Beamforming with global positioning and orientation systems

A wireless communication system for transmitting signals having a wireless positioning system being responsive to incoming signals for processing the same to generate coordinate information for determining the position of said wireless communication system, in accordance with an embodiment of the present invention. The wireless communication system further includes a phase controller module being responsive to said coordinate information for controlling the phase of the output signals for transmission in a specified direction by performing beamforming, said wireless communication system for performing beamforming to increase the range of transmission of said output signals.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the field of remote wireless communication and particularly to a method and apparatus for beamforming with global positioning and orientation systems.

2. Description of the Prior Art

More recently and with the advent of wireless communication systems remote and wireless communication is gaining more popularity among common users. An example is a highway with several base stations. If a vehicle is within the range of a base station information regarding the location and neighborhood may be exchanged between the vehicle and the base stations.

Currently base stations employ beamforming to increase the range and bandwidth of communication systems. For example, in the conventional cellular phones, the base station performs beamforming to communicate with each of the clients resulting in a substantially large data base to track the numerous vehicles on the road. This is sufficient for cellular phone and other voice related communication systems since the bandwidth required is relatively narrow and the range is relatively long.

Alternatively, in a wireless local area network (LAN) the bandwidth is substantially wide but the range is relatively short. Since wireless LAN is often used indoor, such as in an office environment, the relatively short range is acceptable.

The conventional communication systems have reached theoretical limit. The more recent WIMAX communication systems have range and throughput in the middle. Thus, it is desirable to provide a means and apparatus for long range high throughput communication with dramatic broadband system improvements.

SUMMARY OF THE INVENTION

Briefly, an embodiment of the present invention includes a wireless communication system for transmitting signals having a wireless positioning system being responsive to incoming signals for processing the same to generate coordinate information for determining the position of said wireless communication system. The wireless communication system further includes a phase controller module being responsive to said coordinate information for controlling the phase of the output signals for transmission in a specified direction by performing beamforming, said wireless communication system for performing beamforming to increase the range of transmission of said output signals.

The foregoing and other objects, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments which make reference to several figures of the drawing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now toFIG. 1, a wireless communication10is shown to include a wireless positioning system12and a wireless transmission system14, in accordance with an embodiment of the present invention. The wireless positioning system12is coupled to the wireless transmission system14.

The wireless communication system10transmits output signals to a receiver (not shown inFIG. 1) either by transmitting in all directions or by performing beamforming. Transmission of the output signals is mainly in the radio frequency (RF) range although transmission at other frequencies is also possible.

Beamforming is a signal processing technique used to control directionality of, or sensitivity to a radiation pattern. The wireless communication system10by performing beamforming can increase the gain in the direction in which the output signal is to be transmitted. The direction of transmission of the output signal is specified based on the location of the receiver relative to the wireless communication system10. Accordingly, direction of transmission of the output signal depends on the position and possibly orientation of the wireless communication system10. The communication satellite16transmits the position information of the wireless communication system10to the wireless positioning system12. The position information is received by the wireless positioning system12as incoming signals which are processed therein to generate coordinate information indicating the position of the wireless communication system10. The coordinate information is transferred to the wireless transmission system14through which the coordinate information is exchanged between the wireless communication10and the receiver. Accordingly, the coordinate information allows the wireless transmission system14to identify the direction to be used in beamforming. That is the output signal is transmitted by the wireless transmission system14in the direction of the receiver using beamforming.

In beamforming the phase of the transmitted signals is adjusted to focus the energy in a specified direction. The specified direction points from the wireless communication system10to the receiver. The wireless communication system10uses the coordinate information and the position of the receiver to specify the direction of beamforming.

In one embodiment of the present invention the receiver is a base station for receiving and transmitting RF signals. Specifically, the base station transmits and receives signals to and from the wireless communication system10. The base station may also perform beamforming to communicate with the wireless communication system10. Beamforming performed by both the base station and the wireless communication system10improves communication therebetween by increasing the bandwidth and extending the transmission range, as described in detail hereinbelow. Higher bandwidth results in increased throughput which combined with a long transmission range offers substantial improvement over the conventional communication systems.

In one embodiment of the present invention the wireless positioning system12is a global positioning system (GPS) although other types of satellite-assisted positioning systems may be used in other embodiments of the present invention.

In one embodiment of the present invention the wireless communication system10is a mobile system located in a vehicle in which case the wireless communication system10is referred to as an access point. The wireless communication system10communicates with one or more base stations as the vehicle moves about. The position of the vehicle in real-time is determined by the wireless positioning system12to allow beamforming to be performed by both the access point and the base station. Such a mobile access point allows for broadband communication over a substantially long range.

Referring now toFIG. 2, three vehicles22,26, and30are shown to be communicating with three base stations24,28, and32, respectively. In addition an antenna20transmits position information to the vehicles22,26and30. The position information may originate from a communication satellite (not shown inFIG. 2) and transmitted therefrom to the antenna20or directly to the wireless communication systems installed in the three vehicles22,26and30. The wireless communication system10is installed in the three vehicles22,26and30to allow communication with the base stations24,28and32, respectively. The mobile wireless communication system installed in the vehicles is referred to as the access point.

In the conventional mobile wireless communication systems beamforming is performed by the base station. As the number of vehicles communicating with the base stations increases a longer data base is needed in the base station. Accordingly, the cost of base station in the conventional mobile wireless communication systems becomes substantial as the number of vehicles being tracked increases. In recent times WIMAX has increased the range and bandwidth for communicating with the access point to some degree. However, for long range high throughput communication there needs to be considerable improvement as described hereinbelow.

The improvement offered by the WIMAX is approximately 10 decibels (dB) in transmission power enabling the signals to be transmitted over a longer range. The range covered by WIMAX is approximately 10 miles with a throughput of approximately 1 Mbits/sec. However, for current mobile wireless communication systems it is estimated that an improvement of approximately 30 dB is required for long range, broadband communication. To achieve the extra 20 dB of transmission power beamforming is performed by the access point and the base station. The antennas of the access point in the vehicle are directed to perform beamforming in the direction of the base station.

In contrast in the conventional cellular phones the base station performs beamforming to communicate with each of the access points resulting in a substantially large data base to track the numerous vehicles on the road. This is sufficient for cellular phone and other voice related communication systems since the bandwidth required is relatively narrow and the range is relatively long.

Alternatively in a wireless local area network (LAN) the bandwidth is substantially wide but the range is relatively short. Since wireless LAN is often used indoor, such as in an office environment the relatively short range is acceptable.

However, for broadband long range communication beamforming is performed by both the access point in vehicle22and the base station24. Accordingly, the gap between the access point and the base station diminishes and the role of the access point and the base station becomes more balanced. Thus, instead of requiring an expensive base station for communication, the cost is shared between the base station and the access point resulting in reduction of the overall cost.

In the embodiment of the present invention shown inFIG. 2the client, i.e. vehicle22,26or30takes on more function than conventional wireless communication systems by performing beamforming. Beamforming is performed in both directions by the client22and30and the base stations24and32, respectively. For example, the access point in vehicle22communicates with the base station24and people in vehicle22communicate with the access point therein instead of the base station24. As a result, a more powerful wireless communication system may be devised as the access point.

As the cost of wireless communication system10decreases it will be cost effective for the client to employ a plurality of antennas for transmission of signals. In such cases, the IEEE 802.11n standard is followed as specified for multi-input multi-output (MIMO) communication systems.

In addition to knowing the position of the vehicle as specified by the coordinate information, the orientation of the vehicle relative to the base station is also needed for determining the direction for beamforming. To determine the orientation of the vehicle a system such as global orientation system (GOS) is used which functions essentially as an electronic compass. The GOS uses earth's magnetic field to determine the orientation. The GOS is integrated in the wireless communication system10. Thus, position and angle of orientation are used to direct the antenna to focus the transmission power in the direction of communication with the base station.

As the price of GOS and wireless positioning system12decreases the wireless communication system10becomes more readily available and may be installed in vehicles at an affordable cost. InFIG. 2, wireless communication system10is installed in the vehicles22,26and30.

Alternatively,FIG. 2may be seen as indicating a single vehicle at three different positions at three different times. Namely, the vehicle is initially at position22communicating with the base station24, at a later time the same vehicle is at position26communicating with the base station28and finally the same vehicle is at position30communicating with base station32.

To track a client intelligently beamforming is allowed to follow the client on the road which requires knowledge of the position of the client and the base station. Based on the orientation of the client transmitter antennas on the client side are adjusted to perform beamforming in the direction of the base station. The client inFIG. 2is any of the vehicles22,26or30.

Initially as the vehicle starts on the road there is no information on the position of the base station so no beamforming may be performed. As a result the range of transmission is shorter. However, before connecting to base station there are several ways of determining the position of the base station. In some cases the service provider maintains a map wherein the position of the base station is shown. In another case the vehicle may reach the vicinity of a base station and start communicating therewith. The position of the neighboring base stations may then be provided by the service provider. Once the position of the service provider is determined beamforming may be performed to direct the energy in the direction of the base station rather than omni-directional transmission used in the conventional wireless transmission systems. The base station may also employ beamforming as in the case of base stations24and32shown inFIG. 2. Beamforming in both directions allows for broadband long-range communication between the client and base station.

The position information of the client is transmitted by a communication satellite (not shown inFIG. 2) which is received as incoming signals. The position information is processed by the wireless communication system10installed in the vehicles22,26and30to generate coordinate information which is used to identify the direction of beamforming.

Referring now toFIG. 3, a wireless communication system40is shown to include a wireless positioning system41and a wireless transmission system43and a plurality of antennas52-56, in accordance with an embodiment of the present invention. The wireless positioning system41includes a global positioning system (GPS) module42and a GOS module44. The wireless transmission system43includes a phase controller48and a phased array antennas module50.

The GPS module42and the GOS module44are coupled to the phase controller48which is coupled to the phased array antennas50which is coupled to the antennas52-56. Additionally, an antenna46is coupled to the GPS module42. The wireless communication system40may be located in a vehicle communicating with one or more base stations while moving along a road or remaining with one or more base stations while moving along a road or remaining stationary, as shown inFIG. 2.

Antenna46receives incoming signals from a communication satellite (not shown inFIG. 3) which are processed by the GPS module42to generate coordinate information. In addition, the GOS module44determines the orientation of the vehicle wherein wireless communication satellite40is located by measuring the direction of the earth's magnetic field. Thus the GOS module44does not require an antenna to determine the orientation of the vehicle. The information regarding orientation of the vehicle is transferred from the GOS module44to the phase controller48. The coordinate information is also transferred from the GPS module42to the phase controller48.

The phase controller48controls beamforming by controlling the amplitude and phase of the of the output signals at each transmitting antenna to create a pattern of constructive and destructive interference therein. Generally, phase controller48works as an optimizer which converges to a beamforming solution when the constraints are set properly. Adaptive arrays have been used to find such solutions as described in more detail in the publication “Adaptive Antenna Systems” by Widrow, B. Mantey, P. E., Griffiths, L. J. and Goode, B. B., Proceedings of the IEEE, Vol. 55, No. 12, December 1967.

Information regarding the amplitude and phase of the output signals is transferred to the phase arrayed antennas module50which is coupled to a plurality of antennas52-56. The phased arrayed antennas module50varies the relative phases of the output signals being fed to the antennas52-56such that the effective radiation pattern of the output signal is reinforced in a specific direction.

In the conventional phased array antennas assembly, the antennas are fixed and only the phase and possibly amplitudes are adjusted for beamforming. However, in the embodiment of the present invention shown inFIG. 3the antennas may be directed to focus the transmission power in the direction of communication.

One embodiment of the phased array antennas module50may include 16 phased array antennas. Beamforming by the wireless communication system40provides 12 dB of transmission power while beamforming by the base station provides additional 12 dB. Also 10 dB of transmission power is available for outdoor communication through such systems as WIMAX. Thus, more than 30 dB of transmission power is provided by the wireless communication system40allowing for long-range broadband communication between the client and the base station.