**6. General conclusions**

This chapter is focused on all IPv6/MPLS scheme for wireless mobile networks. We presented different integrations of mobility protocols (versions6 IP protocol extensions) with quality of service (QoS) protocols (MLPS, RSVP). The initial integrations were performed in infrastructure networks. The results delivered valuable information on how the protocols operated as well as the different coupling options available. This shows that the best coupling option was that where it is necessary to modify the protocols in a way that all could work as one single protocol. Other options were discarded, since protocols operating independently or even synchronised did not deliver satisfactory results. Among the quality of service protocols, we managed to prove that the RSVP was valid as a signalling protocol. This was also confirmed at the IETF when protocol CR-LPD was discarded as a signalling protocol when it was used together with MPLS.

On the other hand, in order to integrate IP protocol extensions (IP mobile, HMIPv6, F-HMIPv6 and FHAMIPv6) and MPLS protocol, it was necessary to modify MPLS nodes to turn them into mobile MPLS nodes. It was proved that IP mobile protocol, when integrated with MPLS, works better in macromobility scenarios. For micromobility scenarios, it is more convenient to use hierarchical IP mobile extensions since the signalling load is higher. The integration MPLS and HMIPv6 protocol extensions formed a good coupling for infrastructure networks in order to provide QoS. On the contrary, in total ad-hoc networks it is almost impossible because MPLS/Diffserv provides end-to-end quality of service, and when integrated with HMIPv6, the signalling load was so high that the network resulted overloaded.

Another problem was the compatibility of the source codes to perform the simulation to migrate from one version to another. The protocols did not work correctly. For this reason, we tested the F-HMIPv6 and MPLS protocols to verify if this was the best option to provide QoS to the next generation of mobile networks. In full ad-hoc mobile networks, FHMIPv6 showed diverse inconveniences, so it had to be modified to assume a new agent. This new agent was in the origin of the FHAMIPv6 protocol and the AHRA routing protocol. In order to solve the problem of the routing protocol AHRA, FHAMIPv6 was integrate with AODV and the result was successful. Similarly, we integrate FHAMIPv6 and MPLS and the result was satisfactory. With this result, we have achieved to propose an alternative to one of the great challenges of ad hoc networks. Because to provide QoS in ad hoc networks is a big challenge.

The quality of service values were obtained when a handover occurred and the results were satisfactory. In general, we can affirm that during a handover, not only metrics such as delay jitter and throughput improved, but also the default quality level was maintained in the integrations performed. The results obtained allowed us to identify which integration

**2** 

*Taiwan* 

**A QoS Guaranteed Energy-Efficient** 

*Department of Information Management, Tatung University, Taipei* 

Recently, the IEEE 802.16 standard (IEEE Std 802.16-2004, 2004), a solution to broadband wireless access commonly known as Worldwide Interoperability for Microwave Access (WiMAX), has been considered as a promising standard for next generation broadband wireless access networks. IEEE 802.16e (IEEE Std 802.16e-2005, 2005), also called Mobile WiMAX (Li et al., 2007), provides enhancements to IEEE 802.16 to support the mobility of Mobile Subscriber Stations (MSSs) at vehicular speed. Like other wireless systems, conserving energy is one of the critical issues for MSSs in IEEE 802.16e. Therefore, it is required for the protocol to offer a well-designed energy-efficient algorithm for an MSS.

IEEE 802.16e is expected to support Quality of Service (QoS) for real-time applications such as Voice over IP (VoIP), video streaming, and video conferencing with different QoS requirements (Wongthavarawat & Ganz, 2003; Zhu & Cao, 2004). Such applications are delay and delay variation susceptible. For example, when data packets incur vast delays and delay variations, the quality of the application seriously degrades. In order to avoid such situation, QoS provides the guarantee of transmission. IEEE 802.16e defines five types of service classed: Unsolicited Grant Service (UGS), Real-Time Variable Rate (RT-VR), Non-Real-Time Variable Rate (NRT-VR), Best Effort (BE), and Extended Real-Time Variable Rate (ERT-VR). Among them, the UGS is designed to support Constant Bit Rate (CBR) services, such as T1/E1 emulation, and VoIP without silence suppression. These kinds of services generate fixed-size data packets on a periodic basis. They usually require stringent QoS delay constraints, so determining the length of sleeping duration of an MSS in IEEE 802.16e is not only bounded by the total amount of traffic generated by the connections in the MSS, but is also restricted by the connections' QoS delay constraints. IEEE 802.16e was developed for the targets on mobile devices which are generally powered by energy-limited batteries. Thus, the energy-efficiency is an important issue to extend the lifetime of MSSs (Jang et al., 2006; Mukherjee et al., 2005; Tian et al., 2007). When a connection is established, an MSS may shift the operation status into sleep mode in order to save the power consumption if there are no packets to send or to receive in certain frame durations. Under sleep mode, there are two intervals: sleeping interval and listening interval. During the sleeping interval, an MSS can be powered down by putting its wireless network interface into sleep mode. Aside from this, the MSS would be unable to send or to receive packets during sleeping intervals. After a sleeping interval finishes, the MSS switches to listening interval. The MSS wakes up during the listening interval to check

**1. Introduction** 

**Scheduling for IEEE 802.16e** 

Wen-Hwa Liao and Wen-Ming Yen

protocols were the most suitable to ensure QoS in all IPv6/MPLS network. A series of architectures for next generation hybrid networks were proposed, including several important applications for universities, industry and the government. In general, the coupling between the quality of service and mobility protocols mentioned before is an excellent option to provide QoS in mobile networks and, especially, in the ad-hoc mobile ones. An interesting topic that we are currently evaluating is the different security issues that are generated in coupling protocols, which can actually degrade the quality of service by the action of malware or malicious users. On the other hand, we can say that, in next generation networks (4G), an all IPv6/MPLS architecture will be critical in next generation wireless mobile networks, compatible with the standards proposed so far (WIMAX, advanced LTE/SAE, LTE/IMT, WiMAX/IMT).
