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Data Disassembler/Reassembler


OBJECTIVE: Research, design, develop, and prototype a state of the art programmable digital data stream disassembler and reassembler system, including hardware, software and documentation. The system must be affordable, efficient and reliable, and must provide coherent data stream disassembly and reassembly, operating at the non-packetized digital bit level. The intent of this effort is to enable Department of Defense (DoD) and commercial Satellite Communications (SATCOM) users to utilize portions of unused spectral energy by distributing bandwidth over multiple frequencies and varied angular polarizations, and then be reassembled at the destination with as little bandwidth cost as possible over long haul communications. Though the area of immediate interest to the US Army is SATCOM, this technology can also apply to advanced terrestrial microwave communications. In any media, this technology economizes bandwidth use and also provides a layer of passive protection capability against both jamming and man-made scintillation via its data replication summing properties. Protection is furthered by having portions of data reside in two or more planes simultaneously. Current communications technologies utilize inverse multiplexor techniques on circuits that require high overhead costs of packetizing ranging from 15 to 50% or more and are primarily deployed for terrestrial applications. These terrestrial techniques lack flexibility of indiscriminant data rate assignment and do not provide means to programmatically address path latency nor the level of energy per bit by path nor the non symmetrical distribution of multiple paths to accommodate SATCOM bandwidth fragments. These technologies often depend on return feedback via full duplex communications and are incapable of operating in simplex configurations. For years challenges in handling processing issues on a single path with the right level of power per bit has been difficult to model with absolute efficiency without mentioning the given pointing accuracy complexities from a satellite antenna payload in space to an intended ground segment receiver. Today"s tools within DoD can now predict and allocate the proper power and bandwidth based on a single stream of data fairly accurately depending on a static model of a given spacecraft. However, once this predicted path is allocated and assigned for live transmission for a user, the allocation remains as is until that mission ends. Missions ending and beginning each having different bandwidth and duration requirements often leave transponders heavily fragmented. To eliminate this waste and regain back the unused spectrum without mission disruption requires an effective method to use fragmented bandwidth. The ability to coherently disassemble a data stream into smaller usable size rates to consume the gaps of energy and re-aggregate the streams is a means to economizing bandwidth usage. In doing so there are many challenges. Some of the greatest challenges in SATCOM include latency, indeterminate bandwidth availability and varied levels of power. The object is to provide this capability as an alternate means to effectively harvest fragmented SATCOM bandwidth as well as to provide a low-cost passive means of inherent protection against jamming and man-made scintillation. DESCRIPTION: This research and development effort is intended to develop enabling technology that does not exist for a new simplex SATCOM system by leveraging off of existing inverse multiplexing technologies combined with latency compensating technologies used on single SATCOM links today. The solution must demonstrate coherent processing to accurately disassemble and distribute data to four or more paths for long haul over the air transmission. A data stream assembly process, complimentary to the data stream disassembly process on the transmission side, will be required on the receiving side of the communication system in servicing the data side of four or more receivers. The new system will provide a multitude of new benefits such as the ability to transmit large amounts of data across multiple small antennas; the ability to improve bandwidth usage efficiency by sending slices of data across multiple poles of the same antenna. Current circuit capabilities in operation terrestrial deployment are designed around fixed synchronous rates that are largely packetized requiring full duplex feedback and fixed levels of power and do not handle varied latencies and levels found in SATCOM. The solution must address these SATCOM issues adequately and at the same time use minimal overhead techniques such as super-framing and framing to retain a level of efficiency great enough to stay below the 5% threshold. Leveraging the use of dedicating a single path as reference with the association to all other adjacent paths of distribution for coherency is strongly encouraged but independent handling of each path without specifying a path of reference is acceptable. Similar technologies do not address the delays associated with varied complex modulation and buffer processing techniques between paths that are coupled with high latencies found with geosynchronous orbiting satellites operating approximately 22,380 miles in space. The latencies in each segment such as SATCOM can run as high as 250 milliseconds or more while other terrestrial elements can be measured in nanoseconds depending on the processing contribution. This system will have to account for these delays by means of buffering in order to be successful. Lastly, the energy per bit, commonly referenced to a 0 dB noise figure (written in the industry as EB/N0) can grossly impact data throughput. These power levels from path to path will vary. Some path schemes range from unusable to completely error free within a range of less than 2 dB EB/N0. The energy per bit is often not a consideration with much regard in the terrestrial solutions due to not having the additional noise contributions that comes with a SATCOM channel. The offeror will have to consider leveling techniques to ensure proper reassembly is successful. The leveling can be done in either the pre or post-transport state. The combining of multiple solutions to negotiate each of these challenges successfully will be compounded by adding versatility of providing the user the ability to program data speeds and non-symmetric distributions. The research and development effort is comprised of two parts, the Transmitting Data Disassembler and the Receiving Data Reassembler. Specifics for the overall system includes the bandwidth usage of all paths when reassembled at the receiving end in a non-replicating distribution configuration should not consume more than 105% of the original data stream bandwidth comparatively. The means to disassemble a stream of data into 4 or more channels dealing with associated latency without adding excessive overhead is the primary technical risk. The ability to synchronize multiple inputs coming from different sources each having varied latent effects is difficult and should not be underestimated. The scope can be limited to all channels operating within any single band for the purpose of limiting the risks. A great deal of research in determining variations in path specific modulation schemes and frequencies will be required in order to solve the variation of timing of channel data departures and arrivals for reassembly. Key specifics to the Transmitting Data Disassembler will have one input and at least four outputs. Each input and output in the Data Disassembler will be individually capable of handling a digital data stream of 19.2 Kbps through 20 Mbps (threshold). As an objective requirement, the Data Disassembler will support data rates as low as 75 bps (or lower) and as high as 512 Mbps (or more). The Transmitting Data Disassembler must be programmable by the user to distribute between 0-100 percent of the input stream to any of the output streams, to include: replicating 100% to one channel; 100% to each channel; and non-replicated, uneven distribution. As an example, the distribution percentages for a message might be broken up in the following way across four channels: 10%, 25%, 30% and 35%. The number of outputs (at least four) and their loading will be programmable by the user. A user manual will be provided. The Receiving Data Reassembler will have one output and at least four inputs. Each input and output in the Data Reassembler will be individually capable of handling a digital data stream of at least 19.2 kbps through 20 Mbps, as a threshold requirement. As an objective requirement, the Data Reassembler will support data rates as low as 75 bps (or lower) and as high as 512 Mbps (or more). The maximum number of inputs (at least four) on the Data Resassembler will be programmable. A user manual will be provided. All reassembling will be programmable with abilities corresponding to the Data Disassembler. The total data throughput of the system will be 20 Mbps as a threshold requirement and 512Mbs, or more, as an objective requirement. The Data Reassembler will have an equal number of inputs corresponding to the number of outputs on Data Disassembler. As a threshold, the system will use state of the art framing techniques that consume no more than 5% of bandwidth for the overhead information needed for data disassembly and reassembly (3% objective). The overhead will be used for error correction and data sequencing as necessary. The offeror is encouraged to use existing COTS error correction methods such as forward error correctional coding or preambles however if necessary, a proprietary method can be created to meet the threshold overhead requirement. Special care must be taken when designing for data disassembly due to an inherent risk of the reassembly process incorrectly reassembling the data incorrectly thus corrupting the entire data stream. The input channel data rate to the Disassembler will be equal to the output data rate of the Reassembler. The Reassembler must be able to operate successfully with path delay variations of frequency within the same band on the transmitting/receiving channels. Functional processing such as buffering, framing, and sequencing must consider associated latencies with SATCOM frequencies in the C, X, Ku, Ka and Q bands. PHASE I: In Phase I, the contractor shall develop the architecture and design approach for the programmable digital data stream disassembler and reassembler system. The architecture and design should, at a minimum, meet the threshold requirements identified in the Description paragraph, above. Existing technologies such as inverse multiplexing and packetizing are referenced as known architectures and will not be acceptable as a phase I deliverable due to the circuit dependencies requiring feedback, bit stuffing and packetizing. The design must be state of the art and reflect agility in programmatically replicating in a non-symmetrical fashion data streams across four or more channels in a single direction and be re-aggregated at the receiving end using overhead costs within the threshold cited above. The design must show the encoding and preamble methods used on the transmission disassembly that provides a method of recovery at the receiver with means to handle the varied latencies and levels encountered in the reassembly process. PHASE II: In Phase II, the contractor shall build, test and deliver a prototype disassembler /reassembler system in accordance with the design delivered in Phase I, including all required hardware, software and user documentation. The contractor shall develop and deliver a test methodology that includes Government approved test plan, test procedures, verification cross reference matrix (VCRM) and script files as necessary for testing. The contractor shall support demonstration testing at the Joint Satellite Engineering Center (JSEC) laboratory at Aberdeen Providing Ground for one week. The prototype system shall, at a minimum, meet the threshold requirements identified in the Description paragraph, above. The prototype will be tested with multiple data streams for disassembly and reassembly. The prototype is required to be programmable and must be able to be pre-configured by an operator to disassemble/reassemble at programmable data rates and programmable stream distribution sizes. PHASE III: In Phase III, the Disassembler/Reassembler prototype design will be refined, optimized and productized for transition to military Programs of Record and commercial applications. All circuitry, fabrication and interfaces must utilize industry recommended or military standards (i.e.; MIL-STD-530, RS-422, etc.) wherever possible and must meet safety standards prior to delivery and labeled in accordance with best practices. The Disassembler/Reassembler system has the potential for use in multiple emerging digital transmission technologies, where there is a need for coherent data disassembly and reassembly along multiple transmission lines. Immediately, the system will provide an inherent passive Anti-Jam (AJ)/Anti-Scintillation (AS) capability which will undergo testing upon delivery. The current focus is on emerging and existing military communications systems, but this technology may also be of use in commercial areas requiring high volume data communications, including video. Military efforts such as Future Advanced SATCOM Terminals (FAST) are launching efforts to expand the digital domain in today"s transponded SATCOM. Creating a means to programmatically traverse multiple polarizations offers a robust means of communications impervious to man-made scintillation and interference that if appropriately productized can be utilized throughout DoD. REFERENCES: 1."Precision Polarization Bandwidth Expansion"for MILCOM written 2011, by Rick Dunnegan, Deep Gupta, Deborah Van Vechton.
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