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Wireless Multimedia Services and Applications
Published in K.R. Rao, Zoran S. Bojkovic, Dragorad A. Milovanovic, Wireless Multimedia Communications, 2018
K.R. Rao, Zoran S. Bojkovic, Dragorad A. Milovanovic
The demand for multimedia services in mobile networks has raised several technical challenges, such as the minimization of handover latency. In this context, soft and softer handover techniques have played a key role and provided the means for eliminating the handover latency, thus enabling the provision of mobile multimedia services. However, not all radio access networks support soft handover techniques. For example, the notorious IEEE 802.11 wireless local area networks (WLANs) support only hard handovers; consequently the use of multimedia services over such WLANs raises considerable concerns. Another major challenge in both fixed and wireless networks today is QoS provision. For wireless access networks, such as WLANs, the IntServ framework, standardized by the Internet Engineering Task Force (IETF), provides the necessary means for requesting and obtaining QoS per traffic flow. IntServ uses the Resource Reservation Protocol (RSVP) for implementing the required QoS signaling. RSVP is problematic in wireless networks, basically due to the need for reestablishing resource reservations every time a mobile node (MN) changes its point of attachment and the IP route with its corresponding node (CN) has to be updated end-to-end, resulting in increased handover latency.
Mesh Networking in Wireless PANs, LANs, MANs, and WANs
Published in Yan Zhang, Jun Zheng, Honglin Hu, Security in Wireless Mesh Networks, 2008
Neila Krichene, Noureddine Boudriga
Today, most Internet protocols provide best-effort IP forwarding while QoS support is required to satisfy multimedia applications needs. To address this issue, two major QoS models have been proposed: the Integrated Service (IntServ) [73] and the Differentiated Service (DiffServ) [74]. IntServ is a QoS model which adopts virtual circuit connection mechanisms and offers per-flow end-to-end reservations. The Resource ReSerVation Protocol (RSVP) is used as a signaling protocol to set up and maintain virtual connections and reserve resources along a route. IntServ provides hard QoS guarantees; however, the adopted per-flow granularity leads to a scalability problem because the amount of state information increases with the number of flows and nodes. DiffServ was designed to overcome the difficulty of implementing and deploying IntServ and RSVP. In fact, the DiffServ scalable solution provides QoS on the wired Internet by defining a set of QoS classes and then classifying packets into them according to an SLA negotiated with the Internet Service Provider (ISP). Edge routers perform the complicated flows classification while the core routers do not keep per-flow information, but aggregate different packets that were assigned to different classes on a per-hop behavior (PHB). DiffServ aims to provide service differentiation among traffic aggregates over a long timescale, but it does not fit to a fast topology-changing context.
Voice over Internet Protocol Networks
Published in Goff Hill, The Cable and Telecommunications Professionals' Reference, 2012
IntServ requires a signaling system to send the traffic specification from the sender to the receiver and for the resource allocation from the receiver to the sender. The signaling system used for this is the Resource ReSerVation Protocol (RSVP); the operation is shown in Figure 7.12. RSVP operates by sending a traffic specification in the PATH message; this is noted by each router along the path. If a receiver wishes to receive the stream with specific QoS, then it sends a resource specification in the RESV message, which passes along the same route that the PATH message is on. Then as each router receives the RESV message it allocates the resources and passes the RESV message upstream.
Software-Defined Networking Techniques to Improve Mobile Network Connectivity: Technical Review
Published in IETE Technical Review, 2018
Apart from the earlier two approaches, which classify packet-in message and application type, OpenQoS [23] sorts incoming traffic as multimedia and data. Multimedia traffic on QoS guaranteed routes can be allocated dynamically while traditional shortest path can be used by data traffic over OpenFlow networks. OpenQoS is different from the current QoS architecture that enables QoS based on dynamic QoS routing rather than using resource reservation in Integrated Services (IntServ) architecture or priority queuing in Differentiated Services (DiffServ) architecture. Also, available bandwidth for each link is monitored by OpenQoS controller periodically in order to detect whether congestion has happened while link cost parameters are determined for problem optimization. If congestion takes place, QoS routes can be rerouted by deleting route in the routing table which matches multimedia QoS packet in the flow table of the switches so that new flow entries are defined for the multimedia QoS packet [28]. OpenQoS first checks if the packet belongs to multimedia packet based on predefined flow setups. Two paths will be calculated based on QoS optimized path and shortest path. Upon receiving packet-in messages at OpenQoS controller, typical QoS indicator, such as packet loss rate, bandwidth, and delay for each link are used to calculate QoS route and new flow definitions are pushed to forwarders along the path.