tructure of the Lecture Chapter 2 Technical Basics: Layer 1 ethods for edium Access: Layer 2 Chapter 3 Wireless Networks: Bluetooth, WLAN, WirelessAN, WirelessWAN obile Networks: G, GR, UT atellites and Broadcast Networks Chapter 4 obility on the network layer: obile I, Routing, Ad-Hoc Networks obility on the transport layer: reliable transmission, flow control, Qo obility support on the application layer Large variety of standards for different purposes: Bluetooth for wireless ad-hoc connections WLAN for installing wireless local networks (focus on mobility) WirelessAN for broadband access in whole buildings (focus on capacity) WirelessWAN for wireless access in larger regions, also with high speeds eite 1 WAN mallest radio network: Wireless ersonal Area Network (WAN) rominent example: Bluetooth 1994: Ericsson (attison/haartsen), C-link project Renaming of the project: Bluetooth according to Harald Blåtand Gormsen [on of Gorm], king of Denmark in the 10 th century 1998: foundation of the Bluetooth pecial Interest Group (Ericsson, Intel, IB, Nokia, Toshiba), www.bluetooth.org Later joined: 3Com, Agere, icrosoft, otorola ore than 2500 members 2001: first consumer products for mass market, specification v1.1 released Adopted from IEEE WAN Working Group for integration into the 802.15 standard. everal variants: Higher transmission rates Low transmission rates with very low power consumption ore stations per network eite 2 WAN - Bluetooth Bluetooth rotocol tack Universal radio interface for ad-hoc wireless connectivity of heterogeneous devices Interconnection of computers with peripherals, handheld devices, DAs, cellular phones i.e. target group: small devices with low capabilities Embedded in other devices, goal: 5 /device (2002: 50 /U Bluetooth) Often for devices already supporting G/GR or UT hort range (10 m, to achieve a low power consumption) Uses license-free 2,4 GHz I (Industrial-cientific-edical) band Voice and data transmission, ca. 1 bit/s gross data rate Automatic connection with devices in range earching for services installed on other devices ossible: bandwidth reservation, Qo parameters Authentication and ciphering One of the first modules (Ericsson) eite 3 Audio Audio vcal/vcard OBEX NW apps. TC/UD I /BNE Logical Link Control and Adaptation rotocol (L2CA) Baseband Radio AT modem commands RFCO (serial line interface) AT: attention sequence OBEX: object exchange TC BIN: telephony control protocol specification binary BNE: Bluetooth network encapsulation protocol Telephony applications TC BIN anagement D Link anager Control D: service discovery protocol RFCO: radio frequency comm. Host Controller Interface eite 4
Bluetooth rotocols Baseband/Radio rovide radio access for higher layer protocols Link anager rotocol (L) Connection management L2CA rovides several logical channels egmentation of large messages for data transfer Host Controller Interface (HCI) Command interface for access to baseband functions ervice Discovery rotocol (D) earching for services on other devices RFCO Emulation of serial interfaces (by this support of a variety of existing applications) Telephony Control rotocol pecification - Binary (TC BIN) Function for phone call control Radio/Baseband Usage of 2,4 GHz I band 79 channels with a bandwidth of 1 Hz each Channel 0: 2402 Hz Channel 78: 2480 Hz GK for odulation 1-100 mw transmission power edium access: TDD and FH Election of a master for transmission coordination Frequency hopping with 1600 hops/sec (resulting slot duration: 625µs) Hopping sequence in a pseudo random fashion, determined by the master Time Division Duplex for separation of send/receive operation of the master Topology Basic unit: iconet Overlapping piconets (stars) form a scatternet eite 5 eite 6 iconet Forming a iconet Basic unit of a Bluetooth network Connection of devices in an ad-hoc fashion Consists of one master () and up to 7 slaves () The master coordinates medium access (hopping sequence) laves only communicate with the master ossible: independent overlapping piconets. Devices which exchange data belong to the same piconet Each piconet has a unique hopping pattern, participation of a slave in the piconet means synchronization to that sequence = aster = lave = arked = tandby All devices in a piconet hop together The master sends out its clock and device ID Hopping pattern: determined by device ID (48 bit, unique worldwide) hase in hopping pattern determined by clock Addressing Active ember Address (AA, 3 bit) arked ember Address (A, 8 bit) eite 7 eite 8
Baseband tates of a Bluetooth Device tates detach standby transmit AA park A inquiry hold AA tandby: do nothing Inquiry: search for other devices age: connect to a specific device Connected: participate in a piconet page connected AA sniff AA unconnected connecting active low power modi ark: release AA, get A niff: listen periodically, not each time slot Hold: stop ACL, CO still possible, possibly participate in another piconet tandby Each 2048 slots (1.28s) a device listens on 32 of the 79 frequencies Choice of the frequencies bases on its device ID Incoming signals are examined, the device activates itself on demand age The initializing device becomes a master If the master knows the address of another device, it sends a page message directly Otherwise, the page message is sent on 16 of the devices 32 frequencies An answering devices becomes a slave Average time for connection establishment: 0.64 s Inquiry If the receiving device is unknown, this message is sent first by the master to discover its environment eite 9 eite 10 catternet Linking of multiple co-located piconets through the sharing of common master or slave devices Devices can be slave in one piconet and master in the other Communication between piconets By devices jumping forth and back between the piconets Frequency election during Data Transmission 625 µs f k f k+1 f k+2 f k+3 f k+4 f k f k : carrier frequency f in slot k regarding to the hopping sequence f k+5 f k+6 f k+3 f k+4 f k+5 f k+6 t = aster = lave = arked = tandby iconets (each with a capacity of 720 kbit/s) eite 11 f k TDA for coordinating the medium access TDD for duplex transmission: the master send in odd, the slave in even slots If several slaves are in the piconet: capacity is divided, the master cyclically polls all slaves (aster all odd slots, slaves share the even slots) 3 or 5 slots hops can be combined to one frame. No hoping during the frame, the hops are simply skipped f k+1 f k+6 t t eite 12
Link Types CO (ynchronous Connection-Oriented) Voice Reservation of slots in firm intervals 64 kbit/s data rate oint-to-point links, connection-oriented Only FEC (Forward Error Correction), no retransmissions ACL (Asynchronous Connectionless) Data Variable frame size (1,3,5 slots) Asymmetric (723,2:57,6 kbit/s) or symmetric (433,9 kbit/s) bandwidth oint-to-multipoint connections, connectionless with flow control ATER CO ACL CO ACL CO ACL CO ACL f 0 f 4 f 6 f 8 f 12 f 14 f 18 f 20 Baseband Frames Access code Unique identification in the piconet, basing on device ID of the master Consists of a preamble and a synchronization sequence (for hopping) Header Active ember Address (1 aster, 7 laves) acket type, e.g. high quality voice, OLL, Flow: flow control, receiver can stop the sender ARQN/EQN: sequence and acknowledgement numbers HEC: CRC checksum ayload: can use an additional FEC, if necessary (reducing the data rate) 72 54 0-2744 Bits access code header payload LAVE 1 f 1 f 7 f 9 f 13 f 19 LAVE 2 f 5 f 17 f 21 eite 13 1/3-FEC: spend 2/3 of the data for error correction 3 4 1 1 1 8 Bits A address type flow ARQN EQN HEC eite 14 CO ayload Types ACL ayload Types payload (0-343) payload (30) Header (1/2) payload(0-339) CRC (2) HV1 Audio (10) FEC (20) D1 Header (1) payload(0-17) 2/3 FEC CRC (2) HV2 Audio (20) FEC (10) DH1 Header (1) payload(0-27) CRC (2) (Bytes) HV3 Audio (30) D3 Header (2) payload(0-121) 2/3 FEC CRC (2) DV Audio (10) Header (1) payload (0-9) 2/3 FEC CRC (2) (bytes) DH3 D5 DH5 Header (2) payload(0-183) CRC (2) Header (2) payload(0-224) 2/3 FEC Header (2) payload(0-339) CRC (2) CRC (2) High-quality Voice, Data and Voice AUX1 Header (1) payload(0-29) Data edium/high rate eite 15 eite 16
Baseband Data Rates ACL 1 slot 3 slots 5 slots CO ayload ayload ymmetric Asymmetric Header User max. Rate max. Rate [kbit/s] Type [byte] [byte] FEC CRC [kbit/s] Forward Reverse D1 1 0-17 2/3 yes 108.8 108.8 108.8 DH1 1 0-27 no yes 172.8 172.8 172.8 D3 2 0-121 2/3 yes 258.1 387.2 54.4 DH3 2 0-183 no yes 390.4 585.6 86.4 D5 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) 2/3 yes 64.0+57.6 Data edium/high rate, High-quality Voice, Data and Voice eite 17 Example for ower Consumption ode CO connection HV3 (1s interval sniff mode) (lave) 26,0 ma CO connection HV3 (1s interval sniff mode) (aster) 26,0 ma CO connection HV1 (lave) 53,0 ma CO connection HV1 (aster) 53,0 ma ACL data transfer 115,2kbit/s (aster) 15,5 ma ACL data transfer 720kbit/s (lave) 53,0 ma ACL data transfer 720kbit/s (aster) 53,0 ma ACL connection, sniff mode 40ms interval, 38,4kbit/s 4,0 ma ACL connection, sniff mode 1.28s interval, 38,4kbit/s 0,5 ma arked lave, 1,28s beacon interval, 38,4kbps 0,6 ma tandby-odus (connected to host, no radio activity) 47,0 µa Deep sleep mode 20,0 µa eite 18 Acknowledgement echanism Link anager rotocol Retransmissions for ACL only, very fast; 1 Bit for sequence/acknowledgement numbers is enough because master and slave have to send alternating: ATER LAVE 1 LAVE 2 A C C F H B D E G NAK G ACK rovides additional functions to the simple baseband transmission service: Authentication of the communication partner, ciphering of data during transmission Clock synchronization (frequency hopping) by computing a clock offset added to the local time witching of master/slave roles, because the master has a higher power consumption witching of states (park, standby, active) Adaptation of transmission power regarding to measured signal strengths Reaction on varying transmission quality by changing the payload type (e.g. usage of a higher FEC rate when quality goes down) etup of CO connections. Default is ACL, but it can be used up to three CO connections in parallel eite 19 eite 20
L2CA - Logical Link Control and Adaptation rotocol imple data link protocol on top of baseband Connection-oriented and connectionless (based auf ACL), additionally signaling channels everal logical channels on one connection (rotocol multiplex: RFCO, D, ) anagement of Qo specifications per logical channel (delay, jitter, burst, bandwidth) egmentation & reassembly of data packets up to 64Kbyte user data anagement of communication groups L2CA Baseband lave L2CA Baseband aster L2CA Baseband lave Higher Layer rotocols Audio Audio vcal/vcard OBEX NW apps TC/UD I /BNE RFCO (serial line interface) Logical Link Control and Adaptation rotocol (L2CA) Baseband Radio Telephony applications AT modem commands TC BIN anagement D Link anager Control Host Controller Interface AT: attention sequence OBEX: object exchange TC BIN: telephony control protocol specification binary BNE: Bluetooth network encapsulation protocol D: service discovery protocol RFCO: radio frequency comm. Kapitel signaling 3.1: Bluetooth ACL connectionless connection-oriented eite 21 eite 22 D ervice Discovery rotocol rotocols to support Legacy rotocols/applications rotocol for the discovery of available services earching for and browsing services in radio range Adapted to highly dynamic environment Can be completed by other services like L, Jini, Only defines the discovery of services, not the usage Caching of discovered services Gradual discovery ervice record format Information about services provided by attributes Attributes are composed of a 16 bit ID (name) and a value Values may be derived from 128 bit Universally Unique Identifiers (UUID) RFCO Emulation of a serial port (supports a large base of legacy applications) Allows multiple ports over s single physical channel Telephony Control rotocol pecification (TC) Call control (setup, release) Group management OBEX Exchange of objects, replacement for IrDA WA Interactions with applications on cellular phones eite 23 eite 24
rofiles WAN: IEEE 802.15-1 Bluetooth Represent default solutions for a certain usage model Vertical slice through the protocol stack Basis for interoperability Generic Access rofile ervice Discovery Application rofile Cordless Telephony rofile Intercom rofile erial ort rofile Headset rofile Dial-up Networking rofile Fax rofile LAN Access rofile Generic Object Exchange rofile Object ush rofile File Transfer rofile ynchronization rofile rotocols Applications Additional rofiles Advanced Audio Distribution AN Audio Video Remote Control Basic rinting Basic Imaging Extended ervice Discovery Generic Audio Video Distribution Hands Free Hardcopy Cable Replacement rofiles Data rate ynchronous, connection-oriented: 64 kbit/s Asynchronous, connectionless 433,9 kbit/s symmetric 723,2 / 57,6 kbit/s asymmetric Transmission range O (ersonal Operating pace) up to 10 m With special transceivers 100 m Frequency Free 2.4 GHz I band Availability Integrated into several products, several vendors Connection setup time Depends on power mode ax. 2,56s, average 0,64s Quality of ervice Guarantees, ARQ/FEC anageability ublic/private keys needed, key management not specified, simple system integration Advantages/disadvantages Advantages: already integrated into several products, available worldwide, free I band, several vendors, simple system, simple ad-hoc networking, peerto-peer Disadvantages: interferences on I band, limited range, max. 8 devices per network, high setup latency eite 25 eite 26 WAN: IEEE 802.15 Further Developments WAN: IEEE 802.15 Further Developments 802.15-2: Coexistence Coexistence of WANs (802.15) and WLANs (802.11), both are using the same frequencies - quantify the mutual interference 802.15-3: High-Rate (UWB = Ultra Wide-Band) tandard for WANs with high data rate (20 bit/s or higher), while still lowpower and low-cost Data rates: 11, 22, 33, 44, 55 Bit/s, also as a vision: 500 Bit/s Ad hoc peer-to-peer networking ecurity Low power consumption Low cost Designed to meet the demanding requirements of portable consumer imaging and multimedia applications 802.15-4: Low-rate, very low-power (Zigbee) Low data rate solution with battery life time of several month up to several years and with very low complexity otential applications are sensors, interactive toys, smart badges, remote controls, home automation,... Data rates of 2-250 kbit/s, latency down to 15 ms aster/slave or peer-to-peer operation Up to 254 devices upport for critical latency devices, such as joysticks Automatic network establishment by the AN coordinator Dynamic device addressing, flexible addressing format Fully handshaked protocol for transfer reliability ower management to ensure low power consumption 16 channels in the 2,4 GHz I band, 10 channels in the 915 Hz U I band and one channel in the European 868 Hz band eite 27 eite 28
802.15.3 UWB The frequency spectrum is overcrowded thus use all of it! UWB Definition Time-domain behavior 0 1 0 1 Frequency-domain behavior Normal narrowband signal Narrow frequency range usceptible to jamming Frequency odulation Impulse odulation 1 0 1 2.4 GHz time 3 frequency 10 GHz UWB signal Broad frequency range Robust Low transmission power Communication that occupies at least 500 Hz of spectrum Frequency range 3.1 GHz to 10.6 GHz Indoor: up to 20 meters range uitable for short-distance communication with high bandwidth Emitted ignal ower G C 1.6 1.9 2.4 Bluetooth, 802.11b Cordless hones icrowave Ovens 3.1 5 Frequency (Ghz) 802.11a UWB pectrum 10.6 eite 29 eite 30 ossible Applications ossible Applications ersonal Area Networking (AN), connecting cell phones, laptops, DAs, cameras, 3 players with much higher data rates than Bluetooth or 802.11 Can be integrated into automotive in-car services and entertainment Download driving directions from DA/laptop for use by on-board navigation system using G Download music and videos for passenger entertainment Info-station concept: road side markers containing UWB transmitters hort burst of very high rate data (100s of Bit/s for 1-3 sec at a time) essages could contain road conditions, construction, weather advisories Allow for emergency assistance communication Vehicular Radar Collision Avoidance/Detection Driver aid/alert to avoid collisions. Aid for airbag/restraint deployment Resolution to distinguish cars/people/animals/poles on or near road eite 31 eite 32
odulation chemes Different coding schemes how to do modulation with short pulses? ulse length ~ 200ps Voltage swing ~100mV; ower ~ 10uW Common modulations: ulse position modulation () On/Off Keying (OOK) (can code n bit as once using 2 n positions at different times) ulse Amplitude odulation (A) (also: n bit using 2 n amplitude levels) Bi-hase ignaling (BK) (ossible: combination with ) eite 33 Advantages and Challenges Advantages of UWB Ability to share the frequency spectrum Large channel capacity Ability to work with low ignal-to-noise-ratios Low probability of interception and detection Resistance to jamming High performance in multipath channels uperior penetration properties ub-centimeter resolution of localization Low transmission power Challenges ulse-shape distortion High-frequency synchronization ultiple-access interference Low transmission power New higher-layer protocols for efficient use of the new network concept eite 34 UWB Variants: ingleband Approach UWB Variants: ultiband Approach Direct sequence (D-UWB) Use 2 frequency bands: 3.1-4.85GHz, 6.2-9.7GHz CDA has been proposed at the encoding layer Has no carrier frequency Requires wideband antennas otential problem with G and licensed bands ultiband Orthogonal Frequency Division ultiplexing (OFD) imilar in nature to 802.11a/g 14 528Hz bands (simplest devices need to support 3 lowest bands, 3.1GHz 4.7 GHz) Coexistence with other networks by avoiding certain bands edium Access: UWB systems typically use many pulse repetitions (100s) to represent each data symbol A uniform pulse train has spectral lines present (not a smooth spectrum) For multiple access this could also lead to catastrophic collisions. edium Access: utually orthogonal frequency bands for parallel usage Interference-free transmissions Efficient data transmissions eite 35 eite 36
Other Technology in hort Range: RFID Where to use RFID? RFID = Radio Frequency Identification Device Holds a small amount of unique data a serial number or other unique attribute of the item The data can be read from a distance no contact or even line of sight necessary (compared to, e.g., laser scanners) In response to a radio interrogation signal from a reader (base station) the RFID tags transmit their ID RFID tags withstand difficult environmental conditions (sunlight, cold, frost, dirt etc.) roducts available with read/write memory, smart-card capabilities Enables individual items to be individually tracked e.g. from manufacture to consumption Applications Total asset visibility: tracking of goods during manufacturing, localization of pallets, goods, etc Loyalty cards: customers use RFID tags for payment at, e.g., gas stations, collection of buying patterns Automated toll collection: RFIDs mounted in windshields allow commuters to drive through toll plazas without stopping Others: access control, animal identification, tracking of hazardous material, inventory control, warehouse management,... Local ositioning ystems G useless indoors or underground, problematic in cities with high buildings RFID tags transmit signals, receivers estimate the tag location by measuring the signal s time of flight eite 37 eite 38 assive RFID Tags Active RFID Tags Traditional tags used in retail security applications: Tag contains an antenna, and a small chip that stores a small amount of data Tag can be programmed at manufacture or on installation Tag is powered by the high power electromagnetic field generated by the antennas (connected to a reader) usually in doorways The field allows the chip/antenna to reflect back an extremely weak signal containing the data Collision Detection recognition of multiple tags in the read range is employed to separately read the individual tags Low prices Battery owered tags Have much greater range 100m Hold much more information Kbytes Can integrate sensing technology, e.g. temperature, G Can signal at defined time ultiple tags can be recorded at once Used for higher value items hipping containers Babies Electronic assets uch higher costs per item Life between 2 4 years eite 39 eite 40
RFID Tag Attributes RFID Radio Frequency Identification Tag power source Tag battery Availability of power Required signal strength Range ulti-tag reading Data storage Yes Continuous Very Low Up to 100m Active RFID Internal to tag 1000 s of tags recognized up to 160 km/h Up to 128Kb of read/write Energy transferred using RF from reader No Only in range of reader Very High assive RFID Up to 3-5m, usually less Few hundred within 3m distance of reader 128 bytes of read/write Data rate Transmission of ID only (e.g. 48 bit, 64kbit, 1 bit) 9,6 115 kbit/s Transmission range assive: up to 3 m Active: up to 30-100 m imultaneous detection of up to 256 tags, scanning of 40 tags/sec more using active tags Frequencies 125 khz, 13.56 Hz, 433 Hz, 2.4 GHz, 5.8 GHz and many others ecurity Application dependent, typically no coding on RFID device Availability any products, many vendors Connection setup time Depends on product/medium access scheme (typically 2 ms per device) Quality of ervice None anageability Very simple, same like serial interface Advantages/disadvantages Advantages: extremely low cost, large experience, high volume available, for passive RFIDs no power needed, large variety of products, relative speeds up to 300 km/h), broad temperature range Disadvantages: no Qo, simple Do attacks possible, crowded I bands, typically simplex connection (activation, transmission of ID) eite 41 eite 42 RFID Radio Frequency Identification ecurity Denial-of-ervice attacks are always possible Interference of the wireless transmission, shielding of transceivers IDs via manufacturing or one time programming Key exchange via, e.g., RA possible, encryption via, e.g., AE Further trends RTL: Real-Time Locating ystem big efforts to make total asset visibility come true Integration of RFID technology into the manufacturing, distribution and logistics chain ( Future tore in Rheinberg) Creation of electronic manifests at item or package level (embedded inexpensive passive RFID tags) 3D tracking of children, patients eite 43