Dancing with wolves: The COTS illusion
Features
By: Ian Colville, Product Manager, Aculab for Military Embedded Systems, March 2008
Enhanced Voice Processor (EVP) units are at the heart of many a military communications system. When sourcing Commercial Off-The-Shelf (COTS) enabling technology for these communications, there are always two key requirements that come to the fore: high density and low cost per channel. Although COTS is perceived as a one-size-fits-all solution, COTS products rarely meet military systems’ needs all by themselves; often add-on or enabling technologies must be implemented, too. Thus, companies offering COTS equipment for integration into military standard communications systems should be aware of the contradiction in the real-world use of the term “off-the-shelf.” Equally, systems suppliers looking to win defense contracts – and needing to source components to fulfil their procurement specifications – should be prepared for Non-Recurring Engineering (NRE) costs for adapting COTS products.
Military technology has come a long way since the days of William Wallace, who advised his troops before the first battle of Falkirk (on July 22, 1298), “I haif brocht ye to the ring, hop if ye can!” This translates in part as “dance as best you can.”
These days, it is no longer a case of simply doing the best you can – making do with what you’ve got in terms of skill, weapons, and equipment. Today’s military forces, from NATO and KFOR to Iraq and ISAF, demand and get the latest in weapons and technology systems. This is also true of communications, with forces around the world being better equipped than ever before in terms of Command, Control, Communications, Computers, and Intelligence (C4I).
Key to these communications systems are Enhanced Voice Processor units (see sidebar), where interoperability and high functionality are required. However, it is clear that COTS products are unlikely to meet all such requirements themselves, without utilizing “add-on” functionality to provide increased channel density and low cost per channel, for example. Thus, systems suppliers desiring to win defense contracts should be prepared for NRE costs when adopting COTS products.
Enhanced voice processor units
A foundation of the communications element of C4I is the Enhanced Voice Processor (EVP) unit. This forms part of a larger gateway system between disparate networks and is an infrastructure designed to offer more than simply one-to-one gateway functionality. The EVP within this multifaceted gateway often includes voice, fax, data, and video functions.
The multifunction gateway is typically used to provide secure communications at the rear of the battlespace, linking senior commanders back to HQ and forward to the battle area. Systems allow interconnection on a backbone network across a large geographical area as well as the means to interconnect with single service and multinational systems.
Designed to link all the elements of a Joint Force, systems can be deployed in peacekeeping or offensive roles. In practice, systems are fully containerized and can be operated in mounted or dismounted mode. They are also designed to be scalable.
Enabling technologies
In light of modern military communications systems’ stringent requirements for high levels of functionality, what is typically most important to a defense contractor is a high-density channel count. However, most COTS products cannot meet such stringent requirements on their own. But such requirements can be met via technology “add-ons” to the COTS hardware variant. Often the core enabling technology has to be adapted, such as adding a new codec, for example. And in providing high density, the contractor benefits are twofold: gaining reduced cost and increased value per channel.
Enabling technology encompasses a wide range of hardware and software building blocks for the development of high performance, wired and wireless, IP- and TDM-based, enterprise, and telco communications solutions.
Accordingly, enabling technologies for EVPs embrace two main categories: media processing resources and digital network access. Classic examples of media processing resources include voicemail and IVR [interactive voice response] functionality, where record and playback is used alongside DTMF [dual tone multi-frequency] detection.
For digital network access, it is important for the vendor to offer connectivity regardless of network type or geographical location. Requirements for COTS amendments could incorporate any or all of a wide range of CAS, H.323, ISDN, SIP and SS7 protocols. In addition to support for the “vanilla” protocol specifications, the ability to offer national or country specific variants is vital. Thus, for a contractor, finding a vendor with the willingness and ability to make changes [usually under (NRE) arrangements] is vital.
NRE and NDI: One-size COTS doesn’t fit all
porating a growing proportion of COTS products to take advantage of technological breakthroughs in commercial markets. These commercial products have the advantage of being more powerful, more adaptable, and less costly than militarized products.
COTS products are characterized by:
- Reduced risk, because the equipment is available and has been proven commercially;
- Faster time to market;
- The latest technology, because vendors operate in a competitive environment;
- Open architecture;
- Support of international standards.
Notwithstanding this, COTS doesn’t often fit the bill “out of the box”; hence, the recurrent need for NRE. COTS procurement is about making effective use of commercially available enabling technology that can be readily adapted to enable the completion of an end-user system. Since one-size COTS doesn’t fit all, again, “add-ons” must be implemented.
There is no formula for the percentage of NRE costs; however, it should be clear that, in addition to the aforementioned benefits, choosing COTS is fundamentally less costly than scratch development.
Of the many selection criteria for COTS – functional; performance; environmental; reliability – choosing the right vendor is key. COTS products offer functionality that often only partially meets a project's specific needs; therefore, a supplier with the temperament to offer an adaptable, responsive approach to Non-Developmental Items (NDI) is critical. An illustration of this required vendor flexibility in a COTS adaption within a military communications application follows.
Case study: Blending COTS and NRE
One example of how an established COTS product was enhanced through an NRE project to meet high-density requirements within tight timeframes follows:
The client – a major defense contractor in the UK – recently sought a COTS solution featuring an adequate channel count for G.711 A-law, G.729d, and MELPe codecs to develop a voice and data gateway with secure interoperability features to offer into the defense market. The technical challenge was to provide a guaranteed channel count performance, regardless of the combination of codecs in use, within a three-month timeframe.
Having the other codecs already available, Aculab agreed to port the Compandent delivery of MELPe to its COTS product under an NRE project. This was done for an agreed cost, enabling the client to meet its specifications and deadlines, with a high density, small form factor, RoHS compliant, single board CompactPCI gateway (see sidebar).
The result: the first such compliant device in the UK, with secure interoperability features. It was designed to provide up to 120 channels of secure, high-density voice and data to operate in either a red or black network. It allows many conformant devices to achieve end-to-end encrypted communications between secure networks as illustrated in the diagram below. Supporting both commercial and military standard voice codecs, the gateway converts speech and V.32/V.14 modem data from ISDN (Q.SIG and Q.931-based EuroISDN) to RTP/UDP/IP packet data.
Aculab’s Prosody X CompactPCI board was chosen as the enabling technology platform employing Freescale Semiconductor’s multicore StarCore DSP technology, which functions under Aculab’s proprietary DSP operating system. The available suite of media processing algorithms operates under the DSP kernel, which readily enables porting of new firmware, such as the MELPe codec.
The board’s architecture offered the inherent flexibility needed to cope with the tough demands made by the client’s requirements specification. The end result is a classic example of NDI being applied to an industry proven COTS product through a short-term NRE project. The contractor’s project was brought back on track, averting failure or a doubling of costs from using two boards.
Gateway function
One example of an essential CompactPCI gateway function is to receive data from an ISDN channel as G.711 A-law and to encode that data as MELPe, G.729d or G.711 A-law, then to packetize the data and encapsulate it within RTP/UDP/IP for transmission over an IP (Ethernet) interface. In the opposite direction, it recovers the raw data from the RTP/UDP/IP packets, decodes the data from MELPe, G.729d or G.711 A-law and transmits it over an ISDN channel as G.711 A-law.
The payload size and format of the RTP/UDP/IP packets generated by the board in the case study met the rigorous demands for data rates, latency (end-to-end delay), Mean Opinion Score (MOS) assessments, and throughput performance stipulated by the client.
MELPe RTP frames contain 22.5 ms of coded audio and are transmitted on 10 ms boundaries (DSPs run on a 10 ms epoch) so as to average 1 packet every 22.5 ms (1 packet at 30, 50, 70, and 90 ms). G.729d frames will contain 10 ms of coded audio and are transmitted every 10 ms. Each MELPe frame and each G.729d frame are transmitted in separate packets to minimize the end-to-end delay of the system. Delay is measured from receipt of each byte to the transmission of the same byte on the corresponding interface and is under 100 ms for both MELPe and G.729d.
The board is capable of buffering up to N frames of data from the RTP/UDP/IP packets whilst the current frame is being transmitted over the ISDN channel. Jitter buffer size is software selectable and adaptive within N = >0 frames.
Stand easy
When sourcing COTS enabling technology for military communications, two requirements come to the fore – high density and low cost per channel. However, it is clear that functionality is the overriding consideration as the application or system must clearly deliver on the specification. It is apparent that a responsive commitment to NDI through bespoke NRE is often needed from COTS suppliers. This is likely to be true for media processing resources, the kind of functions found in commercial media servers or gateways.
Dancing as best you can is no longer OK when it comes to military equipment, and companies offering COTS equipment to this sector will realize that “add-ons” must usually be implemented. Equally, systems suppliers looking to win defense contracts should be prepared for those NRE costs.
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