Improvement of Vertical Handover Performance in Heterogeneous Network with SCTP

• Main Authors: I-Cheng Lin, 林一成
• Other Authors: Chin-Shiuh Shieh
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/83386287677618170936

碩士 === 國立高雄應用科技大學 === 電子與資訊工程研究所碩士班 === 96 === A heterogeneous wireless network integrating IEEE 802.11 WLAN and 3G/UMTS mobile phone system will be a common scenario in future mobile networking. The multi-homing feature of SCTP and the dynamic address configuration extension had made seamless vertical handover possible in heterogeneous mobile wireless networks. However, due to the switching of radio interfaces and the attenuation of radio signal, the SACK could get lost during the handover process. This will result in unnecessary retransmission after the handover and lead to degradation in network utilization. A solution to this problem will be presented in this article. The proposed approach introduces a new parameter, named Received Last TSN (RLT), to the standard ASCONF control message. The RLT keeps track the sequence number of lastly received packet from the old interface. The mobile node reports the RLT to its corresponding node right after the handover. With this information, the corresponding node can then proceed with effective transmission and avoid the unnecessary retransmission caused by the loss of SACK. In addition, the ongoing SCTP association is switched to a slow-start phase because the congestion window and the slow-start threshold are on an initial state at new path after vertical handover. We propose an approach that can pre-sending probe packet for available bandwidth on the alternate path before a handover. Estimate adaptive slow-start threshold and congestion window size on the alternate path. After handover, setting flow control parameters on the new path. Therefore it skips the slow-start phase. Simulation results reveal that the proposed schemes are feasible and effective measure for the growth of performance during vertical handover in heterogeneous mobile wireless networks.