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DETERMINING BEAMS TO BE UTILIZED IN A COMMUNICATION SYSTEM

IP.com Disclosure Number: IPCOM000008751D
Original Publication Date: 1998-Jun-01
Included in the Prior Art Database: 2002-Jul-09
Document File: 6 page(s) / 267K

Publishing Venue

Motorola

Related People

Steven J. Goldberg: AUTHOR

Abstract

In communication systems beam forming is a known method for improving the reception of an RF signal. Determining the direction and beam width however can be a computationally intensive process. This puts several constraints on the receiver's design. To meet latency requirements, a more expensive processor may be needed. Or the number of individual transmissions that the unit can handle simultaneously may be limited.

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MOZOROLA Technical Developments

DETERMINING BEAMS TO BE UTILIZED

IN A COMMUNICATION SYSTEM

by Steven J. Goldberg

ABSTRACT

  In communication systems beam forming is a known method for improving the reception of an RF signal. Determining the direction and beam width however can be a computationally intensive process. This puts several constraints on the receiver's design. To meet latency requirements, a more expensive processor may be needed. Or the number of individual transmissions that the unit can handle simultaneously may be limited.

  This paper presents a methodology which deter- mines the necessary information, with a minimum or at least guaranteed maximum latency less than the existing methods. This will translate into either a less expensive receiver, or one with the capability to handle more transmissions simultaneously.

EXISTING METHOD

  Figure 1 shows an idealized representation of a receiver ('R'), coverage area (circle) of interest, and beams (ellipses) used to cover the region. This picture is not meant to show the actual contour of coverage area or beams. It is merely drawn to aid in the explanations of the concepts to be described.

  In a preferred embodiment the beams will over- lap each other so that the signal will not be lost in a null. This will mean that sometimes the signal could have been detected in more than one beam sufficiently to declare it to be the correct area. In the invention however this just means there are several search paths which guide the receiver to the same result.

  The number of beams is dependent on the con- ditions of the RF environment, and the distribution of the transmitting units. The received power level from the transmitter and the interface being key factors. It is therefore empirically desirable to narrow the beam so that it maximizes the desired signal and minimizes all other signals. The limit to this however is often defined by the mobility of the transmitter, since movement orthogonal to the beam's maxi- mum gain, will cause a more rapid gain degradation for narrower beams. If the transmitter is not signiZi- cantly mobile, then the natural medium tendency to spread the signal strength becomes the limiting factor. Too narrow of a beam could therefore possibly filter out a significant fraction of the potential received energy.

  In the most general case some arbitrary beam direction is chosen. If the transmission is detected with sufficient signal to interference within the

beam, the beam for data decoding has been found. If not, another beam is selected, calculated, and decided upon. In this process, regardless of the order in which the beams are calculated, it will take an average of N/2, and a maximum of N beam determinations to locate the one to be used.

THE NEW METHOD

  The existence of a signal may be ascertained by the existence of a power signature for isolated channel usage. For multiple users of the same channel,

Fig. 1 Idealized Receiver Coverage Area and Beams

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