Abstract: In the existing cache scheme, the use of cache information can effectively reduce the total location management cost for locating frequently called mobile users. However, when the cache information is invalid, it results in much more cost than that of the IS-41.In order to solve this problem, a kind of hybrid of cache and forwarding pointers mobility management scheme (called HCF scheme) is proposed in this paper, which exploits a user’s movement and call locality. Even if the cache information is not up-to-date, the called mobile user can be found by tracing forwarding pointers starting from that VLR pointed in the cache instead of querying the HLR. Therefore, this scheme can effectively reduce the access to the HLR and the signaling traffic in the location management. Analytic results show that, the proposed scheme outperforms other schemes when a user’s CMR is high or the signaling traffic to the HLR is heavy.

Key words: location management, cache, forwarding pointer, query

摘要： 在基于缓存(cache)的位置管理策略中，通过使用缓存存储经常被呼叫用户的位置信息，从而有效地减少了这类用户的定位开销。然而，当缓存信息失效时，会带来比IS-41标准中的基本策略更大的开销。本文提出了一种将缓存策略与指针推进策略结合的混合位置管理策略(记为HCF策略)，通过利用移动用户移动的移动性以及接受呼入的局部性，在缓存信息失效的情况下，可通过遍历起始于缓存中的推进指针链来获得移动用户的位置信息，从而避免直接访问归属位置寄存器HLR(Home Location Register)数据库。因此，该策略可有效的减少对HLR的访问，减少位置管理中的通信流量。实验结果显示，当一个移动用户的呼叫-移动率较高CMR(Call-to-Mobility Ratio)或HLR的通信流量较大时，提出的策略优于基本策略和现有的缓存策略。

关键词: 移动位置管理, 缓存, 指针推进, 查找