Directional antenna physical layer steering for WLAN

Abstract

A technique for steering a directional antenna such as may be used in a Wireless Local Area Network (WLAN) device. The technique detects signal parameters during reception of short sync pulses in the very beginning portion of a Packet Protocol Data Unit (PPDU) frame. As a result, the antenna can be steered to an optimum direction for reception prior to receiving other portions of a preamble that may be needed to acquire carrier signal phase and frequency.

Description

RELATED APPLICATIONS [0001] This application is a continuation of U.S. application Ser. No. 10 / 675,583, filed on Sep. 30, 2003, which claims the benefit of U.S. Provisional Application No. 60 / 414,947 filed Sep. 30, 2002 and U.S. Provisional Application No. 60 / 415,847 filed Oct. 3, 2002. The entire teachings of the above applications are incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] Wireless Local Area Network (WLAN) equipment continues to be used as a solution for many different data connectivity applications. WLANs are now viewed as an ideal solution for providing access to wireless equipped personal computers within home networks, mobile access to laptop computers and personal digital assistants (PDAs), as well as providing robust and convenient access in business applications. [0003] Indeed, at the present time many laptop computers are shipped from the factory with WLAN interface cards. Certain microprocessor manufacturers, such as Intel, have also announce...

AI Technical Summary

Benefits of technology

"The present invention is about a technique for implementing antenna steering in a WLAN device. This technique allows for quicker and more efficient antenna steering without involving higher communication layers. The invention provides techniques for signal detection during short sync symbol reception in a WLAN frame, which allows the radio receiver equipment to use the remainder of the preamble to acquire carrier phase lock and frequency synchronization, in just about the same manner as if no directional antennal were present. The remaining preamble portions can thus be processed according to standard WLAN frame processing. The invention also involves the use of finite impulse response comb filtering to improve signal to noise ratio and select the best angle for communication. Overall, the invention provides faster and more efficient antenna steering in WLAN devices."

Problems solved by technology

Unfortunately, having tens, if not hundreds, of closely spaced wireless networks using the same radio spectrum means that interference becomes a problem.

That is, although the 802.11 standards provide for robust signaling in the form of spread spectrum radio frequency modulation, and using orthogonal frequency division multiplexing over modulated subcarriers, crowding of the radio spectrum still increases noise and therefore decreases performance for all users.

It has heretofore been thought quite difficult to require WLAN subscriber equipment to steer an antenna array, to one of many possible candidate angles, during such very short intervals.

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