**5. Evaluation and results**

from the source to a destination. The AODV is designed to be used in ad-hoc networks which have provided small numbers of nodes (up to thousands). The main purpose of the protocol is to adapt quickly and dynamically to the changing conditions of the network links, and find routes which can allow it to provide a desirable QoS. In this way it, avoids wasting bandwidth,

The hybrid is a protocol where a certain set of nodes, (only a limited number of nodes) periodically updates the information nodes / routes of possible destinations, and attempts to make a suitable use of the two previous approaches. Examples of hybrid protocols are : HWMP (Hybrid Wireless Mesh Protocol), ZRP (Zone Routing Protocol) and FSR (Fisheye State Routing); the HWMP protocol is the representative of the hybrid protocols used for the following tests of this chapter. HWMP is based on AODV [22] and also has an optional routing

HWMP is a hybrid routing protocol. It has both re-active and proactive components. The creation of HWMP is an adaptation of AODV to radio-aware link metrics and MAC addresses. It is the basic, reactive component of HWMP. The on-demand path setup is achieved through the path discovery mechanism that is very similar to that of AODV. If a mesh point needs a path to the destination, it broadcasts a path request message (PREQ) into the mesh network.

QoS routing is an important parameter for the provision of guaranteed QoS in mesh networks. This issue has been exhaustively studied in wireless mesh networks. The aim of QoS routing for these networks is twofold: to find a best feasible path for each incoming connection in the presence of the underlying link interference and to optimize the usage of the network by

This chapter evaluates the routing problem in the IEEE 802.16 mesh networks. Unlike other routing strategies, this chapter is concerned with providing paths, mainly at certain QoS levels that guarantee traffic flows. The simulations will evaluate multimedia applications such as VOIP, video conference and other multimedia streams that have grown over the Internet, and verify the best qualifications between QoS and routing protocols by evaluating the major

The number of hops is the most common criterion that is adopted by traditional routing protocols. However, it is clear that these protocols are inadequate for multimedia applications, such as VoIP and video conferencing, which require QoS guarantees. Routing protocols with QoS, not only need to find the route with the shortest path, but the best route that meets the requirements of end-to-end QoS, regardless of the number of hops or how the routing protocols need to find the best routes through multiple hops. It, is necessary and important that the new protocols and routing algorithms also take into account the parameters and other measure‐ ments such as power consumption, the closeness of the backbone network output and

minimizing memory usage and processing the nodes that act as routers.

protocol, called RAOLSR (Radio Aware OLSR) based on OLSR [23] [24].

The hybrid routing protocols combine the best features.

impacts on these two important factors in the WMNs.

**4.2. Correlation between QoS and routing**

balancing the load.

*4.1.3. Hybrid routing protocol*

74 Selected Topics in WiMAX

The Simulations experiments were carried out with the aid of Network Simulator version 2 [25] to show the performance of some routing protocols with QoS as network measure in WiMAX Mesh Network. For the WiMAX Mesh simulations it was used a module developed by the Network and Distributed System Laboratory [26] with extensions to use on PMP and mesh mode. The results compare four routing protocols: AODV, OLSR, HWMP Proactive and HWMP Reactive. Figure tal show the topology used for the tests, a random topology.

The simulation scenario chosen for the experiments were formed in a randomly generated with sixteen nodes, but that could easily represent a pre-existing base stations in a city, a rural area or a group of cities in proximity.The base stations act as routers through which network traffic will be routed through them choosing the best path according to its algorithms so that traffic is routed between source and destination.

The scenario (Figure 8) aims to test the choices of the best routes according to the algorithms / routing protocols and verify the flow and the delay due to these choices. The results are found in the simulations are evaluated along with the following analysis of these.

**Figure 8.** Simulated Topology

Faced with this scenario, routing protocols, based on their algorithms must choose the best route for that traffic out of the source node (node 2/BS 2) and reaches the destination node (node 16/BS16) and there is the question. What's the best route? The red route or blue route? Will would other routes? Perhaps green route. Certainly there are several routes and choosing each one behind certain characteristics and particular outcomes to the performance of this network and its communication. Simulated parameters presented below (Table 1).

The result of the hybrid routing protocol show the better results in comparison with other protocols presented here. In other protocols, it takes a long time to find a best route for data flow and sometimes, take congested routes, which reduces the throughput of the network.

A Mobile WiMAX Mesh Network with Routing Techniques and Quality of Service Mechanisms

http://dx.doi.org/10.5772/55863

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In the second situation, the simulations were conducted with Video and CBR traffic (as background traffic). The transmission consists hop-by-hop by four routing protocol: AODV, HWMP Proactive, HWMP Reactive, OLSR. When we analyze the throughput, we observed a better performance by AODV. This case was carried out by using the Evalvid tool [27] that allows control of real video quality called "Grandma". The video simulations parameters

In this particular case the transmitted traffic behind will focus on some decrease in the quality of connections that take the main traffic to the destination and make the hybrid routing algorithms are flawed when compared to non-hybrid and in this case, can best AODV results in selecting the best route and consequently better results regarding the flow, providing a certain QoS to the end customer and the quality of multimedia applications used. The AODV establishes the route more faster than other protocols, for this reason it had better throughput

Traditionally, the performance of network archictetures have been evaluated through Quality of Service (QoS) metrics. QoS is defined as the ability of the network to provide a service at an assured service level. QoS is also a commonly used metric set (e.g., throughput, packet loss, delay, jitter, handoff dropping and blocking probability) to represent the capability of a network to provide guarantees to selected network traffic. QoS considers parameters of a network that can be easily measured, but do not tell how the service is perceived by users. To satisfy the user-centric approaches, QoE is used to quantify the perception of the user about the quality of a particular service or network. The QoEmetrics confirm the previous statement.

The PSNR (Peak Signal to Noise Ratio) [6] [28] is the most traditional QoE/video metric, which estimates the video quality in decibels, comparing the original video with the video received by the user considering the aspects of luminosity. Figure 10 shows the better video quality

**Parameters Value** Resolution 352 x 288 Frame Rate 30 Frame/sec Color Scale Y, U, V Packet Length 1052 Packet Fragmentation 1024

**5.2. Video on CBR traffic**

presented below (Table 2).

and better video performance.

**Table 2.** Video simulation parameters

using the PSNR statistics (Table 3).


**Table 1.** Simulated parameters
