Location and mobile-adaptation of wireless access-points using map-based navigation

A system and method for populating a map database for a vehicle navigation system with the location and type of wireless access points that can be used to update or service wireless systems on the vehicle. The map database can be initially populated with the known wireless access points at the time of manufacture of the vehicle, and then the vehicle communications system can detect new wireless access points as the vehicle travels, which can be stored on the map database. By storing the location and type of the access points in the map database, the vehicle will know the direction of the access point relative to the vehicle, and can compensate for the Doppler shift as a result of the relative movement of the vehicle to the access point.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a system and method for populating a map database associated with a navigation system with the locations and characteristics of wireless access points and, more particularly, to a system and method for populating a map database associated with a vehicle navigation system with wireless access points by pre-installing the location and type of the access points in the database and/or identifying the location and type of the access points as the vehicle travels and then storing the locations in the map database.

2. Discussion of the Related Art

A wide variety of vehicle systems currently being manufactured and anticipated to be manufactured in future vehicles require external communications using wireless protocols. For example, these vehicles may include map databases for navigation systems, weather information systems, traffic information systems, entertainment systems, etc. These systems may require continuous, or near continuous, updating so that the information used by the system is current in order to be effective. The updating techniques for these systems need to be inexpensive and cost effective. Typically, the updating techniques now being used for these types of systems are discretionary and require communications that are not necessarily highly reliable.

It is well known that the motion of an in-vehicle transceiver has various adverse effects on communications, as a result of Doppler shift, multi-path effects and channel variations. Much development effort has been expended in mitigating these effects, including the use of pilot signals, modulation schemes and channel characterization, which have led to success for cellular phones, but less success for wireless local-area networks.

SUMMARY OF THE INVENTION

In accordance with the teachings of the present invention, a system and method are disclosed for populating a map database for a vehicle navigation system with the location and type of wireless access points that can be used to update or service wireless systems on the vehicle. The map database can be initially populated with the known wireless access points at the time of manufacture of the vehicle, and then the vehicle communications system can detect new wireless access points as the vehicle travels, which can be stored in the map database. By storing the location and type of the access points in the map database, the vehicle will know the direction of a nearby access point relative to the vehicle, and can compensate for the Doppler shift as a result of the relative movement of the vehicle to the access point.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following discussion of the embodiments of the invention directed to a system and method for populating a map database for a navigation system with the location and type of wireless access points is merely exemplary in nature, and is in no way intended to limit the invention or its applications or uses. For example, the present invention has particular application for populating the map database for a vehicle navigation system with wireless access points. However, as will appreciated by those skilled in the art, the system and method of the invention may have application for populating other map databases for non-vehicular navigation systems.

FIG. 1is a plan view of a communications situation10used involving a vehicle12traveling along a roadway14. The vehicle12includes several wireless systems, discussed in more detail below, that are capable of receiving and transmitting wireless signals to and from wireless access points16provided at various locations along the roadway14. A steerable antenna28on the vehicle12allows the vehicle12to transmit and receive signals consistent with the discussion herein. The wireless access points16are provided to represent any wireless communications access system intended for public-use that allows the wireless systems in the vehicle12to access the internet. Such public wireless access points16are becoming more prevalent, where various business and municipalities provide such access points for public use. As will be discussed in detail below, the location and type of the wireless access points16relative to the roadway14are stored on the vehicle12so that the vehicle12can provide scheduling, updating and other services for the various wireless systems on the vehicle12.

FIG. 2is a plan view of the vehicle12showing various systems thereon including a navigation system18, a map database20associated with the navigation system18, and other wireless systems20, such as an entertainment system, traffic information system, weather information system, etc. The map database20is a database of the roadways that the vehicle12may be traveling on and the location of various facilities relative to those roadways. Known map databases for vehicle navigation systems and otherwise typically store the location of various businesses and other facilities that a vehicle driver may be interested in, such as restaurants, gas stations, post offices, hotels, church's, grocery stores, etc.

The vehicle12also includes a transceiver24for sending and receiving the wireless signals and a GPS receiver26for estimating the location of the vehicle12. The navigation system18uses outputs from the GPS receiver26, along a dead-reckoning and map-matching, to estimate the relative location of the vehicle12with respect to the roadway14in a manner that is well understood to those in the art.

The public access points16serve as a potential basis for providing low or no cost internet connectivity to vehicles so that the various wireless systems in the vehicle12can be updated using the wireless access points16as the vehicle12travels relative thereto. However, a number of issues arise as a result of using the wireless access points16, including the need to know the location and type of the access points16so that their use can be planned for a specific service and the need to mitigate motion-induced communication degradation due to Doppler shift, channel variation and multi-path effects of signals transmitted and received by the transceiver24. For the type of access point, the access point16may need to have a minimum bandwidth and also may have to be compliant with predetermined security requirements.

According to the present invention, a system and method are provided that allow the map database20to be populated with the location and type of the wireless access point16. The map database22may be initially populated with the location and type of the wireless access points16when the vehicle12is manufactured, and as the vehicle12travels on the roadway14, the location of the wireless access points16that were not originally provided in the initial system can be identified and stored in the map database22. Further, wireless access points16can be deleted from the map database if the vehicle12travels near a location where an access point has been stored in the map database, and no access point is detected. Because the access points16may be temporarily disabled at any given time, it probably will be necessary to determine that the access point is not operating a number of times before the system will delete the access point from the map database20.

The wireless access point information is made available for the navigation system18to schedule communications sessions for specific needs, such as downloading traffic information or uploading e-mail messages. The information is also used to compute adjustments to the transceiver24to accommodate motion-induced communication effects. As the vehicle12approaches an access point16, it may send out a request for a specific update for one or more of the wireless systems22on the vehicle12so that as the vehicle12is passing the proximity of the access point16it can download those updates so that the system stays current. Further, the vehicle operator may want to access the internet for some purpose using a personal device that the operator may have in the vehicle, such as a laptop computer. At the users request, or otherwise, the display associated with the navigation system can display the access points16on the map so that the vehicle operation will know where to go to use those access points16.

The vehicle operation may use the navigation system18to plan a route for a certain trip. The route may be specifically planned to enhance the availability of the wireless access points16to use those access points16when needed. Along the vehicle route, all wireless access points with suitable characteristics, such as air interface, bandwidth, route proximity, cost, etc., are noted. The communications between the vehicle12and the wireless access points16and the timing for all information services are assessed and matched to the specific access point.

Further, by knowing the location of an access point16, three major effects of vehicle motion can be mitigated. First, the speed of the vehicle12relative to the access point16is computed by projecting a relative velocity vector30for the vehicle12, as determined by the navigation system18, along a line connecting the location of the access point16to the vehicle12. The effect of the Doppler shift is to change all carrier frequencies, both sent and received, in a way predicted by the relative vehicle speed. This effect is mitigated by tuning the in-vehicle transceiver24to offset all involved frequencies by a compensation amount. Channel variations due to motion include phase-shift and amplitude attenuation. These are mitigated using both simple mathematical equations and channel parameters tabulated in the map database20. Multi-path effects are mitigated by using a directional electromagnetic field model or the vehicle12and factoring in the orientation of the vehicle12relative to the access points16.

In order to overcome the effects of the Doppler shift, the transceiver24receives a vehicle speed signal either from the GPS receiver26, a vehicle speed sensor (not shown) on the vehicle12, or some other suitable technique that identifies the speed of the vehicle12. The transceiver24also knows the direction of the vehicle12from the navigation system18, or otherwise, and thus, can calculate a forward vector32. The transceiver24also knows the direction of an access point16from the map database20and the GPS information, and thus, can calculate the velocity vector30using the vehicle speed, the vehicle direction and the direction of the access point16. From this information, the transceiver24can calculate the velocity of the vehicle12relative to the access point16by the triangle formed from the vectors32and30. Thus, the transceiver24can compensate for the motion of the vehicle12relative to the access point16, and thus, cancel the Doppler shift. Therefore, the transceiver24can remain tuned to the signals from the access point16as it moves.

Further, because the antenna28is steerable it can be directed towards the access point16because the transceiver24knows the exact direction of the access point16from the map database20and GPS information. By directing the antenna28towards the access point16, a focusing effect can be provided where other signals that are not from the direction of the access point16will not significantly affect or be received by the antenna28. These other effects may include other noise and multi-path effects as a result of reflections of the signal off of various structures, such as buildings, in the particular environment that the vehicle12is traveling. Any suitable technique for steering the antenna28can be employed whether it is a mechanical steering mechanism or an electronic steering mechanism, such as digital beamforming. By providing a narrow angle for the antenna28, other interfering noise can be eliminated.