Device beacon for handoff management of handoffs to access nodes

An access node receives a device beacon transmitted from a wireless communication device in accordance with a system timing of a wireless wide area network (WWAN). When transmitted within a WWAN uplink channel, the device beacon is mapped to designated beacon channels within the time-frequency space of the uplink WWAN channel assignment. In response to the reception of the device beacon, communications between the wireless communication device and the access node are established. In one example, the access node is a femtocell base station. In another example, the access node is a wireless local area network (WLAN) access point.

RELATED APPLICATIONS

This application is related to U.S. patent application entitled “DEVICE BEACON FOR HANDOFF MANAGEMENT OF HANDOFFS TO BASE STATIONS”, Ser. No. 12/267,171, and to U.S. patent application entitled DEVICE BEACON FOR COMMUNICATION MANAGEMENT FOR PEER TO PEER, Ser. No. 12/267,365, both filed concurrently with this application and incorporated by reference in their entirety, herein.

BACKGROUND

The invention relates in general to wireless communication systems and more specifically to device beacon signals in a wireless communication system.

Wireless local area networks (WLANs) and wireless wide area networks (WWANs) provide wireless communication services to portable devices where the WLANs typically provide services within geographical service areas that are smaller than the geographical areas serviced by WWANs. Examples of WWANs include systems that operate in accordance with 2.5G (such as cdma2000), 3G (such as UMTS, WiMax), and other types of technologies such OFDM, where each base station of the WWAN is typically designed to cover a service area having a size measured in miles. The term WWAN is used primarily to distinguish this group of diverse technologies from WLANs that typically have smaller service areas on the order of 100 to 300 feet per base station. Base stations in WLANs are typically referred to as access points. An access point may be connected to the Internet, intranet, or other network through wires or wirelessly through a WWAN. Examples of WLANs include systems using technologies such as Wi-Fi and other wireless protocols in accordance with IEEE 802.11 standards. WLANs typically provide higher bandwidth services than WWANs at the expense of non-ubiquitous coverage whereas WWANs provide increased coverage areas at the cost of bandwidth and/or capacity. In order to provide a wireless user with the increased overall performance and continuous connectivity, multi-mode mode and dual-mode portable communication devices have been developed allowing the communication device to access the particular type of network that provides the most desirable tradeoffs. A multi-mode wireless communication device includes the appropriate components and functionality for communicating within more than one network. For example, a dual-mode portable communication device can communicate within a WWAN and a WLAN.

Unfortunately, conventional techniques for managing the connection status between the portable communication device and the access point are limited in that they require GPS location information or include inefficient searching mechanisms executed by the portable communication device in order to establish service with a new network for performing a handoff between networks. For example, some conventional systems require the mobile communication device to periodically tune to an alternate network channel in an attempt to detect an alternate network resulting in significant power consumption with a limited success rate of detecting alternate networks.

SUMMARY

An access node receives a device beacon transmitted from a wireless communication device in accordance with a system timing of a wireless wide area network (WWAN). When transmitted within a WWAN uplink channel, the device beacon is mapped to designated beacon channels within the time-frequency space of the uplink WWAN channel assignment. In response to the reception of the device beacon, communications between the wireless communication device and the access node are established. In one example, the access node is a femtocell base station. In another example, the access node is a wireless local area network (WLAN) access point.

DETAILED DESCRIPTION

FIG. 1Ais a block diagram of a communication system100that includes a wide area wireless network (WWAN)102, a transceiver node104, and a wireless communication device106. The WWAN provides wireless communication services to one or more wireless communication devices106. The wireless communication device106, at least periodically, transmits a device beacon108in accordance with a system timing110of the WWAN102. The transceiver node104also obtains the system timing110, either wirelessly or through a wired backhaul. A device beacon detector112within the transceiver node104uses the system timing110to monitor device beacon channels and to receive the device beacon108. As discussed below, the transceiver node104may perform any of several tasks in response to detecting the device beacon108where at least some of the tasks may result in establishing communications between the transceiver node104and the wireless communication device106.

The device beacon108may be transmitted within a WWAN channel or may be transmitted in a separate frequency band outside of the WWAN frequency band. Where the device beacon108is transmitted within a WWAN channel, the device beacon108is transmitted within a time slot and frequency that minimizes interference with other communications within the WWAN102. As discussed below, a suitable technique for such an arrangement includes performing a subcarrier mapping of the device beacon108with the time-frequency space of the uplink WWAN channel assignment for the wireless communication device. Some examples of channels that can be used that are outside the WWAN uplink channels include WLAN channels, WWAN adjacent bands, and channels within unlicensed bands such WiFi and Bluetooth. Also, the wireless communication device may transmit beacons during WWAN idle states and WWAN non-idle states. The device beacon detector112is any device that can detect the device beacon108when the wireless communication device106is sufficiently close to the transceiver node104where the particular implementation depends on the type of device beacon108. For the examples discussed below, the device beacon detector112comprises a receiver configured to receive signals transmitted within the frequency band and with the modulation scheme used to transmit the device beacon108.

The transceiver node104may be any portable, mobile, or fixed communication device that is capable of communicating with the wireless communication device106under the appropriate conditions. For one example discussed below with reference toFIG. 1C, the transceiver node104is another wireless communication device that communicates on the WWAN. For the other examples discussed with reference toFIG. 1B, the transceiver node104is an access node providing wireless communication service where the access node may be a base station operating within the WWAN such as a femtocell base station or may be an access point of a wireless local area network (WLAN).

FIG. 1Bis a block diagram of the communication system100where the transceiver node104is an access node114. The communication system100includes at least one access node114and at least one WWAN base station116where the access node114provides wireless communication service within a geographical service area that is smaller than the geographical service area in which the base station116provides wireless service. The communication system100may be implemented in accordance with any of numerous technologies and communication standards where the access node114may use the same or different standard than used by the base station116. Further, the access node114may be part of a separate network or may be part of the same network as the base station116. The access node114may be self-managed or may be managed by the system infrastructure118which may also manage the base station116. In some examples, the access node114is a femtocell base station operating in the same network where the base station116operates as a macrocell base station. In another example, the access node114is a wireless access point providing wireless service in a wireless local area network (WLAN) and the base station116provides service in a wireless wide area network (WWAN) using a different technology and standard than used by the WLAN access point. The access node114, therefore, can be any base station, transceiver, or other communication device that provides wireless communication service to a wireless communication device to connect the wireless communication device to other devices and/or a communication network.

The system infrastructure118is connected to one or more base stations116and access nodes114. Communications between the base station116and wireless communication devices106are at least partially managed by the system infrastructure118for the example. A controller120within the system infrastructure118at least includes hardware, software and/or firmware for receiving and sending control messages. The controller120may include at least portions of a BSC and a MSC. For the example discussed herein, the controller120is the equipment within the communication system100that performs wireless device paging functions and generates paging channel messages.

The wireless communication device106transmits a device beacon108that is based on timing information122received from the base station116. Timing information is derived at the wireless communication device by receiving WWAN downlink signals122transmitted by the base station116. Examples of suitable methods for acquiring WWAN system timing include receiving a sync channel or a sync-type channel. A downlink control signal may be received, for example, and accurate timing derived from the signal. In some circumstances, an early-late gate method is used to derive timing which uses an auto-correlation function. For systems that transmit information in a packetized mode, the synchronization processes may be aided by a sync preamble consisting of a training sequence. These training sequences typically have appropriate cyclic guard intervals. The preambles are periodically transmitted in between data symbols. After acquiring a coarse timing, the wireless communication may implement tracking mode where it tracks/adjusts and maintains the timing information. When the wireless communication device106is sufficiently close to the access node114, the access node114can receive the device beacon108transmitted by the wireless communication device106. The access node114, therefore, at least periodically attempts to receive signals in the designated device beacon channels124. As discussed, the device beacon108may be transmitted within designated WWAN uplink channels or outside of the WWAN band. At the appropriate times (or continuously), the device beacon detector112tunes to the appropriate frequencies and/or uses the appropriate scrambling codes to monitor the device beacon channels124where device beacons108may be present. The device beacon detector112, therefore, is any device that is able to monitor the device beacon channels124and determine when a device beacon108is present. For the examples discussed herein, the device beacon is deterministically transmitted such that a receiver can easily find and acquire beacon signals as needed. The information defining the device beacon assigned parameters may be broadcasted by the WWAN using control channels. Such broadcasts may be autonomous or in response to a request from a WLAN Access Point or femtocell base station. Examples of beacon parameters include beacon transmission times and periods as well as subcarrier and frequency information.

The access node114derives the system timing110either through a backhaul from the system infrastructure118or by monitoring the base station downlink signals122. The WWAN downlink signal122from the base station116to the access node114is shown as a dashed line to illustrate that the signal may or may not be received by the access node114. Where the access node114is femtocell base station, the system timing110is typically obtained through backhaul, GPS or the WWAN. In some circumstances where the access node114is a WLAN assess point, deriving the timing from WWAN downlink signals122may be more efficient than obtaining the system timing directly from the system infrastructure118.

The reception of the device beacon signal108invokes the acquisition of wireless service from the access node114by the wireless communication device106. In the examples discussed, the access node114informs the system infrastructure118of the detection after detecting the device beacon108. In response, the system infrastructure118transmits a search message126to the wireless communication device106that adjusts the searching scheme used by the wireless communication device106to search for alternate wireless service. Where the wireless communication device106is a dual mode device searching for a WLAN, for example, the search message126may result in an activation of the WLAN receiver to search for WLAN signals. Where the access node114is a base station connected on the same cellular network as the base station116, the wireless communication device106may change search parameters of the searching scheme used to search for alternate base stations in response to the search message126. Additional information may be processed by the access node114and/or the system infrastructure118before messages are transmitted by the system infrastructure118and/or the wireless communication device106. As discussed below, for example, the capacity of the access node114and the bandwidth requirements of the wireless communication device106may be evaluated before invoking a handoff to the access node114. In some situations, the detection of the device beacon signal may invoke additional procedures or mechanisms. For example, in situations where the access node is not transmitting a pilot signal until services are to be provided, the detection of the beacon invokes the transmission of the pilot signal.

FIG. 1Cis a block diagram of the communication system100where the transceiver node104is a mobile wireless communication device128. The mobile wireless communication device128is any mobile or portable device that is capable of receiving WWAN downlink signals130and may be, for example, a handset, phone, wireless personal digital assistant (PDA), wireless modem, or wireless laptop computer. In some circumstances, the mobile wireless communication device128may be capable of communication on the WWAN102. In other situations, however, the mobile wireless communication device128may include adequate electronics to receive the WWAN downlink signals122but may be configured to operate on a different network where the network may use the same or different technology and/or protocol than the WWAN102. For example, the mobile wireless communication device128may be a WLAN device that operates in accordance with WiFi but that also includes WWAN receiver. Further, the mobile wireless communication device128may be a multi-mode wireless communication device such as a dual-mode phone capable of operating within a WWAN and a WLAN. Since both of the wireless communication devices106,128receive downlink signals122,130from the WWAN base station116, the two devices106,128both receive system timing information110from the WWAN. Accordingly, the system timing110is used as a reference for transmitting and receiving the device beacon108.

After the beacon detecting wireless communication device128detects the device beacon108, a peer to peer session is established between the wireless communication device106and the beacon detecting wireless communication device128. Peer to peer communication includes peer to peer communication132between the two devices106,128without transmitting data through a network. The arrow representing peer to peer communication is shown with dashed lines inFIG. 1Cto illustrate that the communications132are not established until after the device beacon108is detected. The peer to peer session may be established using any of several techniques and signaling schemes. For example, a device detection message may be sent to the WWAN which invokes a session establishment message that is transmitted by the WWAN to the wireless communication device106. In response to the session establishment message, the wireless communication device106transmits and/or receives messages to establish the peer to peer session. In some situations, the beacon detecting wireless communication device128sends a message directly to the wireless communication device106without using the WWAN.

FIG. 2A,FIG. 2BandFIG. 2Care depictions of exemplary geographical service area relationships200,206,208provided by the WWAN102and the transceiver node104. A WWAN geographical service area202provided by the WWAN base station116and a geographic service area204provided by the transceiver node104may have any of numerous shapes, sizes, and configurations. Accordingly, the clouds representing the service areas generally illustrate the relationships between the service areas and do not necessarily depict the actual shapes of the service areas. Further, the service areas may contain holes of coverage where service is unavailable. In the interest of clarity and brevity, such features are not illustrated in the figures. InFIG. 2A, the service area204of the detecting transceiver node104is completely within the service area202provided by the WWAN102. Such service area relationships200often occur where some base stations within the communication system100provide smaller service regions such as microcell, picocell, and femtocell configurations. A femtocell arrangement, for example, may include a femtocell base station (transceiver node104) located at a residence where the femtocell is a service area for devices used by device users living at the residence. When the wireless communication devices are outside the service area204, service is provided by larger macrocells (e.g. reference base station116). When the authorized wireless communication device is at the residence, however, service is provided by the transceiver node104presenting the smaller femtocell service area204. Further, the relationship200is likely to occur where the transceiver node104is a wireless communication device128. In such situations, the geographic service area is a geographic area within which another wireless communication device can engage in a per-to-peer communication session with the wireless communication device128. Accordingly, in most situations, the service area204of the transceiver node104will be completely within the service area202of the base station116. In some situations, however, the service area204may be partially overlapping with the service area202as shown inFIG. 2Bor may be non-overlapping but adjacent to the service area202as shown inFIG. 2C.

FIG. 3Ais a block diagram of a communication system300where the transceiver node104(access node114) is a base station302such as a femtocell base station, picocell base station, or microcell base station. The system300may be implemented using any variety of communication technologies and cell sizes. For the example discussed with reference toFIG. 3A, the base station302provides wireless service within a femtocell and the base station116provides service within a macrocell. In the interest of clarity, the base station302that detects the device beacon108is referred to as the detecting base station302and the base station116providing the system timing110to the wireless communication device106is referred to as the reference base station116. The base stations302,116operate in accordance with OFDM protocols and standards such as IEEE802.16 and 3GPP LTE. Other communication standards and protocols, however, may be used in some circumstances. Examples of other suitable communication standards include CDMA standards such as cdma20001X, 1xEV-DO and W-CDMA, and GSM standards. The term macrocell is used primarily to distinguish this group of diverse technologies from picocells and femtocells that typically have smaller service areas on the order of 100 to 300 feet per base station. Accordingly, the reference base station116is any base station that provides wireless communication services within relatively large geographical areas as compared to the geographical service area provided by the base station302in the example ofFIG. 3A. The functional blocks ofFIG. 3Amay be implemented using any combination of hardware, software and/or firmware. Two or more of the functional blocks may be integrated in a single device and the functions described as performed in any single device may be implemented over several devices. For example, at least portions of the functions of the system infrastructure118and controller120may be performed by the base station116, a base station controller, or an MSC in some circumstances.

The reference base station116transmits downlink link (forward) signals122to, and receives uplink (reverse link) signals304from, one or more wireless communication devices to provide wireless communication service. The wireless communication device106may be in any of several states while receiving the WWAN downlink signals that provide system timing. The operational states of the wireless communication device106may include idle states, dormant states, active states and other traffic and non-traffic states. The wireless communication device106generates and transmits the device beacon108in accordance with the system timing. The system timing includes at least the timing reference as well as time slot and channel assignment. For the example discussed with reference toFIG. 3A, device beacon108is transmitted at a designated time and channel (subcarrier) within the uplink WWAN time-frequency space. For the example discussed with reference toFIG. 3Bbelow, the device beacon108is transmitted outside of the uplink channel but in accordance with the WWAN system timing.

The system infrastructure118includes the controller120that may be implemented as a mobile switching center (MSC), a combination of an MSC and base station controllers (BSCs), or other similar communication controllers and/or servers. The controller120is connected to the base stations302,116through the system infrastructure118and manages communications within the system300. Although the controller120is illustrated as part of the system infrastructure118, it may be part of the base station116or collocated with the base station116. The controller120may include, or may be part of, the MSC, BSC or other infrastructure. The controller120includes the hardware and software for generating the search message126and, for this example, is the same equipment used to generate paging channel messages.

A network interface306within the detecting base station302facilitates communication with an IP network308through an access router310. The network interface306provides packet data communications and facilitates access to the Internet and to an access gateway312in the system infrastructure118through the access router310. In some circumstances the access router310may be implemented as part of the network interface and the network interface306may directly access the Internet. The access router310may be connected to several base stations and provides communication management and control functions to the detecting base station302. In some circumstances, the connection between the access gateway312and the base station302may include a wireless communication link such as satellite communication link or point-to-point microwave link, for example. Also, in some situations, circuit switched connections may be used to connect the detecting base station302to the system infrastructure118. In a typical arrangement, the detecting base station302is connected to the Internet through an Internet Service Provider (ISP) service provided by a digital subscriber line (DSL) or CATV connection. Accordingly, the access router310is a DSL modem or cable modem in the typical arrangement. In the example, therefore, the system infrastructure118comprises a packet switched core network that includes at least one access gateway312. The access gateway312is a communication interface that allows the base station302to communicate with the system infrastructure118.

The wireless communication device106is any type of communication device that is capable of communicating with the base stations302,116. The wireless communication device106, sometimes referred to as an access terminal, may be a wireless modem, a personal digital assistant (PDA), cellular telephone, or other such device. Examples of suitable wireless communication devices are provided below.

In addition to the functions and features discussed herein, the detecting base station302operates in accordance with the communication protocols of the communication system300and is a femtocell base station. The detecting base station302includes a controller314, memory316, WWAN transceiver318, such as cellular transceiver, and the network interface306in addition to other devices and software for performing the functions of the base station302. The cellular transceiver318includes an uplink receiver320and a downlink transmitter322. The downlink transmitter322transmits WWAN downlink signals132to wireless communication devices such as the wireless communication device106.

In addition to other information, the memory316stores communication device identification values corresponding to each wireless communication device106that is authorized to receive service from the base station302. The communication device identification value may include an electronic serial number (ESN), Mobile station Equipment Identifier (MEID) or International Mobile Subscriber Identity (IMSI) or other unique data identifying the wireless communication device106. An example of a group of identification values stored in memory316includes a collection of ESNs corresponding to the communication devices of the family members of a household where the base station302provides service. The identification values may be stored at the base station302using any of numerous techniques. An example of a suitable method of storing the values includes storing the values during an initialization procedure performed when the base station302is installed. The identification values may be provided, at least partially, by the core network or the macrocell base station116. In some implementations, the identification values may be omitted or the base station302may allow communication devices that do not have corresponding identification values stored at the base station302to receive service from the base station302.

During operation, the detecting base station302monitors, at least periodically, a device beacon channel124which is a wireless channel that may include the device beacon signal108. For the example ofFIG. 3A, the device beacon signal108is within a sub-carrier time slot. In some circumstances, no other channel is assigned for the other frequencies during the time slot assigned for the device beacon. Such a scenario increases the likelihood of the detecting base station302to detect the device beacon signal108since all of the device beacon energy is concentrated at a particular frequency with no other concurrently transmitted signals present. The assignment of subcarriers for the beacon is established at the base band frequencies. Accordingly, the actual transmitted signal at the radio frequencies (RF) may include a wideband signal. The device beacon detector112is formed by at least portions of the controller314, memory316and uplink receiver320. Since the detecting base station302is synchronized with the system infrastructure118, the cellular transceiver318has adequate system timing information to determine the time slot boundary and the timing of uplink signals. The timing facilitates non-blind beacon detection at the receiver. With appropriate beacon designs, blind detection may also be performed. In some circumstances, the device beacon detector112may only search for beacons signals transmitted from wireless communication devices that are authorized to use the detecting base station302. An authorized list of serial numbers or other device identifiers are stored in memory316at the detecting base station302.

In response to detecting the device beacon signal108, the detecting base station302sends a device proximity message324to the controller120which invokes the reference base station116to transmit the search message126to the wireless communication device106. For this example, the controller314determines if the device beacon signal108is successfully received at the detecting base station302. If the signal can be received, the controller314determines that the wireless communication device106is sufficiently close to receive service from the base station302. In some cases, the device beacon signal may be detected and received even though the wireless communication device106is not within the service area of the base station302. In these circumstances, the wireless communication device106may unsuccessfully attempt to acquire service from the base station302after receiving the search message126from the reference base station116. The controller314determines, or at least estimates, the proximity of the authorized wireless communication device106to the detecting base station302based on one or more characteristics of the uplink signal. In the exemplary embodiment, the detection of an uplink signal from the communication device106is sufficient to determine that the communication device106is within a proximity range. The proximity is used to determine whether the communication device106is possibly within range of the base station302and at least possibly able to receive communication service from the base station302. Therefore, the controller314at least determines whether the communication device106is possibly within range of the base station302. If the controller314determines that the wireless communication device106is possibly in range, the device proximity message324is sent to the controller120in the system infrastructure118which results in the transmission of the search message126to the wireless communication device106.

The controller314may determine whether to transmit the device proximity message324based on factors other than proximity of the wireless communication device106or the detection of the device beacon signal108. For example, factors may include the available capacity of the detecting base station302, core network requirements, required bandwidth of the wireless communication device communications, and availability of other base stations or communication service providers in the area. Accordingly, the base station302may not transmit the device proximity message324even if the wireless communication device106is within range in some circumstances. In some situations, the device proximity message324is transmitted every time a wireless communication device106is detected by the detecting base station302and the system infrastructure118determines whether to transmit the search message126.

The device proximity message324is generated by the controller314and transmitted through the network interface306, through the IP network308and/or the access router310to the access gateway312. The access gateway312routes the device proximity message324through the system infrastructure118to the controller120. For the discussed example, the controller120is the same equipment that is used to generate paging messages to the wireless communication device106. The controller120receives the device proximity message324and extracts the appropriate information. In response to the device proximity message324, the controller120generates the search message126which is transmitted from the reference base station116to the wireless communication device106. The search message126triggers an adjustment of the wireless communication device searching scheme that the wireless communication device106employs for searching for alternate base stations. The wireless communication device106, therefore, changes one or more searching parameters of the searching scheme in response to receiving the search message126. Any combination of numerous parameters can be adjusted where the adjustments increase the likelihood of the wireless communication device106detecting a signal transmitted by the detecting base station302. The search message126may result in a change in the search scheme to devote more resources to search for an alternate base station or may result in a change in resources to search for the specific detecting base station302. In some circumstances, the search message126may specifically instruct the wireless communication device106to search for the detecting base station302.

For the example, the search message126is transmitted using the paging channel. Any suitable downlink channel monitored by the wireless communication device106during the non-traffic state, however, may be used. The wireless communication device106searches for signals transmitted by alternate base stations in accordance with the searching scheme. Alternate base station signals from frequencies and/or technologies different than those by the base station116may be searched. The wireless communication device106searches for pilot signals although other signals may be searched. For example, the wireless communication device106may search for base station beacon signals in some situations. Examples of searching parameters include a total time period for searching, time periods for searching particular frequencies, the frequency of searching, the frequency of searching particular frequencies, the groups of frequencies searched, the portions of channels searched, the receiver settings for searching and type of communication technology. Other searching parameters will be apparent to those skilled in the art based on these teachings. As discussed in further detail below with reference toFIG. 4A, therefore, the search message126includes information that results in an adjustment of one or more of the search parameters.

For the present example, device proximity message324are sent only in response to receiving device beacon signals108from authorized users of the detecting base station302. The search message126is sent to the wireless communication device106in response to receiving the device proximity message324at the controller120. In some situations, however, additional criteria may be evaluated before sending the device proximity message324, the search message126, or before sending both. As discussed below, for example, the detecting base station302may evaluate one or more parameters to determine the proximity of the wireless communication device106to the detecting base station302and only send the device proximity message324if the calculated proximity is less than a threshold. Also, the controller120may evaluate system conditions and refrain from sending the search message126if certain system conditions are not met.

Examples of data that may be evaluated by the detecting base station302include the capacity of the detecting base station302, bandwidth requirements of the wireless communication device106and a calculated or estimated proximity of the wireless communication device106to the detecting base station302. Accordingly, the detecting base station302may evaluate a characteristic of the device beacon signal108to determine whether to transmit the device proximity message324. In the example, the reception of the device beacon signal108by the UL receiver320is sufficient to determine that the wireless communication device106is present and that the device proximity message324should be transmitted. In other circumstances, other signal characteristics may be evaluated to determine the proximity. Therefore, a characteristic of the device beacon signal108may be any of numerous parameters with any of numerous thresholds depending on the particular implementation and the characteristic may be whether the device beacon signal108is detectable by the base station receiver320. Examples of other characteristics include a signal to noise ratio (SNR), bit error rate (BER), power level, signal propagation time, and presence of particular data. An example of technique for determining the proximity is discussed in U.S. patent application Ser. No. 11/565,266 entitled “APPARATUS, SYSTEM AND METHOD FOR MANAGING WIRELESS LOCAL AREA NETWORK SERVICE TO A MULTI-MODE PORTABLE COMMUNICATION DEVICE”, filed on Nov. 30, 2006, and incorporated by reference in its entirety herein.

The device proximity message324and search message126may have any of numerous relationships and each message may be dependent on the information within, the format of, and/or other characteristics of the other message. For example, the device proximity message324and the search message126may be the same message in some circumstances. Such a situation occurs where the device proximity message324is an SMS message sent directly to the wireless communication device106indicating that the device beacon signal108transmitted from the device106has been detected by the detecting base station302. The wireless communication device106interprets the device proximity message324as a search message126indicating that the search parameters should be changed. Transmitting the search message126within the paging channel, however, allows for minimizing power consumption since additional resources are not invoked to receive SMS messages.

After receiving the search message126, the wireless communication device106searches for an alternate base station in accordance with the adjusted search scheme. In response to the search message126, the wireless communication device106activates the appropriate circuitry to receive signals transmitted by the detecting base station302such as a beacon pilot signal or communication pilot signals. In most situations, such circuitry is periodically activated in accordance with the search scheme to the reception of the search message and the search message does not directly trigger the activation of the receive circuitry. The adjusted search scheme, however, may result in more frequent activation of the circuitry. The detecting base station302generates and transmits a communication pilot signal which provides control and timing information to the wireless communication device106. In some circumstances, the detecting base station302may refrain from transmitting pilot signals until a wireless communication device106is detected and the proximity message304is sent. In addition, the detecting base station302may transmit a base station beacon pilot signal. After the detecting base station302is found by the wireless communication device106, the wireless communication device106may engage in a handoff procedure where, after a determination that the wireless communication device106should be handed off to the detecting base station302, the system300establishes wireless service to the wireless communication device106from the detecting base station302.

FIG. 3Bis a block diagram of a communication system350where the transceiver node104(access node114) is a base station352such as a femtocell base station, picocell base station, or microcell base station and where the device beacon is transmitted outside of the WWAN uplink frequency band. The system350is similar to the system300discussed with reference toFIG. 3Aexcept that the detecting base station302includes a device beacon detector112that detects device beacons108outside of the WWAN uplink frequency band. For the example ofFIG. 3B, therefore, the wireless communication device106transmits a device beacon with a frequency band outside of the WWAN uplink frequency band. Examples of suitable frequency bands include Bluetooth frequency bands and WLAN frequency bands. The device beacon detector112includes a receiver that can receive the signals transmitted within the device beacon frequency band. After detecting the device beacon, the base station302may perform the functions discussed above with reference toFIG. 3A. In some situations, detecting base station may not be transmitting or receiving any WWAN signals until after detection of the device beacon108. Accordingly, the WWAN pilot signal132may be transmitted in response to the detection of the device beacon signal108.

FIG. 4Ais a block diagram of the search message126where the search message126is transmitted within a paging channel message400. The search message126may contain any of several types of information, may have any of numerous formats, and may be transmitted using a variety of channels and signals. For this example, the search message126is contained within the message body402of a paging channel message400in accordance with one or more OFDMA standards. The paging channel is allocated a set of time-frequency bins where each paging channel message400includes a header field404, a message body402, and a cyclic redundancy check (CRC)406.

For the example, a search message indicator408may be included in the header404. The header404may also include message length information. Typically, length is kept constant for paging messages.]. The search message indicator408is any number of bits that indicates to the wireless communication device106that the paging message is a search message126. The search information includes information related to the search scheme adjustment. In some cases, the search message indicator408is sufficient to notify the wireless communication device106of a need to adjust the searching scheme and the search information410may be omitted. The search information, however, may include any of numerous parameters related to the adjusting the searching scheme. As discussed below in further detail, the search information410may include information that identifies one or more base stations that should be searched or frequencies that should be searched.

The search message126includes information that results in an adjustment of one or more of the search parameters. In some situations, the search message126may only indicate that a more robust search should be performed and the wireless communication device106adjusts searching resources in response. The search information410may be omitted in this case. The search change may be a preprogrammed adjustment or a dynamic adjustment based on other criteria observed by the wireless communication device106. For example, if some detection of energy had been recently observed in a particular channel, the adjustment in search parameters may be adjusted to more heavily target resources to searching that particular channel as compared to the resources that would have been applied to the channel if the search message were not received. In an example where the search scheme is preprogrammed that is not based on other criteria, the wireless communication device may search in accordance with a scheme utilized prior to receiving the search message126but may increase search times or reduce the periods between searches.

The search message126may also include search information410identifying a group of base stations that may be available. Such an indication may be a specific identifier specifically identifying one or base stations or may be a general identification identifying a group of base stations such as an identifier indicating all authorized femtocell base stations. Since the wireless communication device106includes a list of all femtocell base stations that the device is authorized to access, a general identifier will provide sufficient information for identifying specific base stations.

In some circumstances, the search message126may indicate specific frequencies. A pilot frequency or beacon frequency of the detecting base station302may be identified, for example.

The wireless communication device106extracts the information from the search message126and adjusts the searching scheme in accordance with search message126. The adjustment may include any of numerous parameter changes where some examples include adjusting one or more of the following: frequencies searched, channels searched, period between searches, period between searches of specific frequencies, time period of search, time period for search at specific frequencies, search offsets, location of starting search in the search-space, and searcher receiver settings. In circumstances where the wireless communication device106searches for service from a system utilizing a different communication technology and universal searcher is used, similar parameters may be adjusted. Where a new searcher is invoked for the alternate technology base station, the parameters may also include the timing of the activation of the new searcher.

FIG. 4Bis block diagram of a device proximity message324that includes a message identifier452, and a device identifier454. In some cases, proximity data456may also be included. The proximity data456is illustrated with dashed lines to indicate that this feature is optional. The device proximity message324may have any of numerous formats and may be sent using any suitable signaling method. The message identifier452includes any combination of data that indicates to the controller120that the message450is a device proximity message324. Accordingly, the message identifier452may be a single bit flag in some circumstances. The device identifier454includes data that identifies the wireless communication device106that has been detected by the detecting base station302. One example of a device identifier454is a device serial number.

FIG. 5is flow chart of a method of managing wireless service to a wireless communication device106performed at the detecting base station302. The method may be performed by any combination of hardware, software and/or firmware. The order of the steps discussed below may be varied and one or more steps may be performed simultaneously in some circumstances. In the exemplary embodiment, the method is performed, at least in part, by executing code on the controller314in the detecting base station302.

At step502, the wireless channel that may contain a device beacon signal108is monitored. The uplink receiver320attempts to demodulate and/or decode incoming signals within the wireless communication channel. The WWAN system timing is applied to receive the monitor the beacon channels. In this example, the uplink receiver320is tuned to decode any uplink signals304transmitted from any of the communication devices106in the user list stored in memory316. The long code masks derived with the device identification values are applied to incoming signals until an incoming device beacon signal108is detected.

At step504, it is determined whether a device beacon signal108has been detected. In this example, the controller314determines that device beacon signal has been received if an incoming uplink signal can be decoded and determined to be a beacon signal transmitted from an authorized wireless communication device106. If a device beacon signal108has been received, the method continues at step506. Otherwise, the method returns to step502to continue monitoring the device beacon channel.

At step506, it is determined whether the device proximity message324should be transmitted. In some situations, step506can be omitted and the device proximity message324may be transmitted when the device beacon signal108is detected. This procedure is discussed with reference toFIG. 8. In other situations, however, additional processing or communication is invoked before the device proximity message324is transmitted. For example, system conditions of the detecting base station302, other base stations, the core network, and/or alternate networks can be evaluated to determine whether a handoff to the detecting base station302is desired. An example of such a procedure is discussed with reference toFIG. 9. If it is determined that the device proximity message324should be transmitted, the method continues at step508. Otherwise, the method returns to step502. In some circumstances, a response may be sent to the beacon-transmitting wireless communication device. An ACK may be sent, for example, with an appropriate message that assists the wireless communication device in finding the detecting-device. This ACK-message can be transmitted in WWAN or WLAN frequency or any other frequency (pre-defined)].

At step508, the device proximity message324is sent to the system infrastructure. The device proximity message324at least identifies the wireless communication device106and indicates that the wireless communication device106may be within, or near, the service area of the detecting base station302.

FIG. 6is a flow chart of a method of managing communication services to the wireless communication device106performed in the system infrastructure118. The method may be performed by any combination of hardware, software and/or firmware. The order of the steps discussed below may be varied and one or more steps may be performed simultaneously in some circumstances. In this example, the method is performed, at least in part, by executing code on the controller120in the system infrastructure118.

At step602, the device proximity message324is received from the detecting base station302. As described above, the device proximity message324is sent through the IP network308and routed through the access gateway312to the controller120. The controller120extracts information from the device proximity message324which includes at least information identifying the wireless communication device106.

At step604, it is determined whether the search message126should be transmitted to the wireless communication device106. The controller120may evaluate any number of factors in accordance with known techniques for managing handoffs and communication resources in determining whether to transmit the search message. In some circumstances, the threshold may be relatively low and the controller120determines to send the search message126solely in response to receiving the device proximity message324. In other circumstances, the controller120may apply the same criteria as used to determine whether to handoff a device from one base station to another. Some examples of criteria that may be evaluated by the controller120include bandwidth requirements, capacity of the base stations, QoS levels priority levels, and costs. If the controller120determines that the search message126should be sent, the procedure continues at step606. Otherwise, the method returns to step602.

At step606, the search message126is generated and transmitted to the wireless communication device106. The controller120generates a search message126in accordance with page messaging techniques. As discussed above, the search message126includes information for adapting the search parameters of the base station searching scheme used by the wireless communication device106. When the invoking the changes contained in the search message126, the wireless communication device106increases the likelihood of detecting the base station302in a shorter time than if the changes are not made. The search message126is transmitted from the reference base station116.

FIG. 7is a block diagram of a communication system700where the transceiver node104is a WLAN access point702and the wireless communication device106is a multimode wireless communication device704. The system700may be implemented using any variety of communication technologies and cell sizes. For the example discussed with reference toFIG. 7, the WLAN access point702provides WLAN wireless service within a WLAN service area and the base station116provides cellular service within a macrocell. The WLAN access point702operates in accordance with a WLAN protocol such as WiFi protocol. The functional blocks ofFIG. 7may be implemented using any combination of hardware, software and/or firmware. Two or more of the functional blocks may be integrated in a single device and the functions described as performed in any single device may be implemented over several devices. For example, at least portions of the functions of the access router310may be performed by the base station network interface306within the WLAN access point702in some circumstances.

The base station116transmits downlink (forward link) signals122to, and receives uplink (reverse link) signals304from, one or more wireless communication devices to provide wireless communication service. The multimode wireless communication device704may be in any of several states while receiving the WWAN downlink signals that provide system timing. The wireless communication device states may include idle states, dormant states, active states and other traffic and non-traffic states. The wireless communication device704generates and transmits the device beacon in accordance with the system timing and a time and channel assignment. For the example discussed with reference toFIG. 7, the device beacon108is transmitted at a designated time and channel within the uplink WWAN time-channel space. As discussed below with reference toFIG. 8, the device beacon may be transmitted outside the WWAN channels by the multimode wireless communication device in some circumstances.

A WLAN transceiver706within the WLAN access point702facilitates wireless interface with one or more multimode wireless communication devices704. The WLAN transceiver706includes a WLAN receiver708for receiving WLAN uplink signals and a WLAN transmitter710for transmitting WLAN downlink signals in accordance with the WLAN protocol.

The multimode wireless communication device704is any type of communication device that is capable of communicating with the WLAN access point and at least receiving WWAN downlink signals from the base station116. For the example ofFIG. 7, the multimode wireless communication device704is capable of receiving, at least non-simultaneously, wireless service from both the WWAN and WLAN systems. The wireless communication device704, sometimes referred to as an access terminal, may be a wireless modem, a personal digital assistant (PDA), cellular telephone, or other such device.

The system infrastructure118includes the controller120that may be implemented as a mobile switching center (MSC), a combination of an MSC and base station controllers (BSCs), or other similar communication controllers and/or servers. The controller120is connected to the base station116through the system infrastructure118and manages communications at least on the WWAN system. A network interface306within the WLAN access point702facilitates communication with an IP network308through an access router310. The network interface306provides packet data communications and facilitates access to the Internet and to an access gateway312in the system infrastructure118through the access router310. In some circumstances the access router310may be implemented as part of the network interface306and the network interface306may directly access the Internet. The access router310may be connected to several access points. In some circumstances, the connection between the access gateway312and the access point702may include a wireless communication link such as satellite communication link or point-to-point microwave link, for example. Also, in some situations, circuit switched connections may be used to connect the access point702to the system infrastructure118. In a typical arrangement, the WLAN access point302is connected to the Internet through an Internet Service Provider (ISP) service provided by a digital subscriber line (DSL) or CATV connection. Accordingly, the access router310is a DSL modem or cable modem in the typical arrangement. In the example, therefore, the system infrastructure118comprises a packet switched core network that includes at least one access gateway312. The access gateway312is a communication interface that allows the access point702to communicate with the system infrastructure118. The WLAN access point receives system timing information form the WWAN through the network interface for this example. In some situations, a WWAN downlink receiver716can be used to intercept WWAN downlink signals to derive the system timing. The block representing the WWAN DL RX716is shown within dashed lines to indicate that the WWAN DL RX716is optional.

For the example ofFIG. 7, the device beacon signal108is transmitted within a WWAN uplink channel and the device beacon detector112is formed, at least partially by a WWAN receiver718, a controller714and a memory712. The WWAN receiver718is at least periodically tuned to the appropriate WWAN uplink channel in accordance with the system timing to monitor the device beacon channels.

In addition to other information, the memory712stores communication device identification values corresponding to each communication device704that is authorized to receive service from the access point. The communication device identification value may include an electronic serial number (ESN), Mobile station Equipment Identifier (MEID) or International Mobile Subscriber Identity (IMSI) or other unique data identifying the wireless communication device704. In some implementations, the identification values may be omitted or the access point702may allow communication devices that do not have corresponding identification values stored at the access point702to receive service from the access point702.

During operation, the access point702, monitors, at least periodically, a device beacon channel124which is a wireless channel that may include the device beacon signal108. For the example ofFIG. 7, the device beacon signal is transmitted within a sub-carrier time slot. In some circumstances, the time slot is not assigned for any other communications for any frequency. Although the device beacon detector112is formed by at least portions of the controller714, memory712and WWAN receiver718, separate hardware and/or software may be sued to implement the device beacon detector in some cases. Since the WLAN access point receives the WWAN system timing from the system infrastructure118, the WWAN receiver718has adequate system timing information to determine the time slot boundary and the timing of uplink signals. In some circumstances, the device beacon detector112may only search for beacons signals transmitted from wireless communication devices that are authorized to use access point as mentioned above. An authorized list of serial numbers or other device identifiers are stored in memory712at the WLAN access point.

In response to detecting the device beacon signal108, the WLAN access point702sends a device proximity message324to the controller120which invokes the base station116to transmit the search message126to the wireless communication device106. The controller714determines if the device beacon signal108is successfully received at the WLAN access point702. If the signal can be received, the controller714determines that the wireless communication device106is sufficiently close to receive service from the access point702. The controller714determines, or at least estimates, the proximity of the authorized wireless communication device106to the access point702based on one or more characteristics of the uplink signal. In the exemplary embodiment, the detection of an uplink signal from the communication device106is sufficient to determine that the communication device106is within a proximity range. The proximity is used to determine whether the communication device106is possibly within range of the WLAN access point and at least possibly able to receive communication service from the WLAN access point. Therefore, the controller714at least determines whether the communication device is possibly within range of the access point702. If the controller determines that the wireless communication device is possibly in range, the device proximity message324is sent to the controller120in the system infrastructure118which results in the transmission of the search message126to the wireless communication device106.

The controller714may determine whether to transmit the device proximity message324based on factors other than proximity of the wireless communication device106or the detection of the device beacon signal108. For example, factors may include the available capacity of the access point, core network requirements, required bandwidth of the wireless communication device communications, and availability of other, access points, base stations or communication service providers in the area. Accordingly, the access point702may not transmit the device proximity message324even if the wireless communication device106is within range in some circumstances. In some situations, the device proximity message324is transmitted every time a wireless communication device is detected by the access point and the system infrastructure118determines whether to transmit the search message126.

The device proximity message is generated by the controller714and transmitted through the network interface306, through the IP network308and/or the access router310to the access gateway312. The access gateway312routes the device proximity message through the system infrastructure118to the controller120. For the discussed example, the controller120is the same equipment that is used to generate paging messages to the wireless communication device106. The controller120receives the device proximity message and extracts the appropriate information. In response to the device proximity message324, the controller120generates the search message126which is transmitted from the base station116to the wireless communication device106. The search message126triggers an adjustment of the wireless communication device searching scheme that the wireless communication device106employs for searching for access points. In the example ofFIG. 7, the multimode wireless communication device704activates a WLAN receiver to search for WLAN signals. In some circumstances, the search message126may specifically instruct the wireless communication device704to search for the access point and/or provide specific frequencies, channels or other information to assist the device704to search for the access point. For the example, the search message126is transmitted using the paging channel. Any suitable downlink channel monitored by the wireless communication device704, however, may be used.

For the present example, the device proximity message324is sent in response to receiving device beacon signal108from an authorized user of the access point702. The search message126is sent to the wireless communication device106in response to receiving the device proximity message324at the controller120. In some situations, however, additional criteria may be evaluated before sending the device proximity message324, the search message126, or before sending both. As discussed above, for example, the access point702may evaluate one or more parameters to determine the proximity of the wireless communication device106to the access point and only send the device proximity message324if the calculated proximity is less than a threshold. Also, the controller120may evaluate system conditions and refrain from sending the search message126if certain system conditions are not met.

Examples of data that may be evaluated by the access point702include the capacity of the access point, bandwidth requirements of the wireless communication device106and a calculated or estimated proximity of the wireless communication device106to the access point702. Accordingly, the access point702may evaluate a characteristic of the device beacon signal108to determine whether to transmit the device proximity message324. In the example, the reception of the device beacon signal108by the WWAN UL receiver320is sufficient to determine that the wireless communication device704is present and that the device proximity message should be transmitted. In other circumstances, other signal characteristics may be evaluated to determine the proximity. Therefore, a characteristic of the device beacon signal108may be any of numerous parameters with any of numerous thresholds depending on the particular implementation and the characteristic may be whether the device beacon signal108is detectable by the WWAN receiver718. Examples of other characteristics include a signal to noise ratio (SNR), bit error rate (BER), power level, signal propagation time, and presence of particular data. An example of technique for determining the proximity is discussed in U.S. patent application Ser. No. 11/565,266 entitled “APPARATUS, SYSTEM AND METHOD FOR MANAGING WIRELESS LOCAL AREA NETWORK SERVICE TO A MULTI-MODE PORTABLE COMMUNICATION DEVICE”, filed on Nov. 30, 2006, and incorporated by reference in its entirety herein.

After receiving the search message, the wireless communication device704searches for an access point in accordance with the adjusted search scheme. In response to the search message, the wireless communication device704activates the appropriate circuitry to receive signals transmitted by the access point702such as a beacon pilot signal or communication pilot signals. Such circuitry is activated in response to reception of the search message. After the access point702is found by the wireless communication device704, the wireless communication device704may engage in a handoff procedure where, after a determination that the wireless communication device704should be handed off to the access point, the system700establishes wireless service to the wireless communication device704from the access point702. Hence, data and control communication is made through communication channel720between the wireless communication device704and the access point702.

FIG. 8is block diagram of a communication system800where device beacon signal is transmitted in a beacon channel124that is not a WWAN channel. The access point802includes a device beacon detector812that is not a WWAN receiver. Any of numerous frequencies and channels can be used for the beacon channel where the beacon channel is based on the WWAN system timing. The beacon may be transmitted in unlicensed frequency bands in some circumstances. The beacon may be transmitted in accordance existing beacon transmissions within 802.11 (WiFi) systems. Beacon transmissions are part of power conversation used by systems such as 802.11. In some circumstances, the timing of these beacon transmissions could be a function of WWAN system timing (assuming WLAN is aware of WWAN timing as well). The system timing provides a reference for the wireless communication device804and the WLAN access point802to use in sending and receiving the device beacon signal108. The system timing can be applied to establish a designated time for transmitting the beacon even though the actual channel is not a WWAN channel.

Operation of the WLAN access point802is as described above with reference toFIG. 7except that the device beacon detector812does not include a WWAN receiver. Accordingly, system timing is applied to the receiver (not shown) within the device beacon detector812to monitor the appropriate beacon channels for device beacons. The system timing may be derived from information sent through the backhaul or may be derived by intercepting WWAN downlink signal122. The WWAN receiver716is shown with dashed lines to illustrate that the receiver is optional. As discussed above with respect toFIG. 7, the WLAN access point802includes a memory712and a controller714which accomplish the pertinent tasks performed in the WLAN access point702. After the access point802is found by the wireless communication device804, the wireless communication device804may engage in a handoff procedure where, after a determination that the wireless communication device804should be handed off to the access point, the system800establishes wireless service to the wireless communication device804from the access point802. Hence, data and control communication is made through communication channel720between the wireless communication device804and the access point802.

FIG. 9AandFIG. 9Bare block diagrams of examples of wireless communication devices900,910suitable for use as a wireless communication device106andFIG. 9CandFIG. 9Dare block diagrams of examples of multimode wireless communication devices920,930suitable for use as multimode wireless communication devices704. The functional blocks of each of the communication devices shown inFIG. 9A,FIG. 9B,FIG. 9CandFIG. 9Dmay be implemented using any combination of hardware, software and/or firmware. Two or more of the functional blocks may be integrated in a single device and the functions described as performed in any single device may be implemented over several devices. For example, at least portions of the functions of the beacon generator902may be implemented by the controller904in some circumstances.

The wireless communication device900includes at least a beacon generator902, a controller904, a beacon transmitter906, and a WWAN downlink receiver908. As discussed below the beacon transmitter906may include a WWAN transmitter or may include another type of transmitter depending on the channel used for beacon transmission. The WWAN downlink receiver908receives WWAN downlink signal that include WWAN system timing information. The controller derives the system timing information from the signals and the beacon generator applies the WWAN system timing to generate a device beacon. The device beacon is transmitted by the beacon transmitter906.

FIG. 9Bis a block diagram of a wireless communication device910where the beacon transmitter includes a WWAN uplink transmitter912. For the example ofFIG. 9B, a WWAN transceiver914provides an interface to the WWAN. The WWAN transceiver914includes the WWAN uplink transmitter912and the WWAN downlink receiver908. The transceiver914transmits and receives WWAN signals to facilitate wireless communication with the WWAN. The beacon generator902applies the system timing derived from received WWAN signals to generate a device beacon signal that is transmitted within a WWAN uplink channel that is used as the beacon channel. For the examples ofFIG. 9B,FIG. 9CandFIG. 9D, the wireless communication device also includes a memory916. In some cases, the memory is part of the controller. In addition to storing other information and code, the memory stores code, that when run on the controller, manages the functions described herein.

FIG. 9Cis a block diagram of multimode wireless communication device920where the beacon is transmitted by the WWAN uplink transmitter. In addition to the functional blocks described above, the multimode wireless communication also includes a WLAN transceiver926for communicating with a WLAN. The WLAN transceiver includes a WLAN UL transmitter922for transmitting WLAN signals and a WLAN downlink receiver924for receiving WLAN signals. The multimode wireless communication device, therefore, may access both the WWAN and the WLAN for communication services. The WWAN signals may be received in any state and provide the WWAN system timing that is applied to generate and transmit the device beacon signal in a WWAN uplink channel designated for device beacons.

FIG. 9Dis a block diagram of multimode wireless communication device930where the beacon is transmitted within a beacon channel that is not a WWAN uplink channel. The WWAN signal timing derived from the received WWAN signals is applied to generate the device beacon. The device beacon is transmitted through a beacon channel by a beacon transmitter that may include the WLAN uplink transmitter in some circumstances. In some circumstances, the beacon may be transmitted through separate beacon transmitter through a beacon channel that is not a WWAN or WLAN channel. Such beacon channel may be a Bluetooth channel, for example. In order to illustrate that a separate beacon transmitter is not required when the beacon is transmitted through the WLAN transmitter, the beacon transmitter is shown with dashed lines.

FIG. 10is a flow chart of method performed at the wireless communication device where the transceiver node104is a base station302. The method is performed, at least partially, by executing code on the controller904in the wireless communication device106.

At step1002, WWAN downlink signals are received from a WWAN base station116. The signals are any signals that provide WWAN system timing information and may be received during any of several states of the wireless communication device106including idle (non-traffic) and active (traffic) states. As discussed above, examples of WWAN signals including system timing information include downlink control signals.

At step1004, the system timing is derived from the WWAN signals. Typically, the receiver first synchronizes to the time slot boundaries. After achieving synchronization, the receiver detects and decodes information using knowledge about the frame-structure of WWAN downlink signals.

At step1006, the device beacon signal is transmitted. The device beacon signal is generated and transmitted in accordance with the system timing. The beacon generator applies the system timing and any required scaling to generate a sequence that is mapped to a subcarrier channel of the WWAN uplink frequency-time space.

At step,1008, the search message126is received. In accordance with known techniques, the wireless communication device periodically monitors the downlink paging channels to receive control messaging from the system infrastructure118during traffic and non-traffic states. The search message126is received and deciphered to extract the information related changes to the search parameters.

At step1010, the changes included in the search message are applied to the search scheme of the wireless communication.

At step1012, the newly applied search parameters are applied in searching for an alternate base station. The wireless communication device106tunes the WWAN downlink receiver in accordance to the searching scheme to search for a pilot signal transmitted from the detecting base station114(such as a femtocell base station302). In some circumstances, the wireless communication device106may search for beacons or other signals transmitted from the femtocell base station302.

At step1014, it is determined whether the base station302has been detected. If a signal from the base station302is detected, the method continues at step1016, where a handoff procedure is performed. The procedure may include an analysis to determine whether a handoff should be performed. A handoff is initiated in accordance with known techniques. Otherwise, the method continues at step1018.

At step1018, it is determined whether a new search message is being transmitted. If so, the method returns to step1008to receive the new search message. Otherwise, the method returns to step1012to continue searching for the femtocell base station.

FIG. 11is a flow chart of method performed at the wireless communication device where the transceiver node104is a WLAN access point702,802. The method is performed, at least partially, by executing code on the controller904in the wireless communication device106(920,930).

At step1102, WWAN downlink signals are received from a WWAN base station116. The signals are any signals that provide WWAN system timing information and may be received during any of several states of the wireless communication device106including idle (non-traffic) and active (traffic) states. Examples of WWAN signals including system timing information include downlink control signals

At step1104, the system timing is derived from the WWAN signals. Typically, the receiver first synchronizes to the time slot boundaries. After achieving synchronization, the receiver detects and decodes information using knowledge about the frame-structure of WWAN downlink signals.

At step1106, the device beacon signal is transmitted. The device beacon signal is generated and transmitted in accordance with the system timing. The beacon generator applies the system timing and any required scaling to generate a sequence that is mapped to a subcarrier channel of the WWAN uplink frequency-time space. In some circumstances, the beacon signal may be transmitted within a beacon channel that is not a WWAN uplink channel.

At step,1108, the search message126is received. In accordance with known techniques, the wireless communication device periodically monitors the downlink paging channels to receive control messaging from the system infrastructure118during traffic and non-traffic states. For this example, the search message indicates that the WLAN receiver should be activated to search for signals transmitted by the WLAN access point.

At step1110, the WLAN receiver is activated in response to receiving the search message. Accordingly, the wireless communication device106searches for the WLAN access point. In some circumstances, the wireless communication device106may search for beacons or other signals transmitted from the WLAN access point702,802.

At step1112, it is determined whether WLAN access point702,802has been detected. If a signal from the WLAN access point702,802is detected, the method continues at step1114, where a handoff procedure is performed and a handoff is initiated in accordance with known techniques. Otherwise, the method continues at step1116.

At step1116, it is determined whether a new search message is being transmitted. If so, the method returns to step108to receive the new search message. Otherwise, the method returns to step1110to continue searching for the femtocell base station.

FIG. 12A,FIG. 12BandFIG. 12Care graphical illustrations of exemplary relationships1200,1250between the device beacon108and the frequency-time space1202of the uplink WWAN channel when the WWAN system utilizes OFDM techniques. The uplink WWAN channels are divided in time and frequency to allocate channels for wireless communication device uplink transmissions. The carriers are divided in time to provide subcarriers1206that are assigned to the different wireless communication devices.FIG. 12A,FIG. 12BandFIG. 12Care provided for general illustrative purposes and implementations may use different numbers of channels and subcarriers. For the example ofFIG. 12A, the device beacon is transmitted within the WWAN uplink channel where the beacon signal is at an assigned subcarrier and no other subcarriers are assigned during the beacon transmission time period1204. InFIG. 12B, some or all of the subcarriers within the beacon transmission time period1204may include data or control information. In other arrangements, some or all of the subcarriers1208within the device beacon transmission period1204may be assigned for data or control signaling. The subcarriers that may include data within the beacon transmission period1204are illustrated with boxes containing “x”s inFIG. 12B.

FIG. 12Cis a graphical illustration of an example where the device beacon is transmitted outside to the WWAN uplink channel. The device beacon is transmitted at a first frequency during a beacon time period and at a second frequency during a second beacon transmission time period. The first beacon frequency and the second beacon frequency are not within the WWAN uplink channel. The device beacon, however, is transmitted in accordance with the WWAN system timing. Accordingly, the device beacon transmission period1204coincides with subcarrier timing of the WWAN uplink channel.

FIG. 13Ais a block diagram of a beacon generator902connected to a beacon transmitter wherein the device beacon is transmitted within the WWAN uplink channel. The beacon generator902may be implemented with any combination of hardware, software, and/or firmware. The blocks shown inFIG. 13Arepresent functions and may not be performed by distinct hardware blocks. Accordingly, two or more of the functional blocks may be integrated in a single device and the functions described as performed in any single device may be implemented over several devices or processes. For the example ofFIG. 13A, the device beacon is transmitted within the WWAN uplink channel and the beacon transmitter is the WWAN uplink transmitter912. The description ofFIG. 13Amay be applied to different types of OFDM systems by modifying the transmitter chain in accordance with known techniques. For example, the beacon generator maybe used in a Single-Carrier FDMA (SC-FDMA) system by appropriately processing the signals using Discrete Fourier Transform (DFT) and Inverse Discrete Fourier Transform (IDFT) stages at the transmitter and receiver, respectively.

A pilot signal1302, such as baseband bit string, is multiplexed with a beacon message1304in a multiplexer306. The beacon message consists of pre-determined data with a preamble (for acquisition) and/or a repeatable sequence. The beacon message may also include information such at the location of the device106or a transmission power level as well as other information related to the communication device106. The resulting multiplexed signal is scrambled with a pseudorandom sequence1308in a mixer1310. Typically, a scrambling sequence is unique to a specific wireless communication device but other types of sequences (pseudo-unique) are also possible. The mixer1308is an exclusive OR (XOR) circuit in this example. A subcarrier mapping engine1312maps the scrambled beacon and other data1314into the WWAN uplink channel using the WWAN system timing110. In accordance with known techniques, a subcarrier bit and power allocator1316generates the OFDM signal my managing the subcarrier mapping engine1312and adaptive modulator1318which applies BPSK, QPSK, M-QAM or other suitable symbols. Channel condition feedback provided by a receiver is typically applied by the subcarrier bit and power allocator1316to select a different modulation order and power level per subcarrier. In some circumstances, however, the beacon can be transmitted with a pre-determined (fixed) modulation order and power level.

The mapped and processed subcarriers are transmitted by the beacon transmitter which, in this case, is the WWAN uplink transmitter912. The WWAN uplink transmitter912includes an OFDM transmission processor1320and a radio frequency transmitter1322. Accordingly, the WWAN uplink signal including the data and device beacon is transmitted in accordance with OFDM techniques in this example.

FIG. 13Bis a block diagram of a beacon generator902where the device beacon is transmitted outside of the WWAN uplink channel. The beacon message1304is scrambled with the PN generator sequence1308in the mixer1308. The WWAN system timing110is applied to the beacon transmitter932to generate and transmit the beacon in accordance with the WWAN system timing. The beacon transmitter932, includes appropriate modulation and amplification circuitry as well as timing circuitry to control transmission timing. For example, a switching function can be applied to the scrambled sequence to align the device beacon transmission period with one or more WWAN uplink subcarriers. The beacon is transmitted by aligning the uplink frame transmitted to the WWAN base station. A simple switch can be turned on at the same time or at an early/late time-offset relative to the beginning of the uplink frame. Perfect synchronization is not required to receive the beacon. The reference timing increases the successful detection of that beacon detector. In some circumstances the beacon can be time-aligned using a local clock where the local clock is synchronized with the WWAN system timing. The clock is used for triggering transmissions and an early or late offset may be applied as needed. Therefore, even though the device beacon signal is transmitted at a frequency other than an uplink WWAN frequency, the beacon signal has a position in time that is based on the WWAN system timing.

FIG. 14is block diagram of a communication system1400where at least two wireless communication devices are able to communicate through a peer to peer link. The wireless communication devices1402,1404each include at least a peer to peer interface1406and a WWAN downlink receiver1408. In some circumstances, one or more of the devices1402,1404may be a multimode wireless communication device and the WWAN downlink receiver1408may be part of a WWAN transceiver that also includes a WWAN uplink transmitter (not shown). The peer to peer interface is a WLAN transceiver in this example. The peer to peer link, however, may utilize other communication technologies, frequencies, and protocols in some circumstances and the peer to peer interfaces may be something other than WLAN transceivers. At least one of the devices1402includes a beacon generator902and at least one includes beacon detector112. Accordingly,FIG. 14illustrates an example where the transceiver node104is the wireless communication device1404and the other wireless communication device1402is the wireless communication device106ofFIG. 1A. The wireless communication device1404is, therefore, also an example of the wireless communication device128ofFIG. 1C.

Each wireless communication device1402,1404includes a controller1414,1424, a WWAN receiver1408and memory1416,1426. The controller1414(1424) is any electronics, processor, microprocessor or processor arrangement that manages the functions described herein as well as facilitating the overall functionality of the wireless communication device1402(1404). The memory1416,1426is any combination of RAM and/or ROM devices that can store code, ID values and other parameters, values, and data for facilitating the described tasks.

For the example ofFIG. 14, the device beacon signal108is transmitted within the WLAN channel. The beacon generator902generates the beacon signal that is transmitted by the WLAN uplink transmitter1422in the peer to peer interface. The device beacon detector112in the wireless communication device1404is formed by the controller1414, memory1416and WLAN uplink receiver1428. Each wireless communication device1402,1404includes a WWAN downlink receiver1408configured to at least receive WWAN downlink signals that provide WWAN system timing information110. Where the device beacon108is transmitted using a channel other than a WLAN channel, the beacon generator and beacon detector are implemented in accordance with the required frequency, channel and protocols of the beacon channel.

After detecting the device beacon signal108, the wireless communication device1404invokes a communication to the wireless communication device1402. For this example, the wireless communication device1404generates and transmits an acknowledgement message1420to the wireless communication device1402. The acknowledgement message1420is transmitted using a WLAN channel. In some circumstances, an acknowledgement message may be sent through the WWAN system. Further, a device proximity message may be sent to the WWAN communication system and the WWAN communication system may notify the wireless communication device1402that the beacon was detected by sending, for example, a search message. The devices1402,1404establish a peer to peer communication link after communications are exchanged in response to the detection of the device beacon signal. Accordingly, the detection of the device beacon signal initiates a peer to peer link establishment procedure. After the peer to peer link is established, the system1400establishes wireless service between the wireless communication devices1402and1404. Hence, data and control communication is made utilizing WLAN downlink receiver1430and uplink transmitter1422of the wireless device1402in communicating with the WLAN downlink transmitter1432and uplink receiver1428of the wireless device1404.

Clearly, other embodiments and modifications of this invention will occur readily to those of ordinary skill in the art in view of these teachings. The above description is illustrative and not restrictive. This invention is to be limited only by the following claims, which include all such embodiments and modifications when viewed in conjunction with the above specification and accompanying drawings. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.