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Task 4 (UCLM): Improved performance of the multimedia communications over Broadband Wireless Access

Leader: Francisco Delicado; Researchers: Jesús Delicado, Juan Ignacio Del Castillo, José Miguel Villalón

It is important to note that, due to the high activity developed in our laboratories in the field of wireless networking, and the arousing interest in the development of wireless sensor networks, the task number 4 of the original memory has been sub-divided into two tasks: Task 4 (UCLM) & Task 5 (UCLM).

subTask 4.1 Improving the QoS performance in 802.11 (Wi-Fi) networks 

subTask 4.2 Improving the QoS performance in 802.16 (WiMAX) networks

subTask 4.3 Design and evaluation techniques adaptability of video streams

subTask 4.4 Video coding in wireless devices with limited resources

subTask 4.5 Overall evaluation of the proposed systems

1. Brief Description of the Goals

Two wireless technologies are making great inroads in society. These are the Wi-Fi (IEEE 802.11 WLAN) networks, which are the most widely used nowadays, and the recently developed Wi-MAX (IEEE 802.16 WMAN), which, when combined properly with the former, will be in the immediate future at the cutting edge of broadband wireless access. However, in spite of the progress made in recent years, the actual performance of these wireless access networks to support multimedia communications is still very deficient, and hence the deployment of these applications is not yet feasible in a real environment. The main reason for this is that 802.11 networks cannot effectively provide QoS support to this type of applications. Owing to their recent appearance, 802.16 networks still face many challenges, although they have been designed to provide QoS support to this type of applications. From the point of view of multimedia communications over broadband wireless access networks, it is extremely important the integration of efficient QoS support mechanisms within the protocol architectures of the 802.11 and 802.16 standards, further enabling the interconnection of both technologies. This should enable the deployment of metropolitan broadband wireless access networks characterized by a transparent integration of the 802.11 and 802.16 network architectures. This integration should be in line with the requirements of the multimedia applications, mainly the video signal, to be able to adapt to the special conditions imposed by the wireless networks.

In this sense, we aim at improving the performance of the communications requiring QoS guarantees and making use of broadband wireless access networks. Towards this end, we will analyze and correct the deficiencies found in the 802.11 standard when it comes to providing QoS support. This will be done by considering the case of completely heterogeneous scenarios integrating the use of DCF (basic 802.11) mode terminals, and by the analysis and dynamic parameter tuning in the control plane of the access layer of the WLAN medium. We will also implement policies of resource request and allocation into the 802.16 standard, taking into account QoS criteria. We will propose novel admission control schemes adapted to the previous decisions, enabling a simple and transparent interconnection of the 802.11 and 802.16 technologies. Finally, we will design new transcoding mechanisms adapted to the MPEG-4 (part 10)/H.264 standard in order to carry out the adaptation of video flows in terms of the rate and error concealment capabilities in line with the requirements imposed by the wireless channel and the receiver device capacities.

2. Scientific and Technical Developed Activities

Improve the performance of the resource request mechanism has been one of the main aims of this research line. Our research goal has been reduce the overhead and the collision in the contention request mechanism implemented by 802.16 standard. To this end, we have proposed two new request mechanisms based in the contention process of 802.16 named RGPSS and RPSF, both were published by J. Delicado et al. in the ICWCN 2008 Conference, and in the Telecommunications Systems Journal, vol. 50, nº 2 respectively.

Also, we have implemented an algorithm to calculate the optimum size of the contention periods a function of the active connections and granted resources. The work will be published by J. Delicado et al. in the Telecommunications Systems Journal (it is available on-line since August 2011).

Moreover, we have incremented the network performance using an evolution of the EDF scheduler, which reduces the fragmentation overhead in the network, this scheduler was presented by J. Delicado et al. in the ICSNC 2010 Conference.

Furthermore, for networks with OFDMA physical air interface, we have designed a new resource allocation algorithm, which enhances the performance of mechanisms in the literature, optimizing the use of WiMAX frame, supporting the flow QoS requirements, and adapting the granted resources to the quality of the air interface. It was presented by I. del Castillo et al. in the IFIP Networking 2011 Conference.

Enhancement the multimedia transmission over IEEE 802.11 has been other main aim of this research line. We started working to improve the support QoS, and the reliability of the multicast transmissions. Respect to the QoS support, we carried out a performance analysis on the effectiveness of the IEEE 802.11e (EDCA) standard in the presence of traffic generated by legacy 802.11 (DCF) based stations. We focused on assessing the behaviour of the upcoming IEEE 802.11e (EDCA) with different parameter settings. The work was published by J. Villalon et al. in the Telecommunications Systems Journal, vol. 36. After testing the performance of IEEE 802.11e standard, we designed a novel IEEE 802.11e-based QoS protocol capable of providing QoS support to multimedia communications, and able to properly interoperate with legacy DCF based stations. This protocol was published by Villalon et al. in Elsevier Computer Communications Journal, vol. 31 (17). Moreover, a mechanism to reduce the unfairness between the uplink and downlink traffic in IEEE 802.11 networks. It was published by Mico et al. in WMNC 2011 Conference.

Then we have proposed an adaptive IEEE 802.11 multicast protocol design that takes into account the dynamic channel conditions. The mechanism was published by Villalon et al. in IET Communications Journal, vol. 1(5). It requires knowing the operating conditions of the channel as perceived by the multicast group members. An extension to the scheme was proposed a second mechanism for adaptive video multicast streaming over multirate wireless LANs. In this method, published by Villalon et al in IEEE JSAC, vol. 25(4), we adaptive the previous work to a scalable video sequence. Finally, in Villalon et al. Telecommunication Systems Journal, vol. 43, we evaluated the QoS and multicast performance in presence of multicast traffic and different unicast applications.

Furthermore, a multicast transmission protocol, which reduces the probability of collision for multicast traffic in IEEE 802.11 networks, has been designed. This protocol improves the reliability of this traffic and it is totally compatible with the standard. It was published by Santos et al. in IEEE Communications Letter, vol. 15 (11). In conjunction with this protocol, we have designed an architecture for multicast video transmission in Wi-Fi networks. In this architecture we use Scalable Video Coding (SVC) for each multicast stations receive a video quality commensurate with its channel quality. It was published by Santos et al. in IEEE JSAC, vol 30(7).

In order to transmit multimedia applications over 802.16 networks, we have studied the use of hierarchical MPEG-4 video in the work published by F. Delicado et al. in the Telecommunication Systems Journal, vol. 36, nº 1-3. In this work we concluded that transmit hierarchical video increases the quality of video in reception with high load conditions.

Publications:  [FMDeli08], [FMDeli07 ], [JDeli09 ], [JDeli08a ], [JDeli08b ], [JDeli08c ], [JDeli07 ], [Villal08a ], [Villal08b ], [Villal08c ], [Villal08d ], [Villal07a ], [Villal07b ], [Villal07c ]

Projects funded by Public Calls:  [CICYT0609 ],  [COVIMAX ] by  national grants,  [IPTVWiMAX ] by  regional grants.

External collaborations Academia: Thierry Turletti, Qiang Ni, 

External collaborations Industry: --

Company Agreements: Albentia Systems S.A (Spain) 

PhD dissertations: Jesús Delicado MartínezJosé Miguel Villalón Millán

Patents: --