Diversity transceiver for a wireless local area network

• US 7,110,381 B1
• Filed: 09/14/2001
• Issued: 09/19/2006
• Est. Priority Date: 03/19/2001
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Systems Wireless Networking (Australia) Pty Limited (Cisco Systems, Inc.)
• Inventors: Weste, Neil, O'Sullivan, John
• Primary Examiner(s): Duong, Frank
• Application Number:
  US09/953,461
• Time in Patent Office: 1,831 Days
• Field of Search: 370328-339, 370/464, 370/465, 375/267, 375/347, 455101-103
• US Class Current: 370/338
• CPC Class Codes: H04B 7/0814 based on current reception conditions, e.g. switching to different antenna when signal level is below threshold
• CPC Class Codes: H04L 27/2626 Arrangements specific to the transmitter only
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

A wireless local area network system comprises a 5.0+ GHz radio transceiver with two receiving antennas and one transmitting antenna. A transmitter power amplifier output is connected to the transmitting antenna through a 6–8 pole filter to control spurious signal output. Each receiving antenna is fitted with its own low-noise amplifier followed by a simple bandpass filter. Each bandpass filter feeds a diversity switch with a single output to a single receiver. The radio system constitutes a physical-layer (PHY) part of a wireless local-area network.

Claims

1. A network node for operating in a wireless computer-data network that operates according to an IEEE 802.11 standard, that includes a local network client, and that operates according to an IEEE 802.11 PHY standard, the network node comprising:

a physical-layer (PHY) radio receiver for supporting communications from the wireless computer-data network to said local network client, the radio receiver configured for operation using OFDM according to an IEEE 802.11 OFDM PHY standard and including one or more local oscillators, a first downconverter coupled to one of the local oscillators and configured in operation to convert a received signal to an intermediate frequency signal, a filter to filter the intermediate frequency signal to produce a filtered intermediate frequency signal, a second downconverter coupled to one of the local oscillators and configured in operation to convert the filtered intermediate frequency signal to form a signal for digitizing, an analog to digital converter to digitize the signal for digitizing, and a digital processor to process the digitized signal output by the analog to digital converter, the digital processor including a processor implementing a discrete Fourier transform operation, and further including a programmable processor; and

at least two receiver antennas connected through a diversity switch to the PHY radio receiver and providing for alternative diversity reception points that are selectable according to a switch signal determined by the digital processor according to radio signal quality, the diversity switch having a signal path for the switch signal from the digital processor of the PHY radio receiver.

2. A network node as recited in claim 1, wherein the PHY radio receiver is substantially integrated as a single analog chip and a single digital chip.

3. A network node for operating in a wireless computer-data network that operates according to an IEEE 802.11 standard, that includes a local network client, and that operates according to an IEEE 802.11 PHY standard, the network node comprising:

a physical-layer (PHY) radio transmitter for supporting communications from said local network client to the wireless computer-data network, the radio transmitter configured for operation using OFDM according to the IEEE 802.11 OFDM PHY standard and including a digital processor to generate a digital OFDM signal for transmitting, the digital processor including a processor implementing an inverse Fourier transform operation, one or more local oscillators, a digital-to-analog converter coupled to the digital processor to convert the digital OFDM signal for transmitting to an analog signal, a first upconverter coupled to one of the local oscillators and configured in operation to convert the analog signal to an intermediate frequency signal, a filter to filter the intermediate frequency signal to produce a filtered intermediate frequency signal, and a second upconverter coupled to one of the local oscillators and configured in operation to convert the filtered intermediate frequency signal to form a radiofrequency signal, the digital processor further including a programmable processor; and

at least two transmitter antennas connected through a diversity switch to the PHY radio transmitter and providing for alternative diversity transmission points that are selectable according to a switch signal determined by the digital processor according to network responses, the diversity switch having a signal path for the switch signal from the digital processor of the PHY radio transmitter.

4. A network node as recited in claim 3, wherein the PHY radio transmitter is substantially integrated as a single analog chip and a single digital chip.

5. A network node for operating in a wireless computer-data network that operates according to an IEEE 802.11 standard, that includes a local network client, and that operates according to an IEEE 802.11 PHY standard, the network node comprising:

a physical-layer (PHY) radio transmitter for supporting communications from said local network client to the wireless computer-data network, the radio transmitter configured for operation using OFDM according to the IEEE 802.11 OFDM PHY standard and including a digital processor to generate a digital OFDM signal for transmitting, the digital processor including a processor implementing an inverse Fourier transform operation, one or more local oscillators, a digital-to-analog converter coupled to the digital processor to convert the digital OFDM signal for transmitting to an analog signal, a first upconverter coupled to one of the local oscillators and configured in operation to convert the analog signal to an intermediate frequency signal, a filter to filter the intermediate frequency signal to produce a filtered intermediate frequency signal, and a second upconverter coupled to one of the local oscillators and configured in operation to convert the filtered intermediate frequency signal to form a radiofrequency signal;

a physical-layer (PHY) radio receiver for supporting communications from the wireless computer-data network to said local network client, the radio receiver configured for operation using OFDM according to an IEEE 802.11 OFDM PHY standard and including a first downconverter coupled to one of the local oscillators and configured in operation to convert a received signal to an intermediate frequency received signal, a filter to filter the intermediate frequency signal to produce a filtered intermediate frequency received signal, and a second downconverter coupled to one of the local oscillators and configured in operation to convert the filtered intermediate frequency received signal to form a received signal for digitizing, an analog to digital converter to digitize the received signal for digitizing and to provide the digitized received signal to the digital processor for processing, the digital processor including a processor implementing a discrete Fourier transform operation, and further including a programmable processor;

at least two receiver antennas connected through a diversity switch to the PHY radio receiver and providing for alternative diversity reception points that are selectable according to a receive switch signal determined by the digital processor according to received radio signal quality, the diversity switch having a signal path for the receive switch signal from the digital processor of the PHY radio receiver; and

at least two transmitter antennas connected through a diversity switch to the PHY radio transmitter and providing for alternative diversity transmission points that are selectable according to a transmit switch signal determined by the digital processor according to network responses, the diversity switch having a signal path for the transmit switch signal from the digital processor of the PHY radio transceiver.

6. A network node as recited in claim 5, wherein the PHY radio transmitter and PHY radio receiver are substantially integrated together as a single analog transceiver chip and a single digital transceiver chip.

7. A physical-layer (PHY) radio receiver for supporting wireless local area network (WLAN) communications according to an IEEE 802.11 PHY standard, the PHY radio receiver comprising:

at least two receiver antennas connected through a diversity switch to a radio receiver and providing for selectable diversity reception points;

a low-noise amplifier (LNA) integrated with each of the receiver antennas;

one or more local oscillators;

a first downconverter coupled to one of the local oscillators and configured in operation to convert a received signal to an intermediate frequency signal;

a filter to filter the intermediate frequency signal to produce a filtered intermediate frequency signal;

a second downconverter coupled to one of the local oscillators and configured in operation to convert the filtered intermediate frequency signal to form a signal for digitizing;

an analog to digital converter coupled to the second downconverter and configured in operation to digitize the signal for digitizing; and

a digital processor to process the digitized signal output by the analog to digital converter, the digital processor including a processor implementing a discrete Fourier transform operation, the digital processor further including a programmable processor;

wherein the diversity switch follows each antenna and corresponding LNA and provides diversity selection between wireless local area network (WLAN) signals received by the antennas, the diversity switch having a switch signal input and a signal between the switch signal input and the digital processor,

wherein the PHY radio receiver is configured for operation using OFDM according to an IEEE 802.11 OFDM PHY standard, and

wherein, the diversity switch is manipulated during attempts to communicate with a proximate wireless local area network so data networking is supported in real-time.

8. A network node as recited in claim 7, wherein the PHY radio receiver is substantially integrated as a single analog chip and a single digital chip.

9. A physical-layer (PHY) radio transmitter for supporting wireless local area network (WLAN) communications according to an IEEE 802.11 PHY standard, the PHY ratio transmitter comprising:

at least two transmitting antennas connected through a diversity switch to a radio transmitter and providing for selectable diversity transmission points;

one or more local oscillators;

a digital processor to generate a digital OFDM signal for transmitting, the digital processor including a processor implementing an inverse Fourier transform operation, the digital processor further including a programmable processor;

one or more local oscillators;

a digital-to-analog converter coupled to the digital processor to convert the digital OFDM signal for transmitting to an analog signal;

a first upconverter coupled to one of the local oscillators and to the digital-to-analog converter, and configured in operation to convert the analog signal to an intermediate frequency signal,

a filter to filter the intermediate frequency signal to produce a filtered intermediate frequency signal; and

a second upconverter coupled to one of the local oscillators and configured in operation to convert the filtered intermediate frequency signal to form a radiofrequency signal;

wherein the diversity switch precedes both transmitting antennas and provides diversity selection between wireless local area network (WLAN) signals output by the antennas, the diversity switch having a switch signal input and a signal between the switch signal input and the digital processor,

wherein the PHY radio receiver is configured for operation using OFDM according to an IEEE 802.11 OFDM PHY standard, and

wherein, the diversity switch is manipulated during attempts to communicate with a proximate wireless local area network so data networking is supported in real-time.

10. A network node as recited in claim 9, wherein the PHY radio transmitter is substantially integrated as a single analog chip and a single digital chip.

11. A network node for operating in a wireless computer-data network that operates according to an IEEE 802.11 standard, that includes a local network client, and that operates according to an IEEE 802.11 PHY standard, the network node comprising:

physical-layer (PHY) radio receiver means for supporting communications from the wireless computer-data network to said local network client, the radio receiver means configured for operation using OFDM according to an IEEE 802.11 OFDM PHY standard and including;

one or more means for producing a local oscillator signal;

first means for downconverting coupled to one of the means for producing a local oscillator signal and configured in operation to convert a received signal to an intermediate frequency signal;

means for filtering the intermediate frequency signal to produce a filtered intermediate frequency signal;

second means for downconverting coupled to one of the means for producing a local oscillator signal and configured in operation to convert the filtered intermediate frequency signal to form a signal for digitizing;

means for digitizing the signal for digitizing; and

means for digital processing the digitized signal output by the means for digitizing, the means for digital processing including means for implementing a discrete Fourier transform operation, the means for digital processing further including programmable processing means; and

at least two receiver antennas connected through means for switching to the PHY radio receiver means and providing for alternative diversity reception points that are selectable according to a switch signal determined by the means for digital processing according to radio signal quality, the means for switching having a signal path for the switch signal from the digital processor of the PHY radio receiver.

12. A network node as recited in claim 11, wherein the PHY radio receiver means is substantially integrated as a single analog chip and a single digital chip.

13. A network node for operating in a wireless computer-data network that operates according to an IEEE 802.11 standard, that includes a local network client, and that operates according to an IEEE 802.11 PHY standard, the network node comprising:

physical-layer (PHY) radio transmitter means for supporting communications from said local network client to the wireless computer-data network, the radio transmitting means configured for operation using OFDM according to the IEEE 802.11 OFDM PHY standard and including;

means for digital processing for generating a digital OFDM signal for transmitting, the digital processing means including means for implementing an inverse Fourier transform operation, the means for digital processing further including programmable processing means;

one or more means for producing a local oscillator signal;

means for converting of the digital OFDM signal for transmitting to an analog signal for transmitting;

first means for upconverting coupled to one of the means for producing a local oscillator signal and configured in operation to convert the analog signal for transmitting to an intermediate frequency signal;

means for filtering the intermediate frequency signal to produce a filtered intermediate frequency signal; and

second means for upconverting coupled to one of the means for producing a local oscillator signal and configured in operation to convert the filtered intermediate frequency signal to form a radiofrequency signal; and

at least two transmitter antennas connected through a diversity switch to the PHY radio transmitter means and providing for alternative diversity transmission points that are selectable according to a switch signal determined by means for digital processing according to network responses, the diversity switch having a signal path for the switch signal from the means for digital processing.

14. A network node as recited in claim 13, wherein the PHY radio transmitter means is substantially integrated as a single analog chip and a single digital chip.

15. A network node for operating in a wireless computer-data network that operates according to an IEEE 802.11 standard, that includes a local network client, and that operates according to an IEEE 802.11 PHY standard, the network node comprising:

physical-layer (PHY) radio transmitter means for supporting communications from said local network client to the wireless computer-data network, the radio transmitting means configured for operation using OFDM according to the IEEE 802.11 OFDM PHY standard and including;

means for digital processing for generating a digital OFDM signal for transmitting, the digital processing means including means for implementing an inverse Fourier transform operation, the means for digital processing further including programmable processing means;

one or more means for producing a local oscillator signal;

means for converting of the digital OFDM signal for transmitting to an analog signal for transmitting;

first means for upconverting coupled to one of the means for producing a local oscillator signal and configured in operation to convert the analog signal for transmitting to an intermediate frequency signal;

means for filtering the intermediate frequency signal to produce a filtered intermediate frequency signal; and

second means for upconverting coupled to one of the means for producing a local oscillator signal and configured in operation to convert the filtered intermediate frequency signal to form a radiofrequency signal;

physical-layer (PHY) radio receiver means for supporting communications from the wireless computer-data network to said local network client, the radio receiver means configured for operation using OFDM according to the IEEE 802.11 OFDM PHY standard and including;

first means for downconverting coupled to one of the means for producing a local oscillator signal and configured in operation to convert a received signal to an intermediate frequency received signal;

means for filtering the intermediate frequency received signal to produce a filtered intermediate frequency received signal;

second means for downconverting coupled to one of the means for producing a local oscillator signal and configured in operation to convert the filtered intermediate frequency received signal to form a signal for digitizing;

means for digitizing the signal for digitizing to form a digitized signal, coupled to the means for digital processing such that the means for digital processing is configured to process the digitized signal, the means for digital processing including means for implementing a discrete Fourier transform operation;

at least two receiver antennas connected through means for switching to the PHY radio receiver means and providing for alternative diversity reception points that are selectable according to a switch signal determined by the means for digital processing according to radio signal quality, the means for switching having a signal path for the switch signal from the digital processor of the PHY radio receiver; and

at least two transmitter antennas connected through a diversity switch to the PHY radio transmitter means and providing for alternative diversity transmission points that are selectable according to a switch signal determined by means for digital processing according to network responses, the diversity switch having a signal path for the switch signal from the means for digital processing.

16. A network node as recited in claim 15, wherein the wherein the PHY radio transmitter means and PHY radio receiver means are substantially integrated together as a single analog transceiver chip and a single digital transceiver chip.

17. A means for physical-layer (PHY) radio reception for supporting wireless local area network (WLAN) communications conforming to one of the IEEE 802.11 OFDM standards, the radio reception means comprising:

means for connecting at least two receiver antennas through a diversity switch to an OFDM radio receiver and providing for selectable diversity reception points, the OFDM radio receiver including;

one or more means for producing a local oscillator signal;

first means for downconverting coupled to one of the means for producing a local oscillator signal and configured in operation to convert a received signal to an intermediate frequency signal;

means for filtering the intermediate frequency signal to produce a filtered intermediate frequency signal;

second means for downconverting coupled to one of the means for producing a local oscillator signal and configured in operation to convert the filtered intermediate frequency signal to form a signal for digitizing;

means for digitizing the signal for digitizing; and

means for digital processing the digitized signal output by the means for digitizing, the means for digital processing including means for implementing a discrete Fourier transform operation, the means for digital processing further including programmable processing means;

means for integrating a low-noise amplifier (LNA) with each of the receiver antennas; and

means for diversity switching that follows each antenna and corresponding LNA and that provides diversity selection between wireless local area network (WLAN) signals received by the antennas,

wherein, the means for diversity switching is manipulated during attempts to communicate with a proximate wireless local area network so data networking is supported in real-time.

18. A means for physical-layer (PHY) radio transmitting that supports wireless local area network (WLAN) communications conforming to one of the IEEE 802.11 OFDM standards, the radio transmitting means comprising:

means for connecting at least two transmitting antennas through a diversity switch to an OFDM radio transmitter and providing for selectable diversity transmission points, the radio transmitter including;

means for digital processing for generating a digital OFDM signal for transmitting, the digital processing means including means for implementing an inverse Fourier transform operation, the means for digital processing further including programmable processing means;

one or more means for producing a local oscillator signal;

means for converting of the digital OFDM signal for transmitting to an analog signal for transmitting;

first means for upconverting coupled to one of the means for producing a local oscillator signal and configured in operation to convert the analog signal for transmitting to an intermediate frequency signal;

means for filtering the intermediate frequency signal to produce a filtered intermediate frequency signal; and

second means for upconverting coupled to one of the means for producing a local oscillator signal and configured in operation to convert the filtered intermediate frequency signal to form a radiofrequency signal; and

means for diversity switching that precedes both transmitting antennas and that provides diversity selection between wireless local area network (WLAN) signals output by the antennas,

wherein, the means for diversity switching is manipulated during attempts to communicate with a proximate wireless local area network so data networking is supported in real-time.