MRC-IP Over ENG Tech Art

8/4/2019 MRC-IP Over ENG Tech Art

1/14

Page 1 of 14 *

Microwave Radio Communications, 101 Billerica Ave. Building # 6, North Billerica, MA, 01862, U.S.A.

Mic r o w av e Ra d io

IP over ENG:

Broadcast Applications and Solutions For Remote IP

ConnectivityAbstract

There is a significant trend in the industry toward the use of IP interfaces in remote

editing equipment utilized by broadcasters in the field. This is primarily due to theincreased flexibility of the interface to do file transfer, storage and overall management

of content with no degradation to video quality. Consequently, there is a secondary need

to be able to transfer this IP data from the remote location over the remote path withoutchanging formats.

This paper explores the basics of IP including its advantages for managing content. Additionally, the challenges of implementing portable microwave links from the field

including link budgets (carrier to noise vs. transfer rate) and interoperability issues are

reviewed. Sample system solutions for transporting IP data back to the studio including

ENG solutions and backhaul requirements are presented as well. Recent developmentsin generic data return link technology will be explored for the purpose of improving

overall IP data transfer accuracy and integrity. Also included is a brief review of two

key suppliers for field editing equipment and how their equipment could be integratedand configured with the microwave system. These suppliers are Panasonic and Avid.


2/14

Page 2 of 14 *



Legacy Analog Van Systems

For many years, mobile newsgathering vans have utilized 2 GHz terrestrial microwave

links for Electronic News Gathering (ENG) applications. Traditionally, these analognews vans have originated and distributed their news content within the van, using an

analog one-volt peak-to-peak composite video signal. This signal is typically routed

throughout the van via video distribution amplifiers, video switchers and VTR equipment

before being passed off to the 2 GHz microwave equipment for transmission back to thestudio.

Fig. 1 ENG Application

The typical analog method for transmission over the microwave system has been to use

FM modulation techniques. These techniques, which have been utilized successfully formany years, are now being supplemented and, in some cases, substituted with an ever-

increasing amount of digital based product designs. This is primarily due to advances indigital transmission technology coupled with the need for a more efficient use of

spectrum. Further to that end, advances in the area of digital microwave transmission

technology, compact non-linear editing workstations and the integration of digital video

interfaces with Ethernet network capabilities, have spawned an interest in the ability toextend network connectivity to the field.

Extending the Network Capabilities for D-ENG

Microwave Radio Communications (MRC) is working toward extending networkcapabilities to the field utilizing digital radio architectures, which combine robust

modulation techniques such as COFDM, with its own network interface technology.


3/14

Page 3 of 14 *



Additionally, Panasonic has introduced its P2 cam which goes beyond the conventional

work flow requirements as previously described. The P2 cam has built-in next generationstorage drives within its camera that support up to five independent storage cards. The

hot-swappable storage cards replace the legacy VTR applications. These storage cards

can be directly accessed while in the camera using a USB 2.0 connection from the cameraor pulled out of the camera to be inserted into a PCMIA slot of a portable work center or

laptop computer editor. This allows each unique storage card to be recognized as an

independent drive on the work center. Using the drive flexibility, the user can

simultaneously record footage of the news story while still transferring data over thenetwork back to the studio. See Figure 2 for typical flow.

Fig. 2 P2 Cam Work Flow

Avid technology has also introduced a wide range of products that are designed toextend the reach of the network newsroom workflow from the studio to the field. Their

NewsCutter XPmobile software system is a compact mobile non-linear editing (NLE)system that is designed with the intended capability for the user to stay connected while

in the field. It is designed to integrate with media management systems, newsroomcomputer systems, playback servers and web publishing systems thus allowing the

potential for a direct extension of their network capabilities, assuming a wireless high

BW connection could be made from the field. The user can move, store and forwardmaterial from the field over an Ethernet network connection through their Unity LAN

share configuration. Multiple NewsCutter XP clients can be connected within the same


4/14

Page 4 of 14 *



LAN configuration, as shown below in Fig. 3, and then interface with the Ethernetconnection.

Fig. 3 Avid LAN Share Work Flow

Fig. 4 below depicts one possible connection scenario. Avid also supports many othersystem application configurations that would allow for connectivity from the remote

location to the TV studio, if a connection were available. Currently, many of these

applications are supported using transcoder devices or interface converters as depicted below. These devices convert an IEEE 1394 (fire wire) DV25/DV50 type interface to

legacy analog base band style interfaces for distribution purposes.

Fig. 4 Avid Connectivity


5/14

Page 5 of 14 *



As previously mentioned, both Panasonic and Avid are directing their product

development efforts toward enhancing network newsgathering concepts from the field inan effort to maximize workflow efficiency.

The key ingredient to support and fully transition these technologies from Avid and

Panasonic is the digital microwave communications link, from the D-ENG van to the

studio. The microwave link needs to be robust and able to operate in non-line-of-sight(NLOS) conditions and also support a 12 MHz spectrum allocation while offering the

maximum available data rate over the channel.

Digital Microwave Transmission Technology

In 1999, COFDM (Coded Orthogonal Frequency Division Multiplexing) technology was

implemented into D-ENG applications, and it subsequently provided the first step in

support of the migration to fully digital transmission system architecture.

The implementation and modulator architecture facilitate the interface to most types of

digital transport streams, e.g. asynchronous serial interface (ASI), which is used to carrya compressed digital video bit stream; or Internet protocol (IP) network interface, which

is used to carry IP data grams over an Ethernet connection. These two interfaces allow

the user the flexibility to distribute content as a digital video transport stream or as an IPpacket, depending on the configuration within the van. It is also possible and desired to

support both types of transmission inputs simultaneously over the same microwave

channel on a priority basis. The maximum channel bit rate capacity is shared andprioritized between the 188-byte packets of the digital video transport stream and the IP

data grams. As previously mentioned, this allows the simultaneous transfer of FTP data

directly from a laptop editor through a network hub or media gateway and/or compressed

data from the MPEG encoder.

Digital Transmission Requirements Capacity vs. Threshold

The advantages of COFDM technology are apparent in its ability to offer error freetransmission under severe multi-path conditions and its ability to occupy less overall

bandwidth than its previous analog FM counterpart. A typical COFDM waveform

occupies 8 MHz of bandwidth at its 1dB bandwidth points. Its digital implementation is

based on the ETSI standard EN300-744 for DVB framing, channel coding andmodulation architecture. The uniqueness of the standard allows the user to customize his


6/14

Page 6 of 14 *



data throughput as a function of three main parameters: forward error correction, guard

interval, or delay spread and modulation type.

Fig. 5 shows the relationship between these three parameters, which is listed as Table 17

in the previously referenced ETSI standard. The table shows how a user can increase ordecrease his bit rate as a function of his microwave link requirements.

Fig. 5 COFDM Bit Rate Allocation

Like any other communications application, as the modulation density or bits per hertzefficiency increases, so does the carrier-to-noise (C/N) requirement for its receiver.

Meeting the C/N requirement is a major challenge toward achieving a reliable

transmission system. The following graph in Figure 6 shows the C/N requirement as a

function of bit rate for COFDM technology. The graph compares the three differentmodulation techniques - QPSK, 16 QAM, 64 QAM - used within a COFDM domain. As

expected, QPSK affords the minimum C/N requirement while also offering the lowest bit

rate with a C/N of approximately 7 dB and a bit rate of 5.5 Mbits/sec.


7/14

Page 7 of 14 *



Fig. 6 C/N vs. Bit Rate Table

Also, as with many other digital communications systems, there are ways to improve theoverall system C/N requirement for a given microwave path. The main technique that isemployed is antenna diversity.

Digital Transmission Requirements Antenna Diversity Improvement Factors

Currently, there are a number of diversity receive techniques on the market. They

include packet based switching implementations as well as maximal ratio combining

techniques. Each of these techniques has their pros and cons for the application. A

packet-based implementation, while offering errorless switching, yields minimalimprovement in C/N. Whereas maximal ratio combining techniques have the potential to

offer a user up to 5dB improvement in his C/N requirements with two antennas and a

subsequent 8dB improvement with four antennas. The improvement in C/N offers usersthe ability to increase their overall data throughput for the application. However if

throughputs are held constant, the improvement in C/N will improve overall reliability

and robustness of the microwave communications link.


8/14

Page 8 of 14 *



The increase in data throughput allows for a higher quality signal transmission over thelink or the potential for a higher speed downstream IP data transfer.

The following graph shows the comparative increase in throughput for a COFDMapplication with and without two-antenna diversity applied to the microwave

communications link.

Fig. 7 Diversity Improvement

As previously mentioned, we can now relate our channel capacity requirements from

Figure 7 to practical data transfer rates for a digital video compressed bit stream, using anASI interface and/or an IP network interface.


9/14

Page 9 of 14 *



Remote Digital Electronic Newsgathering (D-ENG) Communications to the Van

Currently, in the 2 GHz licensed spectrum band, there are no requirements or provisions

to support an upstream network path from the studio to the D-ENG van. Within the broadcast industry, a separate ATSC (Advanced Television Systems Committee)

specialist group has been formed which will focus on Digital Electronic News Gathering.

Its charter is to develop a standard or Recommended Practice for private communications

services between a DTV station facility and their D-ENG crews, utilizing the ATSCtransport stream.

Some of the potential applications suggested for using an ATSC compliant return path

include the following:

LAN or network access for newsroom management systems Return acknowledgements for a FTP (file transfer protocol) file transfers from

laptop editors as described above in support of the TCP/IP protocol requirements

Metadata to/from the station to newsroom production systems

Low resolution proxy video returns to the van from the studio

Remote monitoring and control of van equipment

Internet connectivity

Remote Vehicle Location Data (GPS) to station and return acknowledgement

IFB (interruptible fold back) communications for program sound and cueinginstructions back to talent and crew.

The way this application could potentially work is that an ASI stream would be used tosupport the digitally encoded video and audio information from an MPEG encoder. At

the same time, the modulator would be able to multiplex IP data from a network or

Ethernet hub. The ASI and IP data would be simultaneously transmitted over the 2 GHzmicrowave link from the van. At the central receive site, the ASI and IP data is extracted

from the COFDM demodulator and associated circuitry, and then distributed back to the

studio over the TSL (transmitter to studio) link in its existing digital format. At thestudio, the ASI data is decoded for its video and audio content and passed on to

newsroom production. Subsequently, the network IP data is supplied to the stations

LAN or communications hub. The stations LAN could then supply the network IP datafor the return upstream data path back to the van via the ATSC transport stream. At the

van, the ATSC off-air signal would be demodulated to complete the returncommunications path for remote ENG communications.

This technique would allow for a high IP down stream bandwidth from the van to the

studio and a significantly lower upstream bandwidth to the van from the studio. See

Figure 8 for system drawing.


10/14

Page 10 of 14 *



MPEG

Encoder

1 2 3 4 5 6

789101112

AB

12x

6x

8x

2x

9x

3x

10x

4x

11x

5x

7x

1x

Ethernet

A

12x

6x

8x

2x

9x

3x

10x

4x

11x

5x

7x

1x

C

2 GHz

Down Stream Data

UHF

Up Stream Data

Digital Microwave

Return Backhaul Link

ASI - IP Data

2GHz Central

Receive Antenna

Central Receive Site

D- ENG Remote

Communications

Studio Facility

DTV Receiver

2 GHz Radio

COFDM ModulatorDVB -ASI

Network Data

Network Hub

Media

Interface

Converter

Video/

Audio POWERFAULTDATA ALARM

Signal

Output

Network Adapter

UHF Signal

Van Equipment

Fig. 8 Remote D-ENG Communications


11/14

Page 11 of 14 *



As previously mentioned, Figure 5 showed the maximum allowable bit rate over the

COFDM channel, which is a function of the applicable ETSI standard. Now we can lookat the potential IP data requirements for the downstream network traffic content.

Network Application Allocated Downstream Transfer Rate

1) LAN or network access for

newsroom managementsystems

256 Kbits/sec

2) File Transfer Protocol (FTP) Full Bit Capacity of Channel - > 5.5

Mbits/sec

3) Metadata to the station -

newsroom production systems

64 Kbits/sec

4) Proxy streaming - low

resolution video preview

384 Kbits/sec

5) Remote vehicle locationdata (GPS) to station

64 Kbits/sec

6) IFB (interruptible fold back)

communications for talent and

crew - VoIP

128 Kbits/sec

Fig. 9 Example ofData Requirements

The chart above shows some of the potential applications, along with a potential

downstream transfer bit rate, for the network connectivity. The FTP application couldoffer the user the full downstream bandwidth while using the ATSC upstream bandwidth

for the return acknowledgements, thus completing the necessary flow control hand

shaking that is required.


12/14

Page 12 of 14 *



Summary

The future of electronic news gathering is presenting new challenges to the status quo in

terms of remote connectivity. Specifically, as field editing capabilities continue to

increase overall efficiency and allow further differentiation between markets, thetechnology utilized to connect news vehicles to the studio will need to adapt in order to

keep from becoming the weakest link.

As the value of remote IP connectivity continues to grow and transform the existing ENGparadigm, microwave radio equipment manufacturers will subsequently need to adapt to

an IP-based front-end hardware environment, thereby enabling a full digital

implementation.

However, the key component facing the industry is the accepted standard or

recommended practice for private communications services between a DTV station

facility and their D-ENG crew for return network connectivity. This standard shouldsupply the necessary upstream data requirements to support some of the network

application requirements.


13/14

Page 13 of 14 *



About the authors

Coauthors: John Wood

Michael Payne

Biographies

John Wood is currently the System Development Manager within R&D for MRC. He

has been involved in the development of 2 GHz COFDM D-ENG radio applications sinceits inception in 1999.

He has over 15 years of Microwave Radio Communications Development experience, hehas also received his Bachelor of Science in Electrical Engineering from the University

of Massachusetts and has taken graduate coursework specialized in the field of

microwave/wireless data communications.

Michael C. Payne is Vice President, Marketing and Business Development for

Microwave Radio Communications (MRC). His responsibilities include strategic planning, forecasting and new product introduction. Michael has over 18 years of

experience in the microwave radio industry. Positions held during his tenure at MRC

include Project Engineer, Product Line Manager and Director of Engineering. AsDirector of Engineering Michael had responsibility for all aspects of Product

Development at MRC. Among the products his team introduced are: the CodeRunner

family of Digital transmitters and receivers and TwinStream and DAR Plus long haulproducts.

Prior to his current Marketing and Business Development position he spent five years inoperations as a senior manager.

In 2005 Michael earned an Executive MBA from Suffolk University located in Boston,

MA and in 1989 he earned his BSEE from Wentworth Institute of Technology alsolocated in Boston, MA. Michael holds a US Patent for: Methods and Apparatus for

Transmitting Analog and Digital Information Signals.


14/14

Page 14 of 14 *



References

1) www.panasonic.com\broadcast - P2 Series

2) www.avid.com\products\broadcast - Avid NewsCutter Family

3) www.avid.com\products\broadcast - Avid Unity LANshare for News

4) Digital Video Broadcasting, (DVB): Framing structure, channel coding and

modulation for digital terrestrial television, ETSI Standard ETSI EN 300 744,version v1.5.1 (2004- 11) page 35

5) www.atsc.org - Requirements for Remote ENG Communications, Doc. # As

040

6) www.avid.com\products\broadcast - Extending the Broadcast Newsroom:

Mobile News Production

* Any use or reproduction of the information contained in this paper, without

written permission from Microwave Radio Communications is expressly prohibited.

Documents

MRC-IP Over ENG Tech Art