Fully saturated multi-tone transceiver

• US 8,270,513 B2
• Filed: 05/24/2007
• Issued: 09/18/2012
• Est. Priority Date: 05/31/2006
• Status: Expired due to Fees

• Current Assignee: Cobham Advanced Electronic Solutions, Inc. (Cobham PLC)
• Original Assignee: Cobham Defense Electronic Systems Corporation (Cobham PLC)
• Inventors: Egri, Robert, Perraud, Laurent
• Primary Examiner(s): Tran, Khanh C
• Application Number:
  US11/753,225
• Publication Number:
  US 20070280372A1
• Time in Patent Office: 1,944 Days
• Field of Search: 375/267, 375/299, 375/347, 375/349, 700/53, 455/101, 455132-141
• US Class Current: 375/267
• CPC Class Codes: H04L 27/2637 with direct modulation of individual subcarriers

Abstract

The present invention provides a method and system for transmitting a multi-frequency signal composed of discrete tones of constant envelope parts that are amplified by a bank of fully saturated transmitters operating in their most power efficient mode. After amplification and transmission, the signals are multiplexed in the air as opposed to multiplexing before amplification that allows for more efficient amplification as well. In a preferred embodiment, the system has two or more transmitting antennas, and the method comprises: (a) generating a first signal of a first carrier frequency and a second signal of a second carrier frequency; (b) transmitting the first signal of a first carrier frequency on a first antenna and the first signal of a second carrier signal on a second antenna for a predetermined time period; and (c) transmitting a second signal of the second carrier frequency on said first antenna and a second signal of the first carrier frequency on the second antenna for the predetermined time period. Preferably, the signals are transmitted using an amplifier that is essentially fully saturated.

Claims

1. A method of transmitting a multi-tone signal over a multiple input multiple output (MIMO) system having two or more transmitting antennas over several time segments, said method comprising:

generating first and second signals having different frequencies;

during a first time segment, transmitting said first signal on a first antenna and said second signal on a second antenna for a predetermined time period; and

during a second time segment transmitting said second signal on said first antenna and said first signal on said second antenna for said predetermined time period.

2. The method of claim 1 wherein said generating step comprises generating third and fourth signals each having a different frequency and wherein said transmission time segments comprise:

a second time segment in which said second and said third signals are transmitted on said first and second antenna respectively;

a third time segment in which said third and said fourth signals are transmitted on said first and second antenna respectively; and

a fourth time segment in which said fourth and said first signals are transmitted on said first and second antenna respectively.

3. The method of claim 1, wherein said transmitting comprises amplifying said first and second signals using a pair of fully-saturated amplifiers.

4. The method of claim 3, wherein said first and second signals are constant envelope signals.

5. The method of claim 4, wherein said signals are multiplexed in space after being transmitted.

6. The method of claim 5, wherein a coherence window of a wireless channel being used for transmitting said signals is at least as long as said predetermined time period times a total number of transmitting antennas over which the signals are transmitted.

7. The method of claim 1 wherein the first and second signals comprise the same payload.

8. A method of transmitting a multi-tone signal over a MIMO system having two or more transmitting antennas, said method comprising:

generating a plurality of signals having different frequencies, each of the plurality of signals having a payload, wherein the payload of each signal is identical; and

transmitting individually each of said signals on each of said antennas for a predetermined time period and in a predetermined sequence.

9. The method of claim 8, wherein said predetermined sequence is arranged such that each of said plurality of signals is broadcast at least once over each antenna over a coherence time of the wireless channel.

10. The method of claim 9, wherein said transmitting comprises amplifying said plurality of signals using fully-saturated or nearly saturated amplifiers.

11. The method of claim 10, wherein said plurality of signals are constant or nearly-constant envelope signals.

12. The method of claim 11, wherein said signals are multiplexed after being transmitted.

13. The method of claim 12, wherein a coherence window of a wireless channel being used for transmitting said signals is at least as long as said predetermined time period times the total number of antennas over which the signals are transmitted.

14. An amplifier circuit comprising:

a signal generator for generating tones of constant envelope signals;

an array of upconverters for converting said tones to a transmittable frequency band, one upconverter for each of the modulated tones; and

an amplifier for amplifying each converted tone for transmission by an antenna; and

a matching circuit to tune each antenna to the modulated tone being transmitted.

15. The amplifier circuit of claim 14, wherein the amplifier circuit is integrated on a chip.

16. The amplifier circuit of claim 14, wherein said amplifier circuit is a single CMOS or BiCMOS integrated circuit chip.