Capítulo I

Since this thesis examines the integration among RPR, EPON, and WiMAX net- works, it was first necessary to explain the various factors that should be considered for this integration. Subsequently, the features and characteristics of each of these standards were reviewed. As the RPR-EPON-WiMAX integration has not yet been

examined, we reviewed literature for the existing EPON-WiMAX and RPR-EPON combinations. EPON-WiMAX networks have been considered in many works, and architectures, bandwidth allocations, and schedulers have been proposed for these networks. However, only two legitimate architectures have been proposed for EPON- WiMAX networks, and these architectures have several drawbacks. Also, the MAC protocol for EPON-WiMAX networks has not yet been considered in a comprehen- sive way, and the Admission Control has not even been mentioned for these networks. Lastly, the bandwidth allocation and schedulers have been discussed individually, so that both of them manage EPON and WiMAX separately. RPR-EPON has been studied as a proposed integration between metro and access networks. Nearly all of the works that considered RPR-EPON suggested the same architecture for this network. Within this architecture, the messages that manage the EPON operation are modified and extended to work with the RPR-EPON integration. However, no single author has proposed a protocol for integrating the MACs of RPR and EPON to manage and maximize the performance of its hybrid network.

Chapter 3

Proposed Solution for EPON-WiMAX

Implementation of wired and wireless access networks into one single network architec- ture which is controlled by a single control system, known as fixed mobile convergence (FMC) [39], results in significant cost reduction. FMC is envisioned as a future archi- tecture for broadband access networks. This work focuses on the integration of EPON and WiMAX technologies as the representatives of optical and wireless technologies respectively.

The complementary features of EPON and WiMAX make the integration of these technologies a superior solution for access networks [10], [18]. This integration combines advantages of both technologies; i.e, the high bandwidth and reliability of EPON networks and the mobility and flexibility of WiMAX networks. Specifically, there are several important factors that motivate such integration.

• First, EPON and WiMAX show a good match in capacity hierarchies. EPON bandwidth can be shared by a group of remote Optical Network Units (ONUs), in a way that gives each ONU a capacity in the range of the bandwidth offered by a WiMAX Base Station (BS).

• Second, integration can improve the overall network performance and QoS sup- port by using integrated packet scheduling and bandwidth allocation.

• Third, since the integration realizes the FMC, it reduces design and operational costs of the network significantly. Moreover, it supports mobility in the access network.

• Fourth, both EPON and WiMAX employ a generic poll/request/grant mecha- nism. A central station (Optical Line Terminal (OLT) or WiMAX Base Station

(WiMAX BS)) polls a remote station (ONU or SS) for bandwidth requests. The remote station responds with requests for bandwidth and the central sta- tion then grants bandwidth. This poll/request/grant mechanism makes EPON and WiMAX very similar in bandwidth allocation and QoS support.

The integration between EPON and WiMAX technologies in hybrid network architecture has advantages over the traditional optical and wireless networks. The advantages of EPON-WiMAX hybrid access networks are summarized as follows:

a. In hybrid access networks, there is no need to lay fiber all the way to every cus- tomer’s premises. This significantly reduces the cost of network deployment and incurred maintenance as compared to that of pure fiber based access networks in built-up neighborhoods.

b. Hybrid networks are more flexible than pure optical access networks. The ”anytime-anywhere” approach is also applicable to the hybrid network because users are served through the wireless frontend of the hybrid network. This allows users inside the network to seamlessly connect with one another.

c. Hybrid networks are more robust than the traditional wired networks. In case of a fiber failure, all users served by a particular fiber/wireless access point pair can immediately move to another serving access point close by.

d. Hybrid networks do not suffer from the problem of congestion and information loss. This is due to the inherent reliability of the network. Moreover, hybrid networks can have a better load-balancing capability due to users’ mobility. e. Fault tolerance, robustness with respect to network connectivity, and load bal-

ancing characteristics of the hybrid networks make them ”self-organizing”. The complete solution for EPON-WiMAX hybrid network should include ar- chitecture and a joint MAC protocol for this architecture in order to improve the performance of hybrid access network. Architectures proposed for EPON-WiMAX in literature either concern on the ways of integrations [10] or have some drawbacks [11]- [12].

Components of MAC protocol; admission control, bandwidth allocation and scheduler; for EPON-WIMAX have been considered in individual manner. But MAC protocol has not been considered jointly to measure effect of all these components on the network performance. Although one work consider joint Admission Control and Bandwidth Allocation, but it did this to implement virtual private networks on EPON-WIMAX.

In this chapter, we propose a new architecture for the integrated WiMAX and EPON networks that overcomes drawbacks of earlier architectures by providing a protection in the EPON part of the network and extends the converge range of the access network. A MAC protocol that includes joint bandwidth allocation algorithm, scheduler, and Admission Control is proposed. This MAC protocol supports QoS for different services types that are incorporated in the proposed architecture.

This chapter is organized as follows: First, the new architectures for EPON- WiMAX networks are presented in Section 3.1. Section 3.2 outlines the general setting of the suggested MAC protocol for the EPON-WiMAX networks. Then in Section 3.3, Distributed Admission Control for one of the proposed architectures is presented. The Multilevel Dynamic Bandwidth Allocation is provided in Section 3.4. Then in Section 3.5, Hybrid Scheduler is presented. The performance of the proposed solution is evaluated and compared with other solutions proposed in the literature in Section 3.6. Finally, Section 3.7 summarizes the chapter.

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