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The Internet has now become such an important infrastructure that is capable of sending information within a very short time and easy to access. It is considered as public networks that provide affordable WAN services to most customers. Applications such as video conferencing, file transfer protocol and VoIP are the example of typical network applications supported by the Internet Protocol. Various...
This paper proposes a solution for throughput and stringent delay problems of VoIP in Ad-Hoc mode of IEEE 802.11 WLAN standards. This paper analyses the behaviour different codecs and schemes of WLAN running on VoIP traffic and draws a conclusion on the performance of network based on the criteria of different QOS parameters. Later the suitability of different routing protocols like AODV, DSR, OLSR...
We propose new authentication protocols that support fast hand-off for real-time applications such as voice over IP and audio/video conferencing in wireless mesh networks (WMNs). A client and a mesh access point (MAP) mutually authenticate each other using one-hop communications. The central authentication server is not involved during the handover process. Fast authentication for roaming from one...
Today, communications technology is one of the most essential roles for our life. People had used many ways of transmissions such as internet, mobile phone and so on. Moreover, VoIP (Voice over Internet Protocol) is also a communications technology. In this paper, we focus on VoIP which transmits voice over packet switched networks such as LANs (Local Area Networks) or WANs (Wide Area Networks). Adding...
Multi-channel multi-radio wireless networks improve network performance by enabling more simultaneous transmissions. Among multi-channel multi-radio protocols, the hybrid multi-channel approach has been shown to be efficient in providing higher system throughput. Voice over internet protocol (VoIP) service is expected to be widely supported in wireless networks, though its capacity has not been studied...
This work presents a study of RTP multiplexing schemes, which are compared with the normal use of RTP, in terms of ITU R-factor quality estimator. The bandwidth saving of the different schemes is studied, and some tests with VoIP traffic are carried out in order to compare R-factor using three different router buffer policies. Network delays are added using an adequate statistical distribution. The...
Different applications in the network have different sensitivity for the certain QoS parameters. The existing mechanisms cannot modify the packet loss policy exactly according to the needs of QoS parameters. Therefore, the network will not maximize its overall efficiency. This paper proposes a novel cognitive approach for QoS. It classifies the applications by various combinations of the QoS parameters...
The performance of mobile ad hoc network is influenced by a number of factors, such as protocol selections, parameter settings, wireless channel conditions, network size, transmission ranges, and traffic loads. In this work, we present an Autonomic Network Performance Management (ANPM) framework for ad hoc networks. The proposed framework follows a control-theoretic approach and is designed to monitor,...
For accessing various resources via mobile device anytime anywhere, the heterogeneous access technologies between wired and wireless networks have been developed and integrated actively. However, real-time services, e.g., Voice over IP (VoIP) and video streaming suffer from long delay, and non-real-time connections, e.g., TCP connections, cause low transmission throughput while occurring timeout and...
IP networks are increasingly being used for the provision of real time media services. This raises new challenges for QoS assurance through real time monitoring due to the complexity of distribution and the need for information correlation across a number of protocols. New tools and approaches are being developed. In this paper we report early results on one such tool, DRAI. In particular we show...
Voice over IP is an effective technology to reduce communication fee between people by means of the Internet. However, the quality of communication in the Internet is still a major challenge to real-time voice communication, such as excessive delay, packet loss, and high delay jitter, all these impair the communication quality. In order to improve the quality of communication between Voice Communication,...
IEEE 802.11 Wireless Local Area Network (WLAN) Physical Layer (PHY) offers multiple data rates. In multi-rate WLANs, 802.11 Medium Access Control (MAC) protocol, Distributed Coordination Function (DCF), essentially provides equal transmission opportunities to each sender host, causing the degradation of system throughput due to some hosts using low rates. In this paper we propose a cross-layer link...
With the proliferation of the Internet, voice over IP and multimedia communication become more and more important. One of the protocol that facilitated this development is Session Initiation Protocol (SIP). SIP is a signaling protocol which manages the session establishment and termination. It can be based on UDP or TCP at the transport layer. In this paper, the strengths and weaknesses of SIP over...
Over the last decade, VoIP has had a fast growth particularly in Small Office Home Office environments overloading the wireless accesses in the last mile. Network Coding schemes have advantageous features for throughput performance but VoIP is a delay critical service requiring fast routing algorithms. In this paper, we design, implement and measure experimental values for a network coding based VoIP...
IP Multimedia Subsystem (IMS) is very important due to the critical role it plays in the Next Generation Network (NGN) of the Fixed and Mobile Networks. Voice traffic in IMS will be served using Internet Protocol (IP) which is called Voice over IP (VoIP). This paper uses the "E-Model", (ITU-T G.107), as an optimization tool to select network and voice parameters like coding scheme, packet...
It needs to consider the establishment and release of IP telephony signaling-SIP or H.323 while analyzing VoIP network performance with OPNET, involving complex protocol configuration such as MGCP. What's more, the simulation efficiency will be greatly reduced in large-scale network. This paper presented an new idea to study the performance of VoIP network, it used the built-in hybrid simulation mechanism...
This paper discusses the delay characteristics and packet drop ratio performance of Busy Tone Multiple Access Protocol (BTMAP) for distances up to 48Km in IEEE 802.11 networks. The impact of the Contention Window (CW) is discussed. We note that a larger CW will increase the mean packet delay but decrease the packet drop ratio. Long range also significantly degrades the delay and packet drop ratio...
In this paper, the authors derived the packet size and transmission protocol which guarantees high quality of data transmission as well as minimizes the initial speech transmission delay and the speech cut-off intervals caused by the packet errors. For this, the authors deducted expected time of data transmission in radiotelegraph using MIL-STD-188-220C. For VoIP communication in radio devices, it...
The transmission of Voice over Internet protocol requires signal processing for reliable & efficient performance over the computer and the communication platform. Speech quality, as perceived by the users of VoIP telephony, is critically important to the update of the service. Signal quality is degraded by network layer problems including delay, jitter and packet loss. The work presented in this...
One-Way Delay Variation (OWDV) has become increasingly of interest to evaluate network state and service quality, especially for real-time and streaming services such as VoIP and video. Measurement of these parameters needs to be performed with the layout infrastructure. Many schemes for OWD measurements require clock synchronization at the source and destination through Global-Positioning System...
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