Communication Mediums for Signal, ITS, and Freeway Surveillance Systems Final Report (1996) / Chapter Skim
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A.1.7 Commercial Communication Services
A.1.7 Commercial Communication Services
Pages 263-344
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From page 263... ...
Table A.~.7.~-2 presents wireless data service rates. Emerging CDPD services win influence these rates in He future.
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From page 264... ...
1 - 3 years . ~ Peak: 7:00 am - 8:00 pm, Monday - Fnday Offpeak: 8:00 pm - ~ ~ :00 pm, Monday - Fnday 7:00 am - Il:OO pm, Weekends Night: Il:00 pm - 7:00 am, 7 days Table A.~.7.~-2 Wireless Data Service Rates Monthly Rate $ | kilobytes | , _ ARDIS $19.95 20 _ $50.00 150 $100.00 350 $190.00 750 _ RAM $25 100 $65 200 $88 275 _ $135 500 CDPD _ Amentech $20 100 $55 500 $99 1,000 AT&T $15 50 $50 500 $ each additional kilobyte $.54 $.35 $.33 $.31 $.27 $.20 $.11 $.10 $.11 to$.16 $.08 L:WCHRP\Phase2~pt\ NCHRP3-51 · Phase2FmalReport A1-256
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From page 265... ...
Often these special configurations require telephone company configuration support, and perhaps additional charges. The traffic on T} and SONET/fiber circuits varies Widely.
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From page 266... ...
Then, a discussion is offered on We ~eory/concepts of satellites as a communication medium. This is followed by short explanations of We various aspects of a satellite system such ., as orbits, satellite frequencies, channel bawds, typical digital bit-rates, and coverage capabilities.
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From page 267... ...
. _ Weather-related Indicate when roads are freezing, sensors flooded' experiencing high-winds, or low-visibility Highway Issue regular reports on the status superstructure stress of bridges, tunnels, overpasses, monitoring sensors and other vulnerable structures Smart signs Notify travelers of traffic congestion and suggest alternate routes Traffic flow control Include changing traffic light timing devices or controlling various traffic control-gates, based on traffic flow data National roadside Dropped off and set-up within assistance phones minutes Collision activated Transmit distress beacon to a distress beacons national reaction center along with precise location of vehicle Highway officials and Broad range of transmission rates' law enforcement from low (modem-type)
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From page 269... ...
For example, a data communications link used to transmit financial account balances must exhibit an extremely low rate of error to be effective. The error-rate specification for such a data communications service is directly translated into a required rate (C/N)
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From page 270... ...
LL 111 Z cn 0 > A llJ LO 111 Z cn 0 ~ cy o ~ o ~ A u]
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From page 271... ...
A channel is a one-way link from a transmuting earth station through the satellite to Me receiving earn station. A circuit is compnsed of two channels used for bi-dimctional communications between two earn stations.
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From page 272... ...
The uplink and downlink bands are separated In frequency to permit simultaneous transmission and reception without self-interference. Moreover, Me lowerfrequency band is normally used on the downJink to exploit the reduced atmospheric losses (at these lower frequencies)
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From page 273... ...
if 1 ' Q ~ 1 ~ ._ o 1 an C ~ a' _ .
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From page 274... ...
The Earth Station The second basic component of a satellite link is an earn station. A block diagram of a typical earth station is shown in Figure A.~.7.2.2.2-3.
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l l ~ ~ .c a' ~ £ i, ~ ~ > ~ o ~ ~ o in r ~ ~ ~ ~ c~ ~ ·Q~ 0 I ~ 116 1 ~ tm ~ !
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From page 276... ...
The Terrestrial Link Referring again to Figure A.~.7.2.2.2-3, He second part of the end-to-end satellite communications problem is embedded in He link between the satellite earth station and the user environment. This part deals more specifically with the baseband signal (i.e.
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From page 277... ...
To exploit the satellite's geometric advantage, there must be a method which permits more Man one each station pair to use a transponder simultaneously. Multiple access techniques have been used extensively in satellite communications.
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From page 278... ...
The main disadvantage of using Me FDMA approach is that its multiple-carriers are vulnerable to degradations due to intermodulation in the transponder. T~me-di~sion Multiple Access The second multiple access technique is time-division multiple access (TDMA)
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From page 279... ...
/ l l >I l ~ ~ Lo ~r - ~ en en - - = ace ~ A a)
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From page 280... ...
The foBow~ng sections offer descriptions of the venous aspects of a satellite system: orbits, satellite frequencies, channel bandwidths, typical digital bit-rates, and coverage capabilities. Orbits Most communications satellites are placed in a geosynchronous orbit which allows Rem to maintain a constant position in tile sky (see Figure A.~.7.2.2.3-~.
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From page 282... ...
One drawback is that by reducing the antenna yarn one risks totally eliminating a broad class of potential services whose performance would depend upon an adequate terminal antenna gain. Another drawback is ~at, by using these very wide beam antennas, one has created a very significant interference problem, which usually results in significant reductions in Be amount of available bandurid~ (because Be available bandwidth may be divided, and sub-divided, into small non-overlapping segments and these segments must be used in a carefully coordinated manner)
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From page 283... ...
vanes significantly depending on local terrain and the specific orbital configuration of the non-geosynchronous satellites. Some configurations spend most of Weir time at lower elevation angles, while others are more likely to be found at more favorable elevation angles.
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Satellite Frequencies There are advantages and disadvantages to using any of the various frequencies allocated to satellite communications. These differences are detailed in Table A.~.7.2.2.4-~.
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From page 285... ...
in · · -~ in hio In~ - .a _in ·· -~ ~as E ~ | m I m T:1~ 1~ m 5 ~ ~ co 0 ~ cat _ ~ ~ ~ ~ of cot ~ ~ ° ~ I m 1 = 1~1~ 1~ m ED Ico I N 12 1~ ~ = ~ L~ So-oO,2-1~5 1'244C`~= I 153 Lo W]
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From page 286... ...
The main drawbacks are that they are susceptible to severe rain losses, they have a somewhat immature technology (and are thus more expensive and somewhat less reliable) , and Heir increased paw loss cancels out the advantages of the increased antenna gains.
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From page 288... ...
The table is arranged win We lowest bit rate first, followed by successively higher bit rates. Note Tat the transmission of digital data can be performed by a custom-designed, application-specific digital canter or by some standardized digital carrier system (such as Me T!
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From page 289... ...
These beams are more power efficient than Me global beams because Hey provide power only in the region where it is needed and they are less likely to cause interference for the same reason. These beams range in size from a hem-beam (which covers approximately half of the global beam coverage)
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From page 290... ...
\ \ ~N \ / / / e m \ ~0 a: m N I / ~Al / a Cat C O N ~ 1` Ad: ~ kJ IS ~ 5w o o a: a: C,8 J
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From page 291... ...
l / lays: :~:1, - ~ -'I ~ Be ' -- ~ o 1 ~ m ,~' 0 0 ~, @~< O 1_ a)
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From page 292... ...
The "cellular-beam" coverage can be thought of as a combination of global coverage and spotbeam coverage (essentially the entire field-of-view of the satellite is covered by spot beams)
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From page 293... ...
(All of the systems typically use the C-band and Ku-band (fixed-service) satellite frequencies, except where noted.)
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From page 294... ...
of air disasters, natural disasters, war-torn regions, impoverished regions, etc. This technology is also used by news crews to provide live "on-~e-scene" reports of local and national events.
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From page 295... ...
may offer hand-held phones for bow land and sea comrnun~cations. L;\NCHRP`Phase2.rp~\ NCHRP 3-51 · Phase 2 Fmal Report A1-287
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From page 296... ...
This significant change in the fortunes of direct-broadcast television services is very illustrative of how a modest improvement in a cntical design element (in this case the required channel bandwidth and powers can transfonn a service/system which was unfeasible into something very desirable. Nadonal satellite paging system These fairly new systems are a logical extension of He more traditional pagers which can only operate within the transmission limits of the local paging company or perhaps in several local markets if "roaming" agreements are effected.
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From page 297... ...
data on land use, the oceans, and many over human and/or natural phenomena The use of satellite imagery for such applications has been a steadily growing industry for many years. Satellite weather services Another, more familiar, use of satellite imaging technology is weaver prediction from He analysis of atmospheric images and other data A logical extension of this capability would be to deliver this information directly to the Raveler.
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From page 298... ...
These degradations include Doppler frequency shifts (changes in the carrier frequency due to the relative movement between He transmitter and receiver) and multipath fading (severe drops in signal power as the unit moves into a region of destructive self-~nterference)
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From page 299... ...
The larger earn stations require a much L;\NCHRP\Phase:.lp~` NCHRP 3-51 · Phase 2 Fmal Report A1-291
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From page 300... ...
more stringent approval process, significant site construction, stand-by diesel power generators, and a full-time maintenance crew, because they cannot be idled by problems. A.1.7.2.S Planning, Design, Installation, Operation, end Related Costs This section presents the planning, design, installation, operation, and related cost issues for a potential satellite-based communications solution, which could serve a broad range of ITS needs.
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From page 301... ...
Includes supermarkets, fast food restaurants, department and hardware stores, etc. A general category which includes software companies, lottery systems, press agencies, newspapers, television and radio stations, and Be media generally.
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· Software Standard software Network Management System (NMS) Protocols Spares (lead time, spares pool location)
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From page 303... ...
/ After sales support (should be part of He contract conditions) · Technical · Sales/marketing Software support (annual maintenance or one-off purchase)
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From page 304... ...
SCPC /point-to-point Mesh systems ~ Voice · Data (At whet rate? Protocolsupport.)
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From page 305... ...
there were numerous grumbles about just how much was being asked by owners for the privilege of installing a dish, which, after all, was "very small." Despite ~is, zoning or planning permission is an issue in all parts of Europe and has definitely slowed Me deployment of many networks. ~ addidon, the instaBadon process, which includes site survey and license application, becomes more complex and more expensive.
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From page 306... ...
be traced to a sub-system and this entire unit removed and replaced, while the faulty unit is returned to the factory for repair. Most users contract for a VSAT network at least partly because of its reliability in comparison to the terrestrial alternative.
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From page 307... ...
L;\.NCHRP`Pha~.~p~\ NCHRP 3-51 · Phase 2 Fmal Report A1-299 l
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From page 308... ...
Table A.~.7.2.5-1 VSAT System Component Pricing Examples I .
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From page 309... ...
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From page 310... ...
Table A.~.7.2.5~2 Characteristics of Various tnmarsat Terminals Features Inm.A Inm-B Inm-C Inm-M Mini-M Channels ~1 ~ ~ ~ ~ ~ ~ ~ Voice ~Analog ~ 16 kbit / s ~ 6.4 kbit / s | 4.8 kbit / s Basic Data ~9.6 kbit/ ~ 9.6 kbit/s ~300 bit/s ~ 1.2 kbit/s ~ 1.2 kbit/s Max Data ~ 64 kbit /s ~ 64 kbit /s ~600 bit /s ~ 2.4 kbit /s ~ 1.2 kb~t /s RFBW T 40kHz | 20kHz | 5kH~ 10kHz | 5kHz Access | FDMA/SC C | FDMA/SCP | FDMA/SCP FDMA/SCP | FDMAISCP Mod FM Offset-QPSK Offset-Q PSK Offset-QPSK Offset-QPSK Type Continuous Burst Burst Burst Burst , HPA 1 40W T 20W I 16W 20W T 4W Talk Time N/A N/A NIA 20 mins. 1.5 furs.
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From page 311... ...
A.~.7.3 Broadcast Suboarriers for ITS (Ihis section is repented from Broadcast Subcarriers for ITS: An Introduction, by Eric Small, win permission of the publisher. Complete book available from: Modulation Sciences, Inc., 12A World's Fair Dnve, Somerset, NJ 08873 USA.)
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From page 312... ...
Broadcast subcarners can provide audio or data transmission channels for almost any ITS application. The range of reliable coverage is excellent, as great as a 40 mile radius for some radio and TV stations.
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From page 313... ...
The economic incentive to keep a radio or TV station on He air is great. The revenue from advertising for an EM radio station can range from $50 to L;\NCHR~Ph~p'\ NCHRP3-51 · Phase2FmalReport A1-305
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From page 314... ...
Subearriers on FM Stations Under die current FCC Rules, an F-M broadcaster has few restrictions on the programming or technical nature of the subcamers. By conventions, a "standard" background music style subcaliber on an FIRM radio station is a frequency modulated analog channel, has an audio frequency response of 50 Hz to 5 kHz and a signal-to-noise ratio of about 40 dB.
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From page 315... ...
RDS Another type of broadcast subcamer in common use, especially in Europe, is caned RDS (Radio Data System)
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From page 316... ...
The widespread availability of low cost hardware and the robustness of the transmission technology make RDS work considering for any llS activity that could function with low, but reliable, data throughput. Traditional "SCA" FCC Rules place almost no restncdons on the technical nature of subcamers on FM radio stations.
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From page 317... ...
6 In-house. Unformatted data transmission for private use by the broadcaster.
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However, a few fine arts stations in the U.S. will not catty any subcarriers, claiming that their presence is audible to some listeners~7.
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From page 319... ...
For example, FM broadcasting in Japan is tightly regulated technically and not highly competitive, very much like traditional European broadcasting. It is suspected that several of Me subcamer systems Tom Japan, if tested on typical U.S.
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From page 320... ...
In TV operation, all of the modulation needed for subcarners is obtained by increasing the total available modulation as needed. If the station is broadcasting stereophonic sound, Me available subcatriers are more or less defined by FCC Rules.
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From page 321... ...
stations operating stereophonically. It is important to note Hat these are baseband spectrum plots, not L;\NC~Phase2rpr~ NCHRP 3-51 · Phase 2 Fmal Report A1-313
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From page 322... ...
sac T°I!
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From page 324... ...
plots of the radio frequency spectrum. This is not how these signals would appear if an RF spectrum analyzer were used to observe them.
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From page 325... ...
Subcatiiers for AM radio stations are subsonic- below He 20 to 30 Hz cutoff for human perception of low frequencies. c:\NCHRP`Phasc2.rp`\ NCHRP 3-51 · Phase 2 Fmal Report A1-317
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From page 326... ...
Such low frequency operation limits He data rates possible with AM subcarIiers to typically less Man 100 bits per second. AM subcarriers have never been widely used, as their low data rate has limited Weir applications.
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From page 327... ...
Signaling speed is the "raw" data rate of the channel in bits per second. It is the most frequently quoted parameter of a data transmission system because it is the largest number that can be legitimately provided, and therefore the most impressive.
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From page 328... ...
Distance is mostly a function of He heights of the transmit and receive antennas and almost independent of He effective radiated power. L:\N~Phasc2.rp'` NCHRP 3-51 · Phase 2 Fmal Report A1-320
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From page 329... ...
These are communications lawyers and are usually based in Washington, DC, because that is where He FCC is. The Federal Communications Bar Association publishes a directory of its memberships.
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From page 330... ...
Bow of these will be digital technologies, and each will include auxiliary, non-program related data channels. L::~.NCHRP\Phase2.rp~\ NCHRP 3-51 · Phase 2 Fmal Report A1-322
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From page 331... ...
Each cell is assigned a group of unique baselmobile transmit frequencies that are not reassigned (i.e., reuse) in adjacent geographical cells except at sufficient distance so that propagation loss is sufficient because the remote signal power is sufficiency attenuated so as to not adversely interfere.
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From page 332... ...
111 11 11 o I ~ en LO I CL LO LLJ _ ~ C \ ~o 1 Z ~_ llJ LO LO ~ ~ CO ~_ I I 0 1 1_ ~X C: ~to | ~ z 1 ~ ~ O I 1 ' 1
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From page 333... ...
Within a cell, a mobile subscriber is assigned a frequency pair (i.e., transmitJreceive) by Me base station.
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From page 334... ...
The allocated frequency bands are presented in Figure A.~.7.4-2. It should be noted Mat Be FCC has allocated bow t.:`NC~Phasc:.rpr\ NCHRP3-51 · Phase2FinalReport A1-326
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From page 336... ...
o hi ~n co In lo ~ ~ y A a ~ in ~ O E u' E Y a A eS 0- ~ lo a O-= .= E m In a, co ~ ._ 0 42 I C,, a: c CO Cat o C)
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From page 338... ...
Data Rate | 4.8 kbps | kbps | 19.2 kbps 19.2 kbps Frequency Band | SMR | MR | Cellular l 800/900 MHz 800/900 MHz 824 - 894 Mbps Number of Channels 10 - 30 Cellular frequencies each Metropolitan area Coverage ~410 MSA 210 MSA 50 MSA (MSA- Metropolitan Service Area) Comment ~ Proprietary protocol ~ Proprietary protocol ~ Public protocol Analog modems over c~rcuit-sw~tched celdular phones are frequently used for wireless data transmissions.
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From page 339... ...
In addidon to the proliferation of wireless communications services, the wireless explosion is providing many standard "air interfaces" Mat could prove useful and adaptable to ITS applications. A.1.7.5 ISDN Integrated Services Digital Network (ISDN)
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From page 341... ...
Deployment over existing telephone company TWP loop plant by providing ISDN terminals at bow the customer premises and Be service CO (also in Figure A.~.7.5-~. PRI provides: Essentially DS-]
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From page 342... ...
: A Survey of Reception Reliability in the UK," Report BBC RD 1987/17, British Broadcasting Corporation Research Department, Engineering Division, Nov 1987.
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From page 343... ...
J Thyme, 'the transmission of Two Program~s From Band ITEM Transmitters: an assessment of 'Storecasdng'," Report BBC RD 1976ll4, British Broadcasting Corporation Research Department, Engineenng Division, June 1976.
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