PTP 800 With Adaptive Coding And Modulation (ACM)
SOLUTION BRIEFPTP 800 with Adaptive Codingand Modulation (ACM)Maximizing PTP 800 link throughput with Hitless and Errorless ACM
ContentsPg Section3Executive Summary4Introduction5ACM Overview6Key Benefits of ACM7How ACM Works8Typical ACM Applications9Sample Case Studies9Using ACM to Achieve Performance Objectives10 Case 1: Fixed Mode for Hospital Link10 Case 2: Increase Hospital Link Throughput11 Case 3: Minimize Hospital Link Outage12 Case 4: Use Smaller Antenna for Hospital Link13Using ACM to Achieve Greater Range13 Case 5: Fixed Mode for Sales Office14 Case 6: Increase the Range of the Sales Office LinkPAGE 215Motorola’s Approach to ACM16Summary
Executive SummaryOrganizations of all types have experienced a continuing increase in demand for high-bandwidth wirelesscommunications to support a wide variety of data, voice and video applications. This increasing demand hasaccelerated the need for high throughput wireless links at a time when most information technology (IT)budgets and staffing have decreased. One way to meet this challenge is to do more with what you have.Adaptive Coding and Modulation (ACM) technology can help you do just that. Designed to help increasethroughput over a radio link while making efficient use of the existing spectrum, ACM functionality adaptscoding and modulation rates to changing environmental conditions. With ACM, you can turn fade margininto increased throughput and improve link availability. This capability can provide significant savings in bothcapital expenditure (CAPEX) and overall operating expenditure (OPEX).This paper explains how ACM can help you achieve these results with your existing or planned MotorolaPoint-to-Point (PTP) 800 Wireless Licensed Ethernet Microwave solutions.Figure 1:PTP 800 Outdoor Unit (ODU)and Compact Modem Unit (CMU)PAGE 3
IntroductionThe universal demand for added throughput is being driven by the growth of multimedia applications.Currently, video-dominated content accounts for an ever-increasing percentage of the multimedia mix.Business and government enterprises need high-performance connectivity and backhaul to supportbandwidth-intensive applications such as on-demand tutorials, video conferencing, online training, mediarelations, product demonstrations, Voice-over-IP (VoIP) and video surveillance. At the same time, consumerswant access to services such as online gaming, social networking and on-demand television.Motorola’s PTP 800 Licensed Ethernet Microwave solutions are high-capacity wireless broadband radiosdesigned to efficiently and affordably transport multimedia traffic. However, as with all microwaveradios, PTP 800 systems can experience rain fade and multipath interference which can adversely affectmicrowave transmissions. ACM can eliminate or greatly minimize the effects of rain fade and multipathinterference.Traditionally, licensed microwave radios have supported only the Fixed Modulation mode. However, PTP800 systems, release 02-00 and higher, support both Fixed Modulation and ACM. In the fixed mode,significant fade margin is reserved during the link planning process to provide adequate link availability incase of rain fade or multipath interference.Fade Margin Difference between Mean Receive Signal Level (Rx)and Receiver Threshold at a Given Modulation ModeMean rx signalFigure 2:Fixed ModulationFade MarginFade marginfor 16QAMLevel requiredfor 16QAM16QAM Avail16QAM UnavailWhen the ACM mode is chosen, the ACM feature can turn reserved fade margin into increased linkcapacity. Without any hardware change, ACM can maximize throughput by automatically adapting to ahigher modulation and coding rate. When a radio is working in a Fixed Modulation mode, a severe rainstorm can cause a link outage when the rain fade exceeds the reserved fade margin. In contrast, ACMcan keep the link in service and improve the link availability with lower throughput by adapting to a lowermodulation mode.Figure 3:ACM Modulation Modes168PSK QAMQPSKPAGE 46432 QAMQAM256QAM256QAM H128LQAM
Introduction continuedACM is a standard feature on PTP 800 systems and requires no additional charge. The major advantages ofMotorola’s ACM implementation include: Hitless and Errorless ACM: No bit errors or suspension of traffic flow during modulation shifts Up to 8 levels of ACM profile; supports QPSK, 8PSK, 16/32/64/128/256 QAM with different coding rates Quick modulation shifts to cope with up to 100 dB/sec fading Easy initial setup; no further user intervention Flexible control; users define the highest and lowest modulation for ACM Easy link planning with the PTP LINKPlanner toolACM OverviewACM is an alternate link adaptation method that promises to raise the overall system throughput andimprove the link availability. When ACM is enabled, the radio automatically “up-shifts” and “down-shifts”the modulation and/or coding rate as radio frequency (RF) path conditions change. This enables the radiotransmitter and receiver to negotiate the highest mutually sustainable data rate for the path conditions.In order to achieve high link availability, a typical licensed microwave link reserves 30 to 40 dB for fademargin. For a radio configured to use Fixed Modulation, the radio’s nominal receive signal level will be muchhigher than the receiver sensitivity threshold of the desired modulation.For a radio operating in the fixed mode and designed with 99.999% link availability, the average link outagewould be 5.3 minutes in a year. This projected outage would be a result of the receive signal level fallingbelow the receiver’s sensitivity threshold. With ACM technology, the radio will down-shift to a lowermodulation if the link budget falls below the threshold that the link can sustain.Let’s consider an example based on a link with a 56 MHz channel operating in the ACM mode. When theRF condition is good, the radio will work at top mode – 256 QAM with a 0.91 coding rate – and deliver 368Mbps (full duplex) throughput. When the link’s Signal-to-Noise Ratio (SNR) falls below the threshold of 256QAM with 0.91 coding, the system will switch to the next lower ACM profile – 256 QAM with a coding rateof 0.80 – and deliver 347 Mbps throughput. The switchover will be errorless and hitless, meaning there willbe no bit error or traffic flow suspension.If the fade intensifies, the radio will shift down to the next ACM profile, 128 QAM, and deliver 303 Mbpsthroughput. Should the RF condition continue to worsen, the modulation will move down step-by-step asthe weather condition requires. ACM and enhanced quality-of-service (QoS) control allow high-priority trafficsuch as voice and real-time services to pass across the link without difficulty.When the weather condition improves, the radio will automatically switch to the next higher modulationmode. In this case, the radio would shift from 128 QAM back to 256 QAM. Switching is always automaticand performed as quickly as necessary. The PTP 800’s ACM functionality is designed to cope with up to 100dB of fading per second.PAGE 5
ACM Overview continued256QAM-H256QAM-L128 QAMFigure 4:ACM Adapting toWeather Conditions64 QAM32 QAM16 QAM8PSKQPSKThe consequences of a link outage are often multiplied, even when the RF link is lost for only 50 milliseconds.Due to TCP/IP timeout, re-routing and recovery, it could easily take several seconds for a TCP/IP session to befully recovered. With exceptionally smooth change steps from QPSK to 256 QAM and errorless and hitlesscoding and modulation, the PTP 800 incurs no service interruption as the modulation steps from one level toanother. In this way, ACM can eliminate the link outage time.Key Benefits of ACMWhen utilizing ACM technology, you can realize several benefits, including: I mproved Spectrum Efficiency: Most of the time, the radio will work at top rate mode and provide ahigher average throughput to the end user. I mproved Link Availability: By shifting to a lower modulation mode and the resulting improvement inreceive signal quality, extra fade margin will be achieved to deliver higher link availability. Minimal Link Outage Damage: By keeping the link in service with a lower capacity during deep fadeconditions, ACM greatly minimizes the consequences of a wireless link outage due to TCP/IP layertimeout, re-routing and recovery. CAPEX and OPEX Savings: On PTP 800 systems, there is no additional cost to enable ACM. Oncethe easy set-up is completed, no further intervention is required. With Motorola’s PTP LINKPlanner, linkplanning with ACM can be completed quickly and easily, often in a matter of hours rather than days. Plus,with ACM, the operator has the option to reduce the antenna size and/or connect over a longer distancethan with radios operating in a fixed mode.PAGE 6
How ACM WorksOperators can enable ACM radios using the installation wizard from the PTP 800 Graphical User Interface(GUI) web page. There are two parameters that define the range of the modulation modes: “Max Mod Mode” defines the highest modulation mode at which the radio can operate “Min Mod Mode” defines the lowest modulation mode at which the radio can operateEach link direction can adapt the modulation mode independently of the other direction. After the minimumand maximum modulation modes are defined, the “Maximum Tx Power” will be limited by the maximumtransmit power of the highest modulation mode.Latency for a given mode in ACM is the same as for the same mode in Fixed Modulation.In operation, the radio will adapt between the “Max Mod Mode” and the “Min Mod Mode” based onmeasurements of received signal quality. As the receive signal quality improves, the radio will adapt tohigher modulations which will provide greater throughput. As the receive signal quality deteriorates, theradio will adapt to lower modulations which will provide lower throughput but greater robustness. Eachmodulation mode has two thresholds: One threshold for up-shifting when the signal quality improves One threshold for down-shifting when the signal quality degrades256QAM, Rate 0.91256QAM, Rate 0.83128QAM, Rate 0.8264QAM, Rate 0.82Figure 5:ACM Thresholds Comparedto Fixed Mode32QAM, Rate 0.8716QAM, Rate 0.91Fixed Mode8PSK, Rate 0.84ACMQPSK, Rate 0.80Signal-to-Noise Radio (SNR)To be hitless and errorless during modulation shifts, ACM requires a higher SNR than with the FixedModulation mode.PAGE 7
Typical ACM ApplicationsACM is designed to improve PTP 800 performance in changing environmental conditions. That improvedperformance provides significant value for the many varied applications for which PTP 800 systems aredeployed, including: Building-to-building and campus connectivityEthernet data, voice and video communicationsBackhaulVideo surveillanceVoice-over-IP (VoIP)Leased-line replacement Last-mile extensionsDisaster recoveryWire-line redundancyDistance learningWiMAX and/or LTE backhaulBusinesses, government and educational agencies, health care providers, utility companies, transportationagencies, service providers, carriers and others use PTP solutions to establish or expand their wirelessnetworks. If a radio cannot send and receive information because of rain fade or multipath interference,your wireless link is not doing the full job.ACM can help you improve link availability and increase throughput without changing hardware. The key isto evaluate your environmental challenges and enable ACM where the technology will help you overcomerain and interference challenges. The following case studies provide detailed information on how ACM canbe applied to specific situations and requirements.PAGE 8
Sample Case StudiesIn the following examples, hypothetical link configurations are presented to illustrate the concept ofenabling ACM to help you achieve specific link objectives. During actual system setup, you can decide howto leverage ACM technology to achieve the best possible results for your individual situation.SampleCasesResults Compared to Fixed ModeConfigurationCase 2 ACM –Hospital Link Higher average link throughput Same link availability No throughput reduction as comparedwith fixed mode Keep “Min Mod Mode” the same aswith the fixed mode Set “Max Mod Mode” to highermodulation than fixed modeCase 3 ACM –Hospital Link Higher average link throughput Minimized link outage with improvedlink availability Set “Min Mod Mode” to lowestmodulation Set “Max Mod Mode” to topmodulation rateCase 4 ACM –Hospital Link Higher average link throughput Same link availability with lowercapacity during deep fade Cost savings on antenna Set “Min Mod Mode” to lowestmodulation Set “Max Mod Mode” to topmodulation rate Reduce antenna sizeCase 6 ACM –Sales OfficeLink Higher average link throughput Same link availability with lowercapacity during deep fade Longer range Set “Min Mod Mode” to lowestmodulation Set “Max Mod Mode” to topmodulation rateUsing ACM to Achieve Performance ObjectivesIn the following examples, the link is 5 miles (8 km), requires 99.999% link availability and needs 250 Mbpsthroughput. For this case, we chose 15 GHz with 56 MHz channel bandwidth.HospitalClinicFigure 6:Hospital-to-Clinic Path ProfileHeight Above Sea Level 14000.25 0.5 0.7511.251.5 1.7522.252.5 2.7533.253.53.7544.25 4.5 4.75Range On Path (miles)PAGE 9
Sample Case Studies continued Case 1: Fixed Mode for Hospital Link The radio is set to Fixed Modulation mode at 64 QAM with a 4-foot antenna at each end. As shownbelow, the link provides 255.22 Mbps throughput with 99.999% link availability.ModeFigure 7:Case 1 Fixed Mode –Hospital Link Performance64QAM0.82HospitalMaxMaxUser IPAggregateIPThroughput FadeUser IPThroughputin ime inMode(%)IPReceiveFadeThroughput Time inMarginAvailability Mode(dB)(%)(%)99.999139.9899.999199.9991Link IP Throughput and AvailabilityMean IP Throughput Required250.00 MbpsMean IP Throughput Predicted255.22 MbpsPercentage of Required IP Throughput102.09%Link SymmetrySymmetricLink Availability99.9991% Case 2: Increase Hospital Link Throughput Now, the objective is to achieve the highest possible throughput with ACM, while still meeting 99.999%link availability and using the same minimum throughput as for the fixed mode. With no change to thehardware and ACM enabled, the “Min Mod Mode” is set to 64 QAM (the same as for the fixed mode).Then the “Max Mod Mode” is set to 256 QAM with a 0.91 coding rate which will allow the link availabilityto achieve the required 99.999%. .ModeFigure 8:Case 2 ACM –Increase Throughput OverHospital LinkHospitalClinicMaxMaxUser IPAggregateIPReceiveIPReceiveThroughput FadeFadeUser IPThroughput Time inThroughput Time inin bility 99900.001037.9899.99900.0010Link IP Throughput and AvailabilityMean IP Throughput Required250.00 MbpsMean IP Throughput Predicted368.64 MbpsPercentage of Required IP Throughput147.45%Link SymmetrySymmetricLink Availability99.9990%In comparison to the radio performance in the fixed mode, the average link throughput has increased to368.64 Mbps with the link availability remaining at 99.999%. Throughput has increased by 44% with nohardware change.PAGE 10
Sample Case Studies continuedWhen changing from Fixed Modulation mode to ACM, the minimum and maximum modulation modesmust be set properly to maintain the same link availability with a guaranteed minimum throughput. The“Min Mod Mode” must remain the same modulation as with the fixed mode and the “Max Mod Mode”needs to be the highest modulation that the link can sustain to meet the link availability requirement. Thesesetup changes can be done easily using the PTP LINKPlanner tool. Case 3: Minimize Hospital Link Outage In this example, the objective is to achieve the highest possible throughput with ACM while minimizingthe link outage time. With no change to the hardware and ACM enabled, the “Min Mod Mode” is set toQPSK, and the “Max Mod Mode” is set to 256 QAM with 0.91 coding rate. Based on this configuration,the system performance would be as shown below.ModeFigure 9:Case 3 ACM –Minimize Link Outage OverHospital LinkHospitalClinicMaxMaxUser IPAggregateIPReceiveIPReceiveThroughput FadeFadeUser IPThroughput Time inThroughput Time inin bility 003Link IP Throughput and AvailabilityMean IP Throughput Required250.00 MbpsMean IP Throughput Predicted368.64 MbpsPercentage of Required IP Throughput147.45%Link SymmetrySymmetricLink Availability99.9996%In comparison to the radio performance in the fixed mode, the backhaul currently delivers an average linkthroughput of 368.64 Mbps and link availability of 99.9996%. The annual link outage time has been reducedfrom 4 minutes 43 seconds in the fixed mode to 2 minutes 6 seconds in the ACM mode. The fade marginhas improved 10.32 dB, and the throughput has increased by 44% with no radio hardware change orantenna change.PAGE 11
Sample Case Studies continued Case 4: Use Smaller Antenna for Hospital Link In this case, the goal is to use a smaller dish while still maintaining 99.999% link availability and thehighest possible throughput with ACM. With the antenna size reduced from 4 feet (1.2 meters) to2 feet (0.61 meters) on both ends and ACM enabled, the “Min Mod Mode” is set to QPSK and the “MaxMod Mode” to 256 QAM with a 0.91 coding rate. Using this configuration, the performance would be asshown below.ModeFigure 10:Case 4 ACM –Smaller Antenna Size forHospital LinkHospitalClinicMaxMaxUser IPAggregateIPReceiveIPReceiveThroughput FadeFadeUser IPThroughput Time inThroughput Time inin bility 010Link IP Throughput and AvailabilityMean IP Throughput Required250.00 MbpsMean IP Throughput Predicted368.62 MbpsPercentage of Required IP Throughput147.45%Link SymmetrySymmetricLink Availability99.9990%In comparison to the fixed mode, the average link throughput has increased to 368.62 Mbps, the linkavailability is still 99.999% and the antenna on each end has been reduced from 4 feet to 2 feet (1.2 metersto 0.61 meter).PAGE 12
Sample Case Studies continuedUsing ACM to Achieve Greater RangeIn this case, a 2-foot (0.61-meter) antenna is chosen for each end of the link using 7 GHz with 28 MHzchannel size. Case 5: Fixed Mode for Sales Office With the radio set to 256 QAM, the link can reach 7.7 miles (12.4 km) with 99.999% link availability.Sales OfficeWarehouseFigure 11:Sales Office Path Profilein Fixed ModeHeight Above Sea Level 140013800.511.522.533.544.555.566.577.5Range On Path (miles)ModeFigure 12:Case 5 Fixed Mode –Sales OfficeLink Performance256QAM0.80Sales OfficeMaxMaxUser IPAggregateIPReceiveThroughput FadeUser IPThroughput Time inin WarehouseIPReceiveFadeThroughput Time inMarginAvailability Mode(dB)(%)(%)17.1399.999199.9991Link IP Throughput and AvailabilityMean IP Throughput Required150.00 MbpsMean IP Throughput Predicted170.51 MbpsPercentage of Required IP Throughput113.67%Link SymmetrySymmetricLink Availability99.9991%Link Distance7.705 miles (12.4 km)PAGE 13
Sample Case Studies continued Case 6: Increase the Range of the Sales Office Link With no hardware change and ACM enabled, the “Max Mod Mode” is set to 256 QAM and the “Min ModMode” to QPSK, allowing the radio to reach up to 16 miles (25.7 km) with 99.999% link availability.Figure 13:Sales Office Path Profilein ACM ModeHeight Above Sea Level (feet)Sales nge On Path (miles)ModeFigure 14:Case 6 ACM –Greater Range forSales Office LinkSales OfficeWarehouseMaxMaxUser IPAggregateIPReceiveIPReceiveThroughput FadeFadeUser IPThroughputTimeinThroughputTime inin bility 7.8630.0999.99910.003530.0999.99910.0035Link IP Throughput and AvailabilityMean IP Throughput Required150.00 MbpsMean IP Throughput Predicted170.23 MbpsPercentage of Required IP Throughput113.48%Link SymmetrySymmetricLink Availability99.9991%Link Distance16.017 miles (25.7 km)In comparison to the fixed mode, the link can now reach 16 miles (25.7 km) with an average throughput of170 Mbps. During deep fade conditions, the link can run on a lower modulation at lower throughput whilekeeping the link availability at 99.999%.PAGE 14
Motorola’s Approach to ACMWith more than six years of experience in implementing ACM on the PTP 500 and PTP 600 unlicensedradios, we have developed considerable expertise in this area. We know how to engineer hitless anderrorless technology with smooth, high-speed modulation shifts. Equally important, “ease of use” hasalways been a paramount objective for all our Wireless Network Solutions.In particular, the ACM provided with PTP 800 Licensed Ethernet Microwave solutions has severaladvantages over comparable systems, including: Support for QPSK, 8PSK, 16/32/64/128 QAM, 256 QAM with 0.83 coding rate and 256 QAM with 0.91coding rate – up to eight levels of modulation and coding. Hitless and errorless modulation – no bit errors or suspension of traffic flow during shifting Flexible control – operators can define the maximum and minimum modulation modes Fast shifting – ACM can cope with up to 100 dB/sec fading change Easy setup – The installation wizard guides operators through a quick configuration procedure. Becausethe regulatory rules have been embedded into the link installation wizard, you do not have to worry aboutviolating licensing rules when ACM is enabled. After initial setup, no further user intervention is required. Fast, accurate link planning – With PTP LINKPlanner, both the Fixed and ACM modes are supported. Plus,LINKPlanner includes many sophisticated features that greatly reduce link planning man-hours and allowyou to easily review and compare performance parameters to configure the solution which best meetsyour requirements.Figure 15:PTP LINKPlanner with ACMPAGE 15
Summary The principle of Adaptive Coding and Modulation is simple: to enable uninterrupted communicationsin poor RF conditions and increase throughput during good RF conditions. ACM accomplishes that byautomatically adjusting modulation and/or coding rates to adapt to changes in environmental conditions. Inpoor conditions, ACM will automatically shift the modulation and/or coding rate to a lower level to maintainan uninterrupted flow of data, voice and video communications. In good conditions, ACM will shift themodulation and/or coding rate to a higher level to deliver faster throughput. In contrast, systems operatingin a Fixed Modulation mode are designed for worst-case conditions, resulting in less efficient utilization ofthe spectrum.ACM can offer significant benefits, including: Maximized spectrum efficiency Increased link capacity Improved link availability Reduced antenna size Extended link distanceIn addition, Motorola’s ACM experience and expertise can help you deploy the best solution for yourindividual situation. Easy-to-use link planning and deployment tools are great time savers for wirelessnetwork staffs that are already stretched too thin.These benefits can help you stretch your wireless dollar much further and help your Motorola PTP 800solutions work much smarter.Wireless Network SolutionsMotorola delivers seamless connectivity that puts real-time information in the hands of users, givingcustomers the agility they need to grow their business or better protect and serve the public. Workingseamlessly together with its world-class devices, Motorola’s unrivalled wireless network solutions includeindoor WLAN, outdoor wireless mesh, point-to-multipoint, point-to-point networks and voice over WLANsolutions. Combined with powerful software for wireless network design, security, management andtroubleshooting, Motorola’s solutions deliver trusted networking and anywhere access to organizationsacross the globe.Motorola, Inc., 1303 E. Algonquin Road, Schaumburg, Illinois 60196 U.S.A. www.motorola.com/ptpMOTOROLA and the Stylized M Logo are registered in the U.S. Patent and Trademark Office. All other product or service names are the property of their respective owners. Motorola, Inc. 2010. All rights reserved.WNS PTP 800 ACM SB 062410GO-23-141
Motorola’s PTP 800 Licensed Ethernet Microwave solutions are high-capacity wireless broadband radios designed to efficiently and affordably transport multimedia traffic. However, as with all microwave radios, PTP 800 systems can experience rain fade and multipath interfe
Point to Point Un-Licensed AIRSPAN FlexNET ASN-700 FlexNET ASN-900 CAMBIUM PTP 100 PTP 200 PTP 500 PTP 600 EXALT EX-i series EX-r series ExtendAir CAMBIUM PTP PTP 800 PTP 810 ERICSSON MINI-LINK CN 210 MINI-LINK CN 500 MINI-LINK CN 510 PT 2010 / 6010 EXALT ExploreAir E
Optional: If the PTP 800 or PTP 810 is part of a Motorola ASTRO system, review the “PTP for ASTRO System Planner” for guidance on link planning and required options and features. 2 Apply for your license using your preferred licensing method or our FCC Microwave License CoordinationFile Size: 2MB
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PTP 800 03-00 MOTOROLA PTP 800 LICENSED ETHERNET MICROWAVE HIGH-THROUGHPUT COMMUNICATIONS FOR MULTI-SERVICE NETWORKS PTP 800 solutions can efficiently and affordably transport the data, voice and video that your bandwidth-intensive applications require without having to contend wi
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