Transmit network for a cellular base-station

• US 7,181,175 B2
• Filed: 03/22/2002
• Issued: 02/20/2007
• Est. Priority Date: 04/04/2001
• Status: Expired due to Fees

• Current Assignee: Quintel Technology Limited (Cirtek Holdings Philippines Corp.)
• Original Assignee: Quintel Technology Limited (Cirtek Holdings Philippines Corp.)
• Inventors: Thomas, Louis David, Bradbeer, Geoffrey Raymond, Nimmo-Smith, Norman Richard, Bullers, Stephen, Spicer, John Allerton
• Primary Examiner(s): Anderson; Matthew D.
• Assistant Examiner(s): Pham; Tuan
• Application Number:
  US10/473,883
• Publication Number:
  US 20040137947A1
• Time in Patent Office: 1,796 Days
• Field of Search: 455/101, 455/103, 455/121, 455/561, 455/562.1
• US Class Current: 455/101
• CPC Class Codes: H01Q 21/30 Combinations of separate antenna units operating in different wavebands and connected to a common feeder system
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A transmit network for cellular mobile radio networks incorporates tow transmit multiplexers (122ABE) and (122CD): the first transmit multiplexer 122ABE receives a group of output signals from three transmitters (124A, 124B and 124E), and filters them in respective band-pass filters (126A, 126B and 126E); the second transmit multiplexer (122CD) receives a group of output signals from two further transmitters (124C and 124D), and filters them in respective band-pass filters (126C and 126D). The transmit frequencies in each signal group are non-adjacent, which improves isolation between transmitters provided by the filters (126). Filtered output signals from respective band-pass filters (126) are combined at filter outputs (128X and 128Y) from which signals are combined in a combiner (132) providing a degree of isolation between these outputs and enabling the signals to be combined with minimal distortion. Signals from the combiner (132) are fed via a duplexer to a transmit/receive antenna.

Claims

1. A transmit network for cellular mobile radio operating over a plurality of contiguous frequency bands, the network comprising:

a plurality of transmitters for generating respective transmitter output signals in respective ones of said contiguous frequency bands;

a plurality of band-pass filters, each filter associated with a respective one of said plurality of transmitters and having a respective pass band for filtering a respective transmitter output signals so as to pass a respective filtered transmitter output signal,

an antenna system having a plurality of antenna elements, and

means for combining the filtered transmitter output signals into a plurality of output signal groups, at least one of said output signal groups including a plurality of non-contiguous frequency bands from within said plurality of continuous frequency bands, and for feeding respective output signal groups to respective antenna elements.

2. A transmit network according to claim 1 wherein the plurality of output signal groups comprises two groups of two and three filtered transmitter output signals respectively.

3. A transmit network according to claim 1 wherein the antenna elements are mutually orthogonally polarised radiating elements arranged to receive respective output signal groups for transmission.

4. A transmit network according to claim 1 including respective isolators between the transmitters and their associated band-pass filters, the isolators being arranged to inhibit output signals passing between transmitters.

5. A method of transmitting signals in a cellular mobile radio system operating over a plurality of contiguous frequency bands from an antenna having a plurality of antenna elements, the method including the steps of:

generating transmitter output signals in respective ones of said contiguous frequency bands;

filtering each transmitter output signal so as to pass respective filtered transmitter output signals;

dividing said filtered transmitter output signals into a plurality of output signal groups at least one of said output signal groups contains a plurality of non-contiguous output signals spaced apart in frequency,

and

combining the output signal groups by feeding the respective output signal groups to respective antenna elements.

6. A method according to claim 5 wherein the dividing step includes dividing said plurality of output signal groups into two groups of two and three filtered transmitter output signals respectively.

7. A method according to claim 6 wherein the antenna elements are mutually orthogonally polarised antenna elements and said combining step feeds respective output signal groups for transmission on respective orthogonally polarized antenna elements.

8. A method according to claim 6 including the step of providing respective isolators between the transmitters and their associated band-pass filters, the isolators being arranged to inhibit output signals passing between transmitters.