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Call Setup Latency Analysis in SIP-Based Voice over WLANs
Sangheon Pack,Hojin Lee IEEE 2008 IEEE COMMUNICATIONS LETTERS Vol.12 No.2
<P>In this letter, we consider session initiation protocol (SlP)-based voice over wireless local area networks (VoWLANs). We derive the analytical expression for the average call setup latency, and we observe the impact of the number of contending mobile nodes in a WLAN. Extensive simulation results are given to validate the analytical results.</P>
Mobility Management in Mobile Hotspots with Heterogeneous Multihop Wireless Links
Sangheon Pack,Xuemin Shen,Mark, J.W.,Jianping Pan Institute of Electrical and Electronics Engineers 2007 IEEE communications magazine Vol.45 No.9
<P>In this article we study two representative mobility management schemes for mobile hotspots with heterogeneous multihop wireless links: the NEMO basic support protocol at the network layer and the SIP-based network mobility support protocol at the application layer. We evaluate their salient features and quantify their handoff latency. It is shown that the SIP-based network mobility support protocol can easily be deployed and reduce the tunneling overhead incurred in the NEMO basic support protocol. However, it increases handoff latency due to longer message length. We also discuss several open research issues for seamless mobility support in mobile hotspots.</P>
RA-PSM: a rate-aware power saving mechanism in multi-rate wireless LANs
Pack, Sangheon,Min, Seongman,Song, Taewon,Kim, Wonjung,Choi, Nakjung,Park, Hyunhee Springer-Verlag 2016 WIRELESS NETWORKS Vol.22 No.6
<P>Improving energy efficiency is one of the most important issues in wireless local area networks (WLANs) and a power saving mechanism (PSM) has been proposed in IEEE 802.11 WLANs. However, the conventional PSMs do not consider multi-rate transmissions and thus the waiting time for retrieving buffered frames from the access point can be unnecessarily long and more energy can be consumed. In this paper, we propose a rate-aware power saving mechanism (RA-PSM) in multi-rate WLANs. In RA-PSM, a station sets its contention window size inversely proportional to the transmission rate and thus a station with higher transmission rate can request the buffered frames at the access point with higher priority. As a result, the overall channel waiting time can be reduced and the energy consumption can be saved accordingly. Analytical and simulation results demonstrate that RA-PSM can reduce the average channel waiting time and the energy consumption by up to 77 and 40.3 %, respectively, compared with the conventional IEEE 802.11 PSM.</P>
Performance Analysis of Mobile Hotspots with Heterogeneous Wireless Links
Sangheon Pack,Rutagemwa, H.,Xuemin Shen,Mark, J.W.,Lin Cai IEEE 2007 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.6 No.10
<P>Mobile hotspot enabling Internet access services in moving vehicles is an important service for ubiquitous computing. In this paper, we propose an analytical framework for studying the packet loss behavior and throughput in a mobile hotspot with heterogeneous wireless links. We first develop a two-state Markov model for the integrated wireless wide area network (WWAN) and wireless local area network (WLAN). We then derive the expressions that describe the experienced packet loss probability, packet loss burst length, and throughput. Finally, we present simulation results to verify the accuracy of our analysis. It is concluded that adaptive and cross-layer approaches should be deployed to improve the performance of mobile hotspots.</P>
Analysis of SIP Transfer Delay in Multi-Rate Wireless Networks
Sangheon Pack,Gwangwoo Park,Kiwon Lee,Wonjun Lee IEEE 2010 IEEE communications letters Vol.14 No.10
<P>In this letter, we analyze the SIP transfer delay over multi-rate wireless networks where different transmission modes based on adaptive modulation code are supported. We consider a Nakagami m fading channel at the physical layer and automatic repeat request at the data link layer. Extensive simulation results are given to validate the analytical results and to demonstrate the effects of message sizes and channel conditions.</P>
Adaptive Route Optimization in Hierarchical Mobile IPv6 Networks
Sangheon Pack,Xuemin Shen,Mark, J.W. IEEE Computer Society 2007 IEEE TRANSACTIONS ON MOBILE COMPUTING Vol.6 No.8
<P>By introducing a mobility anchor point (MAP), Hierarchical Mobile IPv6 (HMIP6) reduces the signaling overhead and handoff latency associated with Mobile IPv6. However, if a mobile node (MN)'s session activity is high and its mobility is relatively low, HMIPv6 may degrade end-to-end data throughput due to the additional packet tunneling at the MAP. In this paper, we propose an adaptive route optimization (ARO) scheme to improve the throughput performance in HMIPv6 networks. Depending on the measured session-to-mobility ratio (SMR), ARO chooses one of the two different route optimization algorithms adaptively. Specifically, an MN informs a correspondent node (CN) of its on-link care-of address (LCoA) if the CN's SMR is greater than a predefined threshold. If the SMR is equal to or lower than the threshold, the CN is informed with the MN's regional CoA (RCoA). We analyze the performance of ARO in terms of balancing the signaling overhead reduction and the data throughput improvement. We also derive the optimal SMR threshold explicitly to achieve such a balance. Analytical and simulation results demonstrate that ARO is a viable scheme for deployment in HMIPv6 networks.</P>
An Adaptive Network Mobility Support Protocol in Hierarchical Mobile IPv6 Networks
Sangheon Pack,Taekyoung Kwon,Yanghee Choi,Eun Kyoung Paik IEEE 2009 IEEE Transactions on Vehicular Technology VT Vol.58 No.7
<P>The network mobility (NEMO) basic support protocol provides collective mobility for a group of nodes in vehicular area networks. Since the NEMO basic support protocol always performs the same operations, regardless of a mobile network's characteristics, it cannot achieve optimal performance. We propose an adaptive NEMO support protocol based on hierarchical mobile IPv6. The proposed protocol jointly optimizes binding update (BU) traffic and tunneling overhead by employing the adaptive BU strategy, depending on the session-to-mobility ratio (SMR). Specifically, both the mobile router (MR) and the visiting mobile nodes (VMNs) configure two care-of-addresses: 1) on-link care-of-address (LCoA) and 2) regional care-of-address (RCoA). If the SMR is lower than a predefined threshold, the MR and VMNs perform RCoA and LCoA BU procedures to their home agents (HAs), respectively. Otherwise, LCoA and RCoA BU procedures are conducted by the MR and VMNs, respectively. Via analytical models, we evaluate the performance of the adaptive NEMO support protocol against other NEMO support protocols and derive the optimal SMR threshold. Numerical results demonstrate that the adaptive NEMO support protocol is a valuable solution for promising NEMO applications.</P>
Performance Analysis of Multicast and Broadcast Services in Mobile WiMAX Systems
Sangheon Pack,Seongyeol Yang,Wonjung Kim,Wonjun Lee IEEE 2011 IEEE communications letters Vol.15 No.11
<P>In this letter, we investigate the performance of multicast and broadcast services (MBS) in mobile WiMAX systems. We develop an analytical model for the session blocking probability and the session disruption probability. Numerical results demonstrate that the session blocking probability and disruption probability are significantly affected by the session arrival rate and session popularity.</P>