Ad-Hoc Networks
▶ Introduction
 

Wireless ad-hoc networks have recently become a popular research topic. Ad-hoc network is a collection of mobile nodes that are connected via wireless links without using an existing network infrastructure or centralized administration. From the applications perspective, wireless ad hoc networks are useful for situations that require quick or infrastructureless local network deployment, such as crisis response, conference meetings, sensor networks, military applications, and possibly home and office networks.

Fig. 1. Wireless Network

Wireless ad hoc networks can be classified add cording to their application:

  • Mobile ad hoc networks (MANET)
  •  - In MANET, The nodes are free to move randomly and organize themselves arbitrarily.

  • Wireless mesh networks (WMN)
  •  - A wireless mesh network is a special type of wireless ad-hoc network. A wireless mesh network often has a more planned configuration, and may be deployed to provide dynamic and cost effective connectivity over a certain geographic area.

  • Wireless Sensor networks (WSN)
  •  - A wireless sensor network (WSN) consists of spatially distributed autonomous sensors to monitor physical or environmental conditions, such as temperature, sound, pressure, etc. and to cooperatively pass their data through the network to a main location.


    ▶ Medium-access control

      A key factor in the design of a MAC protocol for ad hoc networks is the way in which it utilizes the available medium. Earlier approaches assumed a common channel for all stations, while more recent approaches have used multiple channels for more efficient use of the medium. Considering the medium as a single channel was the most prominent approach in the earlier years of MAC design. In the single channel approaches, all the nodes on the network share the medium for all their control and data transmissions. Collisions are an inherent attribute of such protocols. Two stations that transmit simultaneously will both fail. Multichannel MAC protocols have been considered to support simultaneous communication. Although, multichannel protocols support higher throughput, it introduces the multichannel hidden terminal problem. The hidden terminal problems can be solved by efficient network coordination mechanisms.

    A MAC protocol for wireless ad hoc network should be designed by considering the following facts:
  • MAC protocol should be applicable for multi-hop communication.
  • It should be distributed
  • Network self-organization is needed
  • Mobility is low but should also be taken into account.


  • ▶ Research Issues

     
  • Scalable MAC: Most of the existing MAC protocols for multi-hop ad hoc network only solve partial problems of the overall issue. The scalability issue in multi-hop ad hoc networks has not been fully solved yet.

  • MAC/Physical Cross-Layer Design: When advance physical layer techniques are applied, a MAC protocol should be able to utilize the agility provided by the physical layer.

  • Network Coordination: This is one of the most challenging tasks for designing multi-channel MAC protocols, especially for multi-channel cognitive radio ad hoc networks.




  • ▶ Routing

      The design of routing protocols for WMNs is an active research area. An optimal routing protocol for wireless ad hoc network must capture the features: Multiple Performance Metrics, Scalability, Robustness, etc. Existing routing protocols for ad hoc networks have already considered some of these features. However, none of them has captured all of these features.


    ▶ Research Issues
     
  • Scalability: Scalability is essential in routing protocols and new scalable routing protocols need to be developed.

  • Routing/MAC Cross-Layer Design: A routing protocol needs to interact with the MAC layer in order to improve its performance.

  • Energy Efficiency: Energy efficient routing protocols are essential for wireless sensor networks which have limited power resources.



  • ▶ References

     
    1. Jurdak, R., Lopes, C.V. and Baldi, P. “A survey, classification and comparative analysis of medium access control protocols for ad hoc networks” IEEE Communications Surveys & Tutorials, Volume: 6 , Issue: 1, 2004 , Page(s): 2 ? 16
    2. Booysen, M.J., Zeadally, S., van Rooyen, G.-J. “Survey of media access control protocols for vehicular ad hoc networks “ IET Communications, Volume: 5 , Issue: 11 , 2011 , Page(s): 1619 - 1631
    3. Alawieh, B., Yongning Zhang, Assi, C. and Mouftah, H.” Improving Spatial Reuse in Multihop Wireless Networks - A Survey” IEEE Communications Surveys & Tutorials, Volume: 11 , Issue: 3 , 2009 , Page(s): 71 ? 91
    4. Marcelo G. Rubinstein, Igor M. Moraes, Miguel Elias M. Campista, Luis Henrique M. K. Costa, Otto Carlos M. B. Duarte “A Survey on Wireless Ad Hoc Networks” Springer, Volume 211, 2006, pp 1-33
    5. Akyildiz, I.F. “A survey on wireless mesh networks” IEEE Communications Magazine, Sept. 2005, Volume: 43 , Issue: 9 Page(s): S23 - S30


    ▶ Achievements

     
    1. Zaw Htike, Jun Lee, Choong Seon Hong and Sungwon Lee, "A Hybrid MAC Protocol for Cognitive Radio Ad Hoc Networks", IEICE Transactions on Communications Vol.E95-B, No. 04, pp.1135-1142, April 2012
    2. Cao Trong Hieu, Sungwon Lee, Choong Seon Hong, "A routing protocol using a reliable and high throughput path metric for multi-hop multi-rate ad hoc networks", Annals of Telecommunications, Vol. 67, No. 5-6, pp. 269?284, May 2012 (Published online: 27 August 2011)
    3. Cao Trong Hieu, Choong Seon Hong, "RAI: A High Throughput Routing Protocol for Multi-hop Multi-rate Ad hoc Networks", Wireless Personal Communications,Vol. 60, Issue 1, September 2011, pp.69-82
    4. Cao Trong Hieu and Choong Seon Hong, “A Connection Entropy-based Multi-Rate Routing Protocol for Mobile Ad Hoc Networks”, Journal of Computing Science and Engineering, Vol. 4, No. 3, pp.225-239, September 2010
    5. Md. Mamun-Or-Rashid, Muhammad Mahbub Alam Md. Abdul Hamid and Choong Seon Hong, "Flow Rank Based Probabilistic Fair Scheduling for Wireless Ad Hoc Networks", ACM/Springer Wireless Networks, Vol. 16, No. 3, 713-729, April 2010. (published online on Feb. 2009) (SCI)
    6. Md. Mustazur Rahman, Choong Seon HONG,and Sungwon LEE, Nonmember, "A High Throughput On-Demand Routing Protocol for Multirate Ad Hoc Wireless Networks", IEICE Transactions on Communications, Vol.E93-B, No.01, pp.29-39, January 2010. (SCI)
    7. Al-Sakib Khan Pathan, Muhammad Mostafa Monowar, Md. Forhad Rabbi, Muhammad Mahbub Alam, and Choong Seon Hong, “NAMP: Neighbor Aware Multicast Routing Protocol for Mobile Ad Hoc Networks”, International Arab Journal of Information Technology, Vol. 5, No. 1, pp. 102-107, January 2008
    8. Choong Seon Hong, Yubai Yang, "A Hierarchical Secure Ring-Oriented Multicast Protocol over Mobile Ad Hoc Network", Lecture Notes in Computer Science 3462(Networking 2005), pp. 1471-1474, May 2005