Performance of the voice applications depends mainly on the quality of service requirements and in general there are many issues that affect the quality requirements.  In general wireless LAN networks supports a wide range of voice applications and their quality should be improved and thus the main aim of this project is to evaluate the performance of the wireless LAN against the quality of service aspects for different voice applications.

OPNET modeler simulation is done in this context and three scenarios are created where the first scenario deals with low quality speech, second scenario generates the IP telephony traffic and the third scenario deals with GSM quality voice application. Few voice and wireless LAN metrics are used in the simulation process and the exact quality of service requirements are analyzed and the key observations are as given below. 

Three scenarios are created to understand the quality of service requirements for voice application across the MANETs and among these three scenarios a low quality speech application is used for the first scenario, IP telephony application is used for the second scenario and a GSM quality speech is used for the third scenario.

Performance of these applications is estimated against the quality of service requirements using the voice and wireless LAN metrics and based on the results it is clear that GSM quality speech has shown the maximum QoS standards when compared to the other scenarios. When the voice metrics like jitter, MOS, traffic sent and traffic received are considered the GSM quality speech has shown the optimal performance and IP telephony has consumed more resources in terms of bandwidth and the quality of service requirements has reduced a lot with the IP telephony.

When the wireless LAN metrics like delay, medium access delay, load, network load, retransmission attempts and throughput are considered the IP telephony has reduced the quality of service requirements and again the GSM quality has shown the optimal performance and thus with this it is concluded that GSM quality level applications are used to enhance the quality of service requirements in the voice applications and IP telephony need to be fine tuned in lot of aspects to improve the quality of service requirements.