May 2006 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [A Solution to Exposed Node Problem in Mesh Networks] Date Submitted: [18 May, 2006] Source: [Ho-In Jeon (1), Yong-Bae Kim (2), Beom-Joo Kim (2), Jun-Seon Beck (2), Yongsik Shin (3)] Company: [Dept. Electronic Engineering, Kyung-Won University (KWU) (1), LeiiTech Inc. (2) SKTelecom (3)] Address: [San 65, Bok-Jung-Dong, Sung-Nam-Shi, Kyung-Gi-Do, Republic of Korea] Voice 1:[ +82-31-753-2533], Voice 2:[ +82-19-9101-1394] FAX: [+82-31-753-2532], E-Mail:[jeon1394@kornet.net] Re: [This work has been supported by HNRC of IITA.] Abstract: [This document proposes a Solution to Exposed Node Problem in Mesh Networks.] Purpose: [Final Proposal for the IEEE802.15.5 Standard] Notice: This document has been prepared to assist the IEEE P802.15. 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 acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. Ho-In Jeon, Kyung-Won University

A Solution to Exposed Node Problem in Mesh Networks May 2006 A Solution to Exposed Node Problem in Mesh Networks Ho-In Jeon (1), and Yongsik Shin (2) (1) Kyung-Won University, HNRC of IITA Republic of Korea, and (2) SKtelecom Ho-In Jeon, Kyung-Won University

doc.: IEEE 802.15-<doc#> <month year> doc.: IEEE 802.15-<doc#> May 2006 Contents Introduction Issues of mesh networks Hidden Node Problems Exposed Node Problems A Solution to the Exposed Node Problems by Neighbor Table Conclusion Ho-In Jeon, Kyung-Won University <author>, <company>

Issues of Mesh Networks <month year> doc.: IEEE 802.15-<doc#> May 2006 Issues of Mesh Networks Beacon Scheduling for Collision Avoidance Reduction of Power Consumption with Beacon Network Non-beacon-Enabled Network cannot provide a power-efficient operational mode Beacon Aggregation for throughput enhancement in the case of two or more PANs merging. Efficient Real-Time Short Address Allocation Algorithms Routing Algorithm: Proactive or Reactive Power-Efficient Operation Mode Support of Time-Critical or Delay-Sensitive Applications Adoption of RTS/CTS for Solving Hidden Node Problem Exposed Node Problems and Their Solutions Ho-In Jeon, Kyung-Won University <author>, <company>

Association and Direct Link Relations <month year> doc.: IEEE 802.15-<doc#> May 2006 Association and Direct Link Relations B E A C D Blue Line: Association Relations Red Line: Direct Communication Range Ho-In Jeon, Kyung-Won University <author>, <company>

doc.: IEEE 802.15-<doc#> <month year> doc.: IEEE 802.15-<doc#> Hidden Node Problem May 2006 Data Transfer A B C Hidden node problems are solved by adopting RTS/CTS mechanisms. IEEE 802.15.4 Network does not support RTS/CTS under the assumption that the data frame are short enough to cause a serious problem. Ho-In Jeon, Kyung-Won University <author>, <company>

doc.: IEEE 802.15-<doc#> <month year> doc.: IEEE 802.15-<doc#> May 2006 Exposed Node Problem Data Transfer D A B C When node B send data to node A, C cannot send his data to node D, because they adopted CSMA/CA. The truth is that the node C can still send his data to D at the same time when the node B send the data to node A. Ho-In Jeon, Kyung-Won University <author>, <company>

Exposed Node Problem - Visualized <month year> doc.: IEEE 802.15-<doc#> May 2006 Exposed Node Problem - Visualized Data Transfer D A B C Superframe BOP CAP Inactive Period B A B C D Transfer B  A A B C C A B C D A B C Ho-In Jeon, Kyung-Won University <author>, <company>

Exposed Node Problem - Visualized <month year> doc.: IEEE 802.15-<doc#> Exposed Node Problem - Visualized May 2006 Data Transfer D A B C Superframe BOP CAP Inactive Period B A B C D Transfer B  A A B C Cannot be used C A B C D Transfer C  D A B C Ho-In Jeon, Kyung-Won University <author>, <company>

Solution by Using Neighbor Table <month year> doc.: IEEE 802.15-<doc#> May 2006 Solution by Using Neighbor Table Data Transfer D A B C B’s Neighbor Table C’s Neighbor Table Address B Neighbor’s Address A, C Data Transfer Destination A Address C Neighbor’s Address B, D Data Transfer Destination D Superframe BOP CAP Inactive Period B A B C D Transfer B  A A B C C A B C D Transfer C  D A B C Ho-In Jeon, Kyung-Won University <author>, <company>

Conclusions and Discussions May 2006 The operating principles of the Mesh Network has been addresses. Hidden node problems are solved by the adoption of RTS/CTS mechanism. Exposed node problem can be solved by using neighbor tables of each node. The prepared sender has to get the information of the destination node from the receiving signal. The efficiency can not be as good as 100%, in theory. Ho-In Jeon, Kyung-Won University

Acknowledgment This work has been supported by HNRC of IITA. May 2006 Ho-In Jeon, Kyung-Won University