NSMA Annual Conference M 13 & 14 2014 May 13 & 14, 2014 Holiday Inn Rosslyn at Key Bridge Arlington, Virginia Microwave Radio Network Design in IP E i t U i an IP Environment – Upcoming Revisions to TIA TSB 10F George Kizer Alcatel-Lucent George Kizer , Alcatel Lucent
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Holiday Inn Rosslyn at Key BridgeArlington, Virginia
Microwave Radio Network Design in IP E i t U i
g , g
an IP Environment – Upcoming Revisions to TIA TSB 10FGeorge Kizer Alcatel-LucentGeorge Kizer , Alcatel Lucent
So what’s changing in the point to point MW world?
The fixed microwave manufactures, service providers and users are recognizing the world is providers and users are recognizing the world is moving quickly into an Internet Protocol (IP) environment.
Pressure to increase microwave radio bandwidth is leading to the introduction of Adaptive Coded Modulation (ACM) radios [also called Link Adaption (LA) or Adaptive Modulation and Coding (AMC)].
Legacy equipment and system testing methodologies need updating need address these technologies new to microwave radios
An IP radio operates in an Internet Protocol (IP) environment.environment.
One type overlays IP into a TDM radio transport frame Latency is minimized Convenient for frame. Latency is minimized. Convenient for drop and insert applications. TDM waiting time jitter control requires synchronization.
The other encapsulates TDM traffic (pseudowire DS1s and DS3s) into IP packets and transports all ) p ptraffic in native IP packets. Latency is greater. TDM encapsulation requires synchronization. Convenient for asymmetric traffic shaping
An Adaptive Coded Modulation (ACM) radio can operate at different modes depending upon the operate at different modes depending upon the condition of the radio path.
During normal propagation conditions the radio During normal propagation conditions the radio operates at high spectral efficiency (up to2048 QAM).
When path conditions degrade (e.g., during multipath or rain fading), the radio changes p g), gforward error correction and/or QAM mode (as low as 4 QAM) to increase radio threshold (but reduce transmission capacity as much as 3 to 1)
An ACM radio requires the incoming traffic be tagged to some form of Quality of Service (QoS). C tibilit ith th i Q S d fi iti i Compatibility with the various QoS definitions is an issue.
Routers seeing a variable bandwidth IP channel may behave unpredictably. Using an ACM qualified router is suggestedqualified router is suggested.
TIA TSB 10 F, Interference Criteria for Microwave Systems
This bulletin, referenced throughout the FCC rules and regulations, has defined the methodology for designing fixed point to point microwave systems since its publication in 1994.
The clear migration to IP ACM microwave radios requires an update to the existing standards.
Telecommunications Industry Association (TIA) committee TR-45 has formed a working group to address those issues.
TIA Committee TR-45 Working Group on Microwave Systems
Areas of Interest:
A) Automatic Transmit Power Control (ATPC) - Tom Willis, AT&TB) Analog Systems Update - Will Perkins, ComsearchC) Digital Systems Update - George Kizer, FialD) Short and Long Term Objectives - Will Perkins, Comsearch) g j ,E) Broadcast Deployment Guidelines – Dave Myer/Kelly Williams, AT&TF) IP-based MW Radio Development and Deployment Guidelines – George Kizer, FialG) FCC Rules Update (pending) – (Kizer/Picquet), Fial and Alcatel-LucentH) Combine Vertical and Horizontal Antenna Discrimination - Thu Nguyen, Radyn) g y , yI) Define T/I and C/I Criteria - Will Perkins, ComsearchJ) Define Availability and Quality - George Kizer, FialK) Extend Current Rain Models - Tom Willis/George Kizer, AT&T and FialL) Part 25 Interference Methods - Thu Nguyen, Radyn) g y , yM) Position Accuracy Standards – Don Campbell, FCCN) Rewrite Annex E (previously G) – Brad Youngblood, Micronet
Task AAutomatic Transmit Power Control (ATPC)Automatic Transmit Power Control (ATPC) Tom Willis, AT&T Labs
Currently ATPC is defined for multipath Currently ATPC is defined for multipath dominated microwave paths. Can ATPC be used on rain dominated paths and, if so, how can its used be specifiedused be specified.
When operating in fixed mode, the operation of the radio is not different than a current radio.
When operating in ACM mode, what is the When operating in ACM mode, what is the expected operation and how should ATPC be managed?
Task BAnalog System UpdateAnalog System UpdateWill Perkins, Comsearch
Interference into FM-FDM and FM Video receiversInterference into FM FDM and FM Video receivers
Decision made to use ITU-R Recommendation SF 766 (1992) for analog FM FDM Telephony and SF.766 (1992) for analog FM-FDM Telephony and retain other sections as is.
Task CDigital Systems UpdateDigital Systems UpdateGeorge Kizer, Alcatel-Lucent
The current TSB 10F composite fade margin approach only works for analog systems. Support will be added for digital systems. The primary addition will be Dispersive Fade Margin.
Separate outage calculations will support using different diversity improvement for flat, dispersive and interference induced fadingdispersive and interference induced fading.
Task HCombining Vertical and Horizontal AntennaCombining Vertical and Horizontal Antenna DiscriminationThu Nguyen, RadynFor short paths, the radio path does not lie in the horizontal plane.
This task takes into account path inclination to estimate l di i i i
Task IDefine T/I and C/I CriteriaDefine T/I and C/I CriteriaWill Perkins, Comsearch
Radio interference criteria information must be T/I not C/I.
Radio interference criteria must cover the entire range of interest of the analysis. A default T/I curve will be provided if specific data is not available.
Adaptive Coding Modulation radios can operate in different modes. The different modes can have different interference sensitivities as well as different transmit power levelssensitivities as well as different transmit power levels.
Task JDefine Availability and QualityDefine Availability and QualityGeorge Kizer, Alcatel-Lucent
Many users and consultants confuse Availability Many users and consultants confuse Availability and Quality. In addition, the North American and European definitions are significantly differentdifferent.
The definitions of these quantities directly influences the calculation and interpretation of microwave path availability.
This task explains the differences and also addresses the accuracy expectation of the methods used to estimate those quantities
Interference potential between satellite earth stations and fixed service is calculated IAW ITU-R SF.1006.
This task updates the table I of ITU-R SF.1006 for This task updates the table I of ITU R SF.1006 for Earth Station interference into fixed digital systems operation below 10 GHz.
Historically we have used 10-6 BER in a TDM baseband ysignal (such as DS1, DS3, STS-1, OC3, E1, E3 or STM0) as the receiver threshold. That is meaningless in an IP environmentenvironment.
A single error in an IP packet causes that packet to be lost. The effect is to promote a bit error into an dropped frame in TDM traffic.
Proprietary encapsulation methods can reduce this sensitivity, but the basic issue remains.
We are proposing replacing Bit Error Ratio (BER) with F L R t (FLR)Frame Loss Rate (FLR):
FLR = (bytes per frame) * (bits per byte) ( y p ) ( p y )* (probability of error event)= (bytes per frame) * (bits per byte) * (BER threshold / [errors per error burst]) (BER threshold / [errors per error burst])
Bits per byte = 8BER threshold = traditional 10-6
For consistency and to limit the influence of multiple errors we suggest using a specified byte packet.
th h ld t hi h th i it h a threshold at which the receiver switches from a lower complexity (QAM) to the reference complexity (up threshold = THup)p y ( p up)
a threshold at which the receiver switches from the reference complexity to the lower from the reference complexity to the lower complexity mode (down threshold = THdown).
The basic dispersive fading outage models assume minimum and non-minimum fading occurs for equal time.
10-DFMavg/10 = ½ [10-DFMsu/10 + 10-DFMsd/10]10-Bavg/10 = ½ [10-Bsu/10 + 10-Bsd/10][ ]
The subscripts “su” and “sd” represent “Switch Up” and “Switch Down” respectively. These equations may be simplified to the following:simplified to the following:
The radio thresholds for an ACM radio are always higher than the threshold for a fixed modulation radio.
When changing from a fixed modulation IP radio to an ACM radio, the path availability of th f d l ti ( d f the reference modulation (and reference capacity) is always reduced.
The availability of the priority traffic is always significantly increased.