Call Admission Control In EV-DO/WLAN Heterogeneous Network

With the fast development of the wireless communications as well as thegrowing user demand, it is always wished that roaming within all kinds of networkswhile enjoying the guaranteed services only with the same mobile terminal, thus,heterogenous networks convergence is a matter of course. As a result, call admissioncontrol becomes the focus of many researchers’ concern. Many call admissioncontrol schemes has been proposed, but most are transparent to the lower layerprotocols. Thus schemes maybe available to more occasions, but they failed toefficiently use the whole resource or uniformly measure resources from differentnetworks due to inadequate consideration of the lower layer protocols specific tosome kind of network. What’s more, the so-called pingpang effect is anotherproblem in call admission control, it increases the system overhead and signalingoverhead due to the unnecessary handoffs.To solve the problems above, in this paper, a call admission control schemebased on user position information is proposed in the context of EV-DO and WLANheterogeneous networks with voice and data traffic. To be specific, a novel channelcondition evaluation method specific to EV-DO/WLAN networks is firstly proposed.Unlike traditional methods that compare the received signal strengths directly, itmapped them into bit error rates to judge channel condition virtually. Secondly, anovel netowrk load condition evaluation method is proposed to uniformly weigh theresourses in the heterogeneous networks. Last, the call admission scheme isproposed combining them with the user position imformation which is composed ofa parameter measurer, an admission controller and a decision executer. When a newcall or a handoff call arrives, the parameter measurer first obtains channel and loadconditions of available subnetworks as well as the position and mobility informationfor the admission controller. The admission controller then decides whether to admitor reject the call considering both quality of service and load balancing. Thedecision executer carries out the final actions at last.Simulation results show that proposed scheme can reduce pingpang effectwhile maintaining the quality of service requirements in that it can appropriatelyadmit or reject the users’ admission requests. Also, the proposed scheme can achievelower blocking rate than conventional algorithms such as received signal strengthbased algorithm or WLAN first algorithm and can significantly reduce the handoffdropping rate by effective load balancing. Considering metrics such as new callblocking rate, handoff call dropping rate, pingpang times, load balancing rate and soon, the innovation points lie not only in the deep research on the physical and media access control layer protocols of EV-DO and IEEE802.11, coming up with theeffective methods of channel and load condition evaluation, but also the proposal ofthe call admission scheme combining the user mobility information. It is aimed toreduce the pingpang times, blocking rate and dropping rate, increase the loadbalancing rate while maintaining the quality of service.