Showing papers by "AT&T Labs published in 1984"
TL;DR: Analytical and computer simulation techniques are used to determine the performance of optimum combining when the received desired and interfering signals are subject to Rayleigh fading, and results show that optimum combining is significantly better than maximal ratio combining even when the number of interferers is greater than thenumber of antennas.
Abstract: This paper studies optimum signal combining for space diversity reception in cellular mobile radio systems. With optimum combining, the signals received by the antennas are weighted and combined to maximize the output signal-to-interference-plus-noise ratio. Thus, with cochannel interference, space diversity is used not only to combat Rayleigh fading of the desired signal (as with maximal ratio combining) but also to reduce the power of interfering signals at the receiver. We use analytical and computer simulation techniques to determine the performance of optimum combining when the received desired and interfering signals are subject to Rayleigh fading. Results show that optimum combining is significantly better than maximal ratio combining even when the number of interferers is greater than the number of antennas. Results for typical cellular mobile radio systems show that optimum combining increases the output signalto-interference ratio at the receiver by several decibels. Thus, systems can require fewer base station antennas and/or achieve increased channel capacity through greater frequency reuse. We also describe techniques for implementing optimum combining with least mean square (LMS) adaptive arrays.
942 citations
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01 Jan 1984TL;DR: A linear-time approximation algorithm for routing multipoint net channels and the three-parameter model, which is closer to the design rules of current fabrication technologies, is presented, and it is shown that every channel can be routed using 2d+O(1) tracks.
Abstract: @n) tracks. In practice, it appears that the flux never exceeds a small constant. In this case the algorithm performs asymptotically better than the best-known knock-knee algorithm [21], and almost as well as the best-known three-layer algorithm [19], without requiring the use of either knock-knees or three layers of interconnect. In addition, the three-parameter model, which is closer to the design rules of current fabrication technologies, is presented. Under this model, it is shown that every channel can be routed using 2d+O(1) tracks.
30 citations
TL;DR: The fiber SLC1Carder as discussed by the authors is a repeaterless digital loop carrier that employs lightwave features for the transmission of voice and data from a telephone central office to a remote location.
Abstract: The Fiber SLC1Carder System is a repeaterless digital loop carrier that employs lightwave features for the transmission of voice and data from a telephone central office to a remote location. This paper describes the development and application of this 1.3-μm LED/p-in based system. Experience with first applications is reported along with current developments intended to increase its capacity and bring digital capability close to the customer at the DS3 bit rate (44.736 Mbits/s). Services to the customer include DS1 port capability (1.544 Mbits/s), DS2 optical paths (6.312 Mbits/s), voice, and data.
4 citations