CAJ | 학술논문

传统垂直切换技术缺乏切换对称性的考虑,从而导致了切换过程计算复杂度较高.通过对3G和WLAN之间切换过程的分析,提出了基于背景扫描机制的滑动平均值预测法和坡度预测法的改进切换策略.其中滑动平均值预测策略首先实时地计算接收的信号强度平均值,然后统计新接收的信号强度小于该平均值的个数,最后做出切换决策;而坡度预测策略通过计算所接收信号强度的一阶导数来决定是否发起切换.这两种策略的结合使用提高了移动终端发起切换的效率,缩短了切换过程中处于无连接状态的延时.设计了移动终端穿过3G网络、WLAN及其重叠区域的实验,其结果显示切换延迟平均减少了40%,切换过程丢包率平均减少了35%.
전통수직절환기술결핍절환대칭성적고필,종이도치료절환과정계산복잡도교고.통과대3G화WLAN지간절환과정적분석,제출료기우배경소묘궤제적활동평균치예측법화파도예측법적개진절환책략.기중활동평균치예측책략수선실시지계산접수적신호강도평균치,연후통계신접수적신호강도소우해평균치적개수,최후주출절환결책;이파도예측책략통과계산소접수신호강도적일계도수래결정시부발기절환.저량충책략적결합사용제고료이동종단발기절환적효솔,축단료절환과정중처우무련접상태적연시.설계료이동종단천과3G망락、WLAN급기중첩구역적실험,기결과현시절환연지평균감소료40%,절환과정주포솔평균감소료35%.
The lack of consideration of handoff symmetry in traditional vertical handoff technology lends to the high computation complexity of handoff procedure. Thus, the Background Scanning based Moving Average Forecasting Scheme(MAFS)and Gradient Prediction Scheme(GPS)were proposed. MAFS firstly calculates the average value of the received signal strength, and counts the number of signal strengths which are small than average value. MAFS finally triggers the handoff procedure. GPS starts the procedure of handoff through computing the first derivative of the received signal strength. The combination of MAFS and GPS improves the efficiency of vertical handoff and abbreviates the disconnecting time. An experiment in which Mobile Terminal passes through 3G network. WLAN and the overlap area was designed and implemented. The experimental results show that the average handoff delay is cut off 40%and the average handoff packet loss is also reduced 35%.