Radio transmitter/receiver for wireless local area network

• US 5,838,730 A
• Filed: 05/11/1995
• Issued: 11/17/1998
• Est. Priority Date: 06/25/1993
• Status: Expired due to Term

• Current Assignee: Avaya Incorporated
• Original Assignee: Netwave Technologies Limited
• Inventors: Cripps, Peter K.
• Primary Examiner(s): VO, DON NGUYEN
• Assistant Examiner(s): Phan, Hai H.
• Application Number:
  US08/439,083
• Time in Patent Office: 1,286 Days
• Field of Search: 375/200, 375/202, 375/261, 375/219, 375/272, 375/275, 375/303, 375/307, 375/334, 375/335, 455/86, 455/84, 455/73, 455/75, 455/78
• US Class Current: 375/272
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04B 1/7143 Arrangements for generation of hop patterns
• CPC Class Codes: H04B 1/7156 Arrangements for sequence synchronisation
• CPC Class Codes: H04B 2001/71563 Acquisition
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 28/26 Resource reservation
• CPC Class Codes: H04W 36/00 Hand-off or reselection arrangements
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 74/004 in the uplink, i.e. towards network
• CPC Class Codes: H04W 74/006 in the downlink, i.e. towards the terminal
• CPC Class Codes: H04W 74/0808 using carrier sensing, e.g. carrier sense multiple access [CSMA]
• CPC Class Codes: H04W 76/10 Connection setup
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/08 Access point devices
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A wireless local area network includes a radio transmitter/receiver for transmitting and receiving in accordance with the FCC rules for the ISM band. The receiver/transmitter supports spread spectrum frequency hopping in the 2.4 GHz ISM band and can be tuned to one of e.g. 82 different frequencies spaced at 1 MHz intervals. The radio transmitter/receiver is a low cost, low power, small size unit located on a printed circuit board in a PCMCIA form factor. Third order mixers are used in combination with a switched prescaler for a low cost and compact frequency control system capable of rapid switching of the radio between transmitting and receiving functions. No special shielding is needed between the frequency control circuitry and the receiver IF circuitry.

Claims

1. A radio transmitter/receiver circuit for a wireless local area network, comprising:

a first circuit generating a first signal, said first signal having a first frequency f₁ which is switchable between a plurality of frequencies;

a second circuit receiving said first signal and generating a second signal on an output lead, said second signal having a second frequency f₂ which is switchable between a first multiple Af₁ of said first frequency and a second multiple Bf₁ of said first frequency;

an image reject mixer circuit comprising a first third order mixer and a second third order mixer, said image reject mixer circuit having a first input lead, a second input lead and an output lead, said first input lead of said image reject mixer circuit being coupled to an antenna, said second input lead of said image reject circuit being coupled to said output lead of said second circuit;

an IF amplifier, an input lead of said IF amplifier being coupled to said output lead of said image reject mixer circuit; and

a frequency multiplier circuit, an input lead of said frequency multiplier circuit being coupled to said output lead of said second circuit, an output lead of said frequency multiplier circuit being at least selectively coupled to said antenna;

wherein the transmitter/receiver circuit conforms to the PCMCIA form factor.

2. A radio transmitter/receiver circuit, comprising:

an antenna;

a receiver portion coupled to the antenna, for receiving signals in the 2.4 GHZ band; and

a transmitter portion, coupled to the antenna, for transmitting signals in the 2.4 GHZ band;

wherein said transmitter portion comprises a first circuit generating a first signal, said first signal having a first frequency f₁ which is switchable between a plurality of frequencies;

a second circuit receiving said first signal and generating a second signal on an output lead, said second signal having a second frequency f₂ which is switchable between a first multiple Af₁ of said first frequency and a second multiple Bf₁ of said first frequency;

an image reject mixer circuit comprising a first third order mixer and a second third order mixer, said image reject mixer circuit having a first input lead, a second input lead and an output lead, said first input lead of said image reject mixer circuit being coupled to said antenna, said second input lead of said image reject circuit being coupled to said output lead of said second circuit; and

an IF amplifier, an input lead of said IF amplifier being coupled to said output lead of said image reject mixer circuit; and

wherein said transmitter portion further includes a frequency multiplier circuit, an input lead of said frequency multiplier circuit being coupled to said output lead of said second circuit, an output lead of said frequency multiplier circuit being at least selectively coupled to said antenna.

3. A radio transmitter/receiver circuit, comprising:

an antenna;

a receiver portion coupled to the antenna, for receiving signals in the 2.4 GHZ band; and

a transmitter portion, coupled to the antenna, for transmitting signals in the 2.4 GHZ band;

wherein said transmitter portion comprises a first means, for synthesizing a first signal, said first signal having a first frequency f₁ which is digitally switchable between a plurality of frequencies;

a second means, for receiving said first signal and for generating a second signal on an output lead, said second signal having a second frequency f₂ which is digitally switchable between a first multiple Af₁ of said first frequency and a second multiple Bf₁ of said first frequency; and

a third means, for frequency multiplying a signal by a factor C, an input lead of said third means being coupled to said output lead of said second means, an output lead of said third means being at least selectively coupled to said antenna, wherein f₈ =Af₁ *C during a transmit mode and wherein f_IP =f_S -2Bf₁ during a receive mode; and

wherein said receiver portion comprises a fourth means, for performing image rejection comprising a first third order mixer and a second third order mixer, said fourth means having a first input lead, a second input lead and an output lead, said first input lead of said fourth means being coupled to said antenna, a signal of frequency f_S being present on said antenna, said second lead of said fourth means being coupled to said output lead of said second means; and

a fifth means, for amplifying a signal, an input lead of said fifth means being coupled to said output lead of said fourth means, an IF signal of frequency f_IF being present on said input lead of said fifth means.

4. A radio transmitter/receiver circuit, comprising:

an antenna;

a receiver portion coupled to the antenna, for receiving signals in the 2.4 GHZ band; and

a transmitter portion, coupled to the antenna, for transmitting signals in the 2.4 GHZ band;

wherein the radio transmitter/receiver circuit is on a single printed circuit board and conforms to the PCMCIA form factor; and

wherein said transmitter portion comprises a first circuit generating a first signal, said first signal having a first frequency f₁ which is switchable between a plurality of frequencies;

a second circuit receiving said first signal and generating a second signal on an output lead, said second signal having a second frequency f₂ which is switchable between a first multiple Af₁ of said first frequency and a second multiple Bf₁ of said first frequency;

an image reject mixer circuit comprising a first third order mixer and a second third order mixer, said image reject mixer circuit having a first input lead, a second input lead and an output lead, said first input lead of said image reject mixer circuit being coupled to said antenna, said second input lead of said image reject circuit being coupled to said output lead of said second circuit; and

an IF amplifier, an input lead of said IF amplifier being coupled to said output lead of said image reject mixer circuit; and

wherein said transmitter portion further includes a frequency multiplier circuit, an input lead of said frequency multiplier circuit being coupled to said output lead of said second circuit, an output lead of said frequency multiplier circuit being at least selectively coupled to said antenna.

5. A radio transmitter/receiver circuit, comprising:

an antenna;

a receiver portion coupled to the antenna, for receiving signals in the 2.4 GHZ band; and

a transmitter portion, coupled to the antenna, for transmitting signals in the 2.4 GHZ band;

wherein the radio transmitter/receiver circuit is on a single printed circuit board and conforms to the PCMCIA form factor;

wherein said transmitter portion comprises a first means, for synthesizing a first signal, said first signal having a first frequency f₁ which is digitally switchable between a plurality of frequencies;

a second means, for receiving said first signal and for generating a second signal on an output lead, said second signal having a second frequency f₂ which is digitally switchable between a first multiple Af₁ of said first frequency and a second multiple Bf₁ of said first frequency; and

a third means, for frequency multiplying a signal by a factor C, an input lead of said third means being coupled to said output lead of said second means, an output lead of said third means being at least selectively coupled to said antenna, wherein f_S =Af₁ *C during a transmit mode and wherein f_IF =f_S -2Bf₁ during a receive mode; and

wherein said receiver portion comprises a fourth means, for performing image rejection comprising a first third order mixer and a second third order mixer, said fourth means having a first input lead, a second input lead and an output lead, said first input lead of said fourth means being coupled to said antenna, a signal of frequency f_S being present on said antenna, said second lead of said fourth means being coupled to said output lead of said second means; and

a fifth means, for amplifying a signal, an input lead of said fifth means being coupled to said output lead of said fourth means, an IF signal of frequency f_IF being present on said input lead of said fifth means.