Wireless MANs and Location Technology

Transcription

1 Wireless MANs and Location Technology David Tipper Associate Professor Department of Information Science and Telecommunications University of Pittsburgh Slides 4 Wireless Networks Wireless Wide Area Networks (WWANs) Cellular Networks : GSM, cdmaone (IS-95), UMTS, cdma2000 EVDO Satellite Networks: Iridium, Globalstar, GPS, etc. Wireless Metro Area Networks (WMANs) IEEE WiMAX Wireless Local Area Networks (WLANs) IEEE , a, b, g, etc. (infrastructure, ad hoc, sensor) Wireless Personal Area Networks (WPANs) IEEE (Bluetooth), IrDa, Zigbee, sensor, etc. 2

2 Wireless MANs Wireless Metropolitan Area Networks (WMANs) : provide wireless connectivity across a geographical area the size of a city 3 Wireless MANs Wireless MANs Want broadband data rates for last mile connectivity to businesses, homes and network bridging Triple play service (video, voice, data) Claimed Advantages: support for QoS, lower cost than cabling, user mobility in future. Currently variety of technologies, speeds, cost, coverage range, spectrum, etc. Market is fragmented among technology and small Proprietary Solutions Free Space Optical LMDS (Local Multipoint Distribution Systems) MMDS (Multipoint Microwave Distribution Systems) Wireless multi-hop mesh networks (based on ) Standards Based Solutions IEEE also called WiMAX, WirelessMAN IEEE with multi-hop extensions 4

3 Wireless MANs Proprietary Solutions Free Space Optical: point to point high data rates (100 Mbps -2.5Gbps) over short distances Unlicensed, uses infrared lasers LOS required severely effected by weather LMDS (Local Multipoint Distribution Systems) Bulk of deployment focused on backhaul extension of fiber infrastructure and cellular networks Operates in 28, 29 GHz spectrum Range 3-5 miles, weather effects MMDS (Multipoint Microwave Distribution Systems) Operates in MHz licensed spectrum Originally intended for wireless cable TV distribution 20MHz spectrum 99 10Mbps channels Range ~25Km (LOS and NLOS possible) Data rates ~.5-1 Mbps on 10Mbps channel WLAN equipment with mesh routing, scheduling, flow control Use a/g equipment to build mesh need many APs Proprietary equipment seen as a hindrance to market growth 5 IEEE /WiMAX Standard Worldwide Interoperability for Wireless Microwave Access (WiMAX) IEEE Broadband Wireless Access Standards Working Group Started in 1998 led by NIST Since July 1999 IEEE working group meeting bimonthly Suite of WiMAN standards As in WLAN standard focus is Physical and MAC layers only! In parallel to IEEE , European Telecommunication Standards Institute (ETSI) HiperMAN and HiPERACCESS work High performance radio metropolitan area network (HiperMAN) IEEE and HiperMAN have largely converged Same MAC layer and a OFDM as Physical layer baseline 6

4 IEEE /WiMAX Standard Worldwide Interoperability for Wireless Microwave Access (WiMAX) industry alliance (WiMAX Forum) started to promote equipment development and interoperability testing/conformance Interoperable multi-vendor fixed/nomadic/mobile/ wireless access networks using microwaves - line of sight not required Define a set of ``profiles for interoperability/conformance testing Profile specify the physical layer for a frequency band and various MAC layer parameters According to In-Stat ~220,000 WiMAX subscribers in 2006 predict 19.7 million by 2010 mostly fixed service in underdeveloped countries/regions - largest announced network build out in Pakistan Alvarion dominant equipment vendor, Intel dominant chip set vendor. 7 IEEE /WiMAX Standard IEEE developed as a Wireless Metropolitan Area Network (MAN) protocol Focus wireless alternative to DSL and T1 level services for last mile broadband access and backhaul for other technologies (WiFi, cellular) Characteristics of Point to Multipoint (PMP) and Mesh protocol NLOS wireless broadband services including bandwidth on demand QoS support Security Scope expanded to include mobility and higher data rates Focus on both licensed and unlicensed spectrum deployment supports multiple service providers/licenses in same area TDD and FDD duplexing support with flexible channel sizes Terminology Base Station (BS) is WiMAX cell site/access point Subscriber Station (SS) is customer premise equipment and terminates the wireless link to the user location Mobile Station (MS) is a standalone consumer device equipped with a WiMAX radio 8

5 WiMAX Architecture 9 WiMax Service Architectures WiMax services Point to Multi-Point Non-LOS, Wi-Fi sort of service, where a small antenna on a computer/ roof top connects to the tower. Later upgrade for mobile service to computer/handset LOS, where a fixed antenna points straight at the WiMax tower from a rooftop or pole. (LOS can provide higher data rates) Point to Point Focused LOS antennas high data rates with longer distances 10

6 IEEE WiMAX Standards Scope of standard is bottom two protocol layers same as other 802 standards 11 IEEE WiMAX Standards Suite of standards for WiMANs : approved 12/ GHz range LOS only a-2003 : System for 2-11GHz range NLOS (802.16d): System for 2-6 GHz range supports nomadic/limited mobility In a fashion similar to IEEE multiple physical layers with common MAC layer defined a and 2004 define three physical layers SCa single carrier OFDM 256 carriers OFDMA 2048 carriers (OFDM multiple access) (multiple access by assigning a subset to a user) Physical layer standards often called ``WirelessMAN standard Most equipment/wimax conformance on OFDM 256 carrier (802.16d) standard which is common to ETSI HIPERMAN standard 12

7 Main IEEE Standards Dominant standard a e-2005 Date Completed December 2001 January 2003 June 2004 December 2005 Spectrum GHz 2-11 GHz 2-11 GHz 2-6 GHz Operation LOS Non-LOS Non-LOS Non-LOS and Mobile Bit Rate Mbps Up to 75 Mbps Up to 75 Mbps Up to 15 Mbps Omnidirectional Cell Radius 1-3 miles 3-5 miles 3-5 miles 1-3 miles 13 Techniques used in Orthogonal Frequency Division Multiplexing (OFDM) to reduce multipath effects and provide higher speeds Forward error correction rather than ARQ FEC uses an outer RS block code and an inner convolutional code Adaptive modulation and coding adjust the modulation/coding depending on the quality of the radio link, subscriber by subscriber, burst by burst, up and downlink Admission control Ensures that new flows do not degrade the quality of established flows MAC Layer Scheduling: traffic scheduling to provide QoS traffic classes Flexible Channel size nx1.25mhz, n x 1.5MHz, n x 1.75 MHz, Max of 20MHz TDD and FDD modes supported Smart antenna technology 14

8 Physical layers for a/d Sca single OFDM OFDMA carrier Frequency 2-11 GHz 2-11 GHz 2-11 GHz Modulation BPSK, QPSK, 16QAM, 64QAM, 256QAM BPSK, QPSK, 16QAM, 64QAM QPSK, 16QAM, 64QAM No. of subcarriers N/A Duplexing TDD, FDD TDD, FDD TDD, FDD Channel MHz MHz MHz Bandwith OFDM 256 Carrier option is currently available 192 Carriers used for data, 8 pilot channels, 56 guard band 15 IEEE d Coding/Modulation Table of the maximum data rate in Mbps for the various channel/ coding/modulation options in d with 256 carrier OFDM physical layer Modulation rate used on a set of 256 carriers depends on RSS Modulation FEC Coding Channel Bandwidth QPSK 1/2 QPSK 3/4 16 QAM 1/2 16QAM 3/4 64 QAM 2/3 64 QAM 3/ MHz MHz MHz MHz MHz MHz

9 Data Ranges Achievable data rate depends on distance to BS, LOS/NLOS, propagation environment will vary! 18Mbps 4Mbps Data Ranges Achievable data rate depends on distance to BS, LOS/NLOS, propagation environment will vary! 18

10 802.11/ Spectrum UNII International Licensed ISM US Licensed International Licensed Japan Licensed ISM GHz has both licensed and license-exempt options ISM: Industrial, Scientific & Medical Band Unlicensed band (802.11a,b, g) UNII: Unlicensed National Information Infrastructure band Unlicensed band Licensed band 2.5 GHz US and 3.5 GHz International 19 Licensed Systems in U.S. U.S. has licensed spectrum GHz License 22.5 MHz - 8 licenses per geographic area operator can acquire multiple licenses Outside U.S. 3.5 GHz, 4.8GHz and 10.5 GHz bands used for licensed WIMAX Main unlicensed band is U-NII GHz TDD and FDD options for every band For example, TDD used with 5 MHz channels in 2.5 GHz band FDD pair of 2.5 MHz channels (one uplink, one downlink) in 3.5 GHz band TDD cheaper implementation and is recommended more for unlicensed spectrum 20

11 IEEE MAC Layer MAC Layer is independent of physical layer used Point to Multipoint TDMA Scheduled Uplink/Downlink Frames Flexible QoS offerings Connection oriented Per Connection QoS Integrated Security Sublayer Selective ARQ Adaptive Modulation and Coding selection Increase capacity and vary data rates Burst by burst, per subscriber station Adaptive Power Control 21 MAC Addressing SS has a 48 bit IEEE 802 MAC address BS has a 48 bit BS ID 24bits are a network operator indicator Each flow to a SS is assigned a 16bit connection ID (CID) used in the MAC protocol data units and to provide QoS class identifier 22

12 Multiple Access On DownLink SS addressed in TDM stream On Uplink, SS allotted a variable length TDMA slot TDD DL & UL time share the RF channel Dynamic asymmetry SS doesn t transmit receive simultaneously (lowers cost) FDD DL & UL separate RF channels Static asymmetry Half Duplex SSs supported (lower cost) IUC interval usage code specifies a modulation, rate and FEC for a time interval on DL or UL 23 TDD Structure TDD frames is 1ms durations adaptively partitioned among up and downlink 24

13 TDD Structure DL part of frame contains DL-MAP which specifies the modulation and coding for various TDM slots UL-MAP determines which SS gets slots in UL part of frame and modulation and coding used 25 FDD Structure DL part of frame contains DL-MAP which specifies the modulation and coding for various TDM slots TDMA portion is for support of half duplex users UL-MAP determines which SS gets slots in UL part of frame and modulation and coding used 26

14 TDD/FDD UL Structure Contention part for SS to initiate connection followed by TDMA slots 27 FDD Framing 28

15 QoS Services 29 Classes of Uplink Service Unsolicited Grant Services (UGS) For constant bit rate (CBR) or CBR like emulation (e.g., leased T1 service) Real Time Polling Services (rtps) For rt-variable bit rate (rt-vbr) flows such as video Non-Real Time Polling Services (nrtps) For non-rt flows that need better than best effort service such as file transfer Best Effort (BE) 30

16 WiMax Applications According to WiMax Forum it supports 5 classes of applications: 1. Multi-player Interactive Gaming. 2. VOIP and Video Conference 3. Streaming Media 4. Web Browsing and Instant Messaging 5. Media Content Downloads Basically the Triple Play These are mapped into QoS requirements for the MAC layer 31 Application Requirements 32

17 IEEE Security Security is a sublayer of the MAC in the standard Security Mechanisms Authentication and Registration PKI at the BS with X.509 digital certificates installed by manufacturers in SSs Downloaded to BS with manufacturers public key Access Control (similar to WiFi - WPA) MAC/IP address filtering VPN at higher layers, passwords, etc. Privacy DES with 128 bit key (triple DES) Plans to move to AES PKI for key distribution Key refreshed based on activity max usage 20 hours 33 WiMax Rollout WiMax Forum anticipates rollout of its technology in 3 phases: - Phase 1: Fixed Location, Private Line Services, Hot Spot Backhaul. - Phase 2: Broadband Wireless Access/Wireless DSL - Phase 3: Fully Mobile/Nomadic Users. 34

18 WiMax Evolution Path 35 Wireless Networks Network Geographic Coverage Typical Throughput Standards WWANs National, Continent wide 2G: Kbps, 2.5G: Kbps 3G : 50kbsp- 2Mbps 3.5G:.1 10 Mbps 2G: GSM, cdmaone 2.5G: GPRS, cdma X-rtt 3G: UMTS, cdma2000 1x-EDVO 3.5G: HSPDA WMANs Metro, suburb, campus 1-15 km 2~100 Mbps IEEE WLANs In building, campus wide, subdivision wide, Range ~ 100 M per AP Mbps IEEE 80211a, b, g, etc. WPANs 5-10 M around device.1 1Mbps IEEE IrDa, BlueTooth, Zigbee 36

19 Frequency Allocations Europe USA Japan WWANs Licensed WMANs Licensed Unlicensed Cellular: MHz, MHz; PCS: MHz, MHz; MHz, MHz 3G: MHz MHz IEEE GHz SAME as WLANs Cellular MHz, MHz; PCS MHz, MHz; IEEE GHz, GHz Same as WLANs Cellular MHz, MHz; MHz, MHz 3G MHz MHz IEEE GHz Same as WLANS WLANs Unlicensed WPANs Unlicensed IEEE MHz GHz HIPERLAN MHz IEEE MHz IEEE MHz (b, g) GHz (a) IEEE MHz IEEE MHz (b, g) GHz (a) IEEE MHz 37 Location Aware Services Industry forecast that the location services marketplace in the United States will generate $8 billion annually by $40 billion worldwide in 2006 Location Based Applications (LBA) Applications capable of finding the geographical location of an object and providing services based on the location information Not only in mobile systems (911) Examples for mobile systems Traffic updates Next bus Friend finder Direction to nearest X ( X is hospital, store, bar, etc.) 38

20 Location Aware Services Technology originally driven by E-911 mandate in U.S. goal was to develop systems to locate emergency cell phone calls Now many applications envisioned Emergency Services Navigation Directions Traffic management Information Entertainment, shopping info, advertisements Tracking Vehicle tracking, people tracking Billing Location sensitive billing Systems currently being deployed or in use some use rough location information (cell and sector id) others more detailed AT&T M-life buddy finder, Telecom Italia Guardian Angel 3 proximity dating service 39 Taxonomy of Location Absolute and Relative Location Absolute uses a reference grid (Longitude, Latitude) Relative depends on its own frame of reference Nearest hospital to car accident Physical and Symbolic Location Physical Location Uniquely identifies a point on 2D or 3D map of the earth Symbolic location Coarsely identifies a physical location School, work, home, etc. 40

21 Location Accuracy Accuracy needed depends on application Service Emergency Navigation Information Tracking Billing Example 911 call directions Mobile Yellow Pages, Advertisement Vehicle/Package Tracking Location based billing Accuracy High High Medium Low Low to medium 41 Location Services Examples 42

22 Enhanced 911 Location data accompanied with 911 call, expedites Service emergency response Opportunity time can save lifes FCC mandate (94-102) driving demand for location capability Phase I Wireless carriers to supply cell site, sector, and call-back number for 911 calls. Phase II - By December 31, 2004, Undertake reasonable efforts to achieve 100% penetration of Assisted Location Information (ALI) -capable handsets in its total subscriber base. Requires public safety answering point (PSAP) capable of displaying position data 43 FCC Phase II Location Accuracy Requirements FCC Requirements for Location Accuracy For network-based solutions 100 meters for 67% of 911 calls, and 300 meters for 95% of 911 calls For handset-based solutions 50 meters for 67% of 911 calls, and 150 meters for 95% of 911 calls Both approaches require the use of wireless location technology Equipment and algorithms added to network to find user position Location technology options are similar regardless of wireless technology (GSM, IS-95, UMTS, WLAN, etc.) Timing, Triangulation, Received Signal 44

23 Location Technology Network-Based Approaches add equipment to network to locate mobile Time Difference of Arrival (TDOA) Angle of Arrival (AOA) Multipath Analysis (MPA) Handset-Based Approaches Handset determines location and reports it to the network Global Positioning System GPS Advanced Forward Link Trilateration Hybrid (Network+ user assisted approach) Combine handset and network based techniques Assisted GPS A-GPS Enhanced Observed Time Difference (EOTD) 45 Network: Time Difference of Arrival (O-TDOA) Uses existing cell towers/aps and infrastructure to triangulate user s location Uses very accurate clocks to determine the difference in time in which uplink radio signal from user reaches different cell sites. Difference in time is resolved to determine position, velocity, and heading. Can use the same idea with received signal strength but not accurate enough due to obstructions, multipath, etc. Need synchronization of cell sites. 46

24 Network: Angle of Arrival Requires specialized listening receivers to be placed at the base station Requires construction of directional uplink antenna array onto existing cell towers (similar to spot beams) Measures the direction of signal received at multiple towers with respect to antennas of known position to determine mobile position Requires 2 or more basestations or sectors to receive the signal 47 Network: Multipath Analysis Constructed a database of the received uplink multipath signal on a location grid for a specific service area Uses existing cell towers and infrastructure, may require additional specialized receivers to placed at the base station to improve accuracy Uses the multipath database to match the transmitter s signal characteristics to determine a point on the location grid Also called fingerprinting of locations Can be very accurate time consuming 48

25 Handset: Global Positioning System Requires GPS receiver and GPS antenna to be imbedded into the mobile phone Requires traffic or control channel resources for handset to transmit location data Employs signal timing techniques from four or more satellites from a constellation of 24 to determine position Can require a significant time to compute position. GPS signal hard to pick up indoors or dense urban environment 49 Handset: Advanced Forward Link Trilateration A Time Difference of Arrival technique using the handset s receiver and the downlink radio signal MS needs to receive 3 or more BS signals at sufficient signal strength to triangulate it s position Requires phones with precise timing. Needs systemwide Base Station Synchronization Requires traffic/control channel resources to transmit location data from handset 50

26 Hybrid : Assisted Global Positioning System (A-GPS) Requires GPS receiver and GPS antenna to be imbedded into the mobile phone Requires special GPS servers to be placed throughout the area of coverage to assist mobile receivers with acquiring GPS signals or reradiating GPS signal to indoor/shadowed aread Mobile GPS receivers communicate with stationary GPS servers to assist in position determination helps speed up calculation and indoor acquisition Requires traffic/control channel resources to transmit assistance and location data 51 Hybrid: Enhanced Observed Time Difference of Arrival (E-OTDA) A Time Difference of Arrival technique using the handset s receiver and specialized reference receivers to triangulate position Use Forward and Reverse Link measurement Requires phones with precise timing. Requires addition of new uplink receivers throughout the network Requires traffic/control channel resources to transmit assistance messages and location data 52

27 Implementation Considerations Network-based approaches Additional equipment in base station Use of telecommunication links between base station and mobile switch Added system testing Added system maintenance Cost/scalability Handset-based approaches Additional equipment in base station Additional equipment (servers) in network Use of air interface resources between mobile station and base station Use of telecommunication links between base station and mobile switching center Added system testing Added system maintenance Handset upgrades/replacement Distribution/inventory logistics 53 Accuracy Technique TDOA AOA MPA GPS AFLT EOTD AGPS Handset Impact NO NO NO Yes YES YES YES Resolution m m 1-5M (depends on grid size) 3-5 M M M 3-30M 54

28 Evolving Standards for Location Tracking CTIA TR 45.5 geolocation network support for AMPS, NA-TDMA, IS-95 E-OTDA, A-GPS options for each technology 3GPP GSM, GPRS, EDGE, UMTS E-OTDA, A-GPS options for each technology 3GPP2 cdma 2000 (UWC-136B) network assisted A-GPS USA Service Provider Techniques Adopted Verizon, Sprint: A-GPS, AT&T, T-Mobile: E-OTDA Open Mobile Alliance 56 OMA Location Architecture Open Mobile Alliance (OMA) Location working group - absorbed earlier work by Location Interoperability Forum (LIF) LoCation Services (LCS) Architecture Leverages normal infrastructure for transport and resource management - independent of wireless location technology used LCS Architecture Components UE (User Entity) may assist in position calculation LMU (Location Measurement Unit) Maybe required or not depending on location technology approach adopted if used is distributed among the cells SMLC (Serving Mobile Location Center) Coordinates measurements to determine location GMLC (Gateway Mobile Location Center) Location server for outside queries 57

29 OMA LCS Architecture Gateway Gateway Mobile Mobile Location Location Center Center Serving Serving Mobile Mobile Location Location Center Center Two Key Components in backhaul Gateway Mobile Location Center Application interface for location services Application Authentication Privacy checking Interrogates HLR to find visited MSC/SGSN Roaming user can be located Called Mobile Positioning Center (MPC) in IS- 95/3GPP2 Standalone equipment or integrated into GMSC Serving Mobile Location Center Determines the location Talks to access network and user device Standalone equipment or integrated into BSC/RNC or MSC/3GMSC Called Position Determining Entity (PDE) in IS- 95/3GPP2 58 OMA Location Architecture for UMTS/GSM LCS signaling (LLP) LCS signaling (RRLP) over RR/BSSAP over RR-RRC/BSSAP SMLC Ls LMU LMU (Type B) Abis Lb (Type A) Abis A LCS signaling in BSSAP-LE LCS signaling over MAP Lg SN GMLC Lr UE BTS Iub BSC SMLC Gb Iu MSC Gs VLR HLR Lg Lh CN SN GMLC (LCS Server) Le LCS Client LMU Node B (LMU type B) RNC SGSN LCS signaling over RANAP or IP LMU Location Measurement Unit SMLC Serving Mobile Location Center GMLC Gateway Mobile Location Center 59

30 14. Application Response Internet 1.Application Request 3. Location Area RequestI HLR Application Server 4. LA response 2.Location Request 12. Location Response IP 5. PSL Request GMLC 8. Take Measurements 11. PSL Response 9. Get measurements MSC BSC 6. Perform Location Request 10 Perform Location Response SMLC 7. Initiate Measurements Example performing position location of GSM user using E- TDOA LMU BTS BTS BTS LMU LMU Provide Location ESME/ ALI 11. esposreq IP Dialup 10. ESPOSREQ 9. Query Location GMLC PSAP 8a.SLR SAS PSTN 8b. Call setup MSC 4.PCAP req WARN 2.Emergency Call Invoke 3.LRC 7.LRC resp RNC 5.PCAP resp Standards based UMTS Emergency Services Call walkthrough Utilising A-GPS 6.RRC Node B

31 Location Requests MLP Mobile Location Protocol from Location Interopability Forum (LIF) -> now part of Open Mobile Alliance based on HTTP/SSL/XML allows Internet clients to request location services Response includes quality of the location estimate GMLC is the Location Server UE (handset) can be idle, but not off! Immediate or deferred result, can request periodic updates 62 MLP Services Standard Location Immediate Service (SLIS) Provide location of mobile user to an LCS client based on LCS client s request Standard Location Reporting Service (SLRS) Provide location of mobile user to an LCS client based on user s request Triggered Location Reporting Service (SLRS) Provide location of mobile user to an LCS client based on preset events (e.g., time of day) Emergency Location Immediate Service (ELIS) Provide location of mobile user to an LCS client based on emergency LCS client s request (e.g., police) Emergency Location Reporting Service (SLRS) Provide location of mobile user to an LCS client when an emergency call is placed (e.g., 911) 63

32 Summary Wireless MANs Architecture Standards Protocol Location Based Service Techniques for determining location Architecture Protocols 64