Channel Loading Calculator for 700 MHz Regional Planning Committee

This Channel Loading Calculator provides insights into determining the minimum number of channels needed to optimize radio service while conserving spectrum. It focuses on valid data inputs for accurate calculations, based on empirical data from a Motorola 800MHz simulcast trunking system in Oregon. Explore the statistics, including agencies, talk groups, subscribers, push-to-talks, airtime, and default settings such as Grade of Service and Hang Time.

• Channel Loading Calculator
• 700 MHz
• Radio Service
• Spectrum
• Oregon

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1. CHANNEL LOADING CALCULATOR FOR 700 MHz Regional Planning Committee Guidance By Joe Kuran Wednesday March 9th 2016

2. MULTI-AGENCY TRUNKING SYSTEM CHANNEL LOADING CALCULATOR Total with Total with Growth Growth 4876 4876 Description Description Agency A Agency A Agency B Agency B Agency C Agency C Agency D Agency D Agency E Agency E Agency Agency Total Total AVE AVE 4000 4000 25% 25% 1000 1000 6 6 6000 6000 5 5 0.2 0.2 4000 4000 Radios owned by Agency Radios owned by Agency 25.0% 25.0% Percent used Percent used 1000 1000 1219 1219 Radios in use per Hour Radios in use per Hour 6.0 6.0 PTT's per radio per hour PTT's per radio per hour 6000 6000 7314 7314 Total PTT per hour Total PTT per hour 5.0 5.0 0.2 0.2 8.67 8.67 # radios # radios per hour per hour per freq per freq PTT Duration in Seconds PTT Duration in Seconds Hang-Time in Seconds Hang-Time in Seconds 10.56 10.56 Erlangs Erlangs 8.67 8.67 8.67 8.67 Performance Objectives Queue Wait time GoS # radios # radios per freq per freq sec 1 1 FDMA 1% 1% 211 211 53 53 # radios # radios per hour per hour per freq per freq Traffic Characteristics Erlangs # radios # radios per freq per freq 10.6 10.6 TDMA PTT Duration System Type System Type Total Frequencies 5.0 5.0 FDMA 19 19 sec 400 400 100 100 TDMA 10 10 Wait<1 sec wait>1 sec 2.61% 2.61% 0.59% 0.59% 2.0% 2.0% Growth percentage Growth percentage 10 10 Growth in years Growth in years

3. This Channel Loading Calculator is designed for anybody interested in channel loading Discover a fresh approach on how to determine the minimum number of channels needed. With this calculator you will be able to preserve your valuable spectrum and still deliver optimal radio service.

4. The main subject at this time will be to focus on how to get valid data that goes into the calculator. For existing system s airtime is For existing system s airtime is used. used. That could be 1 radio talking 17 minutes. or 17 radios each talking 1 minute

5. This empirical date is based on the C800/WCCCA Motorola 800MHz simulcast trunking system that covers Clackamas County and Washington Counties in Oregon. GenWatch was used to extract the data from the Master Site for the year of 2013.

6. Based on the following statistics Based on the following statistics: : Agencies = 40 Talk groups = 75 Subscribers = 7500 Push-to-talks = 14 million Airtime = 48 million seconds (1.5 years) Repeater hang time = 200mSec Erlang C default settings Erlang C default settings: GoS (Grade of Service) = 1% Busy Queue waiting time = 1 Second Talk groups have the same priority 12.5KHz FDMA/2-Slot TDMA voice only No Site restrictions Data would be a separate element :

7. Site Originations vs: Site Involvement Data is based on the sum of all PTT s that originated from all cells

8. System: ALL Zone: ALL Site: ALL Total Airtime Top 75 Talkgroups 90,000 80,000 70,000 60,000 Minutes 50,000 40,000 30,000 20,000 10,000 0 BV1 BV2 TIPDTAC1 DUNOPS LOPW2 ST-V INET PROVNBG NBPDDISP HBPDREC LOCOM NDPDTAC2 WV-BUS-1 CCSO-SIU WV-BUS-2 FO-FLAG HB1 HB2 NFDISP CCFTRN1 WCF-DISP WALAW1 WCJAIL CCDISP1 CCDISP2 CCDISP3 MER-PARK TCH SRVNET WASHA CLACKA SWPW1 CCTAC1 WCCRTSEC CCTAC2 CCTAC3 BVPDDET KAISERTAN WCSODET WASHB FGPDREC WCSO1 WCSO2 SC1 LOPD-1 CCOMDISP WCSOTAC2 WCSOTAC1 SWPDTAC1 CCCOURT BVPDTAC2 BVPDTAC1 HBPDDET IGET SC2 COPDDET PARKS-1 CNBYDET CCSOSWAT BVPDREC CC-F4-PATCH PROV-1 OPS34 OPS24 OPS25 OPS33 WCLUT1 OPS32 OPS35 OPS42 OPS37 OPS26 OPS39 WCF-TRN1 Talkgroups

9. Radios in use per average peak hour per Talkgroup Radios in use per average peak hour per Talkgroup Jan 1st 2013 WCSO1 WCSO1 Dec 31st 2013 WCSO Time 0:00 1:00 2:00 3:00 ~ 20:00 21:00 22:00 23:00 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Radios 44 41 40 40 ~ 18 23 24 21 44 320 7.27 PTTs 320 205 234 239 ~ 90 89 138 109 Radios 27 17 18 7 ~ 20 40 46 33 46 308 6.70 PTTs 101 75 77 59 ~ 133 245 308 208 Ave for year Peak Radios/Hour Peak PTT/Hour PTT/radio 45 314 6.98 6.59 6.59 40.98 40.98 269.7 269.7 The peak from each of the 365 days is than averaged The peak from each of the 365 days is than averaged

10. WASHINGON COUNTY SHERIFF TALK GROUP BREAKDOWN for 2013 902 Radios Owned by Agency WCSO1 WCSO2 WCJAIL WCSOTAC2 WCSOTAC1 CRTSEC WCSODET WCSO REC TOTAL 23.24 11.61 20.40 1.58 1.33 2.59 0.33 0.08 Daily (Avg Radios/Hour) averaged for the year 61.16 1 Daily (Peak Radios/Hour) averaged for 1 year 40.98 23.04 31.86 6.98 6.18 8.72 2.48 1.13 121.36 2 134.62 101.48 75.01 7.48 6.37 10.94 3.33 0.15 339.36 Daily (Ave PTT/Hour) averaged for the year 3 269.65 226.95 148.12 44.58 41.46 54.36 30.38 2.65 Daily (Peak PTT/Hour) averaged for 1 year 818.15 4 11,342,881 4,507,2363,398,8152,359,831 407,835 351,051 254,999 60,472 2,643 Total Airtime for the year secs 5 1,179,230 888,985 657,050 65,327 55,626 70,861 10,712 643 2,928,434 Total PTT for the year 6 5.77 8.71 3.66 4.66 4.68 3.97 4.39 1.82 4.71 Ave PTT per radio per hour(in 1 year period) 7 6.59 Peak PTT/radio/hour(in 1 year period) 9.97 4.67 6.49 6.64 5.93 7.47 2.09 6.23 8 3.82 Ave PTT duration(in 1 year period) secs 4.41 3.83 3.59 6.40 6.35 3.60 3.90 3.83 9 32.98 34.57 17.20 36.43 34.19 17.25 8.95 5.18 23.34 Peak PTT duration(in 1 year period) secs 10 11Airtime minutes per hour 17.18 14.47 8.86 4.75 4.39 3.26 1.98 0.17 Than the total for each Talkgroup from each agency is Than the total for each Talkgroup from each agency is either summed or averaged either summed or averaged Standard Deviation for WCSO1 Peak Radios/Hour = 5.3 Standard Deviation for WCSO1 Peak PTT/radio = 0.9

11. Than the channel loading from each Talkgroup was calculated. Than the channel loading from each Talkgroup was calculated. TRUNKING SYSTEM CHANNEL LOADING CALCULATOR Based on Erlang C due to queue 3 4 1 2 5 6 7 8 Trunking System, Erlang C due to queue WCSO1 WCSO2 JAIL TAC2 TAC1 CRTSEC DET REC TOTAL AVE AGENCY TALKGROUPS Total Radios owned by Agency 902 902 902 902 902 902 902 902 902 4.54% 2.55% 3.53% 0.77% 0.69% 0.97% 0.27% 0.12% 13% Ratio of Active Radios to Radio Owned 41.0 6.6 269.6 226.9 148.1 44.6 23.0 10 31.9 4.7 7.0 6.5 6.2 6.6 41.5 8.7 5.9 54.4 2.5 7.4 30.4 1.1 2.0 2.6 121 Actual Radios in use per Hour 6.2 PTT's per radio 818 Total Number of PTT per hour 3.8 3.8 3.6 6.4 6.3 3.6 3.9 3.8 4.4 PTT Duration in Seconds Erlangs 0.2863 0.2412 0.1476 0.0792 0.0731 0.0544 0.0329 0.0028 0.9175 Performance Objectives 1 Busies of 1 second or less are considered acceptable. This time is user determined reference waiting time queue in sec (W0) second(s) 1% 1 busy over 1 second per 100 PTT's is considered acceptable. Grade of Service is user determined GoS P(W>W0) Offered Traffic Characteristics 0.92 4.41 FDMA 4 1.53% 0.76% Call traffic (Erlangs) Average Holding Time second(s) Assuming 12KHz channel bandwidth and 2-Slot TDMA in 12.5 KHz channel System Type Frequencies Needed TDMA 3 Frequencies include FDMA control channel Probability that call will not be handled immediately Probability that a call has to wait If the GoS of 1% is entered in line 15, than any thing 1 second or under is considered acceptable. Probability that a call has to wait more than W0

12. Note: CCSO includes Sheriff radios plus all local police in Clackamas County

14. Reference based on Empirical data from multiple agencies Key #:6 PTT s/radio at 5 sec duration from 600 radios/hour TRUNKING SYSTEM CHANNEL LOADING CALCULATOR REFERENCE SHEET WCFire CCSO CCSO WCSO WCSO SCPD SCPD 9 10 8 7 Ownedradio 1112 1009 902 360 334 273 188 148 107 55 Percent Percent 20 20 8% 12% 13% 12% Actual Actualradio 92 92 125 125 121 121 42 42 PTT's PTT's/radio 4 4 6 6 6 6 6 6 Total TotalPTTs 398 398 805 805 818 818 257 257 559 Seconds Seconds/ptt 7 7 5 5 4 4 5 5 Erlangs Erlangs 0.7 0.7 1.1 1.1 1.0 1.0 0.4 0.4 0.7 WCFire BPD BPD 7 HPD HPD 6 PW PW 2 NBFD NBFD LOPD 3 Bus TOTAL TOTAL AVE 2 60 41 4529 4529 38% 15 15 600 600 13% 7 7 178 101 101 3775 4 4 4 4 0.2 0.2 0.2 0.1 0.1 5.2 LOPD H H- -Sec 4 Sec Bus 2 AVE Column1 Column1 Talk Groups Owned 17% 56 56 10 10 559 325 5 5 0.7 0.5 19% 51 51 6 6 325 55 5 5 0.5 0.1 8% 14 14 4 4 55 120 4 4 0.1 0.2 20% 30 30 4 4 120 143 6 6 0.2 0.2 26% 28 28 5 5 143 178 4 4 43% 24 24 7 7 13% 6 6 3775 5 5 5.2 Queue GoS Erlangs PTT sec Type Type Freq's Wait>1 Wait<1 1 1 1% 1% 5.2 5.2 5 5 FDMA 12 12 1.6% 1.6% 0.5% 0.5% Busies of 1 second or less acceptable. 1 busy over 1 sec per 100 PTT's All talkgroups are at the same priority level 12KHz B/W and 2-Slot TDMA in 12.5 KHz ch TDMA 7 7 Frequencies include FDMA control channel Probability Probability

15. MULTI-AGENCY TRUNKING SYSTEM CHANNEL LOADING CALCULATOR Agency Agency E E Total with Total with Growth Growth 3645 3645 Description Description Agency A Agency A Agency B Agency B Agency C Agency C Agency D Agency D Agency Agency Total Total AVE AVE 3300 3300 25% 25% 825 825 6 6 4950 4950 5 5 0.2 0.2 3300 3300 Radios owned by Agency Radios owned by Agency 25.0% 25.0% Percent used Percent used 0 0 6 6 0 0 6 6 0 0 6 6 0 0 6 6 0 0 6 6 825 825 911 911 Radios in use per Hour Radios in use per Hour 6.0 6.0 PTT's per radio per hour PTT's per radio per hour 4950 4950 5468 5468 Total PTT per hour Total PTT per hour 5 5 5 5 5 5 5 5 5 5 5.0 5.0 0.2 0.2 PTT Duration in Seconds PTT Duration in Seconds Hang-Time in Seconds Hang-Time in Seconds 7.15 7.15 7.90 7.90 Erlangs Erlangs 7.15 7.15 Performance Objectives # radios # radios /hour /hour /freq /freq # radios/ # radios/ freq freq 1 1 Queue Wait time (secs) GoS 1% 1% With With 1.0% 1.0% Growth Growth Traffic Characteristics Erlangs 7.2 7.2 7.90 7.90 FDMA 220 220 55 55 PTT Duration (sec) 5.0 5.0 5.0 5.0 TDMA 413 413 103 103 System Type System Type FDMA 2 SLOT-TDMA FDMA 2 SLOT-TDMA Frequencies 15 15 8 8 16 16 9 9 Talk Paths 14 14 14 14 15 15 16 16 Wait<1 sec 1.68% 1.68% 1.74% 1.74% wait>1 sec 0.43% 0.43% 0.42% 0.42% With 1.0% Growth 4 SLOT TDMA FDMA 228 228 57 57 Growth percentage 1.0% 5 5 FREQS TALK PATHS TDMA 405 405 101 101 Growth in years 10 16 16

16. 67radios in use per hr/talk path. 67 x 6 PTT x 5 sec = 33.5 airtime per talk path per hour. About 50% max 33.5 minutes of 50% max loading per talk path. 32 This system would require 15 talk paths: 16 freq FDMA or 9 freq TDMA FDMA FDMA 27 F F r r e e q q u u e e n n c c i i e e s s 22 N N e e e e d d e e d d 1950 radios 1750 radios 17 16 freq needed 16 freq needed TDMA TDMA 12 9 freq 9 freq needed needed When GoS exceeds 1% channel is added 7 1000/15 talk paths = 67 radios/talk path 2 0 500 1000 1500 2000 2500 3000 Radios in use per hour Radios in use per hour

17. This example assumes 25% of 4000 radios are active 700 # # R R a a d d i i o o s s p p e e r r f f r r e e q q TDMA TDMA 600 500 444 radios per freq 444 radios per freq 400 FDMA FDMA 300 250 radios per freq 250 radios per freq 200 100 0 0 500 1000 1500 2000 2500 3000 Radios in use per hour per freq Radios in use per hour per freq

18. The WCCCA Central simulcast provides the majority of the coverage for the WCSO (Washington County Sherriff s Office) subscribers and home of the WCCCA dispatch center. The C800 Central simulcast provides the majority of the coverage for the CCSO (Clackamas County Sherriff s Office) subscribers and home of C800 dispatch center. The ATIA data discovered that about 95% of the WCSO radios originated the WCCCA Central simulcast system and that about 97% of the CCSO radios their calls on the C800 Central Simulcast system. This data is what was used to provide PTT count for this study. 95% of the WCSO radios originated their calls on 97% of the CCSO radios originate Now the ATIA data revealed that about 81% of the 95% WCSO calls were involved 81% of the 95% WCSO calls were involved on the C800 system and that about 95% of the 97% CCSO calls were in involved 95% of the 97% CCSO calls were in involved on the WCCCA system. Since the C800/WCCCA system has no site restrictions, it allows all units/talkgroups to access all sites. Digging deeper into the data reveals that there is the small amount of involvement on all the calls for a majority of originated calls.

19. Dispatcher Radio Involvement time WCSO1 Dispatch WCSO1 Dispatch 41 41 Radios Per Hour 7 7 PTT s per radio per hour 4 4 seconds duration per PTT 41 times 7 = 287 PTT s per hour 287 times 4 seconds = 1,148 seconds = 19 minutes of airtime per hour Assume 3 PTT s per conversation = 287/3 = 96 conversations per hour Each conversation = 4 seconds times 3 PTT s = 12 seconds airtime per conversation Add 1 seconds per PTT to pick up mic,etc = 12 + 3 = 15 seconds per conversation. Add 10 sec for dispatcher to update CAD entries. 15 + 10 = 25 sec per conversation Dispatcher involvement 96 conversations x 25sec = 40 minutes per hour Dispatcher involvement = 40 minutes per hour

20. References This basic layout would not have been possible without all the help from Guy Jouannelle Jouannelle at Televate LLC. Guy Final report of the PSWAC Page 702 has some calculations that predicted future busy hour airtime. It states that each officer would generate 3.7 minutes of airtime per hour. It states that each officer would generate 3.7 minutes of airtime per hour. PSWAC (Public Safety Wireless Advisory Committee) 1996 In contrast, my data for WCSO1 shows 41 officers(radios) each generating 7 PTT s In contrast, my data for WCSO1 shows 41 officers(radios) each generating 7 PTT s per hour at 3.8 seconds each. That results in each officer generating 27 seconds per hour at 3.8 seconds each. That results in each officer generating 27 seconds per hour. per hour. And that one message is comprised of (3) three (5) five second transmissions. Interesting that the data in this document refers to the book by Garry G. Hess. Land-Mobile Radio System Engineering by Garry G. Hess Chapter 13 in this book addresses engineering aspects of a radio system s capacity to carry messages, or radio traffic. Garry G. Hess 1993 The message times per call were based on early 90 s data. This was before the wide spread use mobile data and cell phones and telephone interconnect mobile data and cell phones and telephone interconnect on the trunking system. The author believes that today s call lengths are much shorter and therefore more users per channel is possible. Many thanks to EF Johnson. http://go.efjohnson.com/systemdesign