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This work presents a study of a SIP-based IP telephony system in terms of Quality of Service (QoS) and admission probability. The system is designed for an enterprise with offices in different countries. A software IP PBX maintains the dial plan, and SIP proxies are used in order to implement Call Admission Control (CAC) and to allow the sharing of the gateways' lines. The system is implemented in...
In this paper, we propose new methods to reduce the handoff blocking probability in LTE wireless networks. This reduction is based on an adaptive call admission control scheme that provides quality of service (QoS) guarantees and gives the priority of handoff call (HC) over new call (NC) in admission. The performances of the proposed schemes are compared with other method by simulation. Our new method...
The capacity of a multi-hop wireless network is the traffic payload that it can transport. This is a prominent quality of service issue, particularly in the highly constrained settings of 802.11 wireless mesh network. In this paper, we consider two complementary definitions of the capacity. A network-wise capacity is defined as the sum of the upload traffic, and a flow- wise capacity highlighting...
High latency network is increasingly important in today's telecommunication world. It is widely used for real-time interactive multimedia applications such as video, music, data and graphic files exchange. One example of this network is the satellite communication technology. Unfortunately, the high latency satellite network provides limited network bandwidth and introduces high network latency issues...
Active Queue Management (AQM) algorithm is important to manage buffers and transfer packets for wired/wireless networks. However, the unresponsive flows to the network congestion control is dangerous to the network equilibrium and Quality of Service (QoS), especially from the point of network resource allocation. In some certain scenarios, the limited network resource (buffers) can be occupied by...
In the increasingly popular Voice over IP (VoIP) application domain, a well known issue relates to the management of available network bandwidth which is usually constrained by uplink capacities as well as access point limitations in the case of wireless connections. An approach that has long been advocated for controlling the admission of new connections based on bandwidth availability is Call Admission...
Supporting Quality of Service (QoS) in a core transport is an important feature of a next generation network. This feature not only enables real-time communication services such as Voice over IP (VoIP) and video telephony, but also helps create new applications. However, access gateway such as Packet Data Gateway (PDG) in IMS WLAN Interworking, located at the edge of an IMS core network, must inspect...
With the growing demands for computer network communication, it becomes increasingly important to secure the data flow path. The existing research related to security mechanisms only focuses on securing the flow of information in the communication networks. There is a lack of work on improving the performance of networks to meet quality of service (QoS) constrains for various applications. The security...
In this article we describe the QoS concept of the evolved packet system, which was standardized in 3GPP Release 8. The concept provides access network operators and service operators with a set of tools to enable service and subscriber differentiation. Such tools are becoming increasingly important as operators are moving from a single to a multi-service offering at the same time as both the number...
The transmission of data is from the mesh routers to gateway by multi-hop and then to Internet. The gateway where the traffic congregates becomes the bottleneck of the network. End-to-end delay with upper bound is one of guaranteed services, and whether the upper bound can obtain the guarantee is a key to present QoS guarantees, implement routing effectively, congestion control and load balance in...
Providing strong QoS guarantees for wireless multi-hop networks is very challenging, due to many factors such as use of a shared communication medium, variability in wireless link quality, and so on. However, wireless mesh technology gives the opportunity to alleviate some of these problems, due to lack of mobility in the wireless infrastructure, and presence of natural centralization points in the...
Random Early Detection (RED) can effectively avoid transmitting congestion at routers, but RED can not provide bandwidth fairness. Different packet sizes are one of the reasons that damage fairness. RED routers provide little protection from some bulky data flows that use considerably more bandwidth than other flows in time of congestion. Modifying the formulas of calculating final packet-discard...
One of the vital key elements for providing quality of service (QoS) for VoIP is the call admission control (CAC) capabilities of the session management/call session control function or gateway. Even though the network may be designed to meet a given performance and restoration objective for the engineered traffic loads, the actual traffic may be significantly higher. Without a CAC function in a VoIP...
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