Microwave Radio Network Design in an IP Environment ... · PDF fileMicrowave Radio Network...

NSMA Annual ConferenceM 13 & 14 2014May 13 & 14, 2014

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

Copyright © 2010 Alcatel-Lucent. All rights reserved.NSMA Annual Conference May 13 – 14, 2014 Washington, D. C. 2

technologies new to microwave radios.

What is an IP point to point microwave radio?

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


Convenient for asymmetric traffic shaping.

What is an ACM point to point microwave radio?

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)


reduce transmission capacity as much as 3 to 1)

What is an ACM point to point microwave radio?

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.


What are the new issues with IP microwave radio?

How do you measure the threshold of an IP radio?y(No, the answer is definitely not to measure it on an encapsulated DSx or Ex channel!)

What is the concept of Dispersive Fade Margin (DFM) when an ACM radio has two thresholds per operating mode?operating mode?

How should Automatic Transmitter Power Control (ATPC) f h ACM di h lti l (ATPC) for when an ACM radio has multiple transmission modes?


Where are we today and why do we need to change?

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.

I chair that group.


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


If you are not familiar with these concepts, I can recommend a good reference!

Amazon Books:“ i ki ”“microwave kizer”


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 DDefine T/I and C/I CriteriaDefine T/I and C/I CriteriaWill Perkins, Comsearch

T/I must be clearly differentiated from C/Iy

The required T/I data must be clearly specified

Provision must be made for cases where adequate T/I data is not available


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


actual antenna discrimination pattern.

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


methods used to estimate those quantities.

Task KCurrent Rain ModelsCurrent Rain ModelsTom Willis, AT&T LabsGeorge Kizer, Alcatel-Lucent

North America uses the Crane rain model; Europe uses the ITU-R model. The Crane model has several variations.has several variations.

City Rain Rates ITU-R Rain Rates


Task KDefine Availability and QualityDefine Availability and QualityGeorge Kizer, Alcatel-Lucent

Crane 1996


Task KDefine Availability and QualityDefine Availability and QualityGeorge Kizer, Alcatel-Lucent

Crane 1996 vs City Rain Rates

The purpose of this task is to explain the differences and offer suggestions for the most


accurate methods.

Task LPart 25 Interference Methods UpdatePart 25 Interference Methods UpdateThu Nguyen, Radyn

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.


Task FIP-based MW Radio Development and DeploymentIP-based MW Radio Development and Deployment Guidelines – George Kizer, Alcatel-Lucent

Some radio parameters have fundamentally changed:

Receiver Threshold(related to Flat Fade Margin) Dispersive Fade MarginDispersive Fade Margin


New measurements for IP microwave radios

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.


Proposed IP fixed modulation radio threshold

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.


gg g p y p

Proposed IP fixed modulation radio threshold

Assuming 20 errors per error burst:

BER FLR (64 byte frame) FLR (1518 byte frame)

3 2 110-3 3 x 10-2 6 x 10-1

10-6 3 x 10-5 6 x 10-4

10-9 3 x 10-8 6 x 10-7

10-12 3 x 10-11 6 x 10-1010 3 x 10 6 x 10

BER = Bit Error Ratio FLR = Frame Loss Ratio


Proposed IP ACM microwave radios threshold

For ACM radios there are TWO receiver thresholds:

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).


Proposed IP microwave radios threshold

Receiver flat fading time probability is inversely proportional to fade margin or directly p p g yproportional to receiver threshold:

PDFM = receiver multipath outage probability 10-FFM/10 10TH/10

FFM = flat fade margin= normal RSL (dBm, negative value) – TH

TH i th h ld (dB g ti l )TH = receiver threshold (dBm, negative value)

10THavg/10 = ½ [10THup/10 + 10THdown/10]

This simplifies to the following:

THavg = -3 + 10 log10 [10THup/10 + 10THdown/10]


THavg 3 10 log10 [10 10 ]

Proposed IP microwave radios DFM

Historically Dispersive Fade Margin (DFM) is measured for a given radio threshold:for a given radio threshold:


Proposed IP microwave radios DFM

DFM is calculated based upon a W curve for minimum and non-minimum dispersive fade:and non minimum dispersive fade:

North American MethodBellcore (Telcordia)

International MethodITU-R

39.6 Bn/3.8 Bm/3.839.6

(MHz)Sw [e e ]df


DFM (dB) = 39.6 – 10 log ( Sw )

Proposed IP ACM microwave radios DFM

Traditional Dispersive Fade Margin (DFM) Curves

< replace with new threshold



For ACM radios there are TWO receiver thresholds:

Threshold for transition to a lower QAM

Threshold for transition from a lower QAM



New Dispersive Fade Margin (DFM) Curves



PDFM = dispersive multipath outage probability10 DFM /10 10-DFMavg/10

10-Bavg /10

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:

DFMavg = 3 – 10 log10 [10-DFMsu/10 + 10-DFMsd/10]Bavg = 3 – 10 log10 [10-Bsu/10 + 10-Bsd/10]


IP ACM microwave radio unexpected consequences

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.


New measurements for IP ACM microwave radios

Some parameters are new to radio systems:Some parameters are new to radio systems:

Radio Transmission Capacity (Layer 1 2 or 3)Radio Transmission Capacity (Layer, 1, 2 or 3)


What is an IP point to point microwave radio?

Layer 3

Layer 4Application

Layer 2Information Rate

Layer 3IP Rate

Layer 1Line Rate


What is transmission rate for an IP radio?

Line RateInformation Rate

IP RateIP Rate

Payload

Copyright © 2010 Alcatel-Lucent. All rights reserved.NSMA Annual Conference May 13 – 14, 2014 Washington, D. C.36

What is transmission capacity of an IP radio?

figure adapted from Understanding Carrier Ethernet Throughput, Metro Ethernet Forum, July 2010



What is transmission throughput for an IP radio?





Some parameters are new to radio systems:

Frame Loss Rate (loss vs offered load – determine overload point)

Latency (Delay at 90% capacity)

Frame Delay Variation (Frame Jitter)Frame Delay Variation (Frame Jitter)



Some parameters are new to radio systems:

Back to Back Frames (burst tolerance)

Buffering Recovery Time

Reset TimeReset Time



Some parameters are important but not l b i dd d b h TR 45 ffcurrently being addressed by the TR-45 effort:

Routing, network stability and restorationg, y

Processing of Priority Tagging (“Quality of Service”) of competing trafficService ) of competing traffic.

Security

Note that the above features typically behave differently in IPV4 and IPV6 environments.


Questions?

Copyright © 2010 Alcatel-Lucent. All rights reserved.NSMA Annual Conference May 13 – 14, 2014 Washington, D. C.

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