Method and apparatus for selecting wireless communication systems

Methods and apparatuses are provided that facilitate avoiding one or more wireless communication systems based at least in part on determining a level of unreliability of a reverse link channel related to a system. This can be based at least in part on determining whether the system can be accessed over the reverse link channel. If not, the wireless communication system can be avoided to conserve power utilized to perform such access attempts. Where the unreliability is temporary, however, some access attempts can be performed for systems of higher priority than a current system during the period of avoidance of one or more higher priority systems.

BACKGROUND

The following description relates generally to wireless communications, and more particularly to selecting wireless communication systems.

Wireless communication systems are widely deployed to provide various types of communication content such as, for example, voice, data, and so on. Typical wireless communication systems may be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, . . . ). Examples of such multiple-access systems may include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and the like. Additionally, the systems can conform to specifications such as third generation partnership project (3GPP), 3GPP long term evolution (LTE), ultra mobile broadband (UMB), evolution data optimized (EV-DO), etc.

Generally, wireless multiple-access communication systems may simultaneously support communication for multiple mobile devices. Each mobile device may communicate with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from base stations to mobile devices, and the reverse link (or uplink) refers to the communication link from mobile devices to base stations. Further, communications between mobile devices and base stations may be established via single-input single-output (SISO) systems, multiple-input single-output (MISO) systems, multiple-input multiple-output (MIMO) systems, and so forth. In addition, mobile devices can communicate with other mobile devices (and/or base stations with other base stations) in peer-to-peer wireless network configurations.

In addition, devices in a wireless network can select wireless communication systems for receiving access to the wireless network. For example, a device, while communicating with an base station, can perform reselection to one or more disparate base stations (e.g., where the device is moving and the one or more disparate base stations is more preferred and/or transmit a clearer signal). Moreover, in an example, a device can reselect to an base station related to a disparate wireless communication system. This can occur, for example, where the original base station becomes unreliable or inaccessible, and there are no other base stations related to the wireless communication system that are reliable and/or accessible. In another example, this can occur, upon detecting an base station of a more preferred wireless communication system.

Furthermore, where the original base station becomes unreliable in the example above, the device can place the base station or related wireless communication system in an avoidance list and can avoid connection to the wireless communication system for a specified time. Thus, during a reselection procedure, the device can scan for systems other than those enumerated in the avoidance list to conserve power utilized by the device. When the specified time is reached, the base station or related wireless communication system can be removed from the avoidance list, and thus access is attempted thereto during the next reselection procedure if a corresponding base station is within range.

SUMMARY

In accordance with one or more embodiments and corresponding disclosure thereof, various aspects are described in connection with facilitating determining a level of unreliability related to a wireless communication system. In this regard, the wireless communication system can be avoided based at least in part on the level of unreliability to balance a number of access attempts with the chance that the system can be accessed. Where a preferred wireless communication system is determined to be temporarily unreliable, for example, access can be attempted to the wireless communication system more frequently than if the system is determined to be persistently unreliable.

According to an example, a method is provided that includes receiving communications from a system over a forward link channel and determining a level of unreliability related to a reverse link channel of the system. The method further includes avoiding the system according to one or more timers based at least in part on the level of unreliability.

In another aspect, an apparatus for avoiding systems is provided that includes at least one processor configured to receive one or more signals from a system over a forward link channel and discern a level of unreliability related to reverse link channel of the system as temporary or persistent. The at least one processor is further configured to avoid the system during one or more reselection procedures based at least in part on a timer and the level of unreliability. In addition, the wireless communications apparatus includes a memory coupled to the at least one processor.

In yet another aspect, an apparatus for providing system avoidance is provided that includes means for receiving communications from a system over a forward link channel and means for determining a level of unreliability related to a reverse link channel of the system. The apparatus further includes means for avoiding the system according to a timer based at least in part on the level of unreliability.

Still, in another aspect, a computer-program product is provided for avoiding systems that includes a computer-readable medium having code for causing at least one computer to receive one or more signals from a system over a forward link channel and code for causing the at least one computer to discern a level of unreliability related to reverse link channel of the system. The computer-readable medium further includes code for causing the at least one computer to avoid the system during one or more reselection procedures based at least in part on a timer and the level of unreliability.

Moreover, in an aspect, an apparatus for system avoidance is provided that includes a base station detecting component for receiving communications from a system over a forward link channel and a reliability determining component for discerning a level of unreliability related to a reverse link channel of the system. The apparatus further includes a system connecting component for avoiding the system according to a timer based at least in part on the level of unreliability.

DETAILED DESCRIPTION

As described further herein, a device can determine that a reverse link to a wireless communications system is unreliable, and can also determine whether the unreliability is temporary or persistent. Where the unreliability is persistent, for example, the device can avoid the wireless communication system for a longer amount of time than if temporary. To determine whether the unreliability is temporary or persistent, for example, the device can make various access attempts to the wireless communication system. If the access attempts continue to fail, the device can determine the unreliability is persistent (e.g., after a threshold number of attempts), can avoid the wireless communication system, and can communicate on another wireless communication system, if available. If the avoided wireless communication system is a more preferred wireless communication system, however, the device can continue to attempt access according to a disparate timer, and can reselect to the more preferred wireless communications system where the access attempt is successful.

Referring toFIG. 1, illustrated is a wireless communication system100for selecting from multiple wireless communication systems. System100includes a device102that receives wireless network access from one or more base stations, such as base stations104and/or106, or other devices. Device102can be a UE or other mobile device, a relay node, an access point, and/or the like. Base stations104and106can similarly be UEs (e.g., in peer-to-peer or ad-hoc mode), relay nodes, access points, etc., where base station104or106provides device102with access to a wireless network (not shown). In addition, device102can receive signals over forward link channel108and/or112from base station104and/or106, and can attempt to communicate over reverse link channel110and/or114with base station104and/or106, for example.

According to an example, device102can receive signals from base station104over a forward link channel108, and can attempt to communicate back to base station104over reverse link channel110. Reverse link channel110, however, can be unreliable such that it does not allow for accessing base station104. This can be for a variety of reasons, such as base station104is too far away to receive signals from device102(e.g., it can only transmit over forward link channel108to device102), channel conditions related to reverse link channel110are below a threshold required to maintain a reliable connection, and/or the like, for example. In one example, base station104can be at a higher elevation than device102such that forward link channel108signals can be very strong, and thus device102can hear the signals over forward link channel108, though it is too far away to communicate over reverse link channel110to close the communication loop.

Thus, device102can attempt accessing base station104over reverse link channel110and can fail. For example, device102can avoid base station104, a related wireless communication system, a related channel, etc. for a duration of time, and can attempt access to another base station, which can be of a disparate system and/or utilize a different channel, such as base station106. In one example, device102can add base station104to an avoidance list and initialize an avoidance timer. In this regard, device102can search for other base stations without searching base station104, base stations of a similar wireless communication type, base stations that utilize a same channel for communicating, and/or the like. Once the avoidance timer expires, device102can then search for base station104, etc.

In an example, however, base station104can be preferred over base station106(e.g., base station104can be affiliated with a home wireless communication system of device102, can offer enhanced services to device102, increased bandwidth to device102, and/or the like). In addition, for example, it is to be appreciated that unreliability of reverse link108can be temporary. Thus, for example, device102can attempt to access base station104or another base station on the same wireless communication system or using the same channel during the avoidance period as well. In one example, device102can attempt to access base station104or another base station of the same wireless communication system or channel upon determining to avoid base station104, at various times during a reselection procedure with one or more disparate base stations, according to a reselection timer, and/or the like.

In other examples, base station104can balance reverse link channel110and forward link channel108to allow device102to transmit over resources relative to the power of forward link108at device102. Moreover, for example, base station104can force device102to perform registration after acquiring base station104over forward link channel108. This, for example, can cause registration to fail where the reverse link channel110is unreliable, which can cause device102to attempt reselection to other base stations (e.g., base station106). In yet another example, base station106can be modified to operate at the same priority as base station104relative to device102in areas where base station104has a strong forward link channel108and an unreliable reverse link channel110.

Turning toFIG. 2, illustrated is an example wireless communications system200that determines avoidance procedures for a reverse link challenged base station. System200can include device102, which can communicate with base stations104and/or106over forward links108and/or112and reverse links110and/or114, as described above. In addition, as described, base stations104and106can relate to different wireless communication systems. Device102can comprise a base station detecting component202that can receive forward link channel signals from one or more base stations, and a reliability determining component204that determines whether a level of reliability of a reverse link channel related to the base station. Device102also comprises an avoidance timer component206that initializes an avoidance timer upon determining that a reverse link with the base station cannot be established or has a certain level of unreliability and a system connecting component208that attempts access to the one or more base stations.

According to an example, base station detecting component202can determine one or more base stations within range of device102(e.g., based at least in part on measuring signals from the base stations, etc.), such as base stations104and106. In addition, for example, base station detecting component202can measure the signals as part of device102powering on or otherwise initializing communications, as part of reselection, and/or the like. Reliability determining component204, for example, can determine a level of unreliability related to a reverse link channel of the one or more base stations (e.g., whether the unreliability is temporary or persistent). As described, for example, base station detecting component202can measure a forward link channel108of base station104and can determine that the signal is strong enough (e.g., signal-to-noise ratio (SNR) at or above a threshold level) to serve device102. Thus, reliability determining component204can transmit signals over a reverse link channel110to determine a related level of unreliability.

For example, device102, or reliability determining component204, can initiate a maximum access probe (MAP) procedure where it transmits to base station104over a reverse link channel multiple times at increasing power until it connects or until a threshold power is reached; in this example, the threshold power can be reached with no access to base station104. It is to be appreciated that device102can determine whether it is connected to base station104based at least in part on receiving a response to signals transmitted during the MAP procedure, and reliability determining component204, in this example, can discern whether reverse link channel110is sufficiently reliable to continue communicating with base station104(e.g., based on control data received from base station104). In one example, however, MAP can fail, which can be referred to as MAP exit (MAPE), in which case reliability determining component204can discern that the reverse link channel is unreliable.

In either example (e.g., whether reverse link channel110is determined to be insufficient for communicating with base station104or whether MAPE occurs), reliability determining component204can determine a level of unreliability related to reverse link channel110(e.g., whether the unreliability is temporary or persistent). In one example, reliability determining component204can first assume the reverse link channel108issues are persistent pending further access attempts. Thus, for example, system connecting component208can add base station104to an avoidance list based on reliability determining component204discerning the unreliability, and avoidance timer component206can initialize an associated timer for avoiding base station104and/or base stations of a similar wireless communication system and/or using a similar channel. System connecting component208can perform various procedures to attempt access to base station104or106and/or other base stations (e.g., reselection procedures).

It is to be appreciated, however, that base station104can be of a preferred wireless communication system, as compared to other base stations in the area, such as base station106. In this regard, reliability determining component204can determine whether radio link channel failure at base station104is temporary or persistent based at least in part on whether system connecting component208can access or connect to base station104during or based on one or more procedures performed for acquiring and/or attempting access to other base stations and/or the like. For example, system connecting component208, or one or more disparate components, performs such acquisitions/access attempts even though reliability determining component204placed base station104and/or its related wireless communication system in an avoidance list.

Following a threshold number of access attempts by system connecting component208, for example, reliability determining component204can determine that the reverse link channel110failures are persistent, and can system connecting component208can avoid attempting acquisition of base station104for a longer period of time. This can be based at least in part on, for example, the avoidance timer, another timer initialized by avoidance timer component206for avoiding base station104, etc. Similarly, where no other base stations are within range for the same wireless communication system, system connecting component208can avoid any base stations of the wireless communication system for the longer configured period of time.

Referring toFIG. 3, an example wireless communications system300is shown that determines whether failure or unreliability of a reverse link channel is temporary or persistent. System300can include device102, which can communicate with base stations104and/or106over forward links108and/or112and attempt communication over reverse links110and/or114, as described above. In addition, as described, base stations104and106can relate to different wireless communication systems.

Device102can comprise a base station detecting component202that can locate one or more base stations for attempting connection to, and a reliability determining component204that determines a level of unreliability related to a reverse link channel of the one or more base stations. Device102also comprises an avoidance timer component206that initializes a timer upon determining that a reverse link with the base station cannot be established or is unreliable, a system connecting component208that establishes a connection to one or more base stations, and a reselecting component302that attempts reselection to one or more base stations. Device102additionally comprises an ABSR timer component304that initializes an ABSR timer for attempting access to avoided systems and an out-of-service (OoS) component306that performs one or more OoS procedures to attempt locating other base stations in range.

According to an example, as described, base station detecting component202can determine one or more base stations within range of device102, such as base stations104and106, and reliability determining component204can determine whether at least one of the one or more base stations has a reliable reverse link channel. In one example, base station detecting component202can determine base station104is of a desired wireless communication system and/or that forward link channel108is of a sufficient quality to communicate with base station104. Reliability determining component204, however, can determine that the reverse link channel110is unreliable and/or a level of unreliability (e.g., based at least in part on experiencing MAPE), as described.

In this case, as described, reliability determining component204can determine whether issues with the reverse link channel110are temporary or persistent. In one example, reliability determining component204can first assume the reverse link channel108issues are temporary pending further access attempts by system connecting component208, as described. Thus, for example, reliability determining component204can add base station104to an avoidance list, and avoidance timer component206can initialize an associated timer for avoiding base station104and/or base stations of a similar wireless communication system and/or using a similar channel. For example, avoidance timer component206can initialize the timer based at least in part on a hardcoded, configured, or other static value, based at least in part on historical attempts to access the wireless communication system (e.g., a time value related to eventually gaining access after experiencing MADE, etc.), and/or the like.

It is to be appreciated, however, that base station104can be of a preferred wireless communication system, as compared to other base stations in the area, such as base station106. In this regard, as described, system connecting component208can attempt to access base station104even after reliability determining component204declares base station104to be avoided (e.g., while communicating with other base stations of lower priority wireless communication systems, initializing such communications, and/or the like). Thus, in one example, reselecting component302can consider systems in the avoidance list in attempting to reselect to one or more base stations, where the systems are of a same or higher priority than the current wireless communication system. In one example, reselecting component302can perform an optimized silent redial (OSR) after reliability determining component204discerns the reverse link channel110unreliability, and can consider avoided systems when performing the OSR. Thus, for example, base station detecting component202can acquire base station104again, and if reliability determining component204discerns reverse link channel110is sufficient for communicating with base station104as part of the OSR, system connecting component208can determine that the previous reverse link channel110failure was temporary, and can attempt access to base station104. Where access is granted, for example, the avoidance timer component206can stop the avoidance timer.

In another example, where reliability determining component204discerns reverse link channel110is insufficient for communicating with base station104during the OSR, avoidance timer component206can continue tolling the associated avoidance timer for base station104, and base station detecting component202can evaluate other wireless communication systems. For example, base station detecting component202can acquire base station106, and reliability determining component204can measure reverse link channel114and determine it is sufficient for communicating with base station106. In this example, system connecting component208can access base station106. In either case, avoidance timer component206does not reset the avoidance timer until the timer expires and/or reselecting component302is able to communicate with base station104or another base station of the same wireless communication system. For example, reselecting component302can still attempt access to base station104, since it is related to a more preferred wireless communication system, even though it is in the avoidance list, at least until reliability determining component204determines reverse link channel110issues are persistent.

Thus, in an example, reselecting component302can perform a better service reselection (BSR) to determine whether base stations of more preferred wireless communication systems are within range (e.g., while having an established connection with base station106). Where a system or related base station is in the avoidance list, such as the wireless communication system of base station104, reselecting component302can perform an ABSR to consider the avoided system as well. In this regard, for example, base station detecting component202can acquire base station104, as described, and reliability determining component204can discern whether reverse link channel110is reliable, as described. If so, system connecting component208can attempt access to base station104. If not, avoidance timer component206continues to toll the avoidance timer.

Moreover, where reliability determining component204deems the reverse link channel is unreliable, ABSR timer component304initializes an ABSR timer for performing a next ABSR. It is to be appreciated that ABSR timer component304can initialize the ABSR timer to a value such that reselecting component302can perform multiple ABSRs, without reselecting to the avoided system, before performing another BSR. In this regard, for example, device102can also utilize a BSR timer that has an initialized value greater than that of the ABSR timer. In another example, reselecting component302can determine a configured number of ABSR attempts per BSR attempt, and ABSR timer component304can discern the ABSR timer initialization value according to the number of ABSR attempts and the BSR timer value. In addition, for example, reselecting component302can manage a counter of ABSR attempts per system, base station, or channel, and can decrement the counter after each attempt to conform to the number of determined ABSR attempts. In another example, ABSR timer component304can initialize the ABSR timer based at least in part on one or more events, such as reselecting component302reselecting to a less preferred system, device102releasing a call, device102acquiring limited services from the less preferred system, and/or the like.

Moreover, a number of total ABSR attempts can be determined by reselecting component302(e.g., based on a configuration, based on historical attempts to access the wireless communication system or other systems, as described above with respect to the avoidance timer, etc.). A related counter can also be decremented by reselecting component302for the total ABSR attempts. After the number of total ABSR attempts are reached for a certain wireless communication system and/or base station (such as base station104), system connecting component208can determine reverse link channel110unreliability is persistent, and can avoid base station104and/or the related wireless communication system for the duration of the avoidance timer at avoidance timer component206. In this regard, for example, device102can conserve power previously required to scan for preferred systems while still allowing device102to determine whether reverse link channel unreliability is only temporary for preferred systems.

Moreover, for example, where reliability determining component204discerns that the reverse link channel110is sufficiently reliable during reselection (e.g., whether OSR or ABSR), system connecting component208can determine whether an access will be triggered immediately at base station104. In an example, this can include determining whether a registration is current at base station104and/or the wireless communication system related thereto. If not, reselecting component302can attempt reselection to a next highest order base station (if present), continuing to avoid the system. If so, however, system connecting component208can connect to the system, reliability determining component204can remove the system from the avoidance list, and avoidance timer component206can cancel the avoidance timer for the system

Where reselecting component302cannot locate a suitable base station or related wireless communication system for reselection, OoS component306can perform an OoS procedure. For example, where there is a system in the avoidance list, such as the wireless communication system related to base station104, OoS component306can perform an avoided OoS (AOoS) procedure, such that the avoided system can be scanned and if acquired, system connecting component208can attempt access therewith if the registration is current. If the registration is not current, OoS component306can perform an OoS procedure that does not scan for the avoided system.

Turning now toFIG. 4, depicted is an example wireless communications network400that allows avoided systems to be scanned during BSR. Network400can include a device102that attempts access to a base station104and/or106, as described. Device102can receive forward link channel signals from base station104and can attempt to connect using a corresponding reverse link channel having frequency F1, as described. Device102can experience MAPE on F1during registration402with base station104. In an example, where this is an initial access attempt, device102can initialize an avoidance timer related to the system of base station104and add the system, base station104, or a related channel to an avoidance list. Moreover, for example, device102can additionally experience MAPE with respect to any other base stations that might be in-range and communicate using the same system as base station104. As described, in this example, device102can attempt to access another system. In this regard, device102can acquire a system on frequency F2during an OoS scan404that utilizes base station106. In addition, at this time, device102can start a BSR timer to search for a better system at some future time.

In addition, device102can begin an ABSR on F1406to determine whether base station104, or a base station of the same system, can be accessed, since base station104is of higher priority than base station106. Device102can acquire the avoided system on F1, but MAPE can occur during registration408with base station104. In this regard, device102can keep the system in the avoidance list and continue to toll the timer. Device102can acquire a system on frequency F2during an OoS scan410that utilizes base station106. Moreover, as described, device102can initialize an ABSR timer that expires one or more times during the BSR timer, such that ABSR can be performed more frequently than BSR to attempt access to avoided but more preferred systems. Device102can begin another ABSR on F1412(e.g., upon expiration of the ABSR timer, and can again acquire the avoided system on F1, but MAPE can occur during registration414with base station104. In this regard, device102can keep the system in the avoidance list and continue to toll the timer. Device102can again acquire a system on frequency F2during an OoS scan416that utilizes base station106.

Moreover, as described, device102can decrement one or more ABSR counters at each ABSR406and412. Thus, once the specified number of ABSRs have been performed, device102can consider base station104and/or the related system on F1to have persistent unreliability in the reverse link channel. Thus, device102can avoid the system at least until expiration of the avoidance timer. In this example, the avoidance timer can be cancelled418. It is to be appreciated that before expiration, other BSRs can be performed for systems other than the avoided system. Following cancellation of the timer, the system can be removed from the avoidance list420. Thus, subsequent BSRs, OoS, or similar procedures can attempt access to the previously avoided system. In addition, it is to be appreciated that similar steps can be utilized when performing OSRs as shown with respect to ABSRs above, and described in previous figures.

Referring toFIG. 5, an example wireless communications network500that attempts accessing avoided systems during BSR is shown. Network500can include a device102that tries to access base station104and/or106, as described. Device102can receive forward link channel signals from base station104and can attempt to connect using a corresponding reverse link channel having frequency F1, as described. Device102can experience MAPE on F1during registration402with base station104. In an example, where this is an initial access attempt, device102can initialize an avoidance timer related to the system of base station104and add the system, base station104, or a related channel to an avoidance list. Moreover, for example, device102can additionally experience MAPE with respect to any other base stations that might be in-range and communicate using the same system as base station104. As described, device102can attempt to access another system. In this regard, device102can acquire a system on frequency F2during an OoS scan404that utilizes base station106. In addition, at this time, device102can start a BSR timer to search for a better system at some time.

In addition, device102can begin an ABSR on F1406to determine whether base station104, or a base station of the same system, can be accessed, since base station104is of higher priority than base station106. Device102can acquire the avoided system on F1502(e.g., without MAPE occurring). In this regard, device102can determine that an access attempt can be immediately triggered504at base station104(e.g., based on registration, origination, and/or the like). Thus, device102can connect506to base station104. Moreover, in this regard, device102can remove the system of base station104from the avoidance list508and can cancel the avoidance timer510related thereto. In addition, it is to be appreciated that similar steps can be utilized when performing OSRs as shown with respect to ABSRs above, and described in previous figures.

In reference toFIG. 6, an example wireless communications network600that attempts accessing avoided systems during BSR is shown. Network600can include a device102that tries to access base station104and/or106, as described. Device102can receive forward link channel signals from base station104and can attempt to connect using a corresponding reverse link channel having frequency F1, as described. Device102can experience MAPE on F1during registration402with base station104. In an example, where this is an initial access attempt, device102can initialize an avoidance timer related to the system of base station104and add the system, base station104, or a related channel to an avoidance list. Moreover, for example, device102can additionally experience MAPE with respect to any other base stations that might be in-range and communicate using the same system as base station104. As described, device102can attempt to access another system. In this regard, device102can acquire a system on frequency F2during an OoS scan404that utilizes base station106. In addition, at this time, device102can start a BSR timer to search for a better system at some time.

Furthermore, device102can begin an ABSR on F1406to determine whether base station104, or a base station of the same system, can be accessed, since base station104is of higher priority than base station106. Device102can acquire the avoided system on F1502(e.g., without MAPE occurring). In this regard, device102can determine that an access attempt is not immediately triggered602at base station104(e.g., based on registration, origination, and/or the like). Thus, device102can acquire a system on frequency F2during an OoS scan604that utilizes base station106, as described above. It is to be appreciated that device can continue to toll the avoidance timer and/or perform additional ABSRs. After a period of time, device102can cancel the avoidance timer418and remove the system from the avoidance list420, as described previously. In addition, it is to be appreciated that similar steps can be utilized when performing OSRs as shown with respect to ABSRs above, and described in previous figures.

Turning toFIG. 7, an example wireless communications network700is depicted that performs an AOoS procedure. Network700can include a device102that tries to access base station104and/or106, as described. Device102can receive forward link channel signals from base station104and can attempt to connect using a corresponding reverse link channel having frequency F1, as described. Device102can experience MAPE on F1during registration402with base station104. In an example, where this is an initial access attempt, device102can initialize an avoidance timer related to the system of base station104and add the system, base station104, or a related channel to an avoidance list. Moreover, for example, device102can additionally experience MAPE with respect to any other base stations that might be in-range and communicate using the same system as base station104. Device102can then search for other one or more other base stations702, on other systems or otherwise, and/or can attempt further access with base station104(e.g., in OSR, ABSR, etc.), as described. In an example, where other base stations are not found and/or access cannot be made with base station104for a period of time, device102can determine that registration with base station104and/or a related system is current704, and can transition to an AOoS state706. In this regard, device102can attempt access with base stations including base station104, though it is in the avoidance list. After a period of time with no access, device102can cancel the avoidance timer418and remove the system from the avoidance list420, as described previously.

Referring toFIG. 8, an example wireless communications network800is illustrated for performing an OoS procedure. Network800can include a device102that tries to access base station104and/or106, as described. Device102can receive forward link channel signals from base station104and can attempt to connect using a corresponding reverse link channel having frequency F1, as described. Device102can experience MAPE on F1during registration402with base station104. In an example, where this is an initial access attempt, device102can initialize an avoidance timer related to the system of base station104and add the system, base station104, or a related channel to an avoidance list. Moreover, for example, device102can additionally experience MAPE with respect to any other base stations that might be in-range and communicate using the same system as base station104. Device102can then search for other one or more other base stations702, on other systems or otherwise, and/or can attempt further access with base station104(e.g., in OSR, ABSR, etc.), as described. In an example, where other base stations are not found and/or access cannot be made with base station104for a period of time, device102can determine that registration with base station104and/or a related system is not current802, and can transition to an OoS state804. In this regard, as described, device102can attempt access with base stations excluding base station104, as it is in the avoidance list and registration is not current. After a period of time with no access, device102can cancel the avoidance timer418and remove the system from the avoidance list420, as described previously.

Turning toFIG. 9, an example methodology900is displayed that facilitates avoiding a system based on a determined level of unreliability. At902, communications can be received from a system over a forward link channel. As described, the communications can have a high SNR, and the system can be a preferred system to which connection is desired. At904, a level of unreliability related to a reverse link channel of the system can be determined. As described, for example, the unreliability can include a failed access attempt to the system, insufficient SNR and/or resources related to the reverse link channel, etc. At906, the system can be avoided according to one or more timers based at least in part on the level of unreliability. Thus, as described in one example, where the unreliability is temporary, the system can be avoided for a smaller portion of time than if persistent. As described herein, various procedures can be performed during the timer when the unreliability is deemed temporary to attempt accessing the avoided system.

Referring toFIG. 10, illustrated is an example methodology1000that facilitates avoiding a system when a determined reverse link channel unreliability is temporary or permanent. At1002, a forward link channel signal can be received from a most preferred base station. At1004, a temporary unreliable reverse link channel can be determined for the base station, the base station (or related system) can be added to an avoidance list, and an avoidance timer can be started. As described, the unreliability can be based at least in part on an access failure, insufficient resources or quality thereof, etc. At1006, reselection can be performed including systems in the avoidance list. As described, the reselection can include an OSR for the system (e.g., at least in the first instance of determining the reverse link failure). At1008, it can be determined whether an avoided system is acquired. If so, at1010, it can be determined whether registration on the system is current. If so, at1012, it can be determined whether the system can be accessed (e.g., whether the reverse link channel has sufficient reliability for connection). If so, at1014, the system can be removed from the avoidance list and the timer can be cancelled.

If the avoided system cannot be acquired at1008, the registration is not current at1010, or the system cannot be accessed at1012, it can be determined whether ABSR is expired at1016. This can include verifying whether an ABSR timer is expired, whether a configured number of ABSR attempts (e.g., during a BSR period) have been exhausted, and/or the like. If not, reselection can be performed including systems in the avoidance list (e.g., ABSR) at1006. If ABSR is expired at1016, it can be determined, at1018, that the unreliable reverse link channel for the base station is persistent. In this regard, at1020, BSR can be performed without attempting access to avoided systems. Following the BSR procedure (e.g., whether another system is reselected or whether a BSR timer expires), it can be determined at1022whether a new system is selected in the BSR. If so, reselection can be performed including systems in the avoidance list (e.g., so long as the avoidance timer is not expired). If now, it can be determined whether an avoidance timer is expired at1024. If not, reselection can be performed including systems in the avoidance list at1006. If not, it can be determined whether system registration is current at1026. If not, an OoS is declared at1028, and if so, an AOoS is declared at1030.

With reference toFIG. 11, illustrated is a system1100that avoids a system based at least in part on unreliability of a reverse link channel. For example, system1100can reside at least partially within a base station, mobile device, etc. It is to be appreciated that system1100is represented as including functional blocks, which can be functional blocks that represent functions implemented by a processor, software, or combination thereof (e.g., firmware). System1100includes a logical grouping1102of electrical components that can act in conjunction. For instance, logical grouping1102can include an electrical component for receiving communications from a system over a forward link channel1104. As described, for example, the forward link channel can exhibit radio conditions sufficient for receiving further communications from the base station, and thus, connection can be attempted thereto. In this regard, logical grouping1102can comprise an electrical component for determining a level of unreliability related to a reverse link channel of the system1106.

As described, for example, this can be determined based at least in part on attempting access to the base station, and determining whether the reverse link channel has sufficient radio conditions for communicating with the base station. Moreover, logical grouping1102can comprise an electrical component for avoiding the system according to a timer based at least in part on the level of unreliability1108. As described, electrical component1108can avoid a system for a period of time based on whether the reverse link channel is temporarily or persistently unreliable. Furthermore, for example, electrical component1108can at first assume temporary unreliability and can perform various procedures to determine whether to consider the unreliability to be persistent. Additionally, system1100can include a memory1110that retains instructions for executing functions associated with the electrical components1104,1106, and1108. While shown as being external to memory1110, it is to be understood that one or more of the electrical components1104,1106, and1108can exist within memory1110.

Referring now toFIG. 12, a wireless communication system1200is illustrated in accordance with various embodiments presented herein. System1200comprises a base station1202that can include multiple antenna groups. For example, one antenna group can include antennas1204and1206, another group can comprise antennas1208and1210, and an additional group can include antennas1212and1214. Two antennas are illustrated for each antenna group; however, more or fewer antennas can be utilized for each group. Base station1202can additionally include a transmitter chain and a receiver chain, each of which can in turn comprise a plurality of components associated with signal transmission and reception (e.g., processors, modulators, multiplexers, demodulators, demultiplexers, antennas, etc.), as will be appreciated by one skilled in the art.

Base station1202can communicate with one or more mobile devices such as mobile device1216and mobile device1222; however, it is to be appreciated that base station1202can communicate with substantially any number of mobile devices similar to mobile devices1216and1222. Mobile devices1216and1222can be, for example, cellular phones, smart phones, laptops, handheld communication devices, handheld computing devices, satellite radios, global positioning systems, PDAs, and/or any other suitable device for communicating over wireless communication system1200. As depicted, mobile device1216is in communication with antennas1212and1214, where antennas1212and1214transmit information to mobile device1216over a forward link1218and receive information from mobile device1216over a reverse link1220. Moreover, mobile device1222is in communication with antennas1204and1206, where antennas1204and1206transmit information to mobile device1222over a forward link1224and receive information from mobile device1222over a reverse link1226. In a frequency division duplex (FDD) system, forward link1218can utilize a different frequency band than that used by reverse link1220, and forward link1224can employ a different frequency band than that employed by reverse link1226, for example. Further, in a time division duplex (TDD) system, forward link1218and reverse link1220can utilize a common frequency band and forward link1224and reverse link1226can utilize a common frequency band.

Each group of antennas and/or the area in which they are designated to communicate can be referred to as a sector of base station1202. For example, antenna groups can be designed to communicate to mobile devices in a sector of the areas covered by base station1202. In communication over forward links1218and1224, the transmitting antennas of base station1202can utilize beamforming to improve signal-to-noise ratio of forward links1218and1224for mobile devices1216and1222. Also, while base station1202utilizes beamforming to transmit to mobile devices1216and1222scattered randomly through an associated coverage, mobile devices in neighboring cells can be subject to less interference as compared to a base station transmitting through a single antenna to all its mobile devices. Moreover, mobile devices1216and1222can communicate directly with one another using a peer-to-peer or ad hoc technology as depicted. According to an example, system1200can be a multiple-input multiple-output (MIMO) communication system.

FIG. 13shows an example wireless communication system1300. The wireless communication system1300depicts one base station1310and one mobile device1350for sake of brevity. However, it is to be appreciated that system1300can include more than one base station and/or more than one mobile device, wherein additional base stations and/or mobile devices can be substantially similar or different from example base station1310and mobile device1350described below. In addition, it is to be appreciated that base station1310and/or mobile device1350can employ the systems (FIGS. 1-8and11-12) and/or methods (FIGS. 9-10) described herein to facilitate wireless communication there between. For example, components or functions of the systems and/or methods described herein can be part of a memory1332and/or1372or processors1330and/or1370described below, and/or can be executed by processors1330and/or1370to perform the disclosed functions.

At base station1310, traffic data for a number of data streams is provided from a data source1312to a transmit (TX) data processor1314. According to an example, each data stream can be transmitted over a respective antenna. TX data processor1314formats, codes, and interleaves the traffic data stream based on a particular coding scheme selected for that data stream to provide coded data.

The modulation symbols for the data streams can be provided to a TX MIMO processor1320, which can further process the modulation symbols (e.g., for OFDM). TX MIMO processor1320then provides NT modulation symbol streams to NT transmitters (TMTR)1322athrough1322t. In various embodiments, TX MIMO processor1320applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.

Each transmitter1322receives and processes a respective symbol stream to provide one or more analog signals, and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. Further, NT modulated signals from transmitters1322athrough1322tare transmitted from NT antennas1324athrough1324t, respectively.

At mobile device1350, the transmitted modulated signals are received by NR antennas1352athrough1352rand the received signal from each antenna1352is provided to a respective receiver (RCVR)1354athrough1354r. Each receiver1354conditions (e.g., filters, amplifies, and downconverts) a respective signal, digitizes the conditioned signal to provide samples, and further processes the samples to provide a corresponding “received” symbol stream.

An RX data processor1360can receive and process the NR received symbol streams from NR receivers1354based on a particular receiver processing technique to provide NT “detected” symbol streams. RX data processor1360can demodulate, deinterleave, and decode each detected symbol stream to recover the traffic data for the data stream. The processing by RX data processor1360is complementary to that performed by TX MIMO processor1320and TX data processor1314at base station1310.

A processor1370can periodically determine which precoding matrix to utilize as discussed above. Further, processor1370can formulate a reverse link message comprising a matrix index portion and a rank value portion.

The reverse link message can comprise various types of information regarding the communication link and/or the received data stream. The reverse link message can be processed by a TX data processor1338, which also receives traffic data for a number of data streams from a data source1336, modulated by a modulator1380, conditioned by transmitters1354athrough1354r, and transmitted back to base station1310.

At base station1310, the modulated signals from mobile device1350are received by antennas1324, conditioned by receivers1322, demodulated by a demodulator1340, and processed by a RX data processor1342to extract the reverse link message transmitted by mobile device1350. Further, processor1330can process the extracted message to determine which precoding matrix to use for determining the beamforming weights.

Processors1330and1370can direct (e.g., control, coordinate, manage, etc.) operation at base station1310and mobile device1350, respectively. Respective processors1330and1370can be associated with memory1332and1372that store program codes and data. Processors1330and1370can also perform computations to derive frequency and impulse response estimates for the uplink and downlink, respectively.