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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Efficient Address Assignment for Mesh Nodes in Real-Time ] Date Submitted: [15 July , 200 5] Source: [Ho-In Jeon (1), Sung-Hoon Jeong (2), Yong-Bae Kim (2), Bum-Joo Kim (2)]

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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

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  1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Efficient Address Assignment for Mesh Nodes in Real-Time] Date Submitted: [15 July, 2005] Source: [Ho-In Jeon (1), Sung-Hoon Jeong (2), Yong-Bae Kim (2), Bum-Joo Kim (2)] Company: [Dept. Electronic Engineering, Kyung-Won University(KWU) (1), LeiiTech Inc. (2)] 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 partly by HNRC of IITA.] Abstract: [This document proposes an efficient way of assigning short addresses to mesh nodes in real-time without address conflicts.] Purpose: [Final Proposal for the IEEE802.15.4a 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

  2. Efficient Real-Time Address Assignments for Mesh Nodes Ho-In Jeon Kyung-Won University, HNRC of IITA Republic of Korea Ho-In Jeon, Kyung-Won University

  3. Contents • Introduction • Definition of mesh networks • Issues of mesh networks • Beacon Scheduling • Short Address Allocation • RTS/CTS for Collision Avoidance • Routing • Power-Saving Operation Mode • A Scenario for the operation of Mesh Network • Proposed Address Assignment Scheme • Features of the proposed Scheme • Conclusion Ho-In Jeon, Kyung-Won University

  4. Beacon Scheduling for Collision Avoidance Reduction of Power Consumption with Beacon Network Non-beacon-Enabled Network cannot provide a power-efficient operational mode Short Address Allocation Algorithms Savings of Address Spaces Routing Algorithm: Proactive or Reactive Power-Efficient Operation Mode Support of Time-Critical or Delay-Sensitive Applications Adoption of RTS/CTS for Data Transmission Deterioration of Data Throughput Overall Delay Exposed Node Problem Issues of Mesh Networks Ho-In Jeon, Kyung-Won University

  5. Mesh Mesh PC U-Home with Mesh Network Gas Meter Washer UtilityRoom Room #3 Mesh Mesh VPhone Gas Oven PDA Room #2 Bath- room DTV Refrig. DTV PC Microwave Oven Oven Kitchen STB DCam. : IEEE1394 or UWB Connectivity : IEEE802.11x, 15.3, ZigBee/15.4, 15.5 Mesh Door Phone Living Room VPhone ZigBee/15.4 802.11a/g/n/e, IEEE802.15.3 MeshPNC DTV Meter Reader PVR Room #1 Power Meter PC DCam. Room #4 DTV VDSLMODEM PDA DAM Water Meter PVR Printer Phone Jack HS/MMRG Phone Jack AP or PNC PDA DCam. Cable, Satellite, Terrestrial Internet FTTH DSLAM ONU Ho-In Jeon, Kyung-Won University

  6. Environment Management with Mesh Sensor Gateway N-2 N-1 4 N 1 3 2 Management Center 20 Km • A scenario in which the device 1 wishes to send its sensed data to device N which is the sensor gateway located 20 Km apart. • Assumptions • The RF range of each device is assumed to be 20m. • Multi-hop topology has been used for the propagation of data • Each device is assumed to use beacon to reduce power consumption. • Device 2 listens to the beacon transmitted by device 1 and decides to associate with it. Device 2 determines its beacon transmitting time slot. • Device 1 is 40m apart from device 3 which implies that device 3 cannot listen to device 1. Ho-In Jeon, Kyung-Won University

  7. A Scenario for Mesh Network Operations 4 9 1 2 6 5 2 9 1 6 PNC 3 4 8 7 • Issues to be resolved • Association andReassociation Procedure • Beacon Scheduling • Short Address Allocations • Creation and Update ofNeighborhood Table Ho-In Jeon, Kyung-Won University

  8. PNC Formation of the Mesh 1 1 PNC • Device 1 first scans passively first and actively next. • When it finds that there is no device that he can associate with, it becomes the PNC. • Once a device becomes a PNC, it starts to transmit its beacon at the beginning of the superframe. Ho-In Jeon, Kyung-Won University

  9. Joining of Device 2 to the Mesh 1 2 2 1 PNC • Dev. 2 hears the beacon form PNC and gets associated with it. • When associated, it gets PANID, Short Address, and other sets of information from PNC and determines when to send its beacon. • Dev. 1 and 2 listen to beacons of each other and store information about their neighbor in the Neighborhood Table. Ho-In Jeon, Kyung-Won University

  10. Association Relations and Beacon Tx • Solid blue line represents the Parent-Child relations based on associations. • Red line represents directly reachable. • Every mesh device transmits beacon during the BOP (Beacon-Only Period). • Beacon scheduling has been applied. 2 1 PNC 3 Superframe Inactive Period Active Period CAP BOP 1 2 3 Ho-In Jeon, Kyung-Won University

  11. Association and Direct Links Relations 4 9 1 2 6 5 2 9 1 6 PNC 3 4 8 7 CAP BOP 1 4 6 2 3 5 8 7 9 Ho-In Jeon, Kyung-Won University

  12. Association and Direct Links Relations 2 5 9 1 6 PNC 8 4 3 7 • Blue Line: Association Relations • Red Line: Direct Communication Capable • Association Policy • New nodes are associated with the nodes which are as close to the PNC and possible • If RSSIis not high enough for reliable communications, then it can choose other node as its parent. Ho-In Jeon, Kyung-Won University

  13. Short Address Allocations • Hierarchical Block addressing wastes address space. • Centralized Address allocations • May take too much time for the address allocation. • Distributed Address allocations • No guarantee way of avoiding address conflicts. • A mechanism of assigning short addresses in real-time in an efficient way that can prevent address conflict has been needed. • Combination of the two mechanisms. • Beacon Scheduling mechanism can be used for the address allocation Ho-In Jeon, Kyung-Won University

  14. Efficient Real-Time Address Assignment PNC A [0, 1] [1, 4] [1, 2] [1, 3] D C B • Devices B, C and D hear the beacon of A (PNC) and send Association Request Command. • Since Dev. A is PNC, PNC allocates the Short addresses to devices B,C,D directly. • If other device than PNC allocates shortAddress, it is possible that same address could be allocated to different devices. • To avoid this problem, LAA (LastAddressAssigned) field has been added. • The last address assigned at this point is 4, and the PNC sends this information to other devices using his beacon payload. To let B, C, and C know about this. Ho-In Jeon, Kyung-Won University

  15. Efficient Real-Time Address Assignment PNC A [0, 1] Beacon Update Request Command [1, 4] [1, 2] [1, 3] D C B E [2, 5] • Now, a new device E is on. As soon as he hears the beacon of B, it requests association. • Since B knows that the last address assigned is 4, B assigns the short address 5 to E and notifies the PNC of the new value of the LAA field through BeaconUpdateCommamd. • As soon as PNC receives this information, it modifies his beacon payload and send the modified beacon. Ho-In Jeon, Kyung-Won University

  16. Efficient Real-Time Address Assignment PNC [0, 1] A Beacon Update Request Command [1, 4] [1, 2] [1, 3] D C B [2, 5] E F • When F associates, B assigns address 6 to F and sends the number 6 as the LAA (Last Address Assigned) to A. • Again, when A receives this command, it send his beacon after changing his beacon payload. • Because of the beacon payload, E and F knows the LAA. Ho-In Jeon, Kyung-Won University

  17. Efficient Real-Time Address Assignment PNC [0, 1] A Beacon Update Request Command [1, 4] [1, 2] [1, 3] D C B Beacon Update Request Command [2, 6] I H E [2, 5] F J • When J associates with F, F assigns address 7 to J and sends the number 7 as the LAA (Last Address Assigned) to B, and B sends this information to A. • Again, when A receives this command, it send his beacon after changing his beacon payload, and every device knows the LAA. Ho-In Jeon, Kyung-Won University

  18. Efficient Real-Time Address Assignment [0, 1] PNC A Beacon Update Request Command [1, 2] [1, 3] [1, 4] D C B [2, 9] [2, 6] I H E [2, 5] F [2, 8] [3, 7] J • The same procedure applies to the rest of the devices and every device knows the LAA. Ho-In Jeon, Kyung-Won University

  19. Efficient Real-Time Address Assignment PNC A Beacon Update Request Command Beacon Update Request Command [1, 2] [1, 4] D C B [1, 3] [2, 5] [2, 5] I E Real-Time overlapped address assignment. • A possible problem • When E and I associate, respectively, with B and D simultaneously, the same address may be assigned to tow different devices. • Solution • When this happens, the PNC sends Address Reassignment Command to the later arriving device Ho-In Jeon, Kyung-Won University

  20. Efficient Real-Time Address Assignment PNC A Beacon Update Request Command Beacon Update Request Command Beacon Update Response Command [1, 2] [1, 4] D C B [1, 3] [2, 5] [2, 5] I E Real-Time overlapped address assignment. • A possible problem • When E and I associate, respectively, with B and D simultaneously, the same address may be assigned to tow different devices. • Solution • When this happens, the PNC sends Address Reassignment Command to the later arriving device Ho-In Jeon, Kyung-Won University

  21. Efficient Real-Time Address Assignment PNC A Beacon Update Request Command Beacon Update Request Command Address Reassign Command [1, 2] [1, 4] D C B [1, 3] Address Reassign Command [2, 5] I E [2, 6] • A possible problem • When E and I associate, respectively, with B and D simultaneously, the same address may be assigned to tow different devices. • Solution • When this happens, the PNC sends Address Reassignment Command to the later arriving device Ho-In Jeon, Kyung-Won University

  22. Efficient Real-Time Address Assignment PNC A Beacon Update Request Command Beacon Update Request Command Beacon Update Response Command Address Reassign Command D C B I E G Ho-In Jeon, Kyung-Won University

  23. Efficient Real-Time Address Assignment PNC Beacon Update Request Command A Beacon Update Request Command D G B Beacon Update Request Command I F C E H Ho-In Jeon, Kyung-Won University

  24. Efficient Real-Time Address Assignment PNC A Beacon Update Request Command Beacon Update Request Command Address Reassign D C B Beacon Update Request Command Beacon Update Request Command Beacon Update Request Command Beacon update Response command Address Reassign G H E F Beacon Update Request Command Beacon Update Request Command Beacon update Response command Beacon Update Request Command Address Reassign Address Reassign I J K Ho-In Jeon, Kyung-Won University

  25. Efficient Real-Time Address Assignment B C PNC Beacon Association Request Association Response : Assign the short address 2 to B. Beacon Set the value of LAA (LastAddressAssigned) to 2. Association Request Association Response : Assign the short address 3 to C. Beacon Update Request Command PNC updates his LAA to 3 The new updated LAA value is3. Beacon Transmitted. Ho-In Jeon, Kyung-Won University

  26. New Beacon Payload and Update Commands < LAA + Depth Info + BOPLength + BTTS > <Beacon Update Request Command> LAA: LastAddressAssigned BTTS: BeaconTxTimeSlot < Beacon update Response Command> Ho-In Jeon, Kyung-Won University

  27. New Beacon Payload and Update Commands <Address Reassign Command> <Command Frames> Ho-In Jeon, Kyung-Won University

  28. Features of the Proposed Addressing Scheme • Pros • Allocates short addresses in real-time. • It is a decentralized addressing scheme combined with. • “Running out of addresses” problem is solved. • Network diameter not necessarily fixed. • Cons • New control commands must be added: Address Request, Address Response, Beacon Update, Address Reassign • Some delays occur in the Association process • Increased data processing in the PNC • Address reuse mechanism needs to be addressed. Ho-In Jeon, Kyung-Won University

  29. Conclusions and Discussions • Mesh network requires a lot of problems to be solved • Beacon conflicts • Short Address allocations • Data Conflicts • Hidden node problems • Delay-Sensitive Applications • Power-saving mechanism • Proposed a solution of avoiding beacon conflict by • Beacon scheduling • Proposed a solution of efficient address assignment • Address allocated in real-time by decentralized manner. • Address conflicts resolved by centralized control. • Solved “Running out of address space” problem Ho-In Jeon, Kyung-Won University

  30. Acknowledgment • This work has been supported HNRC of IITA. Ho-In Jeon, Kyung-Won University

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