This Small Business Innovation Research (SBIR) Phase I project targets increased data throughputs in cellular and access backhaul networks that are based on copper twisted-pairs to address the ever-growing demand for capacity and the consequent bottlenecks that are experienced in them. The performance in the multi-twister-pair channels is limited by crosstalk and interference caused by various sources in their noisy environment. The technology to be developed in this Phase I project offers significant increases in throughput through cost-effective interference-mitigation mechanisms. The company?s key innovation is in low-latency dynamic interference cancellation algorithms, which greatly enhance system performance while maintaining acceptable implementation complexity. The project will involve both research and development at the algorithmic level, as well as system implementation challenges associated with the minimization of the system?s cost and power consumption. More specifically, the innovation includes novel approaches to training-sequence design and numerically-robust schemes for the mitigation of both self-induced crosstalk as well as unpredictable crosstalk originating from other systems sharing the cable of twisted pairs (alien interference). Based on preliminary results, it is anticipated that this technology will offer critically needed throughput enhancements ranging from a factor of 2 to a factor of 5, depending on the operating scenario.
The broader impact/commercial potential of this project would be in enabling low-cost broadband services to a greater part of the population and thus also in fostering remote education, telecommuting and e-commerce. About 80% of the cell towers in the US utilize copper twisted-pairs for their backhaul, and the equipment market, valued at $5.6B in 2009, is expected to grow to $11.2B by 2013 due to deployment of bandwidth-intensive smart-phones and cellular Internet offerings. Hence, the relevant market sectors directly impacted are chip and communications equipment manufacturing. Many new micro-cells and femto-cells, offering wireless access in a coverage area smaller than that of a typical cell tower, are being deployed to offer wireless broadband coverage while relying on cooper-based backhaul. The copper infrastructure typically suffers capacity limitations and is interference-dominated while the higher-capacity alternatives, fiber and microwave, are costly and slow to deploy. The interference-mitigation technology enabling this breakthrough, developed in collaboration with the University of Texas at Dallas, may be applicable in other multi-channel communication systems, and can serve, for example, to better utilize scarce wireless spectrum.
This Small Business Innovation Research Phase I project addressed the crosstalk and interference which degrade the capacity of copper backhaul telecommunication infrastructure by sixty percent or more in the presence of typical interference found in the copper binders (e.g. from T1 lines). Copper backhaul infrastructure currently supports about 2/3 of all cell towers in the U.S. and is based on binders, bundles of 25, 50 or up to 100 twisted copper wire pairs, which support an unpredictable variety of signal types including T1 lines and multiple generations of xDSL protocols. These copper binders typically suffer capacity limitations that are interference-dominated while the higher-bandwidth-capacity medium alternatives, fiber and microwave, are expensive and are not being deployed quickly enough to meet the growing demand for bandwidth. Xtendwave’s Crosstalk Mitigation Algorithms (CMA) technology effectively addresses this problem to greatly enhance system performance while maintaining acceptable implementation complexity. The implementation of the Phase 1 project included: Development of a detailed simulation platform for a multi-line vectored DSL system Investigation of the performance and robustness of the CMA Hardware validation of specific test cases, using actual crosstalk transmitted within a shared binder (multi-twisted-pair cable) and estimation of the implementation complexity for the CMA functions The accomplishment of these objectives involved theoretical research, algorithm development, system performance evaluation based on simulations, and practical implementation challenges. The Phase 1 project was successful both in accomplishing the targeted technical objectives, as well as in validating the commercial potential of the crosstalk mitigation technology. Extensive efforts were put forth in the development of the detailed and efficient simulation environment, which served to validate the potential gains of the crosstalk-mitigation-algorithm in various interference scenarios. The hardware platform and lab measurements provided practical insights and further validation of the feasibility of a low-complexity implementation. Simulated and measured results confirmed potential improvements as high as 3× in data-rate using a realizable digital-signal-processing engine, validated the commercial potential of the developed technology and served as a solid starting point for the development of a marketable solution. The demonstrated solution can be expeditiously and cost-efficiently deployed to offer significantly higher capacity than is supported by the existing solutions. The graph included with this report shows the improvement in useable bandwidth simply due to the implementation of Xtendwave’s CMA as demonstrated in Xtendwave’s labs. Throughout the research, results were being shared with various potential customers, as well as with other players in this market, such as service providers who rely on the equipment that would benefit from the technology being developed. These interactions were instrumental in providing valuable inputs that served to fine-tune the research to better address the needs and problems presented by these companies. Xtendwave is a Dallas-based early-stage company focused on the development of physical-layer communication technologies using analog and digital signal processing methods to enable improved performance over various media, currently including interference mitigation, higher data rates, greater distances, and higher quality-of-service.
