**5.2. Video on CBR traffic**

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

> Cover Area 1km Frequency 3,5GHz

> Modulation OFDM

Simulation Time 60s

Router WiMAX Mesh Number 16

In the first situation, the simulations were conducted with CBR traffic (1 MB), the transmission consists hop-by-hop by four routing protocols: AODV, OLSR, HWMP Proactive and HWMP Reactive. By the analyze of the throughput, achieved better performance result by HWMP Reactive (Figure 9). This result is because of the protocol in this scenario constantly keep checking the best route and always find a solution when faced with a new, always managing

to optimize the flow through the best link at any given time.

**Figure 9.** Comparison of CBR traffic throughput for the four routing protocols

Standard IEEE 802.16 (MESH)

Traffic Video and CBR

network and its communication. Simulated parameters presented below (Table 1).

**Table 1.** Simulated parameters

**5.1. CBR traffic**

76 Selected Topics in WiMAX

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 presented below (Table 2).

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 and better video performance.


**Table 2.** Video simulation parameters

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 using the PSNR statistics (Table 3).

For each PSNR range values, there is a qualification for the received video by the user. The Table II shows the PSNR range quality:


**Table 3.** PSNR range

**Figure 11.** SSIM

**Figure 12.** VQM

The Video Quality Metrics (VQM) [6] [28] as MSU VQM metric also compares the original video with the video received by the user. They are considered the most complete metrics because compare the following aspects: noise, distortion and color. Again, AODV (Figure 12) has the best values because the smaller the value of this metric, better the video quality.

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The evaluation of routing protocols are clear when we look at the frames in Figures. The frame number100wasselectedtocomparethequality.Aswecansee,theAODVpresentsthebestresults, followed by hybrid reactive, OLSR and hybrid proactive protocols respectively (Figure 13).

### **Figure 10.** PSNR

The Structural Similarity (SSIM) [6] [28] metric evaluates the received video by the user taking into account the characteristics of the HVS (Human Visual System). The SSIM examines the color, light and structure similarity. The SSIM value is expressed by a number between 0 and 1, where 0 means zero correlation with the original image and 1 means the exact same video. As can be noted (Figure 11) by analyzing the QoS metrics, AODV has the best closeness in quality compared to the original video and HWMP Proactive worse.

### **Figure 11.** SSIM

For each PSNR range values, there is a qualification for the received video by the user. The

**PSNR (dB) Quality** > 37 Excellent 31 – 37 Good 25 – 31 Fair 20 – 25 Poor < 20 Bad

The Structural Similarity (SSIM) [6] [28] metric evaluates the received video by the user taking into account the characteristics of the HVS (Human Visual System). The SSIM examines the color, light and structure similarity. The SSIM value is expressed by a number between 0 and 1, where 0 means zero correlation with the original image and 1 means the exact same video. As can be noted (Figure 11) by analyzing the QoS metrics, AODV has the best closeness in

quality compared to the original video and HWMP Proactive worse.

Table II shows the PSNR range quality:

**Table 3.** PSNR range

78 Selected Topics in WiMAX

**Figure 10.** PSNR

The Video Quality Metrics (VQM) [6] [28] as MSU VQM metric also compares the original video with the video received by the user. They are considered the most complete metrics because compare the following aspects: noise, distortion and color. Again, AODV (Figure 12) has the best values because the smaller the value of this metric, better the video quality.

#### **Figure 12.** VQM

The evaluation of routing protocols are clear when we look at the frames in Figures. The frame number100wasselectedtocomparethequality.Aswecansee,theAODVpresentsthebestresults, followed by hybrid reactive, OLSR and hybrid proactive protocols respectively (Figure 13).

**6. Conclusions**

of quality in real end user.

variability.

This chapter showed an initial study on wireless mesh networks, pointing out the main goals of interest, challenges and issues encountered, highlighting the advantages and disadvantages of this mode of operation. During the work, focused on the IEEE 802.16 popularly known as WiMAX, a technology standardized by the WiMAX Forum as an alternative wireless com‐ munication with wide area coverage and bandwidth, providing high speed and mobility,

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The chapter provides a more detailed study of the WiMAX mesh mode, pointing to two very important points for this type of network the next generation of wireless communications: algorithms / routing protocols and QoS, mainly to meet the demands for new multimedia applications as VoIP, telemedicine, videoconferencing and other real-time applications that require a large bandwidth with constant to meet the constant flow needs, providing quality network metrics such as throughput and delay and qualitative results regarding the perception of the end user when evaluated on the QoE metrics, with valid results on human perception

The studies and validated through simulation showing what the main advantages of routing protocols when incidents of random scenario presented here, however, it is noteworthy that these results are specific to this scenario, not ensuring that the protocols achieve similar results in any type of scenario. It is important to mention that the protocols have different results as there is a variability of scenarios or data flow, increasing them or decreased them and so, some protocols may have better results in some scenarios and worse in others, there is certain

Conclusively, routing protocols have advantages and disadvantages and present very particular results, and there is a protocol that presents the best results ever, nor how to choose

Simulation results shown that the AODV protocol provides the best results when analyzed on the scenario shown to video traffic, however, the hybrid routing protocol that operates in a reactive mode, gives good results and operates in hybrid form, could be better than AODV depending on some parameter variations. This makes us believe that the hybrid reactive would be a protocol that can be relatively good in all cases, although not an optimal model, can be efficiently and effectively providing a good alternative routes and relative quality to the end user about the prospect of QoS and QoE. The hybrid reactive and AODV protocol gave good results as the data flow rate and video quality, but could have different results in other settings

In some future work, the authors intend to make optimizations in routing protocols and mechanisms include your choice between a more complete analysis taking into account other important points beyond the amount of jumps as energy consumption and output communi‐ cations to the Internet outside the backbone of the mesh network with algorithms that also

the best route, nor as to the best results of QoS and QoE.

and with other simulation parameters.

take into consideration the proximity.

important peculiarities in the context of next-generation networks in Future Internet.

**Figure 13.** Result of frame 100 for the four routing protocols

The Figure 14 shows the delay average over time for the four routing protocols, showing their results in this network metric. AODV and HWMP reactive had the lowest delay.

**Figure 14.** Delay average over time

If a routing protocol takes longer time to find the best route and took and thus decide to use your communication path, in normal situations, present a lower performance as measures of network for those with a behavior in choosing the fastest route.
