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IEEE 802.16 and 802.15


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IEEE 802.16 and 802.15

  1. 1. IEEE 802.16 and 802.15
  2. 2. Outline <ul><li>An overview </li></ul><ul><li>An insight into IEEE 802.16 WiMAX </li></ul><ul><li>An introduction to Bluetooth </li></ul>
  3. 3. Background: Wireless Landscape Fixed Broadband Wireless (e.g.802.16) Cellular Mobile Networks (e.g. GPRS,3G) Personal Area Network Increasing Coverage Area High Cost & Complexity High-Speed Connectivity & Hierarchy of Networks Low Cost & Complexity Satellite Global Area Network Local Area Networks (e.g. 802.11)
  4. 4. Background: Wireless Technologies PAN (Personal Area Network) LAN (Local Area Network) MAN (Metropolitan Area Network) WAN (Wide Area Network) PDAs, Mobile Phones, cellular access T1 replacement, last mile access Enterprise networks Peer-to-Peer Device-to-Device Applications Long Medium-Long Medium Short Range 10 to 384Kbps 11 to 100+ Mbps 11 to 54 Mbps < 1Mbps Speed GSM, GPRS, CDMA, 2.5-3G, 802.16 802.16 MMDS, LMDS 802.11 HiperLAN2 Bluetooth, UWB Standards WAN MAN LAN PAN
  5. 5. What is WiMAX? <ul><li>WiMAX ( Worldwide Interoperability for Microwave Access ) </li></ul><ul><ul><li>BWA (Broadband Wireless Access) Solution </li></ul></ul><ul><ul><li>Standard (IEEE 802.16 is the standard) for constructing Wireless Metropolitan Area Networks (WMANs) </li></ul></ul><ul><ul><li>Can go places where no wired infrastructure can reach </li></ul></ul><ul><ul><li>Backhauling Wi-Fi hotspots & cellular networks </li></ul></ul><ul><ul><li>Offers new and exciting opportunities to established and newly emerging companies </li></ul></ul><ul><ul><ul><li>Incorporate cable (wired technology) standard </li></ul></ul></ul><ul><ul><ul><li>Comply with European BWA standard </li></ul></ul></ul>
  6. 6. WiMAX Overview <ul><li>Complement the existing last mile wired networks (i.e. xDSL, cable modem) </li></ul><ul><li>Fast deployment, cost saving </li></ul><ul><li>High speed data, voice and video services </li></ul><ul><li>Fixed BWA, Mobile BWA </li></ul>
  7. 7. Comparing Technologies Cisco, Motorola, Qualcom and Flarion Standards coming Product late ‘06 802.20 in development Licensed <3.5 GHz Full mobility 3 – 8 km Up to 1.5 Mbps each 802.20 Mobile-FI GSM Wireless Industry CW in 6+ cities Part of GSM standard Licensed Existing wireless spectrum Full mobility Coverage is overlaid on wireless infrastructure 384 Kbps – 2 Mbps UMTS 3G Products 2H05 In market today Availability 802.16, 802.16a and 802.16 REVd standardized, other under development 802.11a, b and g standardized Standardization Both Unlicensed Licensing Intel, Fujitsu, Alcatel, Siemens, BT, AT&T, Qwest, McCaw 2-11 GHz for 802.16a 11-60 GHz for 802.16 Fixed (Mobile - 16e) 30 – 50 km 2 - 5 km (’07) Share up to 70 Mbps 802.16 WiMAX Industry-wide Backers 2.4 GHz for 802.11b/g 5.2 GHz for 802.11a Frequency/ Spectrum Portable Mobility 100 meters 30 meters Range (LOS) Range (NLOS) 11-54 Mbps shared Bandwidth 802.11 WiFi
  8. 8. Potential Services None (today) None (today) No Yes No Limited, QoS concerns 802.20 Mobile-FI WEP Developing WEP WEP & 802.11i Security 802.16b in development Yes, large scale Yes Possible, QoS concerns Limited, QoS concerns 802.16 WiMAX None (today) 802.11e QoS No Yes, small scale WLAN Yes Yes Data/Internet Possible, via HSDPA Yes, in home Video Yes Limited, QoS concerns VoIP UMTS 3G 802.11 WiFi
  9. 9. Benefits of WiMAX <ul><li>Speed </li></ul><ul><ul><li>Faster than broadband service </li></ul></ul><ul><li>Wireless </li></ul><ul><ul><li>Not having to lay cables reduces cost </li></ul></ul><ul><ul><li>Easier to extend to suburban and rural areas </li></ul></ul><ul><li>Broad coverage </li></ul><ul><ul><li>Much wider coverage than WiFi hotspots </li></ul></ul>
  10. 10. An Insight into IEEE 802.16
  11. 11. IEEE 802.16 Evolution <ul><li>Fixed BWA at 10-66hz </li></ul><ul><li>Line of sight </li></ul><ul><li>Fixed BWA at 2-11hz </li></ul><ul><li>None line of sight </li></ul><ul><li>Revision of 802.16 </li></ul><ul><li>Combine previous 802.16 standards </li></ul><ul><li>Mobile BWA based on 802.16-2004 (802.16a) </li></ul><ul><li>Roaming with vehicular speed </li></ul>
  12. 12. IEEE 802.16 Specifications <ul><li>802.16a </li></ul><ul><ul><li>use the licensed and license-exempt frequencies from 2 to 11Ghz </li></ul></ul><ul><ul><li>Support Mesh-Network </li></ul></ul><ul><li>802.16b </li></ul><ul><ul><li>Increase spectrum to 5 and 6GHz </li></ul></ul><ul><ul><li>Provide QoS (for real-time voice and video service) </li></ul></ul><ul><li>802.16c </li></ul><ul><ul><li>Represents a 10 to 66GHz system profile </li></ul></ul><ul><li>802.16d </li></ul><ul><ul><li>Improvement and fixes for 802.16a </li></ul></ul><ul><li>802.16e </li></ul><ul><ul><li>Addresses on Mobile </li></ul></ul><ul><ul><li>Enable high-speed signal handoffs necessary for communications with users moving at vehicular speeds </li></ul></ul>
  13. 13. IEEE 802.16 Basics Same as 802.16d with sub-channelization Pedestrian mobility High-speed mobility OFDMA OFDM Up to 75 Mbps at 20MHz Non line of sight < 11 GHz Approved on Dec.7, 2005 802.16e Fixed Mobility Non line of sight Channel Conditions < 11 GHz Spectrum 802.16a: Jan 2003 802.16REVd: Q3’04 Completed Selectable channel bandwidths between 1.25 and 20 MHz Channel Bandwidths OFDM 256 sub-carriers QPSK, 16QAM, 64QAM Modulation Up to 75 Mbps at 20MHz Bit Rate 802.16a/REVd
  14. 14. IEEE 802.16 Operation <ul><li>WiMAX consists of two parts </li></ul><ul><ul><li>A WiMAX tower , similar in concept to a cell-phone tower - A single WiMAX tower can provide coverage to a very large area -- as big as 3,000 square miles </li></ul></ul><ul><ul><li>A WiMAX Receiver The receiver and antenna could be a small box or PCMCIA card, or they could be built into a laptop the way WiFi access is today </li></ul></ul>
  15. 15. How WiMax Works <ul><li>WiMax can provide 2 forms of wireless services: </li></ul><ul><li>- Non-LOS, Wi-Fi sort of service, where a small antenna on a computer connects to the tower. Uses lower frequency range (2 to 11 GHz). </li></ul><ul><li>- LOS, where a fixed antenna points straight at the WiMax tower from a rooftop or pole. The LOS connection is stronger and more stable, so it is able to send a lot of data with fewer errors. Uses higher frequencies, with ranges reaching a possible 66 GHz. </li></ul><ul><li>Through stronger LOS antennas, WiMax transmitting stations would send data to WiMax enabled computers or routers set up within 30 (3,600 square miles of coverage) mile radius. </li></ul>
  16. 16. WiMax Spectrum <ul><li>Broad Operating Range </li></ul><ul><li>WiMax Forum is focusing on 3 spectrum bands for global deployment: </li></ul><ul><li>Unlicensed 5 GHz: Includes bands between 5.25 and 5.85 GHz. In the upper 5 GHz band (5.725 – 5.850 GHz) many countries allow higher power output (4 Watts) that makes it attractive for WiMax applications. </li></ul><ul><li>Licensed 3.5 GHz: Bands between 3.4 and 3.6 GHz have been allocated for BWA in majority of countries. </li></ul><ul><li>Licensed 2.5 GHz: The bands between 2.5 and 2.6 GHz have been allocated in the US, Mexico, Brazil and in some SEA countries. In US this spectrum is licensed for MDS and ITFS. </li></ul>
  17. 17. Benefits of Licensed and License-Exempt Solutions More worldwide options Higher barriers for entrance Lower Costs Better NLOS reception at lower frequencies Fast Rollout Better QoS License-Exempt Solution Licensed Solution
  18. 18. Technical Similarities and Differences Between Licensed and License-Exempt Bands <ul><li>Both solutions are based on IEEE 802.16-2004 standard, which uses OFDM in the physical (PHY) layer. </li></ul><ul><li>OFDM provides benefits such as increased SNR of subscriber stations and improved resiliency to multi-path interference. </li></ul><ul><li>For creating bi-directional channels for uplink and downlink, licensed solutions use FDD while license exempt solutions use TDD. </li></ul>
  19. 19. Time Division Duplexing (TDD) “ Bursty”, asymmetrical data applications, environments with varying traffic patterns, where RF efficiency is more important than cost. Usage Cannot transmit and receive at the same time. Disadvantages Enhanced flexibility, easier to pair with smart antenna technologies, asymmetrical. Advantages A duplexing technique used in license-exempt solutions, which uses a single channel for uplink and downlink. Description
  20. 20. Time Division Duplexing (TDD) <ul><li>In case of TDD both uplink and downlink transmissions share the same frequency but are separated on time </li></ul><ul><li>A TDD frame has a fixed duration and also consists of one uplink and one downlink frame </li></ul><ul><li>TDD framing is Adaptive </li></ul>
  21. 21. Frequency Division Duplexing (FDD) Usage Disadvantages Advantages Description Environments with predictable traffic patterns, where equipment costs are more important than RF efficiency. Cannot be deployed where spectrum is unpaired, spectrum is usually licensed, higher cost associated with spectrum purchase. Proven technology for voice, designed for symmetrical traffic, does not require guard time. A duplexing technique used in licensed solutions that uses a pair of spectrum channels, one for the uplink and another for the downlink.
  22. 22. Frequency Division Duplexing (FDD) <ul><li>In case of FDD both uplink and downlink channels are on separate frequencies </li></ul><ul><li>The capability of downlink to be transmitted in bursts simultaneously supports two different modulation types </li></ul><ul><ul><li>Full Duplex SS's (which can transmit and receive simultaneously </li></ul></ul><ul><ul><li>Half Duplex SS's (which cannot) </li></ul></ul>
  23. 23. Architecture <ul><li>P2MP (Point to Multi point) </li></ul><ul><ul><li>Wireless MAN </li></ul></ul><ul><ul><li>BS connected to Public Networks </li></ul></ul><ul><ul><li>BS serves Subscriber Stations (SS) </li></ul></ul><ul><ul><li>Provides SS with first mile access to Public Networks </li></ul></ul><ul><li>Mesh Architecture </li></ul><ul><ul><li>Optional architecture for WiMAX </li></ul></ul>
  24. 24. P2MP Architecture Line-of-Sight Backhaul 802.16d 802.16 Telco Core Network or Private (Fiber) Network Non Line-of-Sight Point to Multi-Point INTERNET BACKBONE Base Station
  25. 25. Mesh Architecture
  26. 26. Reference Model <ul><li>Supports multiple services (e.g. IP, voice over IP, video) simultaneously, with different QoS priorities </li></ul><ul><li>Covers MAC layer and PHY layer </li></ul>
  27. 27. MAC Layer <ul><li>Wireless MAN: Point-to-Multipoint and optional mesh topology </li></ul><ul><li>Connection-oriented </li></ul><ul><ul><li>Connection ID (CID) </li></ul></ul><ul><li>MAC layer is further subdivided into three layers </li></ul><ul><ul><li>Convergence sub-layer (CS) </li></ul></ul><ul><ul><li>Common part sub-layer (CPS) </li></ul></ul><ul><ul><li>Privacy sub-layer </li></ul></ul>
  28. 28. MAC Addressing <ul><li>SS has 48-bit 802.3 MAC address </li></ul><ul><li>BS has 48-bit base station ID </li></ul><ul><ul><li>Not a MAC address </li></ul></ul><ul><li>Connection ID (CID) </li></ul><ul><ul><li>16 bit </li></ul></ul><ul><ul><li>Used in MAC PDU </li></ul></ul><ul><ul><li>Connection Oriented Service </li></ul></ul>
  29. 29. MAC PDU <ul><li>Each MAC packet consists of the three components, </li></ul><ul><ul><li>A MAC heade r , which contains frame control information. </li></ul></ul><ul><ul><li>A variable length frame bod y , which contains information specific to the frame typ e. </li></ul></ul><ul><ul><li>A frame check sequence (FCS), which contains an IEEE 32-bit cyclic redundancy code (CRC). </li></ul></ul>
  30. 30. MAC PDU Types <ul><li>Data MAC PDUs </li></ul><ul><ul><li>HT = 0 </li></ul></ul><ul><ul><li>Payloads are MAC SDUs/segments, i.e., data from upper layer (CS PDUs) </li></ul></ul><ul><ul><li>Transmitted on data connections </li></ul></ul><ul><li>Management MAC PDUs </li></ul><ul><ul><li>HT = 0 </li></ul></ul><ul><ul><li>Payloads are MAC management messages or IP packets encapsulated in MAC CS PDUs </li></ul></ul><ul><ul><li>Transmitted on management connections </li></ul></ul><ul><li>BW Req. MAC PDUs </li></ul><ul><ul><li>HT = 1; and no payload, i.e., just a Header </li></ul></ul>
  31. 31. MAC PDU Transmission <ul><li>MAC PDU’s are transmitted on PHY bursts </li></ul><ul><li>The PHY burst can contain multiple FEC blocks </li></ul><ul><li>Concatenation </li></ul><ul><ul><li>Multiple MAC PDU's can be concatenated into a single transmission in either uplink or downlink direction </li></ul></ul><ul><li>Fragmentation </li></ul><ul><ul><li>Each MAC SDU can be divided into one or more MAC PDU's </li></ul></ul><ul><li>Packing </li></ul><ul><ul><li>Packs multiple MAC SDU's into a single MAC PDU </li></ul></ul>
  32. 32. MAC CS Sub-layer <ul><li>Interoperability requires convergence sub-layer to be service specific </li></ul><ul><li>Separate CS layers for upper layer (ATM & packet) protocols </li></ul><ul><li>CS Layer: </li></ul><ul><ul><li>Receives data from higher layers </li></ul></ul><ul><ul><li>Classifies data as ATM cell or packet </li></ul></ul><ul><ul><li>Forwards frames to CPS layer </li></ul></ul>
  33. 33. MAC CPS Sub-layer <ul><li>Performs typical MAC functions such as addressing </li></ul><ul><ul><li>Each SS assigned 48-bit MAC address </li></ul></ul><ul><ul><li>Connection Identifiers used as primary address after initialization </li></ul></ul><ul><li>MAC policy determined by direction of transmission </li></ul><ul><ul><li>Uplink is DAMA-TDM </li></ul></ul><ul><ul><li>Downlink is TDM </li></ul></ul><ul><li>Data encapsulated in a common format facilitating interoperability </li></ul><ul><ul><li>Fragment or pack frames as needed </li></ul></ul><ul><ul><li>Changes transparent to receiver </li></ul></ul>
  34. 34. MAC Privacy Sub-layer <ul><li>Provides secure communication </li></ul><ul><ul><li>Data encrypted with cipher clock chaining mode of DES </li></ul></ul><ul><li>Prevents theft of service </li></ul><ul><ul><li>SSs authenticated by BS using key management protocol </li></ul></ul>
  35. 35. How It Works
  36. 36. 802.16 Network Entry <ul><li>Scanning </li></ul><ul><ul><li>Scan for BS downlink channel </li></ul></ul><ul><ul><li>Synchronize with BS </li></ul></ul><ul><ul><li>Specifies channel parameters </li></ul></ul><ul><li>Ranging </li></ul><ul><ul><li>Set PHY parameters correctly </li></ul></ul><ul><ul><li>Establish the primary management channel (for negotiation, authentication, and key management) </li></ul></ul><ul><li>Registration </li></ul><ul><ul><li>Result in establishment of secondary management connection (for transfer of standard based management messages such as DHCP, TFTP ) </li></ul></ul><ul><li>Establishment of transport connection </li></ul>
  37. 37. IEEE 802.16 Features <ul><li>Scalability </li></ul><ul><li>QoS </li></ul><ul><li>Range </li></ul><ul><li>Coverage </li></ul><ul><li>WiMAX vs. Wi-Fi </li></ul>
  38. 38. IEEE 802.11 vs. IEEE 802.16 (1/4) <ul><li>Scalability </li></ul><ul><ul><li>802.11 </li></ul></ul><ul><ul><ul><li>Channel bandwidth for 20MHz is fixed </li></ul></ul></ul><ul><ul><ul><li>MAC designed to support 10’s of users </li></ul></ul></ul><ul><ul><li>802.16 </li></ul></ul><ul><ul><ul><li>Channel b/w is flexible from 1.5 MHz to 20 MHz. </li></ul></ul></ul><ul><ul><ul><li>Frequency re-use. </li></ul></ul></ul><ul><ul><ul><li>Channel bandwidths can be chosen by operator (e.g. for sectorization) </li></ul></ul></ul><ul><ul><ul><li>MAC designed to support thousands of users. </li></ul></ul></ul>
  39. 39. IEEE 802.11 vs. IEEE 802.16 (2/4) <ul><li>Quality Of Service (QoS) </li></ul><ul><ul><li>802.11 </li></ul></ul><ul><ul><ul><li>No QoS support today (802.11e working to standardize ) </li></ul></ul></ul><ul><ul><ul><li>Contention-based MAC (CSMA/CA) => no guaranteed QoS </li></ul></ul></ul><ul><ul><li>802.16 </li></ul></ul><ul><ul><ul><li>QoS designed in for voice/video </li></ul></ul></ul><ul><ul><ul><li>Grant-request MAC </li></ul></ul></ul><ul><ul><ul><li>Supports differentiated service levels. </li></ul></ul></ul><ul><ul><ul><ul><li>e.g. T1 for business customers; best effort for residential. </li></ul></ul></ul></ul><ul><ul><ul><li>Centrally-enforced QoS </li></ul></ul></ul>
  40. 40. IEEE 802.11 vs. IEEE 802.16 (3/4) <ul><li>Range </li></ul><ul><ul><li>802.11 </li></ul></ul><ul><ul><ul><li>Optimized for users within a 100 meter radius </li></ul></ul></ul><ul><ul><ul><li>Add access points or high gain antenna for greater coverage </li></ul></ul></ul><ul><ul><ul><li>Designed to handle indoor multi-path delay spread of 0.8μ seconds </li></ul></ul></ul><ul><ul><li>802.16 </li></ul></ul><ul><ul><ul><li>Optimized for typical cell size of 7-10km </li></ul></ul></ul><ul><ul><ul><li>Up to 50 Km range </li></ul></ul></ul><ul><ul><ul><li>No “hidden node” problem </li></ul></ul></ul><ul><ul><ul><li>Designed to tolerate greater multi-path delay spread (signal reflections) up to 10.0μ seconds </li></ul></ul></ul>
  41. 41. IEEE 802.11 vs. IEEE 802.16 (4/4) <ul><li>Coverage </li></ul><ul><ul><li>802.11 </li></ul></ul><ul><ul><ul><li>Optimized for indoor performance </li></ul></ul></ul><ul><ul><ul><li>No mesh topology support within ratified standards </li></ul></ul></ul><ul><ul><li>802.16 </li></ul></ul><ul><ul><ul><li>Optimized for outdoor NLOS performance (trees, buildings, users spread out over distance) </li></ul></ul></ul><ul><ul><ul><li>Standard supports mesh network topology </li></ul></ul></ul><ul><ul><ul><li>Standard supports advanced antenna techniques </li></ul></ul></ul>
  42. 42. Introduction to Bluetooth
  43. 43. Bluetooth <ul><li>named after a Danish Viking and King, Harald Blåtand </li></ul><ul><li>it is a cable-replacement technology : new technology using short-range radio links, intended to replace the cable(s) connecting portable and/or fixed electronic devices </li></ul><ul><li>conceived initially by Ericsson in 1994, set to commercially come out in bulk around 2002 </li></ul><ul><li>a standard for a small , cheap radio chip to be plugged into computers, printers, mobile phones, etc </li></ul><ul><li>The Bluetooth Special Interest Group (SIG) was founded by Ericsson,IBM,Intel,Nokia and Toshiba in February 1998, to develop an open specification for short-range wireless connectivity </li></ul>
  44. 44. Bluetooth <ul><li>Bluetooth radio modules operate in the unlicensed ISM band centered at at 2.45GHz. RF channels:2402+k MHZ, k=0..78. </li></ul><ul><li>Bluetooth devices within 10m of each other can share up to 720kbps of capacity </li></ul><ul><li>Projected cost for a Bluetooth chip is ~$5. Plus its low power consumption, means you could literally place one anywhere. </li></ul><ul><li>Can operate on both circuit and packet switching modes, providing both synchronous and asynchronous data services </li></ul><ul><li>It is intended to support an open-ended list of applications, including data, audio, graphics and even video. </li></ul>
  45. 45. Bluetooth <ul><li>Bluetooth must be able to: </li></ul><ul><li>Recognize any other Bluetooth device in radio range </li></ul><ul><li>Permit easy connection of these devices </li></ul><ul><li>Be aware of the device types </li></ul><ul><li>Support service discovery </li></ul><ul><li>Support connectivity aware applications </li></ul><ul><li>Examples of Bluetooth uses: </li></ul><ul><li>Briefcase email : access email while the PC is still in the briefcase; when PC receives an email, you are notified thru the mobile phone. Use the mobile phone to browse the email. </li></ul><ul><li>Cordless desktop : connect your desktop/laptop cordlessly to printers, scanner, keyboard, mouse, etc. </li></ul>
  46. 46. IEEE 802.15 <ul><li>In 1999, IEEE established a working group for wireless personal area networks (WPAN) </li></ul><ul><ul><li>Contains multiple subgroups </li></ul></ul><ul><li>IEEE 802.15.1 </li></ul><ul><ul><li>Standardizes the lower layers of the Bluetooth (together with the Bluetooth consortium) </li></ul></ul><ul><ul><li>Bluetooth also specifies higher layers </li></ul></ul><ul><li>IEEE 802.15.2 </li></ul><ul><ul><li>Focuses on the coexistence of WPAN and WLAN </li></ul></ul><ul><ul><li>Proposes the adaptive frequency hopping (used since version 1.2) that requires a WPAN device check for the occupied channels and exclude them from their hopping list </li></ul></ul><ul><li>IEEE 802.15.3 </li></ul><ul><ul><li>For high-rate at low-power low cost </li></ul></ul><ul><li>IEEE 802.15.4 </li></ul><ul><ul><li>Low-rate low-power consumption WPAN enabling multi-year battery life </li></ul></ul><ul><ul><li>Zigbee consortium tries to standardize the higher layers of 802.15.4 </li></ul></ul>
  47. 47. Bluetooth is a PAN Technology <ul><li>Offers fast and reliable transmission for both voice and data </li></ul><ul><ul><li>Can support either one asynchronous data channel with up to three simultaneous synchronous speech channels or one channel that transfers asynchronous data and synchronous speech simultaneously </li></ul></ul><ul><ul><li>Support both packet-switching and circuit-switching </li></ul></ul>
  48. 48. Personal Area Network (PAN)
  49. 49. Bluetooth is a standard that will … <ul><li>Eliminate wires and cables between both stationary and mobile devices </li></ul><ul><li>Facilitate both data and voice communications </li></ul><ul><li>Offer the possibility of ad hoc networks and deliver synchronicity between personal devices </li></ul>
  50. 50. Characteristics of Bluetooth Technology 2M is expected for Bluetooth 2 79 frequencies, each channel is used for 625 microseconds
  51. 51. Bluetooth Topology <ul><li>Bluetooth-enabled devices can automatically locate each other </li></ul><ul><li>Topology is established on a temporary and random basis </li></ul><ul><li>Up to eight Bluetooth devices may be networked together in a master-slave relationship to form a piconet </li></ul><ul><ul><li>One is master, which controls and setup the network </li></ul></ul><ul><ul><li>All devices operate on the same channel and follow the same frequency hopping sequence </li></ul></ul><ul><ul><li>The slave of one piconet can be the master of another piconet </li></ul></ul><ul><li>Two or more piconet interconnected to form a scatternet </li></ul><ul><ul><li>Only one master for each piconet </li></ul></ul><ul><ul><li>A device can’t be masters for two </li></ul></ul><ul><ul><li>piconets </li></ul></ul>
  52. 52. A Typical Bluetooth Network
  53. 53. Piconet <ul><li>Master sends its globally unique 48-bit id and clock </li></ul><ul><ul><li>Hopping pattern is determined by the 48-bit device ID </li></ul></ul><ul><ul><li>Phase is determined by the master’s clock </li></ul></ul><ul><li>Why at most 7 slaves? </li></ul><ul><ul><li>Active member address is 3-bit </li></ul></ul><ul><li>Parked and standby nodes </li></ul><ul><ul><li>Parked devices can not actively participate in the piconet but are known to the network and can be reactivated within some milliseconds </li></ul></ul><ul><ul><li>8-bit for parked nodes </li></ul></ul><ul><ul><li>No id for standby nodes </li></ul></ul><ul><ul><li>Standby nodes do not participate in the piconet </li></ul></ul>
  54. 54. ScatterNet <ul><li>FH-CDMA to separate piconets within a scatternet </li></ul><ul><li>More piconets within a scatternet degrades performance </li></ul><ul><ul><li>Possible collision because hopping patterns are not coordinated </li></ul></ul><ul><li>A device participating in more than one piconet </li></ul><ul><ul><li>At any instant of time, a device can participate only in one piconet </li></ul></ul><ul><ul><li>If the device participates as a slave, it just synchronize with the master’s hop sequence </li></ul></ul><ul><ul><li>The master of a piconet can join another piconet as a slave; in this case, all communication within in the former piconet will be suspended </li></ul></ul><ul><ul><li>When leaving a piconet, a slave notifies the master about its absence for certain amount of time </li></ul></ul><ul><li>Communication between different piconets takes place by devices jumping back and forth between these nets </li></ul>
  55. 55. Frequency Selection <ul><li>FH is used for interference mitigation and media access; TDD is used for separation of the transmission directions </li></ul><ul><ul><li>In 3-slot or 5-slot packets, why frequency does not change? Why some frequencies are skipped? </li></ul></ul>M S M S M S M f k f k+1 f k+2 f k+3 f k+4 f k+5 f k+6 M (3-slot packet) S M S M f k f k+3 f k+4 f k+5 f k+6 M S (5-slot packet) M f k f k+1 f k+6
  56. 56. Physical Links <ul><li>Synchronous Connection Oriented (SCO) : allocates a fixed bw between a point-to-point connection involving the master and one slave. </li></ul><ul><ul><li>The master reserves slots periodically. </li></ul></ul><ul><ul><li>It primarily supports time-bounded information like voice. </li></ul></ul><ul><ul><li>SCO packets do not include a CRC and are never retransmitted. </li></ul></ul><ul><ul><li>The master can support up to 3 simultaneous SCO links </li></ul></ul><ul><li>Asynchronous connectionless (ACL) : a point-to-multipoint link between the master and all slaves in the piconet. </li></ul><ul><ul><li>Packet-switch style of connection </li></ul></ul><ul><ul><li>No bw reservation possible </li></ul></ul><ul><ul><li>Delivery may be guaranteed thru error detection and retransmission </li></ul></ul><ul><ul><li>Only single ACL link can exist </li></ul></ul>
  57. 57. Physical Links <ul><li>Synchronous connection-oriented link (SCO) </li></ul><ul><ul><li>Reserve two consecutive slots at fixed intervals </li></ul></ul><ul><li>Asynchronous connectionless Link (ACL) </li></ul><ul><ul><li>Polling scheme – master polls each slave </li></ul></ul><ul><li>Error recovery </li></ul><ul><ul><li>ACK a packet in the slot following the packet </li></ul></ul><ul><ul><li>Negative ACK or timeout signals a retransmission </li></ul></ul>
  58. 58. Benefits <ul><li>Cable Replacement </li></ul><ul><ul><li>Replace the cables for peripheral devices, USB 1.1 and 2.0, printers, etc </li></ul></ul><ul><li>Ease of file sharing </li></ul><ul><ul><li>Panel discussion, conference, etc. </li></ul></ul><ul><li>Wireless synchronization </li></ul><ul><ul><li>Synchronize personal information contained in the address books and date books between different devices such as PDAs, cell phones, etc. </li></ul></ul><ul><li>Bridging of networks </li></ul><ul><ul><li>Cell phone connects to the network through dial-up connection while connecting to a laptop with Bluetooth. </li></ul></ul>