Lecture 14


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Lecture 14

  1. 1. <ul><li>No or bad connection? Then perform: </li></ul><ul><li>Scanning : scan the environment, i.e., listen into the medium for beacon signals </li></ul><ul><ul><li>Passive scan : listen to the beacons send by other stations and choose a stn based on power levels. </li></ul></ul><ul><ul><li>Active scan : or send probes into the medium and wait for an answer </li></ul></ul><ul><li>Reassociation Request </li></ul><ul><ul><li>station sends a request to one or several AP(s) </li></ul></ul><ul><li>Reassociation Response </li></ul><ul><ul><li>success: AP has answered, station can now participate </li></ul></ul><ul><ul><li>failure: continue scanning </li></ul></ul><ul><li>AP accepts Reassociation Request </li></ul><ul><ul><li>signal the new station to the distribution system </li></ul></ul><ul><ul><li>the distribution system updates its data base (i.e., location information) </li></ul></ul><ul><ul><li>typically, the distribution system now informs the old AP so it can release resources </li></ul></ul>Roaming
  2. 2. IEEE 802.11b <ul><li>Just after the introduction of the IEEE802.11 standard, a few companies started some enhancements to achieve 11 Mbps data rates. </li></ul><ul><li>To avoid market segmentation, a new standard </li></ul><ul><li>IEEE 802.11b emerged. </li></ul><ul><li>The change is mainly in the physical layer. This is a more3 successful standard as regards the industry adaptation. </li></ul>
  3. 3. WLAN: IEEE 802.11b <ul><li>Data rate </li></ul><ul><ul><li>1, 2, 5.5, 11 Mbit/s, depending on SNR </li></ul></ul><ul><ul><li>User data rate max. approx. 6 Mbit/s </li></ul></ul><ul><li>Transmission range </li></ul><ul><ul><li>300m outdoor, 30m indoor </li></ul></ul><ul><ul><li>Max. data rate ~10m indoor </li></ul></ul><ul><li>Frequency </li></ul><ul><ul><li>Free 2.4 GHz ISM-band </li></ul></ul><ul><li>Security </li></ul><ul><ul><li>Limited, WEP insecure, SSID </li></ul></ul><ul><li>Availability </li></ul><ul><ul><li>Many products, many vendors </li></ul></ul><ul><li>Connection set-up time </li></ul><ul><ul><li>Connectionless/always on </li></ul></ul><ul><li>Quality of Service </li></ul><ul><ul><li>Typ. Best effort, no guarantees (unless polling is used, limited support in products) </li></ul></ul><ul><li>Manageability </li></ul><ul><ul><li>Limited (no automated key distribution, sym. Encryption) </li></ul></ul><ul><li>Special Advantages/Disadvantages </li></ul><ul><ul><li>Advantage: many installed systems, lot of experience, available worldwide, free ISM-band, many vendors, integrated in laptops, simple system </li></ul></ul><ul><ul><li>Disadvantage: heavy interference on ISM-band, no service guarantees, slow relative speed only </li></ul></ul>
  4. 4. 802.11b…Commercially …..on Lap Tops
  5. 5. IEEE 802.11b – PHY frame formats synchronization SFD signal service HEC payload PLCP preamble PLCP header 128 16 8 8 16 variable bits length 16 192 µs at 1 Mbit/s DBPSK 1, 2, 5.5 or 11 Mbit/s short synch. SFD signal service HEC payload PLCP preamble (1 Mbit/s, DBPSK) PLCP header (2 Mbit/s, DQPSK) 56 16 8 8 16 variable bits length 16 96 µs 2, 5.5 or 11 Mbit/s Long PLCP PPDU format: mandatory Short PLCP PPDU format (optional) @@Physical Layer Convergence Protocol Difference : Rate encoded; hex code for 1, 2, 5.5, 11 Mbps
  6. 6. Channel selection (non-overlapping) 2400 [MHz] 2412 2483.5 2442 2472 channel 1 channel 7 channel 13 Europe (ETSI) US (FCC)/Canada (IC) 2400 [MHz] 2412 2483.5 2437 2462 channel 1 channel 6 channel 11 22 MHz 22 MHz Depending on national restrictions, a max of 14 channels can be used. Center freq. To be displaced by 25 MHz.
  7. 7. WLAN: IEEE 802.11a <ul><li>Data rate </li></ul><ul><ul><li>6, 9, 12, 18, 24, 36, 48, 54 Mbit/s, depending on SNR </li></ul></ul><ul><ul><li>User throughput (1500 byte packets): 5.3 (6), 18 (24), 24 (36), 32 (54) </li></ul></ul><ul><ul><li>6, 12, 24 Mbit/s mandatory </li></ul></ul><ul><li>Transmission range </li></ul><ul><ul><li>100m outdoor, 10m indoor </li></ul></ul><ul><ul><ul><li>E.g., 54 Mbit/s up to 5 m, 48 up to 12 m, 36 up to 25 m, 24 up to 30m, 18 up to 40 m, 12 up to 60 m </li></ul></ul></ul><ul><li>Frequency </li></ul><ul><ul><li>Free 5.15-5.25, 5.25-5.35, 5.725-5.825 GHz ISM-band </li></ul></ul><ul><ul><li>Requires carrier sense every 4 ms to avoid interference </li></ul></ul><ul><li>Security </li></ul><ul><ul><li>Limited, WEP insecure, SSID </li></ul></ul><ul><li>Availability </li></ul><ul><ul><li>Some products, some vendors </li></ul></ul><ul><li>Connection set-up time </li></ul><ul><ul><li>Connectionless/always on </li></ul></ul><ul><li>Quality of Service </li></ul><ul><ul><li>Typ. best effort, no guarantees (same as all 802.11 products) </li></ul></ul><ul><li>Manageability </li></ul><ul><ul><li>Limited (no automated key distribution, sym. Encryption) </li></ul></ul><ul><li>Special Advantages/Disadvantages </li></ul><ul><ul><li>Advantage: fits into 802.x standards, free ISM-band, available, simple system, uses less crowded 5 GHz band </li></ul></ul><ul><ul><li>Disadvantage: stronger shading due to higher frequency, no QoS </li></ul></ul>
  8. 8. WLAN: IEEE 802.11a <ul><li>To achieve upto 54 Mbps, it uses technologies such as BPSK, QPSK, 16-QAM or 64 QAM. </li></ul><ul><li>To minimize transmission errors, PEC is used with coding rates of 1/2, 2/3 or 3/4. </li></ul>
  9. 9. IEEE 802.11a – PHY frame format rate service payload variable bits 6 Mbit/s PLCP preamble signal data symbols 12 1 variable reserved length tail parity tail pad 6 16 6 1 12 1 4 variable 6, 9, 12, 18, 24, 36, 48, 54 Mbit/s PLCP header
  10. 10. Frame format <ul><li>PCLP Preamble (Physical Layer Convergence Protocol) </li></ul><ul><li>- 12 symbols and used for freq acquisition, channel estimation, synchronization).- 16 micro secs. </li></ul><ul><li>Signal(made of rate – 0x3 for 54 Mbps, 0x9 for 24 Mbps etc, </li></ul><ul><li>length : no. of bytes in payload, parity for parity check). </li></ul><ul><li>DATA </li></ul><ul><li>- service field (to synchronize the descrambler- data scrambled using the poly x 7 + x 4 + 1) </li></ul><ul><li>- payload contains MAC PDU </li></ul><ul><li>- tail : used to reset the encoder </li></ul><ul><li>- pad : ensures that the no. of bits in PDU maps to an integer no. of OFDM symbols. </li></ul>
  11. 11. Operating channels for 802.11a / US U-NII 5150 [MHz] 5180 5350 5200 36 44 16.6 MHz center frequency = 5000 + 5*channel number [MHz] channel 40 48 52 56 60 64 149 153 157 161 5220 5240 5260 5280 5300 5320 5725 [MHz] 5745 5825 5765 16.6 MHz channel 5785 5805
  12. 12. Operating channels for 802.11a / US U-NII <ul><li>Provides a unique numbering of channels with 5 MHz spacing starting from 5 GHz. </li></ul><ul><li>Eight channels defined in the lower two bands (Indoor use) </li></ul><ul><li>- 36, 40, 44, 48, 52, 56, 60, 64 </li></ul><ul><li>Four more channels in the High band (for out door as well as indoor use) </li></ul><ul><li>- 149, 153, 157, 161 </li></ul><ul><li>Channels spacing is 20MHz. </li></ul>
  13. 13. OFDM in IEEE 802.11a (and HiperLAN2) subcarrier number 1 7 21 26 -26 -21 -7 -1 channel center frequency 312.5 kHz pilot <ul><li>OFDM with 52 used subcarriers (64 in total) </li></ul><ul><li>48 data + 4 pilot </li></ul><ul><li>(plus 12 virtual subcarriers) </li></ul><ul><li>312.5 kHz spacing </li></ul>Each channel occupies : 312.5 * 52 + centre freq. = approx. 16.6 MHz.
  14. 14. Distinctions <ul><li>IEEE 802.11b IEEE 802.11a </li></ul><ul><li>2.4 GHz 5 GHz </li></ul><ul><li>Data rates up to 11 Mbps Data rates up to 54 Mbps - Depending on SNR, </li></ul><ul><li>signal conditions and </li></ul><ul><li>distance b/w sender and </li></ul><ul><li>receiver, data rates may </li></ul><ul><li>drop. </li></ul><ul><li>- MAC layer adds </li></ul><ul><li>overheads </li></ul><ul><li>5.3(6), 18(24), 24(36), 32(54) </li></ul>
  15. 15. OFDM in IEEE 802.11a (and HiperLAN2) <ul><li>The 52 sub-carriers are equally spaced around the centre frequency. </li></ul><ul><li>Spacing between sub-carriers is 312.5 kHz. </li></ul><ul><li>26 sub-carriers are to the left and 26 are to the right of the centre frequency. </li></ul><ul><li>The sub-carriers -21, -7, 7, 21 are used as pilot signals to enable signal detection robust against frequency offsets. </li></ul>
  16. 16. WLAN: IEEE 802.11 – future developments (03/2005) <ul><li>802.11c: Bridge Support </li></ul><ul><ul><li>Definition of MAC procedures to support bridges as extension to 802.1D </li></ul></ul><ul><li>802.11d: Regulatory Domain Update </li></ul><ul><ul><li>Support of additional regulations related to channel selection, hopping sequences </li></ul></ul><ul><li>802.11e: MAC Enhancements – QoS </li></ul><ul><ul><li>Enhance the current 802.11 MAC to expand support for applications with Quality of Service requirements, and in the capabilities and efficiency of the protocol </li></ul></ul><ul><ul><li>Definition of a data flow (“connection”) with parameters like rate, burst, period… </li></ul></ul><ul><ul><li>Additional energy saving mechanisms and more efficient retransmission </li></ul></ul><ul><li>802.11f: Inter-Access Point Protocol </li></ul><ul><ul><li>Establish an Inter-Access Point Protocol for data exchange via the distribution system </li></ul></ul><ul><ul><li>Currently unclear to which extend manufacturers will follow this suggestion </li></ul></ul><ul><li>802.11g: Data Rates > 20 Mbit/s at 2.4 GHz ; 54 Mbit/s, OFDM </li></ul><ul><ul><li>Successful successor of 802.11b, performance loss during mixed operation with 11b </li></ul></ul><ul><li>802.11h: Spectrum Managed 802.11a </li></ul><ul><ul><li>Extension for operation of 802.11a in Europe by mechanisms like channel measurement for dynamic channel selection (DFS, Dynamic Frequency Selection) and power control (TPC, Transmit Power Control) </li></ul></ul>
  17. 17. WLAN: IEEE 802.11– future developments ( 03/2005 ) <ul><li>802.11i: Enhanced Security Mechanisms </li></ul><ul><ul><li>Enhance the current 802.11 MAC to provide improvements in security. </li></ul></ul><ul><ul><li>TKIP enhances the insecure WEP, but remains compatible to older WEP systems </li></ul></ul><ul><ul><li>AES provides a secure encryption method and is based on new hardware </li></ul></ul><ul><li>802.11j: Extensions for operations in Japan </li></ul><ul><ul><li>Changes of 802.11a for operation at 5GHz in Japan using only half the channel width at larger range </li></ul></ul><ul><li>802.11k: Methods for channel measurements </li></ul><ul><ul><li>Devices and access points should be able to estimate channel quality in order to be able to choose a better access point of channel </li></ul></ul><ul><li>802.11m: Updates of the 802.11 standards </li></ul><ul><li>802.11n: Higher data rates above 100Mbit/s </li></ul><ul><ul><li>Changes of PHY and MAC with the goal of 100Mbit/s at MAC SAP </li></ul></ul><ul><ul><li>MIMO antennas (Multiple Input Multiple Output), up to 600Mbit/s are currently feasible </li></ul></ul><ul><ul><li>However, still a large overhead due to protocol headers and inefficient mechanisms </li></ul></ul><ul><li>802.11p: Inter car communications </li></ul><ul><ul><li>Communication between cars/road side and cars/cars </li></ul></ul><ul><ul><li>Planned for relative speeds of min. 200km/h and ranges over 1000m </li></ul></ul><ul><ul><li>Usage of 5.850-5.925GHz band in North America </li></ul></ul>
  18. 18. WLAN: IEEE 802.11– future developments ( 03/2005 ) <ul><li>802.11r: Faster Handover between BSS </li></ul><ul><ul><li>Secure, fast handover of a station from one AP to another within an ESS </li></ul></ul><ul><ul><li>Current mechanisms (even newer standards like 802.11i) plus incompatible devices from different vendors are massive problems for the use of, e.g., VoIP in WLANs </li></ul></ul><ul><ul><li>Handover should be feasible within 50ms in order to support multimedia applications efficiently </li></ul></ul><ul><li>802.11s: Mesh Networking </li></ul><ul><ul><li>Design of a self-configuring Wireless Distribution System (WDS) based on 802.11 </li></ul></ul><ul><ul><li>Support of point-to-point and broadcast communication across several hops </li></ul></ul><ul><li>802.11t: Performance evaluation of 802.11 networks </li></ul><ul><ul><li>Standardization of performance measurement schemes </li></ul></ul><ul><li>802.11u: Interworking with additional external networks </li></ul><ul><li>802.11v: Network management </li></ul><ul><ul><li>Extensions of current management functions, channel measurements </li></ul></ul><ul><ul><li>Definition of a unified interface </li></ul></ul><ul><li>802.11w: Securing of network control </li></ul><ul><ul><li>Classical standards like 802.11, but also 802.11i protect only data frames, not the control frames. Thus, this standard should extend 802.11i in a way that, e.g., no control frames can be forged. </li></ul></ul><ul><li>Note: Not all “standards” will end in products, many ideas get stuck at working group level </li></ul><ul><li>Info: www.ieee802.org/11/, 802wirelessworld.com, standards.ieee.org/getieee802/ </li></ul>
  19. 19. ETSI – HIPERLAN (historical) <ul><li>ETSI standard </li></ul><ul><ul><li>European standard, cf. GSM, DECT, ... </li></ul></ul><ul><ul><li>Enhancement of local Networks and interworking with fixed networks </li></ul></ul><ul><ul><li>integration of time-sensitive services from the early beginning </li></ul></ul><ul><li>HIPERLAN family </li></ul><ul><ul><li>one standard cannot satisfy all requirements </li></ul></ul><ul><ul><ul><li>range, bandwidth, QoS support </li></ul></ul></ul><ul><ul><ul><li>commercial constraints </li></ul></ul></ul><ul><ul><li>HIPERLAN 1 standardized since 1996 – no products! </li></ul></ul>
  20. 20. Overview: original HIPERLAN protocol family HIPERLAN 1 never reached product status, the other standards have been renamed/modfied !
  21. 21. HIPERLAN 1 - Characteristics <ul><li>Data transmission </li></ul><ul><ul><li>point-to-point, point-to-multipoint, connectionless </li></ul></ul><ul><ul><li>23.5 Mbit/s, 1 W power, 2383 byte max. packet size </li></ul></ul><ul><li>Services </li></ul><ul><ul><li>asynchronous and time-bounded services with hierarchical priorities </li></ul></ul><ul><ul><li>compatible with ISO MAC </li></ul></ul><ul><li>Topology </li></ul><ul><ul><li>infrastructure or ad-hoc networks </li></ul></ul><ul><ul><li>transmission range can be larger then coverage of a single node („forwarding“ integrated in mobile terminals) </li></ul></ul><ul><li>Further mechanisms </li></ul><ul><ul><li>power saving, encryption, checksums </li></ul></ul>
  22. 22. Highlights of Hyperlan-1 <ul><li>Ability to transfer packets using several relays </li></ul><ul><li>Supports p-savers. A node sets up specific wake-up patterns </li></ul><ul><li>Need p-supporters that contain info about wake-up times </li></ul><ul><li>P-supporters (forwarding entities) need buffering mechanisms. </li></ul>
  23. 23. HIPERLAN 1 - Physical layer <ul><li>Scope </li></ul><ul><ul><li>modulation, demodulation, bit and frame synchronization </li></ul></ul><ul><ul><li>forward error correction mechanisms </li></ul></ul><ul><ul><li>measurements of signal strength </li></ul></ul><ul><ul><li>channel sensing </li></ul></ul><ul><li>Channels </li></ul><ul><ul><li>3 mandatory and 2 optional channels (with their carrier frequencies) </li></ul></ul><ul><ul><li>mandatory </li></ul></ul><ul><ul><ul><li>channel 0: 5.1764680 GHz </li></ul></ul></ul><ul><ul><ul><li>channel 1: 5.1999974 GHz </li></ul></ul></ul><ul><ul><ul><li>channel 2: 5.2235268 GHz </li></ul></ul></ul><ul><ul><li>optional </li></ul></ul><ul><ul><ul><li>channel 3: 5.2470562 GHz </li></ul></ul></ul><ul><ul><ul><li>channel 4: 5.2705856 GHz </li></ul></ul></ul>
  24. 24. HIPERLAN 1 - Physical layer frames <ul><li>Maintaining a high data-rate (23.5 Mbit/s) is power consuming - problematic for mobile terminals </li></ul><ul><ul><li>packet header with low bit-rate comprising receiver information </li></ul></ul><ul><ul><li>only receiver(s) address by a packet continue receiving </li></ul></ul><ul><li>Frame structure </li></ul><ul><ul><li>LBR (Low Bit-Rate) header with 1.4 Mbit/s </li></ul></ul><ul><ul><li>450 bit synchronization </li></ul></ul><ul><ul><li>minimum 1, maximum 47 frames with 496 bit each </li></ul></ul><ul><ul><li>for higher velocities of the mobile terminal (> 1.4 m/s) the maximum number of frames has to be reduced </li></ul></ul><ul><li>Modulation </li></ul><ul><ul><li>GMSK for high bit-rate, FSK for LBR header </li></ul></ul>LBR synchronization data 0 data 1 data m-1 . . . HBR
  25. 25. HIPERLAN 1- MAC <ul><li>EY-NPMA : Elimination yield, non-preemptive, multiple-access: Divides the medium access of competing nodes into three phases: </li></ul><ul><li>(i) Prioritization : highest priority of data packet ready to be sent </li></ul><ul><li>(ii) Contention : Eliminate all but one contender </li></ul><ul><li>(iii) Transmission : Finally, transmit the packet of the remaining node. </li></ul>
  26. 26. HIPERLAN 1 - CAC sublayer <ul><li>Channel Access Control (CAC) </li></ul><ul><ul><li>assure that terminal does not access forbidden channels </li></ul></ul><ul><ul><li>priority scheme, access with EY-NPMA </li></ul></ul><ul><li>Priorities </li></ul><ul><ul><li>5 priority levels for QoS support </li></ul></ul><ul><ul><li>QoS is mapped onto a priority level with the help of the packet lifetime (set by an application) </li></ul></ul><ul><ul><ul><li>if packet lifetime = 0 it makes no sense to forward the packet to the receiver any longer </li></ul></ul></ul><ul><ul><ul><li>standard start value 500ms, maximum 16000ms </li></ul></ul></ul><ul><ul><ul><li>if a terminal cannot send the packet due to its current priority, waiting time is permanently subtracted from lifetime </li></ul></ul></ul><ul><ul><ul><li>based on packet lifetime, waiting time in a sender and number of hops to the receiver, the packet is assigned to one out of five priorities </li></ul></ul></ul><ul><ul><ul><li>the priority of waiting packets, therefore, rises automatically </li></ul></ul></ul>
  27. 27. HIPERLAN 1 - EY-NPMA I <ul><li>EY-NPMA (Elimination Yield Non-preemptive Priority Multiple Access) </li></ul><ul><ul><li>3 phases: priority resolution, contention resolution, transmission </li></ul></ul><ul><ul><li>finding the highest priority </li></ul></ul><ul><ul><ul><li>every priority corresponds to a time-slot to send in the first phase, the higher the priority the earlier the time-slot to send </li></ul></ul></ul><ul><ul><ul><li>higher priorities can not be preempted </li></ul></ul></ul><ul><ul><ul><li>if an earlier time-slot for a higher priority remains empty, stations with the next lower priority might send </li></ul></ul></ul><ul><ul><ul><li>after this first phase the highest current priority has been determined </li></ul></ul></ul>prioritization contention transmission transmission synchronization priority detection priority assertion t user data elimination burst elimination survival verification yield listening I YS I PS I PA I ES I ESV
  28. 28. HIPERLAN 1 - EY-NPMA II <ul><li>Several terminals can now have the same priority and wish to send </li></ul><ul><ul><li>contention phase </li></ul></ul><ul><ul><ul><li>Elimination Burst: all remaining terminals send a burst to eliminate contenders (11111010100010011100000110010110, high bit- rate) </li></ul></ul></ul><ul><ul><ul><li>Elimination Survival Verification: contenders now sense the channel, if the channel is free they can continue, otherwise they have been eliminated </li></ul></ul></ul><ul><ul><ul><li>Yield Listening: contenders again listen in slots with a nonzero probability, if the terminal senses its slot idle it is free to transmit at the end of the contention phase </li></ul></ul></ul><ul><ul><ul><li>the important part is now to set the parameters for burst duration and channel sensing (slot-based, exponentially distributed) </li></ul></ul></ul><ul><ul><li>data transmission </li></ul></ul><ul><ul><ul><li>the winner can now send its data (however, a small chance of collision remains) </li></ul></ul></ul><ul><ul><ul><li>if the channel was idle for a longer time (min. for a duration of 1700 bit) a terminal can send at once without using EY-NPMA </li></ul></ul></ul><ul><ul><li>synchronization using the last data transmission </li></ul></ul>
  29. 29. WATM services <ul><li>Office environment </li></ul><ul><ul><li>multimedia conferencing, online multimedia database access </li></ul></ul><ul><li>Universities, schools, training centers </li></ul><ul><ul><li>distance learning, teaching </li></ul></ul><ul><li>Industry </li></ul><ul><ul><li>database connection, surveillance, real-time factory management </li></ul></ul><ul><li>Hospitals </li></ul><ul><ul><li>reliable, high-bandwidth network, medical images, remote monitoring </li></ul></ul><ul><li>Home </li></ul><ul><ul><li>high-bandwidth interconnect of devices (TV, CD, PC, ...) </li></ul></ul><ul><li>Networked vehicles </li></ul><ul><ul><li>trucks, aircraft etc. interconnect, platooning, intelligent roads </li></ul></ul>
  30. 30. Modication for Wireless ATM : WATM <ul><li>Seamless integration of wireless terminals to ATM network </li></ul><ul><li>Mobility is needed for ATM support networks in local and global situations. </li></ul><ul><li>ATM should have a wireless extension. </li></ul><ul><li>Other wireless services offer best effort services and at tiles, time bounded services; WATM offers QoS to the level of ATM networks. </li></ul>
  31. 31. WATM components <ul><li>WMT (Wireless Mobile ATM Terminal) </li></ul><ul><li>RAS ( Radio Access System ) </li></ul><ul><li>EMAS-E (End-user Mobility-supporting ATM Switch - Edge) </li></ul><ul><li>EMAS-N (End-user Mobility-supporting ATM Switch - Network) </li></ul><ul><li>M- NNI (Network-to-Network Interface with Mobility support) </li></ul><ul><li>LS (Location Server) </li></ul><ul><li>AUS (Authentication Server) </li></ul>
  32. 32. Reference model WMT WMT EMAS-E EMAS-N EMAS-N M-NNI RAS RAS LS AUS
  33. 33. User plane protocol layers WATM terminal adapter MATM termi- nal RAS EMAS -E EMAS -N ATM- Switch fixed end system radio segment fixed network segment
  34. 34. Reference model with further access scenarios I <ul><li>1: wireless ad-hoc ATM network </li></ul><ul><li>2: wireless mobile ATM terminals </li></ul><ul><li>3: mobile ATM terminals </li></ul><ul><li>4: mobile ATM switches </li></ul><ul><li>5: fixed ATM terminals </li></ul><ul><li>6: fixed wireless ATM terminals </li></ul><ul><li>WMT: wireless mobile terminal </li></ul><ul><li>WT: wireless terminal </li></ul><ul><li>MT: mobile terminal </li></ul><ul><li>T: terminal </li></ul><ul><li>AP: access point </li></ul><ul><li>EMAS: end-user mobility supporting ATM switch (-E: edge, -N: network) </li></ul><ul><li>NMAS: network mobility supporting ATM switch </li></ul><ul><li>MS: mobile ATM switch </li></ul>
  35. 35. Reference model with further access scenarios II RAS ACT WMT WMT RAS RAS T MT WT RAS EMAS -N T RAS EMAS -E WMT 1 2 3 4 5 6 NMAS MS EMAS -E
  36. 36. BRAN – Broadband Radio Access Networks <ul><li>Motivation </li></ul><ul><ul><li>deregulation, privatization, new companies, new services </li></ul></ul><ul><ul><li>How to reach the customer? </li></ul></ul><ul><ul><ul><li>alternatives: xDSL, cable, satellite, radio </li></ul></ul></ul><ul><li>Radio access </li></ul><ul><ul><li>flexible (supports traffic mix, multiplexing for higher efficiency, can be asymmetrical) </li></ul></ul><ul><ul><li>quick installation </li></ul></ul><ul><ul><li>economic (incremental growth possible) </li></ul></ul><ul><li>Market </li></ul><ul><ul><li>private customers (Internet access, tele-xy...) </li></ul></ul><ul><ul><li>small and medium sized business (Internet, MM conferencing, VPN) </li></ul></ul><ul><li>Scope of standardization </li></ul><ul><ul><li>access networks, indoor/campus mobility, 25-155 Mbit/s, 50 m-5 km </li></ul></ul><ul><ul><li>coordination with ATM Forum, IETF, ETSI, IEEE, .... </li></ul></ul>
  37. 37. Broadband network types <ul><li>Common characteristics </li></ul><ul><ul><li>ATM QoS (CBR, VBR, UBR, ABR) </li></ul></ul><ul><li>HIPERLAN/2 </li></ul><ul><ul><li>short range (< 200 m), indoor/campus, 25 Mbit/s user data rate </li></ul></ul><ul><ul><li>access to telecommunication systems, multimedia applications, mobility (<10 m/s) </li></ul></ul><ul><li>HIPERACCESS </li></ul><ul><ul><li>wider range (< 5 km), outdoor, 25 Mbit/s user data rate </li></ul></ul><ul><ul><li>fixed radio links to customers (“last mile”), alternative to xDSL or cable modem, quick installation </li></ul></ul><ul><ul><li>Several (proprietary) products exist with 155 Mbit/s plus QoS </li></ul></ul><ul><li>HIPERLINK – currently no activities </li></ul><ul><ul><li>intermediate link, 155 Mbit/s </li></ul></ul><ul><ul><li>connection of HIPERLAN access points or connection between HIPERACCESS nodes </li></ul></ul>
  38. 38. BRAN and legacy networks core network ATM core network IP network convergence sublayer BRAN data link control BRAN PHY-1 BRAN PHY-2 ... <ul><li>Coordination </li></ul><ul><ul><li>IETF (TCP/IP) </li></ul></ul><ul><ul><li>ATM forum (ATM) </li></ul></ul><ul><ul><li>ETSI (UMTS) </li></ul></ul><ul><ul><li>CEPT, ITU-R, ... (radio frequencies) </li></ul></ul><ul><li>Independence </li></ul><ul><ul><li>BRAN as access network independent from the fixed network </li></ul></ul><ul><ul><li>Interworking of TCP/IP and ATM under study </li></ul></ul><ul><li>Layered model </li></ul><ul><ul><li>Network Convergence Sub-layer as superset of all requirements for IP and ATM </li></ul></ul>
  39. 39. HiperLAN2 (historical) <ul><li>Official name: BRAN HIPERLAN Type 2 </li></ul><ul><ul><li>H/2, HIPERLAN/2 also used </li></ul></ul><ul><li>High data rates for users </li></ul><ul><ul><li>More efficient than 802.11a </li></ul></ul><ul><li>Connection oriented </li></ul><ul><li>QoS support </li></ul><ul><li>Dynamic frequency selection </li></ul><ul><li>Security support </li></ul><ul><ul><li>Strong encryption/authentication </li></ul></ul><ul><li>Mobility support </li></ul><ul><li>Network and application independent </li></ul><ul><ul><li>convergence layers for Ethernet, IEEE 1394, ATM, 3G </li></ul></ul><ul><li>Power save modes </li></ul><ul><li>Plug and Play </li></ul>
  40. 40. HiperLAN2 architecture and handover scenarios 2 3 1 AP APT APC Core Network (Ethernet, Firewire, ATM, UMTS) APT APT APC AP Access Point Transceiver Access Point controller MT 4 MT 3 MT 2 MT 1
  41. 41. Centralized vs. direct mode AP/CC AP data control control data control Centralized Direct data control MT 1 MT 2 MT 1 MT 2 MT 1 MT 2 +CC
  42. 42. HiperLAN2 protocol stack Higher layers Convergence layer Data link control - basic data transport function Scope of HiperLAN2 standards DLC control SAP DLC user SAP Radio link control sublayer Physical layer Radio resource control Assoc. control DLC conn. control Error control Radio link control Medium access control SAP : Service Access Point
  43. 43. Physical layer reference configuration scrambling FEC coding interleaving mapping OFDM PHY bursts (PPDU) PDU train from DLC (PSDU) radio transmitter PDU : protocol Data Units
  44. 44. Operating channels of HiperLAN2 in Europe 5150 [MHz] 5180 5350 5200 36 44 16.6 MHz center frequency = 5000 + 5*channel number [MHz] channel 40 48 52 56 60 64 5220 5240 5260 5280 5300 5320 5470 [MHz] 5500 5725 5520 100 108 16.6 MHz channel 104 112 116 120 124 128 5540 5560 5580 5600 5620 5640 132 136 140 5660 5680 5700
  45. 45. Basic structure of HiperLAN2 MAC frames MAC frame MAC frame MAC frame MAC frame 2 ms 2 ms 2 ms 2 ms broadcast phase downlink phase uplink phase random access phase . . . TDD, 500 OFDM symbols per frame variable variable variable LCH PDU type sequence number payload CRC UDCH transfer syntax (long PDU) 54 byte 2 10 396 24 bit LCH PDU type payload CRC 2 406 24 LCH transfer syntax bit
  46. 46. Valid configurations of HiperLAN2 MAC frames MAC frame MAC frame MAC frame MAC frame 2 ms 2 ms 2 ms 2 ms BCH FCH ACH DL phase DiL phase UL phase RCHs . . . BCH FCH ACH DiL phase UL phase RCHs BCH FCH ACH DL phase UL phase RCHs BCH FCH ACH UL phase RCHs BCH FCH ACH DL phase DiL phase RCHs BCH FCH ACH DiL phase RCHs BCH FCH ACH DL phase RCHs BCH FCH ACH RCHs Valid combinations of MAC frames for a single sector AP broadcast downlink uplink random access BCH : Broadcast Channel FCH : Frame Channel ACH : Association Control Function RCH : Random Channel
  47. 47. Mapping of logical and transport channels BCCH FCCH RFCH LCCH RBCH DCCH UDCH UBCH UMCH BCH FCH ACH SCH LCH downlink UDCH DCCH LCCH ASCH SCH LCH RCH uplink UDCH UBCH UMCH LCH DCCH RBCH SCH LCCH direct link
  48. 48. Blue Tooth <ul><li>Idea </li></ul><ul><li>– Universal radio interface for ad-hoc wireless connectivity </li></ul><ul><li>– Interconnecting computer and peripherals, handheld devices, PDAs, cell </li></ul><ul><li>phones – replacement of IrDA </li></ul><ul><li>– Embedded in other devices, goal: 5€/device (2002: 50€/USB bluetooth) </li></ul><ul><li>– Short range (10 m), low power consumption, license-free 2.45 GHz ISM </li></ul><ul><li>– Voice and data transmission, approx. 1 Mbit/s gross data rate </li></ul><ul><li>One of the first modules (Ericsson) </li></ul>
  49. 49. Blue Tooth
  50. 50. Blue Tooth
  51. 51. Characteristics <ul><li>2.4 GHz ISM band, 79 (23) RF channels, 1 MHz carrier spacing </li></ul><ul><ul><li>Channel 0: 2402 MHz … channel 78: 2480 MHz </li></ul></ul><ul><ul><li>G-FSK modulation, 1-100 mW transmit power </li></ul></ul><ul><li>FHSS and TDD </li></ul><ul><ul><li>Frequency hopping with 1600 hops/s </li></ul></ul><ul><ul><li>Hopping sequence in a pseudo random fashion, determined by a master </li></ul></ul><ul><ul><li>Time division duplex for send/receive separation </li></ul></ul><ul><li>Voice link – SCO (Synchronous Connection Oriented) </li></ul><ul><ul><li>FEC (forward error correction), no retransmission, 64 kbit/s duplex, point-to-point, circuit switched </li></ul></ul><ul><li>Data link – ACL (Asynchronous ConnectionLess) </li></ul><ul><ul><li>Asynchronous, fast acknowledge, point-to-multipoint, up to 433.9 kbit/s symmetric or 723.2/57.6 kbit/s asymmetric, packet switched </li></ul></ul><ul><li>Topology </li></ul><ul><ul><li>Overlapping piconets (stars) forming a scatternet </li></ul></ul>
  52. 52. Piconet
  53. 53. Piconet <ul><li>Parked Devices : </li></ul><ul><li>Have no connection with the network. </li></ul><ul><li>But are known to the network and can be activated in milli seconds. </li></ul><ul><li>If a parked device has to participate, one slave has to go to parked mode and the slave can enter the network. </li></ul><ul><li>Devices in Standby do not participate in the network. </li></ul><ul><li>All devices adjust their clock w.r.t the master. </li></ul>
  54. 54. Piconet <ul><li>All Active devices are assigned a 3-bit AMA (Active Member Address) </li></ul><ul><li>All parked devices are assigned a 8-bit PMA(Parked Member Address) </li></ul><ul><li>Standby Devices do not need an address. </li></ul>
  55. 55. History <ul><li>– 1994: Ericsson (Mattison/Haartsen), “MC-link” project </li></ul><ul><li>– Renaming of the project: Bluetooth according to Harald “Blåtand” Gormsen [son of Gorm], King of Denmark in the 10th century </li></ul><ul><li>– 1998: foundation of Bluetooth SIG, www.bluetooth.org </li></ul><ul><li>– 2001: first consumer products for mass market, spec. version 1.1 released </li></ul><ul><li>• Special Interest Group </li></ul><ul><li>– Original founding members: Ericsson, Intel, IBM, Nokia, Toshiba </li></ul><ul><li>– Added promoters: 3Com, Agere (was: Lucent), Microsoft, Motorola </li></ul><ul><li>– > 2500 members </li></ul><ul><li>– Common specification and certification of products </li></ul>
  56. 56. Characteristics <ul><li>2.4 GHz ISM band, 79 (23) RF channels, 1 MHz carrier spacing </li></ul><ul><li>– Channel 0: 2402 MHz … channel 78: 2480 MHz </li></ul><ul><li>– G-FSK modulation, 1-100 mW transmit power </li></ul><ul><li>• FHSS and TDD </li></ul><ul><li>– Frequency hopping with 1600 hops/s </li></ul><ul><li>– Hopping sequence in a pseudo random fashion, determined by a master </li></ul><ul><li>– Time division duplex for send/receive separation </li></ul><ul><li>• Voice link – SCO (Synchronous Connection Oriented) </li></ul><ul><li>– FEC (forward error correction), no retransmission, 64 kbit/s duplex, point-to-point, </li></ul><ul><li>circuit switched </li></ul><ul><li>• Data link – ACL (Asynchronous ConnectionLess) </li></ul><ul><li>– Asynchronous, fast acknowledge, point-to-multipoint, up to 433.9 kbit/s symmetric or </li></ul><ul><li>723.2/57.6 kbit/s asymmetric, packet switched </li></ul><ul><li>• Topology </li></ul><ul><li>– Overlapping piconets (stars) forming a scatternet </li></ul>
  57. 57. User Scenarios <ul><li>Connection to Peripheral Devices </li></ul><ul><li>PC connections namely Keyboard, mouse, Joystick, speakers etc can be linked in a wireless manner using bluetooth. </li></ul><ul><li>Support fro Adhoc Networking </li></ul><ul><li>Several Devices (lap tops, PDA’s etc can talk to each other) </li></ul><ul><li>Bridging Networks </li></ul><ul><li>A Mobile phone can act as a bridge between a local Piconet and a Global GSM (and other global networks) </li></ul>
  58. 58. Piconet
  59. 59. Forming a Piconet
  60. 61. Scatternet
  61. 62. Scatternet <ul><li>If a device wants to participate in a Piconet, it has to Sync with the hopping sequence of that Piconet. </li></ul><ul><li>Bluetooth applies FH-CDMA to separate the piconets. </li></ul><ul><li>Adding Piconets increases collision. </li></ul><ul><li>If the hopping sequences are not properly coordinated, two devices may use the same frequency and so collisions may occur. </li></ul><ul><li>If a slave wants to participate in another piconet, it informs the current master that it will be unavailable for a certain duration. </li></ul><ul><li>When a Master leaves the piconet to participate as a slave for anothet piconet, all activities in this piconet are suspended till it returns. </li></ul><ul><li>Two devices can not be masters for two piconets since the common hopping sequence is not possible. </li></ul>
  62. 63. Scatternet <ul><li>What happens to a device that moves to another piconet? </li></ul><ul><li>Once a slave is attached to another piconet, it no more participates in the formet piconet. </li></ul><ul><li>Before leaving the piconet, it informs the former that it wants to join the new piconet for a specific duration. </li></ul><ul><li>If a device shunts back and forth between piconets, communication(asynchronous) between piconets can be established. </li></ul>
  63. 64. Bluetooth protocol stack
  64. 65. Bluetooth layers in a nutshell <ul><li>Radio : </li></ul><ul><ul><li>Specifications for frequencies, modulation and transmit power. </li></ul></ul><ul><ul><li>Packet format, timing and QoS parameters </li></ul></ul><ul><li>Link Manager : </li></ul><ul><ul><li>Link management between devices </li></ul></ul><ul><ul><li>Security functions </li></ul></ul><ul><li>Service Discovery Protocol (SDP) </li></ul><ul><ul><li>Querying of service characteristics </li></ul></ul><ul><ul><li>Device discovery </li></ul></ul><ul><li>RFCPM </li></ul><ul><ul><li>Cable Replacement Protocol </li></ul></ul><ul><ul><li>Emulates replacement of cables in serial devices </li></ul></ul><ul><ul><li>(management of legacy devices working on serial ports) </li></ul></ul>
  65. 66. Bluetooth layers in a nutshell <ul><li>Telephony Control Protocol Specs (TCS-BIN) </li></ul><ul><ul><li>Call Control </li></ul></ul><ul><ul><li>Signaling Mechanism for voice and data between Bluetooth devices </li></ul></ul><ul><li>Host Controller Interface (HCI) </li></ul><ul><ul><li>Command Interface between baseband and L2CAP </li></ul></ul><ul><ul><li>Provides access to the HW status and registers </li></ul></ul><ul><li>Bluetooth network Encapsulation Protocol (BNEP) </li></ul><ul><ul><li>More efficient than TCP/IP for networking applications </li></ul></ul><ul><li>AT Modems </li></ul><ul><ul><li>For conventional telephone applications </li></ul></ul><ul><li>Calender & Business Card(vCalendar /vCard) </li></ul><ul><ul><li>Can be exchanged using Object Exchange Protocol (OBEX) </li></ul></ul><ul><li>Audio Application </li></ul><ul><ul><li>Use Baseband Layer directly after encoding audio signals </li></ul></ul>
  66. 67. RADIO <ul><li>License-Free 2.4 GHz bandwidth </li></ul><ul><li>FH /Time Division Duplex used for transmission </li></ul><ul><li>Hopping Rate : 1600 hops/sec </li></ul><ul><li>Bluetooth Receivers use GFSK for modulation and are available in three classes: </li></ul><ul><li>Class 1: Max Power of 100 mW and min power of 1 mW. (100 m range without obstacles) – power control mandatory </li></ul><ul><li>Class 2 : Max Power 2.5 mA and min power 0.25mW (10m range without obstacles) – Power control optional </li></ul><ul><li>Class 3: Max Power is 1 mW </li></ul>
  67. 68. Baseband Layer <ul><li>Determines frequency hopping and also packet formats. </li></ul><ul><li>Master sends a data fk, Slave answers at fk+1. </li></ul><ul><li>The upper portion of the figure shows a 1-slot packets as the data uses 625 micro secs- slot. </li></ul><ul><li>A device may use a 3-slot or 5-slot transmission for larger size packets </li></ul><ul><li>But it reverts back to 1-slot transmission(as defined by the hopping sequence) for the next Master/Slave transmission. </li></ul>
  68. 69. Frequency Selection during Transmission S f k 625 µs f k+1 f k+2 f k+3 f k+4 f k+3 f k+4 f k f k f k+5 f k+5 f k+1 f k+6 f k+6 f k+6 M M M M M M M M M t t t S S S S S
  69. 70. Baseband <ul><li>Piconet/channel definition </li></ul><ul><li>Low-level packet definition </li></ul><ul><ul><li>Access code </li></ul></ul><ul><ul><ul><li>Channel, device access, e.g., derived from master </li></ul></ul></ul><ul><ul><li>Packet header </li></ul></ul><ul><ul><ul><li>1/3-FEC, active member address (broadcast + 7 slaves), link type, alternating bit ARQ/SEQ, checksum </li></ul></ul></ul>access code packet header payload 68(72) 54 0-2745 bits AM address type flow ARQN SEQN HEC 3 4 1 1 1 8 bits preamble sync. (trailer) 4 64 (4)
  70. 71. Baseband <ul><li>Access Code: </li></ul><ul><li>Needed for timing synchronization and piconet identification </li></ul><ul><li>Packet Header : </li></ul><ul><li>Contains address, packet type, flow & Error control, Checksum </li></ul><ul><ul><li>3-bit active address will specify address of the slave </li></ul></ul><ul><ul><li>If Master sends the address, it is the receiver address </li></ul></ul><ul><ul><li>If a slave sends the address, it is the sender address </li></ul></ul><ul><ul><li>0-value represents the broadcast type of data. </li></ul></ul><ul><li>Flow : </li></ul><ul><ul><li>If Flow=0, transmission must stop </li></ul></ul><ul><ul><li>If flow=1, transmission must resume </li></ul></ul>
  71. 72. SCO payload types (Synchronous Connection Oriented) payload (30) audio (30) audio (10) audio (10) HV3 HV2 HV1 DV FEC (20) audio (20) FEC (10) header (1) payload (0-9) 2/3 FEC CRC (2) (bytes)
  72. 73. ACL Payload types (ex., web traffic) payload (0-343) header (1/2) payload (0-339) CRC (2) header (1) payload (0-17) 2/3 FEC header (1) payload (0-27) header (2) payload (0-121) 2/3 FEC header (2) payload (0-183) header (2) payload (0-224) 2/3 FEC header (2) payload (0-339) DH5 DM5 DH3 DM3 DH1 DM1 header (1) payload (0-29) AUX1 CRC (2) CRC (2) CRC (2) CRC (2) CRC (2) CRC (2) (bytes)
  73. 74. Baseband data rates Payload User Symmetric Asymmetric Header Payload max. Rate max. Rate [kbit/s] Type [byte] [byte] FEC CRC [kbit/s] Forward Reverse DM1 1 0-17 2/3 yes 108.8 108.8 108.8 DH1 1 0-27 no yes 172.8 172.8 172.8 DM3 2 0-121 2/3 yes 258.1 387.2 54.4 DH3 2 0-183 no yes 390.4 585.6 86.4 DM5 2 0-224 2/3 yes 286.7 477.8 36.3 DH5 2 0-339 no yes 433.9 723.2 57.6 AUX1 1 0-29 no no 185.6 185.6 185.6 HV1 na 10 1/3 no 64.0 HV2 na 20 2/3 no 64.0 HV3 na 30 no no 64.0 DV 1 D 10+(0-9) D 2/3 D yes D 64.0+57.6 D ACL 1 slot 3 slot 5 slot SCO Data Medium rate, Data High rate, High Quality Voice, Data & Voice,
  74. 75. Baseband link types <ul><li>Polling-based TDD packet transmission </li></ul><ul><ul><li>625µs slots, master polls slaves </li></ul></ul><ul><li>SCO (Synchronous Connection Oriented) – Voice </li></ul><ul><ul><li>Periodic single slot packet assignment, 64 kbit/s full-duplex, point-to-point </li></ul></ul><ul><li>ACL (Asynchronous ConnectionLess) – Data </li></ul><ul><ul><li>Variable packet size (1,3,5 slots), asymmetric bandwidth, point-to-multipoint </li></ul></ul>f 6 f 0 f 1 f 7 f 12 f 13 f 19 f 18 SCO SCO SCO SCO ACL f 5 f 21 f 4 f 20 ACL ACL f 8 f 9 f 17 f 14 ACL Master Slave-1 Slave-2
  75. 76. Robustness <ul><li>Slow frequency hopping with hopping patterns determined by a master </li></ul><ul><ul><li>Protection from interference on certain frequencies </li></ul></ul><ul><ul><li>Separation from other piconets (FH-CDMA) </li></ul></ul><ul><li>Retransmission </li></ul><ul><ul><li>ACL only, very fast </li></ul></ul><ul><li>Forward Error Correction </li></ul><ul><ul><li>SCO and ACL </li></ul></ul>A C C H F G G B D E NAK ACK Error in payload (not header!) Master Slave-1 Slave-2
  76. 77. Robustness <ul><li>FH-CDMA separates different Piconets within a Scatternet. </li></ul><ul><li>Additionally, FEC can bet used. </li></ul><ul><ul><li>Bluetooth’s 1/3 FEC sends 3 copies of the same bit. </li></ul></ul><ul><ul><li>Receiver performs a majority decision </li></ul></ul><ul><ul><li>Each receiver bit is subjected to a majority decision.Whichever bit is in majority is used. It takes care of single bit errors. </li></ul></ul>
  77. 78. Baseband states of a Bluetooth device standby inquiry page connected AMA transmit AMA park PMA hold AMA sniff AMA unconnected connecting active low power Standby: do nothing Inquire: search for other devices Page: connect to a specific device Connected: participate in a piconet detach Park: release AMA, get PMA Sniff: listen periodically, not each slot Hold: stop ACL, SCO still possible, possibly participate in another piconet
  78. 79. Example: Power consumption/CSR BlueCore2 <ul><li>Typical Average Current Consumption (1) </li></ul><ul><li>VDD=1.8V Temperature = 20°C </li></ul><ul><li>Mode </li></ul><ul><li>SCO connection HV3 (1s interval Sniff Mode) (Slave) 26.0 mA </li></ul><ul><li>SCO connection HV3 (1s interval Sniff Mode) (Master) 26.0 mA </li></ul><ul><li>SCO connection HV1 (Slave) 53.0 mA </li></ul><ul><li>SCO connection HV1 (Master) 53.0 mA </li></ul><ul><li>ACL data transfer 115.2kbps UART (Master) 15.5 mA </li></ul><ul><li>ACL data transfer 720kbps USB (Slave) 53.0 mA </li></ul><ul><li>ACL data transfer 720kbps USB (Master) 53.0 mA </li></ul><ul><li>ACL connection, Sniff Mode 40ms interval, 38.4kbps UART 4.0 mA </li></ul><ul><li>ACL connection, Sniff Mode 1.28s interval, 38.4kbps UART 0.5 mA </li></ul><ul><li>Parked Slave, 1.28s beacon interval, 38.4kbps UART 0.6 mA </li></ul><ul><li>Standby Mode (Connected to host, no RF activity) 47.0 µA </li></ul><ul><li>Deep Sleep Mode(2) 20.0 µA </li></ul><ul><li>Notes: </li></ul><ul><li>(1) Current consumption is the sum of both BC212015A and the flash. </li></ul><ul><li>(2) Current consumption is for the BC212015A device only. </li></ul><ul><li>(More: www. csr .com ) </li></ul>
  79. 80. Example: Bluetooth/USB adapter (2002: 50€)
  80. 81. L2CAP - Logical Link Control and Adaptation Protocol <ul><li>Simple data link protocol on top of baseband </li></ul><ul><li>Connection oriented, connectionless, and signalling channels </li></ul><ul><li>Protocol multiplexing </li></ul><ul><ul><li>RFCOMM, SDP, telephony control </li></ul></ul><ul><li>Segmentation & reassembly </li></ul><ul><ul><li>Up to 64kbyte user data, 16 bit CRC used from baseband </li></ul></ul><ul><li>QoS flow specification per channel </li></ul><ul><ul><li>Follows RFC 1363, specifies delay, jitter, bursts, bandwidth </li></ul></ul><ul><li>Group abstraction </li></ul><ul><ul><li>Create/close group, add/remove member </li></ul></ul>
  81. 82. L2CAP logical channels baseband L2CAP baseband L2CAP baseband L2CAP Slave Slave Master ACL 2 d 1 d d 1 1 d 2 1 signalling connectionless connection-oriented d d d
  82. 83. L2CAP <ul><li>L2CAP available for ACLs only </li></ul><ul><li>SCOs have to use baseband frequencies directly </li></ul><ul><li>L2CAP provides three types of logical channels: </li></ul><ul><li>Connectionless – Unidirectional channels used for broadcast from master to slaves </li></ul><ul><li>Connection-oriented – Bi-directional, supports QoS </li></ul><ul><li>Signaling : exchanging signaling info between L2CAP entities </li></ul><ul><li>Signaling Channels use signaling id of 1 </li></ul><ul><li>2 reserved for connectionless channels </li></ul><ul><li>For connection oriented channels, a unique CID (>= 64) is dynamically assigned at each end of the channel to identify connection </li></ul>
  83. 84. L2CAP <ul><li>In the figure: </li></ul><ul><li>Master has a bi-directional signaling channel to each slave </li></ul><ul><li>CID for this master is 1 </li></ul><ul><li>Also, master maintains a connectionless uni-directional channel ato both slaves. </li></ul><ul><li>CID of slave is 2 while the CID at the beginning of the connectionless channel is dynamically assigned. </li></ul><ul><li>L2CAP provides features to add / remove slaves from the group. </li></ul><ul><li>Dynamically assigned Ids are from 64 to 65535 </li></ul>
  84. 85. L2CAP packet formats length 2 bytes CID=2 2 PSM  2 payload 0-65533 length 2 bytes CID 2 payload 0-65535 length 2 bytes CID=1 2 One or more commands Connectionless PDU Connection-oriented PDU Signalling command PDU code ID length data 1 1 2  0
  85. 86. Security E 3 E 2 link key (128 bit) encryption key (128 bit) payload key Keystream generator Data Data Cipher data Authentication key generation (possibly permanent storage) Encryption key generation (temporary storage) PIN (1-16 byte) Pairing Authentication Encryption Ciphering E 3 E 2 link key (128 bit) encryption key (128 bit) payload key Keystream generator PIN (1-16 byte)
  86. 87. SDP – Service Discovery Protocol <ul><li>Inquiry/response protocol for discovering services </li></ul><ul><ul><li>Searching for and browsing services in radio proximity </li></ul></ul><ul><ul><li>Adapted to the highly dynamic environment </li></ul></ul><ul><ul><li>Can be complemented by others like SLP, Jini, Salutation, … </li></ul></ul><ul><ul><li>Defines discovery only, not the usage of services </li></ul></ul><ul><ul><li>Caching of discovered services </li></ul></ul><ul><ul><li>Gradual discovery </li></ul></ul><ul><li>Service record format </li></ul><ul><ul><li>Information about services provided by attributes </li></ul></ul><ul><ul><li>Attributes are composed of an 16 bit ID (name) and a value </li></ul></ul><ul><ul><li>values may be derived from 128 bit Universally Unique Identifiers (UUID) </li></ul></ul>
  87. 88. Additional protocols to support legacy protocols/apps. <ul><li>RFCOMM </li></ul><ul><ul><li>Emulation of a serial port (supports a large base of legacy applications) </li></ul></ul><ul><ul><li>Allows multiple ports over a single physical channel </li></ul></ul><ul><li>Telephony Control Protocol Specification (TCS) </li></ul><ul><ul><li>Call control (setup, release) </li></ul></ul><ul><ul><li>Group management </li></ul></ul><ul><li>OBEX </li></ul><ul><ul><li>Exchange of objects, IrDA replacement </li></ul></ul><ul><li>WAP </li></ul><ul><ul><li>Interacting with applications on cellular phones </li></ul></ul>
  88. 89. Profiles <ul><li>Represent default solutions for a certain usage model </li></ul><ul><ul><li>Vertical slice through the protocol stack </li></ul></ul><ul><ul><li>Basis for interoperability </li></ul></ul><ul><li>Generic Access Profile </li></ul><ul><li>Service Discovery Application Profile </li></ul><ul><li>Cordless Telephony Profile </li></ul><ul><li>Intercom Profile </li></ul><ul><li>Serial Port Profile </li></ul><ul><li>Headset Profile </li></ul><ul><li>Dial-up Networking Profile </li></ul><ul><li>Fax Profile </li></ul><ul><li>LAN Access Profile </li></ul><ul><li>Generic Object Exchange Profile </li></ul><ul><li>Object Push Profile </li></ul><ul><li>File Transfer Profile </li></ul><ul><li>Synchronization Profile </li></ul>Additional Profiles Advanced Audio Distribution PAN Audio Video Remote Control Basic Printing Basic Imaging Extended Service Discovery Generic Audio Video Distribution Hands Free Hardcopy Cable Replacement Profiles Protocols Applications
  89. 90. WPAN: IEEE 802.15-1 – Bluetooth <ul><li>Data rate </li></ul><ul><ul><li>Synchronous, connection-oriented: 64 kbit/s </li></ul></ul><ul><ul><li>Asynchronous, connectionless </li></ul></ul><ul><ul><ul><li>433.9 kbit/s symmetric </li></ul></ul></ul><ul><ul><ul><li>723.2 / 57.6 kbit/s asymmetric </li></ul></ul></ul><ul><li>Transmission range </li></ul><ul><ul><li>POS (Personal Operating Space) up to 10 m </li></ul></ul><ul><ul><li>with special transceivers up to 100 m </li></ul></ul><ul><li>Frequency </li></ul><ul><ul><li>Free 2.4 GHz ISM-band </li></ul></ul><ul><li>Security </li></ul><ul><ul><li>Challenge/response (SAFER+), hopping sequence </li></ul></ul><ul><li>Availability </li></ul><ul><ul><li>Integrated into many products, several vendors </li></ul></ul><ul><li>Connection set-up time </li></ul><ul><ul><li>Depends on power-mode </li></ul></ul><ul><ul><li>Max. 2.56s, avg. 0.64s </li></ul></ul><ul><li>Quality of Service </li></ul><ul><ul><li>Guarantees, ARQ/FEC </li></ul></ul><ul><li>Manageability </li></ul><ul><ul><li>Public/private keys needed, key management not specified, simple system integration </li></ul></ul><ul><li>Special Advantages/Disadvantages </li></ul><ul><ul><li>Advantage: already integrated into several products, available worldwide, free ISM-band, several vendors, simple system, simple ad-hoc networking, peer to peer, scatternets </li></ul></ul><ul><ul><li>Disadvantage: interference on ISM-band, limited range, max. 8 devices/network&master, high set-up latency </li></ul></ul>
  90. 91. WPAN: IEEE 802.15 – future developments 1 <ul><li>802.15-2: Coexistance </li></ul><ul><ul><li>Coexistence of Wireless Personal Area Networks (802.15) and Wireless Local Area Networks (802.11), quantify the mutual interference </li></ul></ul><ul><li>802.15-3: High-Rate </li></ul><ul><ul><li>Standard for high-rate (20Mbit/s or greater) WPANs, while still low-power/low-cost </li></ul></ul><ul><ul><li>Data Rates: 11, 22, 33, 44, 55 Mbit/s </li></ul></ul><ul><ul><li>Quality of Service isochronous protocol </li></ul></ul><ul><ul><li>Ad hoc peer-to-peer networking </li></ul></ul><ul><ul><li>Security </li></ul></ul><ul><ul><li>Low power consumption </li></ul></ul><ul><ul><li>Low cost </li></ul></ul><ul><ul><li>Designed to meet the demanding requirements of portable consumer imaging and multimedia applications </li></ul></ul>
  91. 92. WPAN: IEEE 802.15 – future developments 2 <ul><li>Several working groups extend the 802.15.3 standard </li></ul><ul><li>802.15.3a: </li></ul><ul><ul><li>Alternative PHY with higher data rate as extension to 802.15.3 </li></ul></ul><ul><ul><li>Applications: multimedia, picture transmission </li></ul></ul><ul><li>802.15.3b: </li></ul><ul><ul><li>Enhanced interoperability of MAC </li></ul></ul><ul><ul><li>Correction of errors and ambiguities in the standard </li></ul></ul><ul><li>802.15.3c: </li></ul><ul><ul><li>Alternative PHY at 57-64 GHz </li></ul></ul><ul><ul><li>Goal: data rates above 2 Gbit/s </li></ul></ul><ul><li>Not all these working groups really create a standard, not all standards will be found in products later … </li></ul>
  92. 93. WPAN: IEEE 802.15 – future developments 3 <ul><li>802.15-4: Low-Rate, Very Low-Power </li></ul><ul><ul><li>Low data rate solution with multi-month to multi-year battery life and very low complexity </li></ul></ul><ul><ul><li>Potential applications are sensors, interactive toys, smart badges, remote controls, and home automation </li></ul></ul><ul><ul><li>Data rates of 20-250 kbit/s, latency down to 15 ms </li></ul></ul><ul><ul><li>Master-Slave or Peer-to-Peer operation </li></ul></ul><ul><ul><li>Up to 254 devices or 64516 simpler nodes </li></ul></ul><ul><ul><li>Support for critical latency devices, such as joysticks </li></ul></ul><ul><ul><li>CSMA/CA channel access (data centric), slotted (beacon) or unslotted </li></ul></ul><ul><ul><li>Automatic network establishment by the PAN coordinator </li></ul></ul><ul><ul><li>Dynamic device addressing, f lexible addressing format </li></ul></ul><ul><ul><li>Fully handshaked protocol for transfer reliability </li></ul></ul><ul><ul><li>Power management to ensure low power consumption </li></ul></ul><ul><ul><li>16 channels in the 2.4 GHz ISM band, 10 channels in the 915 MHz US ISM band and one channel in the European 868 MHz band </li></ul></ul><ul><li>Basis of the ZigBee technology – www.zigbee.org </li></ul>
  93. 94. ZigBee <ul><li>Relation to 802.15.4 similar to Bluetooth / 802.15.1 </li></ul><ul><li>Pushed by Chipcon, ember, freescale (Motorola), Honeywell, Mitsubishi, Motorola, Philips, Samsung </li></ul><ul><li>More than 150 members </li></ul><ul><ul><li>Promoter (40000$/Jahr), Participant (9500$/Jahr), Adopter (3500$/Jahr) </li></ul></ul><ul><li>No free access to the specifications (only promoters and participants) </li></ul><ul><li>ZigBee platforms comprise </li></ul><ul><ul><li>IEEE 802.15.4 for layers 1 and 2 </li></ul></ul><ul><ul><li>ZigBee protocol stack up to the applications </li></ul></ul>
  94. 95. WPAN: IEEE 802.15 – future developments 4 <ul><li>Several working groups extend the 802.15.4 standard </li></ul><ul><li>802.15.4a: </li></ul><ul><ul><li>Alternative PHY with lower data rate as extension to 802.15.4 </li></ul></ul><ul><ul><li>Properties: precise localization (< 1m precision), extremely low power consumption, longer range </li></ul></ul><ul><ul><li>Two PHY alternatives </li></ul></ul><ul><ul><ul><li>UWB (Ultra Wideband): ultra short pulses, communication and localization </li></ul></ul></ul><ul><ul><ul><li>CSS (Chirp Spread Spectrum): communication only </li></ul></ul></ul><ul><li>802.15.4b: </li></ul><ul><ul><li>Extensions, corrections, and clarifications regarding 802.15.4 </li></ul></ul><ul><ul><li>Usage of new bands, more flexible security mechanisms </li></ul></ul><ul><li>802.15.5: Mesh Networking </li></ul><ul><ul><li>Partial meshes, full meshes </li></ul></ul><ul><ul><li>Range extension, more robustness, longer battery live </li></ul></ul><ul><li>Not all these working groups really create a standard, not all standards will be found in products later … </li></ul>
  95. 96. Some more IEEE standards for mobile communications <ul><li>IEEE 802.16: Broadband Wireless Access / WirelessMAN / WiMax </li></ul><ul><ul><li>Wireless distribution system, e.g., for the last mile, alternative to DSL </li></ul></ul><ul><ul><li>75 Mbit/s up to 50 km LOS, up to 10 km NLOS; 2-66 GHz band </li></ul></ul><ul><ul><li>Initial standards without roaming or mobility support </li></ul></ul><ul><ul><li>802.16e adds mobility support, allows for roaming at 150 km/h </li></ul></ul><ul><ul><ul><li>Unclear relation to 802.20, 802.16 started as fixed system… </li></ul></ul></ul><ul><li>IEEE 802.20: Mobile Broadband Wireless Access (MBWA) </li></ul><ul><ul><li>Licensed bands < 3.5 GHz, optimized for IP traffic </li></ul></ul><ul><ul><li>Peak rate > 1 Mbit/s per user </li></ul></ul><ul><ul><li>Different mobility classes up to 250 km/h and ranges up to 15 km </li></ul></ul><ul><li>IEEE 802.21: Media Independent Handover Interoperability </li></ul><ul><ul><li>Standardize handover between different 802.x and/or non 802 networks </li></ul></ul><ul><li>IEEE 802.22: Wireless Regional Area Networks (WRAN) </li></ul><ul><ul><li>Radio-based PHY/MAC for use by license-exempt devices on a non-interfering basis in spectrum that is allocated to the TV Broadcast Service </li></ul></ul>