Conclusion

Users usually have dial- number locality, they often utilize the address books in the MS. Keeping the routing information in the 3G/WLAN dual- mode MS (DMS) has the benefits of reducing the response time of routing information queries. The efficiency of telecommunications NP service is improved along the probability of utilizing the DMS address book and the cache hit rate increases. The routing information on users’

terminal effectively alleviated traffic congestion and workload on NPAC to reduce the response time of ported number translation.

Our proposed method benefits both users and the NP service providers, which saves call setup time for users, and saves computing and communication resources for NP service providers. NP service providers can provide better performance to more users without extending of equipment and computing power. Without changing the existing signaling system and network architecture, the propose mechanism is a low-cost, effective, and efficient solution for improving the performance of mobile NP service.

On the other hand, long call-origination delay (COD) and high VHO overhead are the common drawbacks of WLAN/3G dual- mode mobile communication service. The drawbacks results in more battery energy consumption and shortened the standby time of dual- mode mobile handsets (DMS). In this chapter we proposed a service and terminal level solution to overcome the drawbacks. We study the mobile and calling behavior of dual- mode users to analyze the factors represented the condition of the communication environment and proposed to keep the factors in DMS. Also we propose a very simple algorithm, which is easy to implement on DMS, to infer the condition of the visited communication circumstance and to determine the preferred

network to avoid the drawbacks of dual- mode services. Without changing existing communication architecture and protocols, the proposed method has the advantages of low complexity, easy to implement, and low-development cost.

We also evaluated the efficiency of the proposed method by establishing a simulation model to show that COD and VHO overhead of dual- mode communication service are alleviated effectively. Accordingly, the communication resource of WLAN and the 3G network can be utilized more efficiently, and the battery energy consumption is alleviated that the standby time of DMS is extended.

Chapter 6. Conclusion

6.1 Conclusion

Telecommunications technologies evolved from fixed- lined voice and data services to mobile multimedia communications. The long evolution of PSTN and the population of mobile communications system bring about the demand of fixed and mobile convergence (FMC) to supply a common platform for the intercommunications between fixed and mobile telecommunications users. In FMC environment, both the fixed- lined and mobile switching networks need to be able to determine and to route calls to the destination networks of the called parties.

Occurring with telecommunications liberation, more service providers join the telecommunications market, both for fixed and mobile telecommunications. Users have more choices and are more likely to change service providers according to the service, quality, and the billing policy offered by the operators. Number portability (NP) service allows a user to keep the same telephone number even when she changes operators. Calls set to a ported number can be routed to the subscription network and the destination address of the called party where the calling and called parties need not to sense about that. In the competitive telecommunications market, operators must provide NP service to attract subscribers and to enhance their competitiveness.

According to NP services, telecommunications systems need to maintain the mapping of subscriber numbers and the routing information to connect the subscriber.

The large amount of NP users brings about the issue of long NPAC data searching delay that may bring about the accumulation of offered traffic in NPAC and result in long ported number translation delay to prolong the NP call setup time.

Based on the results of many researches, performing ported number translations in the early stage of NP call setup can effectively improve the efficiency of NP service.

Caching the routing information of ported numbers for both fixed-lined and mobile telecommunications systems is an effective and feasible approach to solve the problems of serving NP functions in telecommunications environment. However, the size of cache and the update of cached data are important issues.

Cache performs well when the access of cached data has locality. By analyzing the hierarchy of telecommunications network, we found that the dialed numbers of users usually have locality. With respect to the evolution of the telecommunications environment, we proposed different cache-based solutions to alleviate the problem of

telecommunications NP service. In the fixed- lined telecommunications system, such as PSTN, we proposed a PBX-based caching mechanism; in the mobile telecommunications systems before 2.5G, we proposed a mobile PBX telecommunication system and an approach of mobile PBX-based cache to alleviate the problem of NP service; in the mobile telecommunications system beyond 2.5G which possesses the capability of customized data service, we proposed to cache the routing information of an individual user ’s most frequently dialed ported numbers in the intelligent mobile handset.

According to the communication characteristics of users, we suggest adopting static cache policy. A static cache is established manually by system administrators in previous, rather than automatically performed by the communication system. The update of cached data is performed by IP-based networks. Hence, the update process can provide accurate routing information in time without occupying the telecommunication resource. The policy is simple and easy to implement, and the cache size is small enough to be arranged in memory that the turn-around time of cache consulting is very slight.

The most important considerations of caching mechanism are distributing the distribution of routing information of ported numbers, and allowing the public switching network to recognize the translated routing information. In this dissertation we proposed feasible and cost-effective mechanisms to fulfill the demands for different telecommunications environment. We also evaluated the efficiency and discussed the cost-benefit issues of the proposed method.

The improved NP call setup efficiency results in better communication resource serviceability. The call drop rate reduced remarkably along the decrease of call setup delay and the network resource can be effectively utilized. Therefore, our proposed methods benefit both users and the NP service providers, which can save call setup time for users, and save computing and communication resources for NP service providers. NP service providers can provide better performance to more users without extending of equipment and computing power. Without changing the existing signaling system and network architecture, the proposed mechanism is a low-cost, effective, and efficient solution for improving the performance of mobile NP service.

In addition, fixed- mobile convergence (FMC) is an evolution trend of data and telecommunications systems. User terminals which support FMC functions usually confront the issues of long call-origination delay (COD) and high VHO overhead. The issues will result in more battery energy consumption and shortened the standby time of user terminals. In this dissertation we proposed a service and terminal level solution to overcome the issues in the 3G-WLAN integrated communication environment. We study the mobile and calling behavior of 3G-WLAN dual- mode

users to analyze the factors represented the condition of the communication environment and proposed to keep the factors in 3G/WLAN dual- mode mobile handsets (DMS). Also we propose a very simple algorithm, which is easy to implement on DMS, to infer the condition of the visited communication circumstance and to determine the preferred network to avoid the drawbacks of dual- mode services.

Without changing existing communication architecture and protocols, the proposed method has the advantages of low complexity, easy to implement, and low-development cost.

The contributions of our works are:

n We proposed a novel approach to reduce the ported number translation delay in FMC telecommunications environment.

n With respect to the evolution of telecommunications systems, we proposed solutions to solve the NP problems in different telecommunications environment.

n The proposed solutions are easy to implement, cost-effective, and benefit users and service providers.