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AN ACTIVE ADAPTIVE DISTRIBUTED ANTENNA SYSTEM

IP.com Disclosure Number: IPCOM000009440D
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2002-Aug-23
Document File: 3 page(s) / 119K

Publishing Venue

Motorola

Related People

Neil Bilcliff: AUTHOR [+2]

Abstract

Coverage within in-building cellular networks can be difficult to achieve, often leading to the use of large basestation transmitter powers split in dividing networks and radiated using distributed antenna systems. This is costly, inefficient and gen- erates another problem - interference.

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Developments Technical 0 M MOZOROLA

AN ACTIVE ADAPTIVE DISTRIBUTED ANTENNA SYSTEM

by Neil Bilcliff and Neil Turner

  Coverage within in-building cellular networks can be difficult to achieve, often leading to the use of large basestation transmitter powers split in dividing networks and radiated using distributed antenna systems. This is costly, inefficient and gen- erates another problem - interference.

  Frequency reuse and network capacity is nor- mally limited by interference. This is caused by multiple basestation sites operating on the same fre- quency at sufficient power that mobiles receive more than one co-channel signal at the same time.

  One way of overcoming this interference is by reducing the power transmitted by the basestations. The limitation is that this also reduces the signal strength received by the mobiles being served.

  What is required is a way of localizing the RF power to just the area around each specific mobile. This would overcome the need for large, high-power infrastructure and improve network capacity by reducing interference. This paper describes a novel way of using information available to the basesta- tion to locate and direct power to mobiles within an in-building environment.

L5 Mobile

PicoceIIular E3cs&ation

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Antenna segments (eg. leaky feeders)

Fig. 1 A Distributed Antenna With Periodic Delay Elements

  This shows a BTS with a distributed duplex more remote location than 'B'. This is because the (simultaneous transmit and receive) antenna. The basestation can measure the round trip delay of the effect of the delay elements is to make the segments RF path using the timing advance information of the antenna appear a long distance apart, e.g. the derived from its equalizer. For this to operate, the signals transmitted and received by the section of round trip delay introduced needs to be at least one the antenna labelled 'A' appear to have come from a step of the equalizer's timing resolution.

BMommla,l"c. ,999 72 September 1999

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Developments Technical 0 M MO7VROLA

For GSM/DCS specified timing this equates to:

  max. round trip distance/speed of light in air/no. of steps of timing advance for max. delay

= round trip delay per step

70km / 3~10~ ms-' / 64 s...