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DeKalb County Technology Workshop July 12, 2005

DeKalb County Technology Workshop July 12, 2005. Agenda. Workshop Objectives Voice Communications Mobile Data Information Systems Key Considerations Discussion and Questions. Objectives. Develop a common understanding of common public safety communications and information technology terms

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DeKalb County Technology Workshop July 12, 2005

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  1. DeKalb CountyTechnology WorkshopJuly 12, 2005

  2. Agenda • Workshop Objectives • Voice Communications • Mobile Data • Information Systems • Key Considerations • Discussion and Questions

  3. Objectives • Develop a common understanding of common public safety communications and information technology terms • Improve understanding of current technologies currently used by DeKalb County • Familiarize and demystify technology • Understand key trends

  4. Voice Communications

  5. Voice Communications • Single Channel Radio Basics • Coverage Extension • Multi-Channel Systems • Analog & Digital • Spectrum Choices • Standards and Regulatory Issues • Vendors

  6. Single Channel Radio Basics • Simplex • Half-duplex • Full-duplex

  7. Simplex Communications • Talk-around; car-to-car • Much like a kid’s walkie-talkie • Radios transmit and receive on the same frequency • No infrastructure required • Higher frequencies roughly limited to line of sight Tx = 851.250 Rx = 851.250

  8. Simplex OperationMobile to Base (Talk-In) Tx & Rx = 851.250 Mobile 2 Mobile 1 Tx & Rx = 851.250 Tx & Rx = 851.250 • Dispatcher can hear Mobile 1 • Mobile 2 is out of range

  9. Simplex OperationBase to Mobile (Talk-Out) Tx & Rx = 851.250 Mobile 2 Mobile 1 Tx & Rx = 851.250 Tx & Rx = 851.250 • Mobile 1 & 2 hear dispatcher

  10. Half Duplex • Use of 2 frequencies allows base station to “repeat” communications • Base station transmits on mobile’s receive frequency • Mobile/portable radios transmit on base station’s receive frequency • Half-duplex equipment does not allow simultaneous transmission and reception for users

  11. Half Duplex (Repeater) OperationMobile to Mobile Tx = 866.250 Rx = 821.250 Rx = 866.250 Mobile 2 Mobile 1 Tx = 821.250

  12. Full Duplex • User can talk and listen simultaneously • Transmitter and receiver can be both powered and active full time • We are use to cellular phones working this way • Usually reserved for one-to-one communications • Not typical in wide-area private radio systems (one-to-many) • Wire line dispatch consoles can have “dispatcher priority” • User radios restricted to half-duplex operation

  13. Full Duplex (Repeater) OperationDispatch Priority Tx = 866.250 Rx = 821.250 Tx = 821.250 Rx = 866.250 Mobile 2 Mobile 1 Tx = 866.250 Rx = 821.250 (simultaneously) Wire line Console

  14. Frequency Utilization and Coverage Extension • Single-Site Repeated • Receiver Voting • Multicast • Simulcast • Regional Architecture

  15. Single-Site Repeated Tx = 866.250 Rx = 821.250 Rx = 866.250 Mobile 2 Mobile 1 Tx = 821.250 Rx = 866.250 Mobile 3

  16. Receiver Voting • Improves talk-in coverage (from field) • Does not extend talk-out coverage (to field) • Compares and selects the best signal from multiple sites to be repeated from transmitter • Ensures that the best audio from receivers is processed • Economical solution for limited applications

  17. Rx = 821.250 Voting Receiver Rx = 821.250 Voting Receiver Receiver Voting (Portable) Tx = 866.250 Rx = 821.250 Rx = 866.250 Mobile 2 Comparator (Voter) Tx = 821.250 Portable 1

  18. Multicast • Provides wide-area coverage by using multiple sites • Sites use different frequencies (frequency intense) • Variable density capabilities (some sites can have more channels than other sites) • Can have local area calls (calls that only appear on one site) • Cost effective use of infrastructure

  19. Multicast Tx = 866.250 Rx = 821.250 Channel 1 Tx = 868.500 Rx = 823.500 Channel 2 Rx = 866.250 Channel 1 Portable 2 Switch Or Patch Portable 4 Rx = 868.500 Channel 2 Rx = 868.500 Channel 2 Portable 3 Tx = 823.500 Channel 2 Portable 1

  20. Simulcast • Similar to multicast - wide area coverage by keying multiple transmitters simultaneously • Frequency efficient - each site uses the same frequencies • No variable density capabilities (all sites need the same number of channels) • All calls broadcast wide-area • Good for in-building urban coverage • Technically complex timing requirements – potential reception problems in overlap region • Expensive

  21. Simulcast Tx = 868.500 Rx = 823.500 Channel 2 Tx = 868.500 Rx = 823.500 Channel 2 Rx = 868.500 Channel 2 Portable 2 Comparator (Voter) Portable 4 Rx = 868.500 Channel 2 Rx = 868.500 Channel 2 Portable 3 Tx = 823.500 Channel 2 Portable 1

  22. Multi-Channel Systems • Conventional Systems • Trunked Systems

  23. Conventional Systems • Earliest form of radio communications systems • Most common type of two-way radio system • Individual agencies usually do not share channels • Frequencies are dedicated to specific channels and/or users • When channel is in use, others must wait their turn to use the channel

  24. Conventional Systems Street Maint EMS Fire Channel Law Channel Repeaters

  25. Advantages Simple to use Lower cost Non-proprietary Supported by a large number of radio vendors Usable in all frequency bands Disadvantages Incompatible frequency ranges Difficult to share channels Inefficient use of resources Separate systems for each agency Difficult to coordinate on a wide scale Conventional Systems

  26. Trunked Systems • Based on Telco queuing techniques • Developed to increase communications efficiency • Allows multiple users to share pool of channels • Computer controls radio and base stations • Radios have unique addresses • Talkgroups are “virtual channels” for groups of users that are temporarily assigned channels • Systems operate in 450, 700, 800 and 900 MHz bands • Ideal for regional systems serving many users from different agencies

  27. 3 3 Trunked Communications Radio 3003 receives Radio 3003 “APD” Users meet on Channel “3” Repeaters Radio 3001 transmits a channel request Channel 3 Channel 2 Radio 3001 transmits Channel 1 Radio 3001 Control Channel Main Site User depresses PTT The System finds channel “3” available The System Scans for all users on the “APD” talkgroup Radio 3001 transmits to radio 3003 on the “APD” talkgroup on channel 3 The System assigns channel “3” and transmits a message for users on the “APD” talkgroup With Users Identified, the System scans for an available channel

  28. Advantages Spectrum efficient Better channel utilization System redundancy Fault tolerance Talk group flexibility Scalable for additional users and talkgroups on a wide-area basis Enhanced features Disadvantages Proprietary systems Technically complex High cost Trunked Systems

  29. Regional Architecture Region Controller

  30. Analog and Digital Networks • Analog • Continuously transmit radio waves from one point to another by converting audio signals into radio frequency signals • Can also carry data by converting it to an analog signal via a modem • Digital • Emerging trend in voice communications • Translate an audio signal into a digital bit stream of ones and zeros using “vocoder” • Stream is sent over the airwaves and decoded at the receiving end • Receiving radio translates the digital stream into an audio signal equivalent to the original voice message

  31. Analog Advantages Proven, reliable technology Simple technology Lower component costs – cost to transition to digital can be very high Vendor compatibility Digital Advantages Spectrum efficiency Enhanced audio quality in fringe coverage areas Improved encryption capabilities Reduction of noise and interference Analog and Digital Networks

  32. Spectrum Choices • VHF Low Band • VHF High Band • UHF • 800 MHz • 700 MHz • 4.9 GHz

  33. Emerging Standards • APCO Project 25 (Phase I) • Identifies common air interface (CAI) (vocoder interface, encryption) • Federal grants encouraging purchase of P25 radios • Only 1 infrastructure provider • APCO Project 25 (Phase II) • Will increase channel capacity by 2x over Phase I • Not fully defined; may support “competing standards”, e.g., TDMA & FDMA • Limited vendors with ability to offer an end-to-end solution • TETRA • TErrestrial Trunked Radio – an open digital standard defined by the European Telecommunications Standards Institute • 4 channels per 25 KHz channel

  34. Regulatory Issues • Refarming • Focuses on reducing the bandwidths of Part 90 radio systems operating below 512 MHz • Reduction is in two stages: • 25/30 KHz to 12.5/15 KHz • 12.5/15 KHz to 6.25/7.5 KHz • Intended to increase efficiency of radio channels • Dates for implementation are a moving target • 700 MHz • Based on Balanced Budget Act of 1997 order to the FCC to allocate 24 MHz of spectrum for public safety usage • Channel availability dependent on television broadcast stations vacating operations on TV channels 60-69 • Regional planning committees working on licensing plans

  35. Standards and Regulatory Issues 4.9 GHz • Broadband technology for public safety • Goal is to create Wi-Fi functionality in a frequency that is exclusive to public safety • Typically, same members working on regional plans are working on the 4.9 GHZ plan

  36. Systems EF Johnson Kenwood M/A-COM Motorola Radios Datron DTC Communications DX Radio Systems EF Johnson Harris Icom Kenwood M/A-COM Midland Radio Motorola Relm Wireless Tait Thales Vertex Yaesu Vendors

  37. Mobile Data

  38. Background • Mobile data is the transmission and receipt of information using radio frequency signals • Several types of users are supported by wireless technologies • Mobile/portable users • Remote users • Telecommuters • Benefits include: • Immediate access to critical information • Field personnel empowerment • Reductions in voice radio traffic • Remote interactive access to business applications • Work order processing • Maintenance Management and Inventory • Project Management • GIS • Office automation (email, etc.)

  39. Mobile Data • Agency-Owned Networks • Commercial National Data Networks • Telco Networks • iDEN • CDPD • GPRS • EDGE • CDMA 1xRTT • Other Mobile Data Technologies

  40. Agency-Owned Networks • Private radio networks owned by agencies • Limited data speeds available • Often able to re-use key components of voice infrastructures • Packet switched, message based technologies • Dedicated access for users • Can be conventional or trunked technology • Wide-area coverage system providers include Dataradio, EF Johnson, M/A-COM and Motorola

  41. Advantages Optimizes existing infrastructure Agency control Dedicated use Potentially lower recurring costs Can provide coverage where needed (everywhere) Disadvantages Requires radio frequencies Additional administration and maintenance responsibilities Moderate data rates Requires fixed infrastructure throughout entire coverage area Capitalizing on technology advances can be costly High initial costs Agency-Owned Networks

  42. Commercial National Data Networks • Commercially developed data systems • Networks developed around population centers and major thoroughfares • Use proprietary, but widely available technology • Major networks include ARDIS and Mobitex • Some companies claim to cover 90% of the U.S. area containing 80% of the population – areas not well covered by other commercial carriers • Packet data network technology utilizing a satellite and terrestrial network • Data rates are noticeably slower (<8 kbps) than those offered by Telco's

  43. Advantages Network store and forward allows packets to be stored for sending at a later time Encryption available, if desired Costs are proportional to usage – ideal for limited usage Disadvantages Slow throughput Not efficient for long messages Commercial National Data Networks

  44. Telco Networks • No agency frequencies required • Minimal up-front costs • Lower hardware and software costs • Higher monthly recurring costs • Migration paths more feasible and economical • No site development required • Ability to provide for wide area roaming • Maintenance and service not the responsibility of the agency

  45. iDEN (Nextel) • Integrated Digital Enhanced Network • Motorola packet-switched technology • Throughput of 14.4 Kbps • No migration path decisions made to date • Nextel has submitted consensus plan to FCC for refarming 800 MHz spectrum

  46. Cellular Digital Packet Data (CDPD) • First commercial service widely adopted by public safety agencies • Utilized for traditional mobile data applications • Dispatch, status and vehicle-to-vehicle messaging • Automatic Vehicle Location (AVL) • Database inquiries • Maximum throughput of 19.2 Kbps – actual speeds typically 10-14 Kbps • Service is available in most metropolitan areas • Two major carriers offering national CDPD service plan to discontinue the service: • Verizon: Announced that CDPD service will end in 2005 • AT&T Wireless (Cingular): Announced that CDPD service will end in June 2004. Recently retracted this statement; however, they still plan to shut down the network in the near future. • Not a viable alternative due to coming obsolescence

  47. GPRS • General Packet Radio Services • Most widely deployed wireless technology worldwide • Maximum throughput of 115 Kbps – actual speeds typically 30-50 Kbps • Security concerns due to dynamic IP addressing • Major carriers include AT&T/Cingular and T-Mobile • Part of GSM migration path to faster data speeds that will minimize technology replacement costs for agencies.

  48. EDGE • Enhanced Data Rates for Global Evolution • Backward compatible with GPRS; only modem replacement required • Maximum throughput of 384 Kbps – actual speeds typically 80-128 Kbps • Successor to GPRS • Rollouts to begin in 2004 • Migration path leads to UMTS (Universal Mobile Telecommunications System) – throughput of 2 Mbps

  49. CDMA 1xRTT • Code Division Multiple Access – Single Carrier Radio Transmission Technology • Digital spread spectrum technology – efficiently uses spectrum • Competing technology to GPRS and EDGE • Major carriers include Verizon and Sprint • Maximum throughput of 144 Kbps – actual speeds typically 40-60 Kbps • Migration path leads to CDMA 2000 – up to 2.4 Mbps in throughput

  50. Other Mobile Data Technologies • Wireless Local Area Networks • Mesh Networks • Satellite

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