analysis we can find the optimal number of transmission opportunities for transmitting Bandwidth Requests of the TBEB satisfying QoS on delay bound and loss bound.
Eunju Hwang - One of the best experts on this subject based on the ideXlab platform.
-
delay analysis and optimization of Bandwidth Request under unicast polling in ieee 802 16e over gilbert elliot error channel
IEICE Transactions on Communications, 2009Co-Authors: Eunju Hwang, Frank Roijers, Bong Dae ChoiAbstract:In the centralized polling mode in IEEE 802.16e, a base station (BS) polls mobile stations (MSs) for Bandwidth reservation in one of three polling modes; unicast, multicast, or broadcast pollings. In unicast polling, the BS polls each individual MS to allow to transmit a Bandwidth Request packet. This paper presents an analytical model for the unicast polling of Bandwidth Request in IEEE 802.16e networks over Gilbert-Elliot error channel. We derive the probability distribution for the delay of Bandwidth Requests due to wireless transmission errors and find the loss probability of Request packets due to finite retransmission attempts. By using the delay distribution and the loss probability, we optimize the number of polling slots within a frame and the maximum retransmission number while satisfying QoS on the total loss probability which combines two losses: packet loss due to the excess of maximum retransmission and delay outage loss due to the maximum tolerable delay bound. In addition, we obtain the utilization of polling slots, which is defined as the ratio of the number of polling slots used for the MS's successful transmission to the total number of polling slots used by the MS over a long run time. Analysis results are shown to well match with simulation results. Numerical results give examples of the optimal number of polling slots within a frame and the optimal maximum retransmission number depending on delay bounds, the number of MSs and the channel conditions. Copyright © 2009 The Institute of Electronics, Information and Communication Engineers.
-
Delay Analysis of Bandwidth Request in Truncated Binary Exponential Backoff Mechanism over Error-Free/Error-Prone Channels in IEEE 802.16e
2008 16th Interntional Workshop on Quality of Service, 2008Co-Authors: Eunju Hwang, Andrey Lyakhov, Bong Dae ChoiAbstract:We investigate the delay of the Bandwidth Request under the truncated binary exponential backoff (TBEB) mechanism in the IEEE 802.16e, considering error-free/error- prone wireless channels. We derive the distribution of delay of Bandwidth Request packets in the TBEB by an analytic method on the assumption of Bernoulli Request arrival process and error-free channel conditions, and extend the analytic results to the error-prone channel condition where the Request transmissions have error with i.i.d. By numerical analysis we can find the optimal number of transmission opportunities for transmitting Bandwidth Requests of the TBEB satisfying QoS on delay bound and loss bound.
-
delay analysis of Bandwidth Request in truncated binary exponential backoff mechanism over error free error prone channels in ieee 802 16e
International Workshop on Quality of Service, 2008Co-Authors: Eunju Hwang, Andrey Lyakhov, Bong Dae ChoiAbstract:We investigate the delay of the Bandwidth Request under the truncated binary exponential backoff (TBEB) mechanism in the IEEE 802.16e, considering error-free/error- prone wireless channels. We derive the distribution of delay of Bandwidth Request packets in the TBEB by an analytic method on the assumption of Bernoulli Request arrival process and error-free channel conditions, and extend the analytic results to the error-prone channel condition where the Request transmissions have error with i.i.d. By numerical analysis we can find the optimal number of transmission opportunities for transmitting Bandwidth Requests of the TBEB satisfying QoS on delay bound and loss bound.
-
IWQoS - Delay Analysis of Bandwidth Request in Truncated Binary Exponential Backoff Mechanism over Error-Free/Error-Prone Channels in IEEE 802.16e
2008 16th Interntional Workshop on Quality of Service, 2008Co-Authors: Eunju Hwang, Andrey Lyakhov, Bong Dae ChoiAbstract:We investigate the delay of the Bandwidth Request under the truncated binary exponential backoff (TBEB) mechanism in the IEEE 802.16e, considering error-free/error- prone wireless channels. We derive the distribution of delay of Bandwidth Request packets in the TBEB by an analytic method on the assumption of Bernoulli Request arrival process and error-free channel conditions, and extend the analytic results to the error-prone channel condition where the Request transmissions have error with i.i.d. By numerical analysis we can find the optimal number of transmission opportunities for transmitting Bandwidth Requests of the TBEB satisfying QoS on delay bound and loss bound.
R. Nakkeeran - One of the best experts on this subject based on the ideXlab platform.
-
investigation on group based contention Bandwidth Request in lte a networks under high delay spread environment
Wireless Networks, 2016Co-Authors: A. Rajesh, R. NakkeeranAbstract:In this paper, contention Bandwidth Request has been investigated for long term evolution-advanced (LTE-A) networks under extended typical urban based multipath fading channel that displays high delay spread environment. As the choice of preambles has to provide high detection probability under such environments, at the outset, this paper examines various group based preamble selection mechanisms, namely, Type I, Type II and Type III preamble sets. With suitable type of group based preamble, the challenge during contention Bandwidth Request is the appropriate choice of contention window during contention resolution. The contention window in this paper is chosen based on the indicators of various failure events, namely, probability of collision due to contention, probability of unavailability of Bandwidth, probability of channel error and probability of improper detection of Zadoff---Chu sequences. After suggesting a scheme to account the possible failure events, an analytical model for contention-based Bandwidth Request has been developed for LTE-A networks. In addition, two backoff mechanisms are proposed to resolve contention among user equipment's effectively and these mechanisms are compared to the existing techniques, namely, binary exponential backoff and uniform backoff. Further, the contention mechanism has been substantiated for varying depth of channel errors. With Type I grouping, the backoff with optimized contention window improves the efficiency by 13.95 %, reduces the access delay by 18.71 % and decreases the dropping probability by 59.33 % than the existing uniform backoff mechanism.
-
investigation on uplink collaborative contention based Bandwidth Request for wimax three hop relay networks
Journal of Network and Computer Applications, 2013Co-Authors: A. Rajesh, R. NakkeeranAbstract:This paper suggests a collaborative contention Bandwidth Request (BR) mechanism for worldwide interoperability for microwave access (WiMAX) three-hop relay networks. By complimenting message and code BR in three hops of a link, the proposed framework enables low block error rate (BLER), packet dropping and signaling overhead while preserving the connection throughput and access delay requirements of best effort (BE) services. With three hops between base station (BS) and mobile station (MS) via relay station 1 (RS1) and relay station 2 (RS2), there take place eight possible BR mechanisms with message and code BR. Among eight BR mechanisms, message-message-code (MMC) BR performs better with message dominant BR and code-message-code (CMC) BR performs better with code dominant BR. Further, with CMC BR, the BLER is reduced by 5.88%, packet dropping is reduced by 8.68%, medium access control (MAC) overhead is reduced by 7.6%, MAC wastage is reduced by 4.47%, connection delay is reduced by 28.30%, queuing delay is reduced by 8.65%, queue size is reduced by 15.25% and throughput is improved by 11.51% than MMC BR mechanism.
-
Performance analysis of Bandwidth Request mechanism in ITU-R vehicular pathloss model
2013 IEEE Conference on Information & Communication Technologies, 2013Co-Authors: A. Rajesh, R. NakkeeranAbstract:In this paper, we investigate the performance of contention Bandwidth Request (BR) mechanisms for WiMAX two-hop relay network under ITU-R vehicular pathloss model. The first hop and second hop corresponds to air interface from mobile station (MS) to relay station (RS) and from RS to base station (BS), respectively. To overcome fixed Bandwidth allocation at RS, the proposed system carries out contention BR mechanism. Under these circumstances, the contributions made in this paper are two-fold. First, unique failure models are developed for two hops of a link and the stations (MS and RS) adaptively set their contention window based on the developed model. Such technique effectively reduces collision due to contention with reduced access delay during contention Bandwidth Request. Finally, the two-hop BR along with the failure model is realized with four combinations of message and code BR mechanism. Simulations validate the effectiveness of the joint BR mechanisms under ITU-R vehicular environment.
-
Performance analysis of contention Bandwidth Request mechanism in emerging wireless networks
2013 International Conference on Communication and Signal Processing, 2013Co-Authors: A. Rajesh, R. NakkeeranAbstract:The contention based Bandwidth Request mechanisms are gaining much interest due to dynamic assignment of Bandwidth to mobile stations (MS). The contribution made in this paper is twofold. First contention based Bandwidth Request is investigated for worldwide interoperability for microwave access (WiMAX) and long-term evolution networks (LTE) networks under various mobility conditions. It is found that the LTE networks exhibit high throughput amid low end-to-end delay and jitter than WiMAX networks. Even under immobile conditions, the throughput with LTE networks is 75.58% more than WiMAX networks. Finally, the contention performance of LTE networks is extended for heterogeneous of LTE and wireless local area networks (WLAN) with varying traffic conditions and scenarios. Simulation results conclude that contention based Bandwidth Request is more appropriate for carrying out non-real time traffics in emerging LTE based wireless networks.
-
contention based Bandwidth Request with signaling analysis in ieee 802 16 two hop relay networks
Computers & Electrical Engineering, 2013Co-Authors: A. Rajesh, R. NakkeeranAbstract:In this paper, we propose a joint contention-based Bandwidth Request mechanism for WiMAX two-hop relay networks. For this purpose, we considered contention by message and code mechanisms. These are normally deployed in single-hop networks. This message scheme suffers from low contention efficiency and higher access delay when the number of mobile stations (MSs) in the network increases. Conversely, this code technique undergoes transmission failure due to the inappropriate setting of the detection threshold at relay stations (RSs). However, these message and code mechanisms are advantageous when they are carried out at appropriate hops. Among the four possible options created by combining the message and code methods, the message Requests from MS to RS and code Requests from RS to base stations (BSs) performed better than other possible combinations. Using a comprehensive case study and simulation results, we generated signaling examples that confirmed the significance of the proposed method in terms of signaling overhead, network throughput, connection delay and queuing size.
Sang-wook Kwon - One of the best experts on this subject based on the ideXlab platform.
-
VTC Fall - CDMA Code-Based Bandwidth Request Mechanism in IEEE 802.16j Mobile Multi-Hop Relay (MMR)Systems
2008 IEEE 68th Vehicular Technology Conference, 2008Co-Authors: Sang-wook KwonAbstract:In the IEEE 802.16 system, a relay station (RS) is required for the purpose of coverage extension and throughput improvement. However, if we use the RS, original Bandwidth Request mechanism is not applied to subscriber station (SS) which is connected to RS since the Bandwidth Request mechanism is optimized for single-hop environment. Therefore, we propose an efficient contention based CDMA Bandwidth Request mechanism for SS located in RS region in the IEEE 802.16 MMR system. In the proposed scheme, an SS can receive the uplink resource very well wherever an SS is located. Through the analysis, we show that the proposed Bandwidth Request mechanism reduces the signaling cost and delay of system.
-
CDMA Code-Based Bandwidth Request Mechanism in IEEE 802.16j Mobile Multi-Hop Relay (MMR)Systems
2008 IEEE 68th Vehicular Technology Conference, 2008Co-Authors: Sang-wook KwonAbstract:In the IEEE 802.16 system, a relay station (RS) is required for the purpose of coverage extension and throughput improvement. However, if we use the RS, original Bandwidth Request mechanism is not applied to subscriber station (SS) which is connected to RS since the Bandwidth Request mechanism is optimized for single-hop environment. Therefore, we propose an efficient contention based CDMA Bandwidth Request mechanism for SS located in RS region in the IEEE 802.16 MMR system. In the proposed scheme, an SS can receive the uplink resource very well wherever an SS is located. Through the analysis, we show that the proposed Bandwidth Request mechanism reduces the signaling cost and delay of system.
