Patent Application
20060246887
This invention relates generally to wireless communication systems and more specifically to determining locations of weak radio frequency (RF) signal coverage within areas where communication services are to be provided.
Cellular network providers use a plurality of overlapping cells in an effort to provide continuous communication services to mobile users within predetermined geographic regions. However, even within the predetermined geographic regions there will typically be areas of low RF signal strength which correspond to poor, if any, quality of communications. Such areas may be referred to as dead or weak coverage areas. For a cellular mobile user that moves into such an area during an existing call, the quality of the communications will degrade or the call may be dropped.
Known techniques for identifying such low signal strength areas include having technicians drive around in areas thought to have low signal strength in vehicles equipped to continuously log and monitor signal strength from one or more base stations in the telecommunication network. Such work is time consuming and may not locate all weak RF signal coverage areas. For example, a user with a hand-held cellular telephone may move through locations with signal strength characteristics that differ substantially from a signal strength measurement made from the nearest road. Thus, there exists a need for a more flexible and easier to utilize method to map areas of weak signal strength within a region in which communication services are to be provided.
The invention in one implementation encompasses an exemplary wireless mobile device that includes an RF transmitter and receiver where the receiver monitors signal strength of a radio frequency (RF) signal from a base station. A control logic module compares the signal strength to a comparison level. The control logic module creates and stores a record in a memory module. The record includes a first signal strength level and parameters related to conditions existing at the time the comparing was done. The control logic module creates and stores the record if the level of said signal strength is less than the comparison level.
Another implementation of the invention encompasses a method for collecting signal strength data for a wireless system. Signal strength of a radio frequency (RF) signal received from a base station is monitored by a mobile device. The level of the signal strength is compared to a comparison level. If the level of the signal strength is less than the comparison level, a record is created and stored in the mobile device where the record includes a first signal strength level and parameters related to conditions existing at the time the comparing was done.
A further implementation of the invention encompasses an article. The article comprises one or more computer-readable signal-bearing media. The article includes means in the one or more media for practicing the actions of the above method.
Features of exemplary implementations of the invention will become apparent from the description, the claims, and the accompanying drawings in which:
The concepts in accordance with the present invention are applicable in a variety of wireless communication environments. Although the embodiments of the present invention are described with regard to a cellular communication system, the concepts of the present invention are generally applicable to wireless communication systems in which mobile/portable transceivers are utilized. As used herein a “mobile device” refers to an RF communication device intended to support communications while the transceiver moves between locations, e.g. a transceiver mounted in a vehicle or a hand-held transceiver carried by a person.
Cellular antennae 22 and 24 are coupled to base stations 12 and 14, respectively. Cellular antennae 22 and 24 are designed to support communications with wireless devices within cells 26 and 28, respectively. Cells 26 and 28 have corresponding extended coverage areas 30 and 32 in which communications can be supported under favorable conditions with mobile devices in these extended coverage areas. However, coverage within the extended areas will become increasingly marginal as the mobile user moves farther away from the respective base station cellular antenna.
Mobile device 34 is clearly within the primary area of coverage of cell 26 and is served by antenna 22 and base station 12. (Reference herein to a mobile device or a mobile user may be used interchangeably with it being apparent from context as to whether reference is being made to the device itself or the user of the device.) Mobile device 36 is located within the primary area of coverage of both cells 26 and 28, i.e. located within an area of overlap. This device may be served by either antenna and its corresponding base station. If the corresponding user is moving in a direction generally towards the center of cell 26 or 28, then a hand off will be made if the mobile device was being previously supported by the other cell. Mobile device 38 is outside of the primary coverage of cells 26 and 28, but within the extended coverage areas 30 and 32 of these respective cells. Assuming no other cell is present to provide service, it may be served by either antenna 22 or 24. Mobile device 40 is just outside of the extended coverage areas 30 and 32. Mobile device 40 may be served by either antenna 22 or 24 with what will likely be a marginal strength signal.
In the above paragraph, mobile devices were described in terms of location relative to the respective cellular antennae, and hence relative to designed areas of coverage for each respective cell. In a relatively unobstructed RF environment, the signal strength between the mobile device and the cellular antenna will typically diminish proportional to increasing distance. Thus, as the mobile device moves further away from the cellular antenna, the signal strength will diminish and will eventually reach a level at which communications cannot be maintained. However, an obstruction such as a tall building 42 can give rise to what is known as a shadow that is normally cast in the direction away from the transmitting antenna. For example, building 42 may be located so as to cast an RF shadow with regard to antenna 22 that extends to mobile device 36. Assuming that the mobile device 36 is being served by antenna 22 and has moved from a first location within cell 26 having no shadow from building 42 to a position in which it encounters a shadow from building 42, a significant loss of signal strength will likely result. It will be noted that this loss of signal strength is within the intended area of primary coverage 26 for antenna 22. Additionally, other conditions even within an intended area of primary coverage may give rise to a significant loss of signal strength such as a tunnel, bridge, etc.
One object of the embodiment of the present invention is to provide a map of locations with low signal strength within a region in which telecommunications services are to be provided. In a preferred implementation it is desirable only to map those locations with low signal strength that may be reasonably remedied. That is, an elevator compartment completely enclosed by metal within the intended communication region may give rise to unacceptably low signal strengths, but a reasonable and economically justified remedy may not be available. Another aspect resides in balancing the amount of signal strength map information to transmit to an infrastructure database versus the bandwidth needed for such transmission.
A general description of the operation of the illustrated embodiment will be helpful in understanding the flow diagrams described below. The mobile device continuously monitors the signal strength of the received RF signal from at least the base station antenna currently providing communications support. In a preferred implementation, other received RF signals from other base stations are also monitored with regard to signal strength. This monitoring occurs whenever the mobile device is ON, i.e. during a conversation and during times when the mobile device is merely active and capable of receiving an incoming call. When a monitored signal experiences a signal strength below a predetermined level, the mobile device generates a corresponding record that is stored locally in memory. The record includes the measured signal strength and the location of the mobile device such as obtained from a local GPS module. Of course, location information can be obtained by other ways, either independently by the mobile device or incorporation with external devices, e.g. infrastructure equipment. The record will preferably contain additional information and parameters that can be of use in identifying areas of low signal strength and in determining whether appropriate remedies should be implemented. For example, the records may also include a time and date stamp, velocity of the mobile device, and the signal strength of other concurrently received RF signals, i.e. other base stations, at the time of the generation of the record. The signal strength may be periodically determined and corresponding records generated and stored at the mobile device. The information (records) transmitted to the database 20 can be processed by infrastructure or external equipment with processing capabilities in order to identify areas that are poorly served in terms of signal strength. Additional base stations and/or antennae could be strategically placed or existing base stations adjusted to serve areas of poor signal strength to remedy the quality of service issue.
While the mobile device continues to encounter low signal strength conditions, the records will continue to be stored locally in the mobile device. When the mobile device enters a relatively strong RF coverage area, the mobile unit can automatically transmit the stored records to database 20. The information can be transmitted by any appropriate data transmission method, e.g. short messaging system (SMS) protocol or a packet data transmission. The analysis of the transmitted records can be performed by network infrastructure equipment. This technique effectively gives each mobile device the capability to be an RF signal recorder.
In the exemplary embodiment of the mobile device 50, the receiver module 56 periodically makes signal strength measurements that are transferred as an input to the control logic module 58 that makes the comparison of the measured signal strength versus a comparison level. If a record is to be generated and stored as indicated in
It is also foreseeable that the mobile device may travel the same routes repetitively such as going from home to work and returning from work and home. “Repetitive records” mean records that have common parameter values over a similar time interval or over the same route. If the signal strength measurements made while traveling from home to work are substantially similar to previous signal strength measurements made while traveling the same route, the system designer may elect not to have such repetitive data transmitted from the mobile device to the central database since such information would be substantially redundant. Intelligence implemented by the mobile device such as by control logic module 58 can suspend the transmission of the stored records even upon entering an area of strong signal strength when a repetitive route and time interval are present, e.g. going to or coming from work over the same route. Assuming the signal strength measurements during a just completed trip shows substantially the same areas of low signal strength as normally encountered during previous trips over the same route, such repeated records need not be transmitted. Such a determination can be made by comparing the records during the current trip to previous records retained in storage in memory 62 of prior trips. A comparison of GPS location data of the current trip and prior trips can confirm that the same route was traversed. A NO determination results in the process returning to the beginning of step 120 and the transmission of the records as explained in step 114.
A YES determination by step 120 indicates that related, but not repetitive, records are present. These related records are identified and grouped by step 122. Each group of related records is condensed into a composite record that reflects the substance of the related records in step 124. In step 126 the composite records are transmitted to the infrastructure database 20.
The apparatus 50 in one example employs one or more computer-readable signal-bearing media. The computer-readable signal-bearing media store software, firmware and/or assembly language for performing one or more portions of one or more embodiments of the invention. The computer-readable signal-bearing medium for the apparatus 50 in one example comprise one or more of a magnetic, electrical, optical, biological, and atomic data storage medium. For example, the computer-readable signal-bearing medium comprise floppy disks, magnetic tapes, CD-ROMs, DVD-ROMs, hard disk drives, and electronic memory. In another example, the computer-readable signal-bearing medium comprises a modulated carrier signal transmitted over a network comprising or coupled with the apparatus 50, for instance, one or more of a telephone network, a local area network (“LAN”), a wide area network (“WAN”), the Internet, and a wireless network.
The steps or operations described herein are just exemplary. There may be many variations to these steps or operations without departing from the spirit of the invention. For instance, the steps may be performed in a differing order, or steps may be added, deleted, or modified.
Although exemplary implementations of the invention have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions, and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the following claims.
