HK1126065B - Method and apparatus for locating a wireless local area network in a wide area network - Google Patents

Description

Method and apparatus for locating wireless local area network in wide area network

Priority requirements under 35 U.S.C. § 119

This patent application claims priority to provisional application No.60/702,591 entitled "ASSISTED WIRELESS NETWORK ACCESS services NETWORKs portal IN WIRELESS COMMUNICATION NETWORK FOR assisted wireless NETWORK ACCESS point searching" filed on 25.7.2005, AND provisional application No.60/750,920 entitled "METHOD AND APPARATUS FOR LOCATING wireless local area NETWORKs in wide area NETWORKs" filed on 16.12.2005, AND provisional application No.60/750,919 entitled "METHOD AND APPARATUS FOR LOCATING wireless local area NETWORKs in wide area NETWORKs" filed on 16.12.2005, AND provisional application No. MAINTAINING A FINGERPRINT FOR aires NETWORK (METHOD AND APPARATUS FOR maintaining fingerprints of wireless NETWORKs) "filed on 16.12.2005, which are assigned to the assignee of the present invention AND are hereby expressly incorporated herein by reference.

Background

FIELD

The present disclosure relates generally to telecommunications, and more particularly to systems and methods for supporting mobile communication devices capable of communicating via two different types of communication networks.

Background

The demand for wireless information services has led to the development of an ever increasing number of wireless networks. CDMA 20001 x is only one example of a wireless network that provides wide area telephony and data services. CDMA 20001 x is a wireless standard using Code Division Multiple Access (CDMA) technology as promulgated by the third generation partnership project 2(3GPP 2). CDMA is a technology that employs spread-spectrum processing to allow multiple users to share a common communication medium. One competing wireless network that is commonly employed in europe is the global system for mobile communications (GSM). Unlike CDMA 20001 x, GSM utilizes narrow band Time Division Multiple Access (TDMA) to support wireless telephony and data services. Some other wireless networks include General Packet Radio Service (GPRS), which supports high speed data services at data rates suitable for email and web browsing applications, and Universal Mobile Telecommunications System (UMTS), which can deliver broadband voice and data for audio and video applications.

These wireless networks can be generally considered to be wide area networks employing cellular technology. Cellular technology is based on a topology in which a geographical coverage area is broken down into several cells. Within each of these cells is a fixed Base Transceiver Station (BTS) that communicates with mobile users. A Base Station Controller (BSC) is typically employed in the geographic coverage region to control the BTSs and route communications to the appropriate gateways for the various packet-switched and circuit-switched networks.

As the demand for wireless information services continues to grow, mobile devices are evolving to support integrated voice, data, and streaming media while providing seamless network coverage between wide area wireless networks (WANs) and wireless Local Area Networks (LANs). Wireless LANs typically provide telephony and data services over relatively small geographic regions using a standard protocol, such as IEEE 802.11, bluetooth, or the like. The existence of wireless LANs provides a unique opportunity to increase user capacity in a wide area wireless network by extending wide area communications to the unlicensed spectrum using the infrastructure of the wireless LAN.

Recently, various techniques have been employed to enable mobile devices to communicate with different wireless networks. Complementary techniques have been employed to allow a mobile device to search for the presence of a wireless LAN to determine if a wireless LAN is available for connection. However, frequent or continuous searches for wireless LANs unnecessarily consume power and may quickly discharge the battery in the mobile device. Thus, by intelligently searching for available wireless LANs, improvements in power consumption and battery life will be made possible for the mobile terminal.

Summary of the invention

A wireless communication device of an aspect is disclosed. The wireless communication device includes a memory configured to store information related to a first communication network, and a processor configured to determine whether the wireless communication device is in proximity to the first communication network based on the information stored in the memory and one or more reference signals from a second communication network.

A wireless communication device of another aspect is disclosed. The communication device includes a memory configured to store information relating to a plurality of wireless LANs dispersed throughout a WAN, and a processor configured to determine whether the wireless communication device is in proximity to one of the wireless LANs based on the information stored in the memory and one or more reference signals from the WAN.

A computer-readable medium containing a program of instructions executable by a computer to perform a method of communication is disclosed. The method includes accessing information in a memory related to a first communication network, receiving one or more reference signals from a second communication network, and determining whether a wireless communication device is in proximity to the first communication network based on the information accessed from the memory and the one or more reference signals from the second communication network.

A method of communication is disclosed. The method includes accessing information in a memory related to a first communication network, receiving one or more reference signals from a second communication network, and determining whether a wireless communication device is in proximity to the first communication network based on the information accessed from the memory and the one or more reference signals from the second communication network.

A wireless communication device of yet another aspect is disclosed. The wireless communication device includes means for storing information relating to a first communication network, and means for determining whether the wireless communication device is in proximity to the first communication network based on the information and one or more reference signals from a second communication network.

It is to be understood that other embodiments of the present disclosure are within the scope of the following detailed description, wherein various embodiments of the disclosure are shown and described by way of illustration only. As will be realized, the disclosure is capable of other and different embodiments and its several details are capable of modifications in various other respects, all without departing from the spirit and scope of the present disclosure. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.

Brief description of the drawings

Aspects of a wireless communication system are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which:

FIG. 1A is a conceptual block diagram of one embodiment of a wireless communication system;

FIG. 1B is a conceptual block diagram of another embodiment of a wireless communication system;

FIG. 2 is a functional block diagram illustrating one example of a mobile device capable of supporting both wide area wireless and wireless LAN communications; and is

FIG. 3A depicts a flow diagram of an exemplary method of creating a fingerprint on a mobile communication device;

FIG. 3B depicts a flowchart of an exemplary method of comparing fingerprints at different locations; and

FIG. 4 depicts a flow diagram of an exemplary method of optimizing an existing fingerprint for a known location;

detailed description of the invention

The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present disclosure and is not intended to represent the only embodiments in which the present disclosure may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the present disclosure. In some embodiments, well-known structures and components are shown in block diagram form in order to avoid obscuring the concepts of the present disclosure.

In the following detailed description, various techniques will be described in connection with handing off a mobile user from one network to another. Several of these techniques will be described in the context of a mobile communication device traveling through a wide area WAN having one or more wireless LANs distributed throughout the WAN coverage area. The mobile communication device may be any suitable device capable of wireless telephony or data communication, such as a cellular telephone designed to operate in a CDMA 20001 x network. The mobile communication device may be capable of accessing the wireless LAN using any suitable protocol, including, for example, IEEE 802.11. Although the techniques may be described in the context of a WAN telephone capable of communicating with an IEEE 802.11 network, the techniques can be extended to other mobile communication devices capable of accessing multiple networks. For example, the techniques may be applied to a mobile communication device capable of switching between a CDMA 20001 x network and a GSM network. Accordingly, any reference to a cellular telephone capable of communicating with an IEEE 802.11 network, or any other specific embodiment, is intended only to illustrate various aspects of the present disclosure, with the understanding that these aspects have a wide range of applications.

Fig. 1A is a conceptual block diagram of one embodiment of a wireless communication system. A mobile device 102 is shown in a series of dashed lines as migrating through the WAN 104. The WAN 104 includes a BSC 106 that supports a number of BTSs dispersed throughout the WAN coverage area. A single BTS 108 is shown in fig. 1 for ease of explanation. A Mobile Switching Center (MSC)110 may be used to provide a gateway to a Public Switched Telephone Network (PSTN) 112. Although not shown in fig. 1, the WAN 104 may employ numerous BSCs each supporting any number of BTSs to extend the geographic reach of the WAN 104. When multiple BSCs are employed throughout the WAN 104, the MSC 110 may also be used to coordinate communications between the BSCs.

WAN 104 may also include one or more wireless LANs dispersed throughout the wide area wireless coverage region. A single wireless LAN114 is shown in fig. 1. The wireless LAN114 may be an IEEE 802.11 network, or any other suitable network. The wireless LAN114 includes an access point 116 to enable the mobile device 102 to communicate with an IP network 118. A server 120 may be employed to interface the IP network 118 with the MSC 110 providing a gateway to the PSTN 112.

When power is initially applied to the mobile device 102, it will attempt to access either the WAN 104 or the wireless LAN 114. The decision to access a particular network may depend on various factors relating to the specific application and the overall design constraints. For example, the mobile device 102 may be configured to access the wireless LAN114 when the quality of service meets a minimum threshold. To the extent that the wireless LAN114 can be utilized to support mobile telephony and data communications, valuable bandwidth can be freed up for use by other mobile users.

The mobile device 102 can be configured to continuously or periodically search for beacons from the access point 116 or any other access point of the wireless LAN. This beacon is a periodic signal with synchronization information transmitted by the access point 116. WLAN beacon scanning requires the mobile device to in turn tune to and scan, either actively or passively, possible WLAN channels in one or more operational frequency bands of the WLAN system. In passive scanning, the mobile device simply tunes to the channel and receives for a certain period of time waiting for a beacon transmission. In active scanning, the mobile device tunes to the channel and transmits a probe request after following an access procedure to avoid collisions with existing devices on the channel. Upon receiving the probe request, the access point transmits a probe response to the mobile device. In the event that the mobile device 102 fails to detect a beacon or does not receive a probe response to a probe request, which may be the case if power is applied to the mobile device 102 at location a, then the mobile device 102 attempts to access the WAN 104. With respect to fig. 1B, described later, instead of continuously (or periodically) scanning for WLAN access points, the mobile device 102 scans for WLAN access points only when it determines that it is in proximity to the wireless LAN 114. The mobile device 102 may access the WAN 104 by acquiring a pilot signal from the BTS 108. Once this pilot signal is acquired, a radio connection can be established between the mobile device 102 and the BTS 108 by means well known in the art. The mobile device 102 may register with the MSC 110 using a radio connection with the BTS 108. Registration is the process by which the mobile device 102 makes its whereabouts known to the WAN 104. When the registration process is complete, the mobile device 102 may enter an idle state until a call is initiated by either the mobile device 102 or the PSTN 112. In either case, an air traffic link may be established between the mobile device 102 and the BTS 108 to set up and support the call.

When the mobile device 102 travels from location a to location B in the WAN 104 in the depicted embodiment, it is now able to detect a beacon from the access point 116. Once this occurs, a radio connection may be established between the two by means well known in the art. The mobile device 102 then obtains the IP address of the server 120. The mobile device 102 may utilize the services of a Domain Name Server (DNS) to determine the IP address of the server. The domain name of the server 120 may be delivered to the mobile device 102 via the WAN 104. With the IP address, the mobile device 102 can establish a network connection with the server 120. Once the network connection is established, information from the server 120 can be used in conjunction with the local measurements to determine whether the quality of service of the wireless LAN114 is sufficient to handoff the mobile device 102 to the access point 116.

It should be noted that although fig. 1A generally depicts a cellular WAN, other WANs may also be employed. This may include those WANs that do not employ an MSC or other cellular structure, as well as those WANs that employ other communication protocols including wideband CDMA (wcdma), TD-CDMA, GSM, or the like.

Referring now to fig. 1B, the wireless LAN114 and BTS 108 are illustrated in the context of a larger WAN having multiple BTSs 122, 124, 126 and also multiple wireless LANs 129, 131 and associated access points 128, 130. As shown in fig. 1B, the mobile device 102 is not within the coverage area of any wireless LAN. Thus, searching for a beacon signal while in this position would prove futile and would unnecessarily consume power. Searching for wireless LAN beacon signals can quickly consume power even though the mobile device may frequently enter a sleep or idle mode to conserve power. In a typical 802.11 network configuration, these beacon signals occur over an interval measured in tens of milliseconds; thus the mobile device must stay awake and search for at least that period of time per channel, and given that wireless LAN access points may be configured for different frequency ranges and different channels within those ranges, the mobile device 102 must have a significant amount of time to stay awake to search for an available wireless LAN access point. Similarly, in the case of active scanning, the mobile device must stay awake to follow the channel access procedure on the channel, then transmit a probe request and stay awake to receive a probe response. It must do this on every channel. In this case, the mobile device 102 must also stay awake for an appreciable amount of time to search for an available wireless LAN access point, which may result in increased power consumption and processing overhead.

However, by limiting the search beacon signal to the time periods in which the mobile device is within region 140, considerable power savings can be realized. Thus, the mobile device 102 can also determine its location when it periodically wakes up to listen to the paging channel or the quick paging channel in the WAN. If the mobile device determines that its location is within the area 140, it may search for wireless LAN beacon signals. Otherwise, the mobile device may avoid unnecessarily searching for beacon signals.

The mobile device 102 can monitor beacon and pilot signals from base stations of the WAN. These signals may include pilot and paging signals. The mobile device monitors these signals to measure the primary and neighbor signal strengths to perform a handoff between base stations. Also in networks where the base stations are synchronized, the mobile device may also measure the phase of each pilot signal to assist in making the handoff determination. Thus, at any location within network 104, mobile device 102 observes up to n base stations with measurable signal strengths that can be characterized as two vectors x₁，...，x_nAnd y₁，...，y_n. Where each x value is the signal strength of the pilot signal from the base station and each y value is the pilot signal from the base stationThe phase of the signal. When fewer than n signals are observed, the remaining values are set to null. Because the pilot signals have pilot phase offsets associated with them, these signal strengths and phases can be readily identified as originating from a particular base station. In other WAN technologies, such as GSM, neighboring base stations may be identified by their frequency channels or other base station identification elements and the signal strength associated with each base station. In certain aspects, any signal used for acquisition, timing, etc. may be utilized as the signal used to obtain the measurements forming the one or more vectors described above. Further, the vectors need not be formed, stored, or used as two vectors as described or include the information in the format described above. Thus, in some aspects, information identifying the source and at least one characteristic of a reference signal, e.g., a pilot or paging signal, is utilized.

As is known in the art, the mobile device 102 monitors beacon and pilot signals from various base stations of the cellular network. These signals may include pilot and paging signals. The mobile device monitors these signals to measure the primary and neighbor signal strengths to perform a handoff between base stations. Similarly, in a network where the base stations are synchronized, the mobile device can also measure the phase of each pilot signal to assist in making a handoff determination. Thus, at any location within network 104, mobile device 102 observes up to n base stations with measurable signal strengths that can be characterized as two vectors x₁，...，x_nAnd y₁，...，y_n. Where each x value is the signal strength of the pilot signal from the base station and each y value is the phase of the pilot signal from the base station. When fewer than n signals are observed, the remaining values are set to null. Because the pilot signals have pilot phase offsets associated with them, these signal strengths and phases can be readily identified as originating from a particular base station. In other WAN technologies, such as GSM, neighboring base stations may be identified by their frequency channels or other base station identification information and the signal strength associated with each base station.

In WCDMA, the base stations may not be synchronized. As in CDMA, when a mobile device camps in an idle state on a paging channel of a particular base station, it scans for neighboring base station signals. In the case of CDMA, each base station utilizes the offset of the same pseudo-random spreading sequence. In the case of WCDMA, each base station transmits several signals designed to allow the mobile station to quickly acquire synchronization with the signals transmitted by the base station and, once synchronized, determine the spreading code group and spreading code employed by the base station. The set of spreading codes and their signal strengths may be used to create a fingerprint that identifies a location in WCDMA coverage, which corresponds to a pilot offset and pilot signal strength in a CDMA system. The relative timing offsets of neighboring base stations, which correspond to the pilot phases in CDMA, may also be utilized, but if the base stations are not synchronized, their clocks may have relative drift, making the timing offsets an unreliable indicator.

This information may be used as a conceptual fingerprint or signature of the location of the mobile device 102. Thus, if there is a known fingerprint at various locations within the area 140, the mobile device can determine its current fingerprint and compare it to the known fingerprint to determine if the mobile device is located within the area 140. Although the above discussion only mentions utilizing two attributes of the WAN (i.e., pilot signal strength and phase). Further, other dynamic attributes of the WAN may be used instead of or in combination with both attributes, as discussed above. For example, a pilot offset value may be used as a fingerprint; even the number of available pilot signals is one possible attribute for use with fingerprints. Further, the attributes that make up the fingerprint need not necessarily be attributes of the WAN. For example, many mobile devices have GPS receivers that can be used to determine the location of the mobile device relative to the wireless LAN. The GPS information may be used directly or even indirectly. As an example of the latter scenario, a base station ID along with phase measurements of GPS signals from different satellites may be used to define a fingerprint corresponding to the location of the mobile device. Thus, in its broadest sense, a fingerprint is a collection of attributes of a first communication network that change based on location and can be used by a mobile device to determine the proximity of a second communication network. Additionally, the fingerprint may also include characteristics of a transmitter of the second communication network (e.g., MAC ID, tone, channel, RSSI information of the WiFi access point). In such an instance, the WAN parameters may be considered trigger parameters, such that a match of these parameters triggers a WLAN search. These WLAN parameters may be used during a search as search parameters for a triggered search.

These attributes may be calculated in a variety of different ways without departing from the scope of the present disclosure. For example, instantaneous measurements of attributes such as pilot signal strength and phase can be taken and used as a fingerprint. However, even when the mobile device is stationary, the values of these attributes may change due to environmental variability. Accordingly, multiple measurements may be taken and averaged together or combined in some statistically significant manner to generate a fingerprint.

Fig. 2 is a functional block diagram illustrating one example of a mobile device capable of supporting both WAN and wireless LAN communications. The mobile device 102 may include a WAN transceiver 202 and a wireless LAN transceiver 204. In at least one embodiment of the mobile device 102, the WAN transceiver 202 can support CDMA 20001 x, WCDMA, GSM, TD-CDMA, or other WAN communications with a BTS (not shown), and the wireless LAN transceiver 204 can support IEEE 802.11 communications with an access point (not shown). It should be noted that the concepts described in connection with the mobile device 102 may be extended to other WAN and wireless LAN technologies. Each transceiver 202, 204 is illustrated as having a separate antenna 206, 207, respectively, but the transceivers 202, 204 may also share a single broadband antenna. Each antenna 206, 207 may be implemented with one or more radiating elements.

The mobile device 102 is also illustrated as having a processor 208 coupled to both transceivers 202, 204, although a separate processor may be used for each transceiver in alternative embodiments of the mobile device 102. The processor 208 may be implemented as hardware, firmware, software, or any combination thereof. For example, the processor 208 may include a microprocessor (not shown). This microprocessor may be used to support software applications that (1) control and manage access to the wide area wireless communications network and wireless LAN, and (2) interface the processor 208 to the keypad 210, display 212, and other user interfaces (not shown), among others. The processor 208 may also include a Digital Signal Processor (DSP) (not shown) with an embedded software layer that supports various signal processing functions, such as convolutional encoding, Cyclic Redundancy Check (CRC) functions, modulation, and spread-spectrum processing. This DSP may also perform vocoder functions to support telephony applications. The manner in which the processor 208 is implemented will depend on the particular application and the design constraints imposed on the overall system. It should be noted that hardware, firmware, and software configurations are interchangeable under these circumstances and how the described functionality is best implemented for each particular application.

The processor 208 may be configured to execute an algorithm that triggers a handoff from one network to another. The algorithm may be implemented as one or more software applications supported by the microprocessor-based architecture discussed earlier. Alternatively, the algorithm may be a module separate from the processor 208. The module may be implemented in hardware, software, firmware, or any combination thereof. Depending on specific design constraints, the algorithm may be integrated into any entity within mobile device 102, or distributed across multiple entities within mobile device 102.

The signal strength from the access point may be measured at the mobile device 102 with a Received Signal Strength Indicator (RSSI) block 216 for certain purposes known in the art. This RSSI is most likely a measure of the strength of the existing signal that is fed back to the wireless LAN transceiver 204 for use in automatic gain control and therefore can be provided to the processor 208 without increasing the circuit complexity of the mobile device 102. Alternatively, the quality of the radio connection may be determined from the beacon. Since the beacon is a spread spectrum signal known a priori, a copy of the beacon may be stored in memory 211 at mobile device 102. The demodulated beacon may be used with this replica beacon stored in memory to estimate the energy of the transmitted beacon by means well known in the art.

Returning to the previously mentioned fingerprints, the mobile device 102 also includes an algorithm executable by the processor 208 to create multiple fingerprints and compare different fingerprints to each other. For example, using keypad 212, a user of mobile device 102 may select a key that causes mobile device 102 to create a current fingerprint and store the fingerprint in memory 211. If the mobile device is connected to a wireless LAN upon this fingerprint being created, the stored fingerprint will be associated with the wireless LAN access point. In addition, the fingerprint may also be automatically recorded on a periodic basis or on a programmed event, such as successful access, successful access at a desired quality of service, and the like.

As a result of the above procedure, the memory 211 may contain a wireless LAN search table organized similar to, for example, the following table:

the first column of the table refers to the WAN ID of the WAN. The WAN ID identifies the system and network of the WAN, which is referred to as SID/NID in a wide area wireless system. A particular base station in the WAN may be identified by a pilot offset, pilot signal strength, or other attribute that forms part of a fingerprint as discussed below. The fingerprint identifies the location of the mobile device. The second column refers to the text identifier of the WLAN network. The third identifier refers to a wireless LAN access point (also referred to as BSS). In this exemplary table there are three access points (a) within the first coverage area of base station a₁，A₂，A₃). Similarly, there are two access points within the coverage area of base station B. Of course, there may be many more wireless LANs in an area covered by any of the wan ids, but the user of the mobile device may not be interested in those access points because they are associated with wireless LANs to which the user is not allowed access. Accordingly, the table above may include only the fingerprints of those access points to which the user is typically connected.

The remaining two columns include those values that make up the fingerprint itself. In this example table, access point A₁、A₂And A₃Includes both intensity and phase information. However, access point B₁And B₂Includes only signal strength information. It is also noted that although this is the caseEach fingerprint in the table is annotated by a vector of length n, but the non-null amount of the vector may be less than n. That is, there are several values that may be null, and thus fingerprint matching is limited to those vector components that are not null. In operation, the mobile device may wake up from a sleep or idle mode and compute a fingerprint for its current location and compare it to the information in columns 4 and 5 in the table above. The mobile device typically limits fingerprint matching to entries corresponding to the WAN ID with which it is currently registered. Thus, when registered with WAN ID a, only the fingerprint in the table above associated with WAN ID a is used for matching. Fingerprint creation and comparison may also occur during ongoing calls. Based on this comparison, the mobile device can determine that an access point having an SSID and BSSID indicated in columns 1 and 2 is sufficiently close to search for its beacon signal; otherwise it may return to idle mode without having to expend searching for wireless LAN beacon signals.

The above table is exemplary in nature and does not describe all possible information that may be used to characterize a fingerprint nor all different combinations of WAN IDs relative to access point IDs. For example, since most areas are covered by multiple WAN service providers each with their own WAN ID (SID/NID), an entry for one access point may appear multiple times, each associated with a different WAN ID and with a respective signature. In addition to the tables depicted above, a separate table may be employed (or additional entries in the original table may be employed to store information about responding access points (i.e., BSS IDs) such that, for example, wireless LAN access points are typically configured to operate on a particular channel in a particular frequency band.

The creation of the fingerprint table is described with reference to the flowchart of FIG. 3A. At step 302, the mobile device connects to a wireless LAN. The mobile device scans for WLAN access points in a typical manner without ever benefiting from any pre-stored fingerprint. Once the mobile device has connected with the access point, the user may signal the device to capture the current fingerprint at step 304. This step may typically be user initiated, as the user may only want certain wireless LANs to be stored in the fingerprint database, such as those wireless LANs to which the user typically subscribes or connects. However, creation of the fingerprint may also be initiated automatically by the mobile device as one of these many steps performed when connecting to the wireless LAN.

At step 306, the mobile device captures the values of those attributes that make up the fingerprint, and at step 308, the device stores this fingerprint in a database. It would be advantageous to store the attributes of the wireless LAN currently connected to along with this fingerprint.

The comparison of the current fingerprint to the stored fingerprint may be performed in various ways without departing from the scope of the present disclosure. One particular technique is described below. However, many alternative but functionally equivalent techniques may be employed.

The attributes that make up a fingerprint may have values that vary (even for the same location) or are difficult to measure with high accuracy. Thus, the alignment between fingerprints should not rely on exact repetitiveness as a test to determine a match. Similarly, region 140 may reflect operational decisions that place greater importance on early detection of an access point at the expense of false alarms. In other words, if zone 140 is selected to be much larger than zone 114, mobile device 102 will determine that it should search for a beacon signal (i.e., a false alarm) while it is not already within zone 114. However, if region 140 is selected to be close to fit region 114, there will be instances where the mobile device should be searching for a beacon signal but the fingerprint matching algorithm has not instructed it to do so.

To account for such variability in fingerprints, an amount of "bias" is defined that helps control the determination of whether a fingerprint matches a stored fingerprint.

The table above includes the deviation values of the signal strength and the phase portion of the fingerprint alone. The use of these values will be explained with respect to the flow chart of fig. 3B. At step 320, the mobile wakes up or otherwise is controlled to capture a fingerprint of its current location. Continuing the example where the signal strength of the fingerprint has a vector and the phase has a vector, a pair of vectors x are collected₁，...，x_nAnd y₁，...，y_n。

At step 322, the current WAN ID is checked and a table entry for the access point associated with the WAN ID is determined. Further search optimization is possible by searching the database for identifiers of observable pilots. For a CDMA network, the search criterion may be the PN phase offset of the observable pilots. The respective fingerprints of the access points are then compared to the current fingerprint to determine if there is a match at step 324. Algorithmically, this alignment and determination is performed as follows:

for i ═ 1 to n:

determine if | x_i-s_i(·)|＜d_i(·)

Determine if y_i-p_i(·)|＜q_i(·)

Thus, the deviation values d and q can be used to select how close the current fingerprint (x and y vectors) must match the stored fingerprint (s and p vectors). The larger these deviations, the larger the difference between these values may be and still have a match.

If there is a match at step 324, a determination may be made at step 326 as to all differences (e.g., | x) for a given access point_i-s_i(·) | and | y_i-p_i(v) |) whether the sum also falls below the respective threshold (e.g., X and Y). This additional test may help capture certain scenarios where individual differences may show a match but when the fingerprint is considered in aggregate, it may be determined that there is no match.

If the tests in steps 324 and 326 are satisfied for a wireless LAN access point in the table above, the mobile device is controlled to search for a beacon signal for that access point. If there is no match at steps 324 or 326, the mobile device continues to look for a match on another fingerprint for another BSS ID. Where there may be more than one access point fingerprint matching the current location fingerprint, then a magnitude of the difference, or a sum of the differences, or some other determination may be made to select the access point whose fingerprint most closely matches the current fingerprint. In such a multiple matching scenario, when the mobile device scans for WLAN access points, it can locate one or more access points.

FIG. 4 depicts a flow diagram of an exemplary method of optimizing fingerprint entries. At step 402, the mobile device, after searching for and acquiring a beacon signal, connects to an access point of the wireless LAN as is known in the art. The access point has a MAC address that is used as its BSS ID. Other identifiers may also be used to distinguish between different access points; however, the BSS ID is a convenient value. Thus, at step 404, the mobile device determines whether the access point to which it is connected has an entry in the fingerprint table. If not, a current fingerprint may be generated (see FIG. 3A) and stored at step 406. If the access point already has a fingerprint entry present, the current fingerprint may be utilized to optimize the already present fingerprint at step 408. As part of this optimization process, the deviation values, if any, may also be optimized at step 410.

This optimization procedure utilizes the current fingerprint to modify the stored fingerprint such that the stored fingerprint does not simply represent the situation when the access point was first found, but instead actually benefits from the values measured during multiple times the access point was found. An example of such an optimization may be described with reference to signal strength parameters, but it is equally well applicable to phase parameters or any other property used to create fingerprints. According to the method, a record of the number of times the fingerprint is updated is also maintained. In this example, access point A₁Is updated the kth time. The fingerprint comprising a vector s₁(A₁)...s_n(A₁) And the current fingerprint includes a vector x₁，...，x_n. Root of each value of the s vectorUpdated according to the following formula:

novel s_i[ (K-1) (old s)_i)+x_i]/K

This type of running average optimization is merely exemplary in nature and there are many acceptable mathematical techniques that can be used to optimize fingerprint values without departing from the scope of the present disclosure. Optimization of the fingerprint may also be achieved by adding values of new attributes (e.g., the number of measurable pilot signals) to the fingerprint instead of or in addition to changing existing values.

The deviation value may also be optimized. For example, the initial offset value may be a default value. Such as, for example, 10dB (with respect to signal strength), or the default value of deviation may be variable, such as 5% of the fingerprint value. In this example, the measured deviation vector between the x and s vectors is vector m₁，...，m_n. New deviation value d_iFrom MAX [ (previous d)_i)，m_i(default))]To calculate.

In these examples above, the mobile device generates and stores fingerprints in the fingerprint database. However, some or all of these fingerprints may alternatively be stored somewhere further upstream in the wide area wireless communications network, such as in a database 111 accessible by the MSC 110. In this case, processing requirements and storage requirements for the mobile device may be reduced. In operation, the mobile device will create a current fingerprint and transmit that fingerprint to the MSC (or possibly to the BSC if the database is there). The MSC will then perform a fingerprint comparison and instruct the mobile device whether to search for an access point beacon signal. Under this orchestration, the MSC can receive fingerprints from multiple mobile devices, and its database of available access points is much larger than can be found in a single mobile device. Alternatively, a personalized fingerprint database may be created for each user of the wide area wireless communication network and stored at their home system.

The various illustrative logical blocks, modules, circuits, elements, and/or components described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic component, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing components, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The methods or algorithms described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. A storage medium may be coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor.

The above description provides certain exemplary aspects and embodiments. Various modifications to these embodiments and aspects are within the scope of the disclosure, and the generic principles defined herein may be applied to other embodiments. Thus, the following claims are not intended to be limited to the embodiments shown herein, but are to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more. All structural and functional equivalents to the elements of the various embodiments described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the appended claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the appended claims. No claim element is to be construed under the 35 u.s.c. § 112 sixth paragraph unless the element is explicitly recited using the phrase "means for … …", or in the case of a method claim the element is recited using the phrase "step for … …".

Claims (20)

1. A wireless communication device, comprising:

a memory configured to store a fingerprint of a first communication network; and

a processor configured to create a fingerprint of the first communication network by capturing values of at least one attribute of at least one reference signal transmitted by a second communication network when the wireless communication device is in proximity to the first communication network; and determining whether the wireless communication device is currently in the vicinity of the first communication network based on the fingerprint stored in the memory and one or more reference signals received from the second communication network.

2. The wireless communication device of claim 1, wherein the processor is further configured to determine whether the wireless communication device is in the vicinity of the first communication network by creating a fingerprint of the wireless communication device using the one or more reference signals from the second communication network and comparing the fingerprint of the wireless communication device to fingerprints stored in the memory.

3. The wireless communication device of claim 1, wherein the processor is further configured to utilize relative phase information from the one or more reference signals to determine whether the wireless communication device is in the vicinity of the first communication network.

4. The wireless communication device of claim 1, wherein the processor is further configured to utilize relative signal strengths of the one or more reference signals to determine whether the wireless communication device is in the vicinity of the first communication network.

5. The wireless communication device of claim 1, wherein one or more reference signals comprise a pilot signal.

6. A wireless communication device, comprising:

a memory configured to store a fingerprint of each of a plurality of wireless LANs dispersed throughout a WAN; and

a processor configured to create a fingerprint of each wireless LAN by capturing a value of at least one attribute of at least one reference signal transmitted by the WAN when the wireless communication device is in proximity to the wireless LAN; and determining whether the wireless communication device is currently in proximity to one of the plurality of wireless LANs based on the fingerprint stored in the memory and one or more reference signals from the WAN.

7. The wireless communication device of claim 6, wherein the processor is further configured to determine whether the wireless communication device is in proximity to the one of the plurality of wireless LANs by creating a fingerprint of the wireless communication device using the one or more reference signals from the WAN and comparing the fingerprint of the wireless communication device to a fingerprint of the one of the plurality of wireless LANs stored in the memory.

8. The wireless communication device of claim 6, wherein the processor is further configured to utilize relative phase information from the one or more reference signals to determine whether the wireless communication device is in proximity to the one of the plurality of wireless LANs.

9. The wireless communication device of claim 6, wherein the processor is further configured to utilize relative signal strengths of the one or more reference signals to determine whether the wireless communication device is in proximity to the one of the plurality of wireless LANs.

10. The wireless communication device of claim 6, wherein the one or more reference signals comprise pilot signals.

11. An apparatus for performing a communication method for a wireless communication apparatus, comprising:

means for creating a fingerprint of a first communication network by capturing values of at least one attribute of at least one reference signal transmitted by a second communication network when the wireless communication device is in proximity of the first communication network;

means for storing the fingerprint in a memory;

means for processing one or more reference signals received from the second communication network; and

means for determining whether a wireless communication device is currently in proximity to the first communication network based on the one or more reference signals from the fingerprint stored in the memory and from the second communication network.

12. The apparatus of claim 11, wherein the means for determining whether the wireless communication device is currently in the vicinity of the first communication network further comprises: means for creating a fingerprint of the wireless communication device using the one or more reference signals from the second communication network, and comparing the fingerprint of the wireless communication device to fingerprints stored in the memory.

13. The apparatus of claim 11, wherein the apparatus further comprises means for creating the fingerprint by detecting the first communication network during a search, establishing a fingerprint of the first communication network using the one or more reference signals from the second communication network, and storing the fingerprint in the memory.

14. A communication method for a wireless communication device, comprising:

creating a fingerprint of a first communication network by capturing values of at least one attribute of at least one reference signal transmitted by a second communication network when the wireless communication device is in the vicinity of the first communication network;

storing the fingerprint in a memory;

receiving one or more reference signals from the second communication network; and

determining whether the wireless communication device is in proximity to the first communication network based on the fingerprint stored in the memory and the one or more reference signals from the second communication network.

15. The method of claim 14, wherein the determining whether the wireless communication device is in the vicinity of the first communication network further comprises: creating a fingerprint of the wireless communication device using the one or more reference signals from the second communication network and comparing the fingerprint of the wireless communication device to fingerprints stored in the memory.

16. The method of claim 14, further comprising creating the fingerprint by detecting the first communication network during a search, establishing a fingerprint of the first communication network using the one or more reference signals from the second communication network, and storing the fingerprint in the memory.

17. The method of claim 14, wherein the one or more reference signals comprise pilot signals.

18. A wireless communication device, comprising:

means for creating a fingerprint of a first communication network by capturing values of at least one attribute of at least one reference signal transmitted by a second communication network when the wireless communication device is in proximity of the first communication network;

means for storing the fingerprint; and

means for determining whether the wireless communication device is currently in the vicinity of the first communication network based on the fingerprint stored therein and one or more reference signals received from the second communication network.

19. The apparatus of claim 18, wherein the one or more reference signals comprise pilot signals.

20. The apparatus of claim 18, wherein the means for determining comprises means for creating a fingerprint of the wireless communication device using the one or more reference signals from the second communication network and comparing the fingerprint of the wireless communication device to fingerprints stored in the memory.