1. doc.: IEEE 802.11-05/0461r0 Submission May 2005 CH Yeh, Queen's UniversitySlide 1 Ad Hoc/Sensor Networking and Multihop WLANs Notice: This document has been prepared to assist IEEE 802.11. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at.http:// ieee802.org/guides/bylaws/sb-bylaws.pdfstuart.kerry@philips.compatcom@ieee.org Date: 2005-05-18 Authors:

2. doc.: IEEE 802.11-05/0461r0 Submission May 2005 CH Yeh, Queen's UniversitySlide 2 Abstract Current problems, issues, status, and motivations concerning multihop networking, including mobile ad hoc networks, sensor networks, multihop WLANs.

3. doc.: IEEE 802.11-05/0461r0 Submission May 2005 CH Yeh, Queen's UniversitySlide 3 Examples for Multihop Networks Ad hoc networks (MANET) Sensor networks Mesh networks Home networks with repeaters Multihop WLANs Others: Multihop cellular networks

4. doc.: IEEE 802.11-05/0461r0 Submission May 2005 CH Yeh, Queen's UniversitySlide 4 Advantages for Multihop Networking Ad hoc networks –Infrastructureless Sensor networks –Great commercial values WLAN Mesh –Range extension with lower infrastructure cost Multihop WLAN/cellular networks –Range extension without additional infrastructure –Dead zone elimination –Lower power consumption –Higher throughput

5. doc.: IEEE 802.11-05/0461r0 Submission May 2005 CH Yeh, Queen's UniversitySlide 5 Why Commercial Ad Hoc Networking Has Not Happened? Routing protocols were not standardized till 2004 The number of laptop computers did not reach a critical mass Poor performance based on current products Lack of killer applications –E.g., ad hoc networking in conference venue is not needed – covered by WLANs

6. doc.: IEEE 802.11-05/0461r0 Submission May 2005 CH Yeh, Queen's UniversitySlide 6 Driving Forces for Ad Hoc Networking and Multihop WLANs Now VOIP over WLAN –802.11 becoming available on smart phones Critical mass Extended range required Power consumption is critical Proliferation of 802.11 hot spots Muni WiFi to be deployed

7. doc.: IEEE 802.11-05/0461r0 Submission May 2005 CH Yeh, Queen's UniversitySlide 7 Problems with Current WLAN MAC Interference problems –Interference-range hidden/exposed terminal problem –Additive interference problem Problems resulted from power control –Heterogeneous hidden/exposed terminal problem –Single-channel MAC difficult QoS and fairness problems –Alternate blocking problems Exposed terminal problem

8. doc.: IEEE 802.11-05/0461r0 Submission May 2005 CH Yeh, Queen's UniversitySlide 8 Issues Needed to Be Addressed Resolving/mitigating aforementioned problems Routing Mobility Energy efficiency Emerging technologies Applicability to sensor networks Cooperation (among users) Business model

9. doc.: IEEE 802.11-05/0461r0 Submission May 2005 CH Yeh, Queen's UniversitySlide 9 Distinction from TGS TGS focus on the following context: –Residential networks –Office networks –Campus/public networks –Safety/military networks Mesh points are different from laptops/smart phones –Infrastructure –Power supply –Stationary –Up to 32 nodes only –Single-hop networking from users to mesh points

10. doc.: IEEE 802.11-05/0461r0 Submission May 2005 CH Yeh, Queen's UniversitySlide 10 Distinction from TG5 Synchronized MAC Hierarchical architecture Lower mobility Smaller range Relatively lower speed Not applicable to 802.11 PHY

11. doc.: IEEE 802.11-05/0461r0 Submission May 2005 CH Yeh, Queen's UniversitySlide 11 Current Status in Research and Development Four experimental routing protocol RFC standardized by IETF in 2004 Numerous ad hoc network testbeds in universities Some commercial products based on AODV Intensively researched in academia and industry –Military applications for about 3-4 decades –Renewed interests for about 1 decade –Focused on routing –Problems well known –Interesting techniques and solutions but may be complex or even infeasible

12. doc.: IEEE 802.11-05/0461r0 Submission May 2005 CH Yeh, Queen's UniversitySlide 12 Concluding Remarks Everything will be ad hoc in the future Multihop networking will be a norm, rather than an exception Time to look into multihop networking issues and consider emerging technologies

13. doc.: IEEE 802.11-05/0461r0 Submission May 2005 CH Yeh, Queen's UniversitySlide 13 References 11-05-0065-00-000s-on-hidden-and-exposed-terminal- problems