Дослідження тайм-ауту повторної передачі транспортного з’єднання в мережах, що самоорганізуються

Розглянуто ключовий аспект забезпечення надійності транспортного рівня мереж на основі стека TCP/IP, такий як тайм-аут повторної передачі даних. Вказано механізми підвищення ефективності транспортного з’єднання за рахунок адаптації тайм-ауту повторної передачі протоколу транспортного рівня до умов функціонування радіомереж, що самоорганізуються. Основою запропонованого нового методу визначення часу тайм-ауту повторної передачі пакетів є обчислення часу тайм-ауту для кожного маршруту окремо, а не сукупного часу очікування пакетів-квитанцій. Це дає змогу для мереж, що самоорганізуються, обчислювати таку кількість тайм-аутів, скільки маршрутів знайдено до кінцевого отримувача. Доведено, що такий підхід дає можливість істотно зменшити час очікування у разі втрат пакетів і повторної їх передачі, а отже, підвищує загальну пропускну здатність транспортного з’єднання.This article describes a key aspect of providing the reliability of the network transport layer TCP/IP based networks, such as a retransmission timeout. We are improving the efficiency of the transport mechanisms by adapting the retransmission timeouts of the transport protocol to the conditions of operation of self-organizing radio networks. The basis for the proposed new method for determining the retransmission timeout of packets is to calculate the timeout for each route individually, rather than the cumulative timeout packet-receipts. This allows for a self-organizing networks to calculate such a number of timeouts, how many routes found up to the final destination. It is proved that such an approach can significantly reduce the waiting time in the case of packet loss and retransmit, and thus increase the overall throughput of the transport connection

A cross-layer approach for QoS topology control in wireless ad hoc networks

Wireless ad hoc networks using omni-directional antennas do not scale well due to interference between nearby nodes. Maintaining the QoS of the communications in this type of network is a difficult task. Using multiple narrow beam directional antennas alleviates this problem at the expense of connectivity. Multi-beam smart antennas allow the network topology to be adjusted dynamically by adjusting the beamwidth and beam directions to minimize interference and to maximize the number of possible concurrent network communications. This in turn helps to maintain the QoS of the communications. QoS routing has long been used to meet the user requirements by finding appropriate paths to the destinations. We extend this concept to create an adaptive QoS topology control (AQTC) system using smart antennas. We use a cross-layer approach to control the topology dynamically where the topology control layer sits between the MAC and the routing protocol. The performance of our protocol has been evaluated using extensive simulations. Simulation results show that different topologies for a set of communications perform differently. AQTC always forms a topology to facilitate the current communications and improves the network throughput and end-to-end delay

A Scalable Link Quality Routing Protocol For Multi-radio Wireless Mesh Networks

Due to their installation and management simplicity, Wireless Mesh Networks (WMNs) have become a natural way to deliver wireless coverage for local, campus and metropolitan areas. In order to provide backhaul support, it is necessary to enhance the capacity of WMNs. In this paper, a scalable link quality routing protocol for multi-radio WMNs is proposed. We incorporate a local link quality metric and multi-radio support in the OLSR (Optimized Link State Routing) protocol. This simple and scalable approach helps to find shortest paths with better quality. Simulations were conducted and the results showed expressive performance improvements of the proposed protocol over the original OLSR, with a minimum overhead increase.10531058IEEE 802.15 WPAN™ Task Group 5, , http://www.ieee802.org/15/pub/TG5.html, AvailableIEEE 802.11s TG, Status of Project IEEE 802.11s "ESS Mesh Networking", , http://grouper.ieee.org/groups/802/11/Reports/tgs_update.htm, AvailableIEEE 802.16's Relay Task Group, , http://grouper.ieee.org/groups/802/16/relay/index.html, AvailableWaharte, S., Boutaba, R., Iraqui, Y., Ishibashi, B., Routing protocols in wireless mesh networks: Challenges and design considerations (2006) Multimedia Tools and Applications, 29 (3), pp. 285-303. , Springer Netherlands, JunGupta, P., Kumar, P.R., The capacity of wireless networks (2000) IEEE Trans. Information Theory, 46, pp. 388-404. , MarGong, M.X., Midkiff, S.F., Mao, S., A cross-layer approach to channel assignment in wireless ad hoc networks (2007) Mobile Networks and Applications, 12, pp. 43-56. , JanKyasanur, P., Vaidya, N.H., Routing and interface assignment in multi-channel multi-interfece wireless networks (2005) IEEE WCNC, 4, pp. 2051-2056. , New Orleans, USA, MarY. Qu, C.-H. Lung, and A. Srinivasan, Multi-channel OLSR with dedicated control interface, in SPECTS, Calgary, Canada, Jul-Aug. 2006Raniwala, A., Chiueh, T., Architecture and algorithms for an IEEE 802.11-based multi-channel wireless mesh network (2005) IEEE Infocom, pp. 2223-2234. , Miami, USA, MarAlicherry, M., Bathia, R., Li, L., Joint channel assignment and routing for throughput optimization in multi-radio wireless mesh networks (2005) ACM Mobicom, pp. 58-72. , Cologne, Germany, pp, Aug-SeptAkyildiz, I.F., Wang, X., Wang, W., Wireless mesh networks: A survey (2005) Computer Networks Journal (Elsevier), 47 (4), pp. 445-487. , MarKyasanur, P., Vaidya, N.H., Routing and link-layer protocols for multi-channel multi-interface ad hoc wireless networks (2006) ACM Mobile Computing and Communications Review, 10, pp. 31-43. , JanClausen, T., Jacquet, P., (2003) Optimized link state routing protocol (OLSR), , IETF RFC 3626, Oct(1999) IEEE Standard for Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, IEEE 802.11 WG, ISO/IEC 8802-11:1999, IEEE Std. 802.11(2004) IEEE Standard for Local and Metropolitan Area Networks - Part 16: Air Interface for Fixed Broadband Wireless Access Systems, IEEE Std. 802.16-2004Ogier, R., Templin, F., Lewis, M., (2004) Topology dissemination based on reverse-path forwarding (TBRPF), , IETFRFC 3684, FebPerkins, C., Belding-Royer, E., Das, S., (2003) Ad hoc on-demand distance vector (AODV) Routing, , IETF RFC 3561, JulJohnson, D.B., Maltz, D.A., Hu, Y., The dynamic source routing protocol for mobile ad hoc networks (DSR) (2004) IETF Internet Draft, , JulCouto, D.S.J.D., Aguayo, D., Bicket, J., Morris, R., A high throughput path metric for multi-hop wireless routing (2003) ACM Mobicom, pp. 419-434. , San Diego, USA, pp, SeptDraves, R., Padhye, J., Zill, B., Routing in multi-radio, multi-hop wireless mesh networks (2004) ACM Mobicom, pp. 114-128. , Philadelphia, USA, pp, Sept-OctYang, Y., Wang, J., Kravets, R., Designing routing metrics for mesh networks (2005) IEEE WiMesh, , Santa Clara, USA, SeptSubramanian, A.P., Buddkihot, M.M., Miller, S., Interference aware routing in multi-radio wireless mesh networks (2006) IEEE WiMesh, , Reston, USA, SeptM. Bahr, Proposed routing for IEEE 802.11s WLAN mesh networks, in WICON, Boston, USA, Aug. 2006OLSR implementation, , http://hipercom.inria.fr/OOLSR, Hipercom Project, INRIA, AvailableNetwork Simulator NS-2, , http://www.isi.edu/nsnam/ns, AvailableWireless mesh network solution, , http://products.nortel.com/go/solution_content.jsp?segld=0& parld=0&prod_id=47160&locale=en-US, AvailableCisco Systems, Outdoor wireless network solution. Available: http://www. ci sco. com/go/wirelessmeshBelAir, Networks, , http://www.belairnetworks.com, AvailableMicrosoft, Microsoft research mesh networks projetct, , http://research.microsoft.com/mesh, AvailableD. Passos, D. V. Teixeira, D. C. Muchaluat-Saade, L. C. S. Magalhães, and C. V. N. Albuquerque, Mesh network performance measurements, in I2TS, Cuiabá, Brazil, pp. 48-55, Dec. 2006Bicket, J., Aguayo, D., Biswas, S., Morris, R., Architecture and evaluation of an unplanned 802.1 lb mesh network (2005) ACM MobiCom, pp. 31-42. , Cologne, Germany, pp, Aug-Sep