System and method for frequency offsetting of information communicated in MIMO-based wireless networks

• US 8,254,865 B2
• Filed: 02/20/2009
• Issued: 08/28/2012
• Est. Priority Date: 04/07/2006
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: BelAir Networks (Telefonaktiebolaget LM Ericsson)
• Inventors: Soul, Colin H., Smith, Roland A., Rayment, Stephen G.
• Primary Examiner(s): NGUYEN, TUAN HOANG
• Application Number:
  US12/390,062
• Publication Number:
  US 20090180466A1
• Time in Patent Office: 1,285 Days
• Field of Search: 455/230, 455/502, 370/350, 375/267
• US Class Current: 455/230
• CPC Class Codes: H03J 7/04 where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04L 2027/0016 Stabilisation of local oscillators
• CPC Class Codes: H04L 2027/0028 at passband only
• CPC Class Codes: H04L 27/0014 Carrier regulation of chaotic carriers H04L27/001; for multicarrier receivers H04L27/2657

Abstract

A communications system includes a multiple-input/multiple-output (MIMO) architecture for high capacity switched mesh networks. The MIMO architecture has a plurality of radio frequency chains. One of the plurality of radio frequency chains is configured to apply a first frequency offset to a base frequency of an output signal to generate a first transmitting frequency; and another of the plurality of radio frequency chains being configured to apply a second frequency offset to the base frequency to generate a second transmitting frequency. The system uses the carrier frequency offset to lock the clock of the master subsystem to the clock of the slave subsystem, thereby enabling bandwidth expansion to be employed on the MIMO data streams.

Claims

1. A method of synchronizing a receiver with a transmitter in a communications system comprising a multiple-input/multiple-output (MIMO) architecture, the architecture comprising a first and a second radio frequency chain, the communications system being configured to transceive at least two signals having a predetermined frequency separation, and the method comprising the steps of:

a) locking a frequency of the receiver to an external timing reference, wherein the external timing reference comprises a Global Positioning System (GPS) timing reference; and

b) locking a frequency of the transmitter to the external timing reference,

wherein each of steps a) and b) is carried out independently of one another, and wherein the GPS timing reference is configured to lock a plurality of transceivers such that the method is usable in any of a point-to-point application, a point-to-multipoint application, and a multipoint-to-multipoint application.

2. The method of claim 1, wherein the GPS timing reference is configured to lock a variable crystal oscillator.

3. The method of claim 2, wherein the variable crystal oscillator comprises a 40-MHz variable crystal oscillator.

4. A method of synchronizing a receiver with a transmitter in a communications system comprising a multiple-input/multiple-output (MIMO) architecture, the architecture comprising a first and a second radio frequency chain, the communications system being configured to transceive at least two signals having a predetermined frequency separation, and the method comprising the steps of:

a) locking a frequency of the receiver to an external timing reference, wherein the external timing reference comprises an IEEE 1588 timing reference; and

b) locking a frequency of the transmitter to the external timing reference,

wherein each of steps a) and b) is carried out independently of one another, and

wherein the IEEE 1588 timing reference is configured to lock a plurality of transceivers such that the method is usable in any of a point-to-point application, a point-to-multipoint application, and a multipoint-to-multipoint application.

5. The method of claim 4, wherein the IEEE 1588 timing reference is configured to lock a variable crystal oscillator.

6. The method of claim 5, wherein the variable crystal oscillator comprises a 40-MHz variable crystal oscillator.

7. The method of claim 4, wherein the IEEE 1588 timing reference is configured to be frequency locked to a GPS timing reference.

8. The method of claim 4, wherein the IEEE 1588 timing reference is configured to be frequency locked to a Building Integrated Timing Source (BITS) reference.