Frequency selection method to mitigate in-band interference from inter-modulation spur of the collocated radio transmitter

• US 8,290,020 B2
• Filed: 06/16/2009
• Issued: 10/16/2012
• Est. Priority Date: 06/16/2009
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Liu, Hsin-Yuo, Roth, Leora, Zhu, Jing
• Primary Examiner(s): Flores, Leon
• Application Number:
  US12/485,833
• Publication Number:
  US 20100316089A1
• Time in Patent Office: 1,218 Days
• Field of Search: 375/130, 375/132, 375/133, 375/135, 375/136, 375/219, 375/220, 375/295, 375/316, 370/272, 370/273, 370/276, 370/297, 370/320, 370/329, 370/335, 370/342, 370/431, 370/441, 370/464, 370/479, 455/39, 455/41.2, 455/62, 455/63.1, 455/73, 455/76, 455/91, 455/114.2, 455/130
• US Class Current: 375/133
• CPC Class Codes: H04B 15/04 the interference being caused by substantially sinusoidal oscillations, e.g. in a receiver or in a tape-recorder
• CPC Class Codes: H04B 2215/065 by changing the frequency of clock or reference frequency
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal

Abstract

A radio transmitter select its operating frequency based on the frequency characteristics of a collocated receiver and clock harmonics. The radio transmitter can dynamically change its operating frequency in a wide enough range so as to avoid frequencies where its spurs fall on the receive frequency of the collocated receiver. The frequency characteristics of the clock harmonic of the radio transmitter and the collocated receiver are obtained, then a range of operating frequencies is calculated to enable the collocated devices to operate without undue interference.

Claims

1. A system comprising:

a receiver operating at a predetermined frequency, starting at F, and bandwidth, B;

a transmitter/receiver operating within a predetermined range of frequencies, the transmitter/receiver comprising an internal clock running at a clock frequency, f₀ and bandwidth, b₀; and

a frequency selection engine to select a range of operating frequencies of the transmitter/receiver within the predetermined range, the frequency selection engine to select a plurality of operating frequency ranges using ether of the following equations;

{x<

F+f₀}, {F+B+(k−

1)f₀+b₀<

x<

F+kf₀, (k>

1)}, or

{F+B−

kf₀<

x<

F−

b₀−

(k−

1)f₀, (k>

1)}, {F+B−

f₀<

x},

wherein k is an integer and x indicates either an operating frequency or a range of operating frequencies of the transmitter/receiver;

wherein the receiver does not experience transmission spurs of the transmitter/receiver due to inter-modulation.

2. The system of claim 1, wherein the receiver is a WiMAX receiver.

3. The system of claim 2, wherein B is 10 MHz.

4. The system of claim 3, wherein the WiMAX receiver operates between 2503 MHz and 2513 MHZ.

5. The system of claim 1, wherein the transmitter/receiver is a Bluetooth device operating at a 1 MHz bandwidth.

6. The system of claim 5, wherein the Bluetooth transmitter/receiver performs frequency hopping.

7. The system of claim 5, wherein and the predetermined range of frequencies is between 2402 MHz and 2480 MHz.

8. A method implemented in a frequency selection engine, comprising:

obtaining a desired operating frequency and bandwidth of a receiver;

obtaining a clock frequency of a frequency hopping spread spectrum radio transmitter, wherein the frequency hopping spread spectrum transmitter operates over a single channel at a time of a multiple-channel transmission spectrum;

either adding or subtracting the clock frequency from the desired operating frequency to generate a first frequency;

either adding or subtracting twice the clock frequency from the desired operating frequency to generate a second frequency;

either adding or subtracting three times the clock frequency from the desired operating frequency to generate a third frequency; and

programming the frequency hopping spread spectrum radio transmitter to not operate in the following operating ranges;

the first frequency through the first frequency plus the bandwidth;

the second frequency through the second frequency plus the bandwidth; and

the third frequency through the third frequency plus the bandwidth.

9. The method of claim 8, obtaining a desired operating frequency and bandwidth of a receiver further comprising:

obtaining a desired operating frequency and bandwidth of a victim receiver.

10. The method of claim 9, obtaining a desired operating frequency and bandwidth of a victim receiver further comprising:

obtaining a desired operating frequency and a bandwidth of a WiMAX receiver.

11. The method of claim 9, obtaining a desired operating frequency and a bandwidth of a WiMAX receiver further comprising:

obtaining a desired operating frequency of 2508 MHz and a bandwidth of 10 MHz.

12. The method of claim 8, obtaining a clock frequency of a frequency hopping spread spectrum radio transmitter further comprising:

obtaining a clock frequency of a Bluetooth radio transmitter.

13. A system comprising:

a victim receiver operating at a predetermined frequency, F, and bandwidth, B;

a transmitter/receiver operating within a predetermined range of frequencies, the transmitter/receiver comprising an internal clock running at a clock frequency, f₀; and

a frequency selection engine to select a range of operating frequencies of the transmitter/receiver within the predetermined range, the frequency selection engine to;

select a first operating frequency range of F±

f₀ through F±

f₀+B;

select a second operating frequency range of F±

2f₀ through F±

2f₀+B;

select a third operating frequency range of F±

3f₀ through F±

3f₀+B;

wherein the victim receiver does not experience transmission spurs of the transmitter/receiver due to inter-modulation.

14. The system of claim 13, wherein the victim receiver is a WiMAX receiver.

15. The system of claim 14, wherein the WiMAX receiver operates between 2503 MHz and 2513 MHz.

16. The system of claim 13, wherein the transmitter/receiver is a fixed operating frequency device with a wide range of operating frequencies.

17. The system of claim 13, wherein the transmitter/receiver performs frequency hopping.

18. The system of claim 13, wherein the transmitter/receiver is a Bluetooth transmitter/receiver.

19. The system of claim 13, wherein the first, second, and third operating frequency ranges are adjusted to conform with the operating frequency range of the transmitter/receiver.