1. 2002/12/27 Chung-Hsien Hsu Bluetooth Location Networks F.J. Gonzalez-Castano, J. Farcia-Reinoso Departamento de Ingenieria Telematica, Universidad de Vigo Globecom '02 Speaker: Chung-Hsien Hsu

2. 2002/12/27Chung-Hsien Hsu Outline Introduction Introduction Motivation Motivation Background Background Bluetooth Location Networks Bluetooth Location Networks BLN Protocols BLN Protocols Configuration Configuration Location Protocol Location Protocol Location zones Location zones Scalability Scalability Performance Evaluation Performance Evaluation Conclusions Conclusions

3. 2002/12/27Chung-Hsien Hsu Introduction-Motivation Proposing a Bluetooth Location Network (BLN) for location-aware or context-driven mobile networks. Proposing a Bluetooth Location Network (BLN) for location-aware or context-driven mobile networks. Existing service servers that need to know user location in real-time, and send context-oriented information to user handhelds when necessary. Existing service servers that need to know user location in real-time, and send context-oriented information to user handhelds when necessary. M-commerce (mobile e-commerce) M-commerce (mobile e-commerce) Electronic guidance. Electronic guidance.

4. 2002/12/27Chung-Hsien Hsu Introduction-Background Many user-positioning solutions have been proposed: Many user-positioning solutions have been proposed: Based on specialized devices. Based on specialized devices. Not supported by commercially available data terminals. Not supported by commercially available data terminals.

5. 2002/12/27Chung-Hsien Hsu Introduction-Background (cont.) Positioning systems supported by commercial terminals: Positioning systems supported by commercial terminals: Cell phone location services and GPS. Cell phone location services and GPS. Effective for outdoor application. Effective for outdoor application. HP’s Cooltown. HP’s Cooltown. Based on IR beacons. Based on IR beacons. User-dependent. User-dependent. ( user must aim the infrared port to location beacons.)

6. 2002/12/27Chung-Hsien Hsu Introduction-Background (cont.) User-dependent vs. User-independent User-dependent vs. User-independent User-independent is only a disadvantage in aggressive systems. User-independent is only a disadvantage in aggressive systems. They are complementary. They are complementary. iPAQ H3870 could use Cooltown to retrieve information on a single object. iPAQ H3870 could use Cooltown to retrieve information on a single object. Bluetooth-assisted context awareness to retrieve information on the surrounding hall. Bluetooth-assisted context awareness to retrieve information on the surrounding hall.

7. 2002/12/27Chung-Hsien Hsu Introduction-BLNs Assumption: Assumption: Users carry a Bluetooth-enabled terminal, or any mobile data terminal and an independent Bluetooth location badge. Users carry a Bluetooth-enabled terminal, or any mobile data terminal and an independent Bluetooth location badge. The badge interacts with the BLN, which provides service servers with real-time user position. The badge interacts with the BLN, which provides service servers with real-time user position.

8. 2002/12/27Chung-Hsien Hsu Introduction-BLNs (cont.) Philosophy: establishing a cooperative location network. User modem addresses Bluetooth stations addresses.

9. 2002/12/27Chung-Hsien Hsu Introduction-Motivation (cont.) Advantages of BLN: Advantages of BLN: Transmitting position information to the service servers without user participation. Transmitting position information to the service servers without user participation. Not subject to line-of-sight constraints. Not subject to line-of-sight constraints. Base technology is supported by existing commercial handhelds. Base technology is supported by existing commercial handhelds. Admitting alternative uses as a security network when the target area is closed to the public, or as a spare network for emergencies. Admitting alternative uses as a security network when the target area is closed to the public, or as a spare network for emergencies.

10. 2002/12/27Chung-Hsien Hsu BLN Protocol-Configuration Configuration: Configuration: BLN is composed by mobile badges and static Bluetooth units (SN). BLN is composed by mobile badges and static Bluetooth units (SN). Using Hexagonal tiling. Using Hexagonal tiling. Any SN has at most seven closest neighbors. Any SN has at most seven closest neighbors. SN units use to scan their surroundings periodically. SN units use Bluetooth inquiry calls to scan their surroundings periodically.

11. 2002/12/27Chung-Hsien Hsu All SNs are organized in a radial scatternet around a master node. BLN Protocol-Configuration (cont.) SN X-Y : the Bluetooth address of SN Y in layer X. Each SN is a slave of all six surrounding neighbor SNs. Service servers

12. 2002/12/27Chung-Hsien Hsu BLN Protocol-Configuration (cont.) Rules: Rules: All SNs perform inquiry cycles periodically. All SNs perform inquiry cycles periodically. If SN a detects an inquiry from SN b, and b is not currently listed in a’s routing table. If SN a detects an inquiry from SN b, and b is not currently listed in a’s routing table. A must send its to b. A must send its minimum distance to the master node to b. All SN minimum distances are set to ∞ at power up. All SN minimum distances are set to ∞ at power up. Exception the master node’s, which is set to 0. Exception the master node’s, which is set to 0. If SN does not receive an answer from one of its neighbors that was previously listed in the routing table, it deletes the corresponding entry. If SN does not receive an answer from one of its neighbors that was previously listed in the routing table, it deletes the corresponding entry.

13. 2002/12/27Chung-Hsien Hsu BLN Protocol-Configuration (cont.) If change its minimum distance to the master node, the SN transmits a new minimum distance packet to all its slaves. If change its minimum distance to the master node, the SN transmits a new minimum distance packet to all its slaves. The routing table stores pairs of neighbor SN addresses and their distances to the master node. The routing table stores pairs of neighbor SN addresses and their distances to the master node. Which is sorted by distance. Which is sorted by distance.

14. 2002/12/27Chung-Hsien Hsu BLN Protocol-Configuration (cont.) Master node SN1-1 SN2-1 SN1-2 SN1-3 SN2-2 SN2-3 SN2-4 SN2-5 SN3-5 SN3-6 inquiry SN 2-4 ∞ SN 1-2 ∞ SN 1-3 ∞ SN 2-3 ∞ SN 2-5 ∞ SN 3-6 ∞ SN 3-5 ∞ distance packet Minimum distance SN 3-5 ∞ SN 2-4∞

15. 2002/12/27Chung-Hsien Hsu BLN Protocol-Configuration (cont.) Master node SN1-1 SN2-1 SN1-2 SN1-3 SN2-2 SN2-3 SN2-4 SN2-5 SN3-5 SN3-6 0 SN 1-2 ∞ SN 1-1 ∞ SN 1-3 ∞ SN 2-2 ∞ SN 2-3 ∞ SN 2-4 ∞ ∞ SN 1-2 ∞ SN 1-3 ∞ SN 2-3 ∞ SN 2-5 ∞ SN 3-5 ∞ SN 3-6 ∞ SN 1-2 1 SN 1-1 ∞ SN 1-3 ∞ SN 2-2 ∞ SN 2-3 ∞ SN 2-4 ∞ 1 2 SN 1-2 1 SN 1-3 ∞ SN 2-3 ∞ SN 2-5 ∞ SN 3-5 ∞ SN 3-6 ∞ 2

16. 2002/12/27Chung-Hsien Hsu BLN Protocol-Configuration (cont.) Remark: Remark: A simple authentication handshake avoids connection establishment with invalid Bluetooth modems. A simple authentication handshake avoids connection establishment with invalid Bluetooth modems. Invalid badges answer inquiry cycles with FHS packet. Invalid badges answer inquiry cycles with FHS packet. Badges do not try to establish data connections with SNs. Badges do not try to establish data connections with SNs. Does not violate the seven-slave constraint. Does not violate the seven-slave constraint.

17. 2002/12/27Chung-Hsien Hsu BLN Protocol-Location Protocol The main goal of the BLN is user tracking. The main goal of the BLN is user tracking. All SNs have to inquiries and collect badge responses. All SNs have to inquiries and collect badge responses. The SN detect a badge is in charge of building. The SN detect a badge is in charge of building location packets.

18. 2002/12/27Chung-Hsien Hsu BLN Protocol-Location Protocol (cont.) BD-3BD-13BD-17BD-3BD-7BD-11BD-19 BT addr.DetectedNew BD-3NoNo BD-7NoNo BD-11NoNo BD-13NoNo BD-17NoNo BD-7BD-11 BT addr.DetectedNewBD-3YesNo BD-7 BD-11 BD-13YesNo BD-17YesNo BD-19Yes BT addr.DetectedNewBD-3No BD-13 BD-17 BD-19 Master node Location Packet

19. 2002/12/27Chung-Hsien Hsu BLN Protocol-Location Protocol (cont.) Remark: Remark: SN responses to SN inquiry cycles are ignored by the location protocol. SN responses to SN inquiry cycles are ignored by the location protocol.

20. 2002/12/27Chung-Hsien Hsu BLN Protocol-Location zones Do not take signal strength nor signal delay into consideration. Do not take signal strength nor signal delay into consideration. Location precision depends on the number of SNs that detect a given badge, and on the range of their modems. Location precision depends on the number of SNs that detect a given badge, and on the range of their modems.

21. 2002/12/27Chung-Hsien Hsu BLN Protocol-Location zones (cont.) Class I zone: only three SNs detect the badge. Class II zone: only four SNs detect the badge. Class III zone: at the edges of the target area. Class IV zone: a single SN.

22. 2002/12/27Chung-Hsien Hsu BLN Protocol-Scalability When the configuration protocol converges to an equilibrium point, the maximum distances to the different master nodes are similar. The area managed by each master node was inversely proportional to the number of master nodes.

23. 2002/12/27Chung-Hsien Hsu Performance Evaluation Analyze BLN protocol timings. Analyze BLN protocol timings. The inquiry cycle should last for 10.24 s at most. The inquiry cycle should last for 10.24 s at most. Use the IBM simulator. Use the IBM BlueHoc simulator. Estimate the worst individual badge response time to SN inquiries, as the number of badges grow. Estimate the worst individual badge response time to SN inquiries, as the number of badges grow. Calculate location packet hop transfer timings. Calculate location packet hop transfer timings. Use 210-byte DM-5 packets to instead of DM-1 packets. Use 210-byte DM-5 packets to instead of DM-1 packets.

24. 2002/12/27Chung-Hsien Hsu Performance Evaluation (cont.)

25. 2002/12/27Chung-Hsien Hsu Conclusions BLN has the following characteristics: BLN has the following characteristics: Transmit position information to the service servers without user participation. Transmit position information to the service servers without user participation. Based on a RF technology available in existing handhelds. Based on a RF technology available in existing handhelds. Can be used as a general-purpose data network. Can be used as a general-purpose data network. Infrastructure consists of small, completely independent Bluetooth nodes. Infrastructure consists of small, completely independent Bluetooth nodes. The spontaneous topology configuration is scalable, by placing as many master nodes as necessary. The BLN can coexist with Bluetooth devices that are not part of the location system, such as printers or headphones.

26. 2002/12/27Chung-Hsien Hsu Conclusions (cont.) Forthcoming work: Forthcoming work: Study BLN survivability. Study BLN survivability.