METHOD AND APPARATUS FOR OPTIMIZING THE FREQUENCY OF AUTONOMOUS SEARCH FUNCTIONS FOR DISCOVERING CSG CELLS

Apparatus and methods of maintaining a cell database for wireless communications include discovering a second cell to which a user equipment may reselect. In an aspect, the user equipment may be currently served by a first cell and the second cell is a closed subscriber group cell. Further, aspects include querying a fingerprinting database to determine whether the second cell was previously recorded in the fingerprinting database. Upon determining that the second cell was not previously recorded, further aspects include adding the second cell to the fingerprinting database. Adding the second cell may comprise indicating an association between the first cell and the second cell in the fingerprinting database.

DETAILED DESCRIPTION

The present disclosure provides methods and apparatuses for maintaining associations between wireless cells serving one or more user equipment (UE) by maintaining a fingerprinting database. Thus, in an aspect, the present disclosure presents methods of maintaining cell associations such that where a particular cell is associated with one or more other cells in some way, one or more of the cells may be fingerprinted to the other cell or cells.

For example, in an aspect, the first time that a UE reselects its serving cell from a first cell to a second cell, a fingerprinting manager or fingerprinting component at the UE and/or one or more of the network entities (e.g., NodeB, eNodeB, base station, femtocell, picocell, or other wireless cell serving device) may create or update one or more elements associated with the first and/or second cell in a fingerprinting database. In another example, the UE, currently camped on a first cell, may discover a second cell to which the UE may successfully reselect in the future. The second cell may be discovered through, for example, the UE's local search and measurement outcome. In response to the discovery of the second cell, and not necessarily the UE reselecting to the second cell from the first cell, the fingerprinting manager or fingerprinting component at the UE and/or one or more of the network entities may create or update one or more elements associated with the first and/or second cell in a fingerprinting database. In an aspect, the one or more elements may include an identifier corresponding to the first cell and/or second cell. In some examples, this identifier may comprise the cell Public Land Mobile Network (PLMN), Absolute Radio Frequency Channel Number (ARFCN), and/or its cell identification number.

Furthermore, the first cell may be a macro cell (e.g., a cellular network cell and/or sector), though the first cell may also be any other wireless cell (e.g., a picocell, femtocell, WiFi cell, or the like). Additionally, the first cell and second cell may operate according to different communication technologies, such as, but not limited to, GSM, WCDMA, and/or LTE. In addition, the second cell may be a closed subscriber group (CSG) cell, and may be a picocell, femtocell, WiFi cell, or the like (though the second cell may be a macro cell or larger wireless network serving cell as well).

In an additional aspect, a neighbor cell list of the second cell may be fingerprinted to the second cell. The neighbor cell list may be obtained either from the network associated with the first cell or the second cell, from the UE's local search and measurement outcome when camped on the first cell before reselection, and/or the second cell after reselection. Alternatively or additionally, the neighbor cell list of the second cell can also be fingerprinted to the first cell (and/or vice versa). Again, this neighbor list may be obtained either from the network or from the UE's local search and measurement outcome after the UE has camped on the second cell, though it may be obtained from another source at the UE and/or the first or second cells. Additionally, the second cell, which may be one or more CSG cells, may be identified by its PLMN, Absolute Radio Frequency Channel Number (ARFCN), cell identification number, the CSG ID, and/or a homeNodeB name (HNB).

In an additional aspect of the present disclosure, where an association between two or more cells is established (e.g., a fingerprint entry associating the two cells), for example, at cell discovery or reselection, the UE and/or one or more of the first and second cells may create or update a timestamp of the association or fingerprint. This timestamp may allow the fingerprinting database entries to be updated after expiration of a timer. For example, where such a timer expires without the occurrence of a subsequent association or fingerprinting update, the UE and/or the first or second cell may remove the association between the cells.

Thus, where a UE reselects its serving cell from a first cell to a second cell, the UE may query a fingerprinting database to determine whether the second cell is an existing entry in the fingerprinting database. If no such entry exists, the second cell, the first cell, and/or an association between the cells may be added and/or timestamped. Alternatively, where such an entry already exists (i.e., was previously entered), then the UE may check whether the associated cell is an existing entry in the database. In another example, the UE may query the fingerprinting database in response to the UE discovering a second cell to which it may reselect from a first cell.

Additionally, if a cell in the database (e.g., second cell) has not been detected as associated with another cell in the database (e.g., first cell) after a certain amount of time, which may be tracked using one or more timers, then the UE can deem that fingerprint as out-of-date, and can remove or delete the fingerprint or association between the cells from the fingerprinting database. Furthermore, if the second cell only has one fingerprint (the first cell) upon expiry of a timer, then the second cell may also be removed or deleted from the database. In another aspect, a counter may be used by the UE to maintain a record of information about a cell and, if the counter reaches a threshold value, the UE may determine the cell to be out-of-date, and delete an entry associated with the cell in the fingerprinting database. For example, the counter may track a number of times the cell was discovered by the UE without a successful reselection to the cell by the UE.

Thus, by implementing the procedures outlined above and further described below, the UE may perform a limited cell search guided by the fingerprinting database, for instance, to find CSG cells associated with a currently serving cell, rather than performing a battery-draining traditional autonomous search function.

Referring toFIG. 1, a wireless communication system1is illustrated for improved cell selection using a maintained fingerprinting database. System1includes a UE10that may communicate with one or more cells, such as first cell12and/or a second cell16to receive wireless network access. In an aspect, first cell12may be an original serving cell and second cell16may be a cell to which the UE10reselects, or to which the UE10may be able to reselect, thus receiving wireless service from the second cell16upon reselection. In some non-limiting examples, the second cell16may be a CSG cell, first cell12may be a macro cell, and coverage areas between the first cell12and second cell16may overlap at least partially or may be otherwise associated. Thus, though not limited to this example, first cell12and second cell16may have an association due at least in part to these partially overlapping coverage areas.

In some examples, wireless communication between UE10and the cells may occur on one or more wireless links14and/or18. In a further aspect, first cell12and/or second cell16may have an associated network component, such as an access point, including a base station (BS) or NodeB, a relay, a peer-to-peer device, a radio network controller (RNC), an authentication, authorization and accounting (AAA) server, a mobile switching center (MSC), picocell, piconode, femtocell, femtonode, WiFi access point, etc., that can enable UE10to communicate and/or that can establish and maintain a communication link, such as wireless links14and/or18. In addition, UE10may be a multimode device, which may allow the UE to communicate with multiple technology type networks.

In addition, for purposes of the present disclosure the communication technology used for communication between one or more of UE10, first cell12, and second cell16may be of a 3G technology type, such as, but not limited to, data optimized (DO), WCDMA, Time Division Synchronous Code Division Multiple Access (TDS-CDMA), or any other third-generation mobile communications technology. Additionally, in some examples, the communication technology may be a 2G technology type, such as, but not limited to, GSM, GPRS, or EDGE. Furthermore, example RAT types may include more advanced RATs, such as, but not limited to, Long-Term Evolution (LTE), Time-Division Long-Term Evolution (TD-LTE), or any other fourth-generation mobile communications technology. Alternatively or additionally, any other communication technology type may be used for such communication.

Furthermore, UE10may include a fingerprinting manager102, which may be configured to manage a fingerprinting database108that may store associations between one or more serving cells (e.g., first cell12and/or second cell16). In an aspect, the fingerprinting manager102may alternatively or additionally be located at and/or maintained, by a network entity, such as a network entity associated with first cell12and/or second cell16. In addition, fingerprinting manager102may include a reselection component104, which may be configured to manage serving cell reselection for UE10(or one or more served UEs if fingerprinting manager102is located at a cell). In an aspect, reselection component104may periodically perform ASF or otherwise scan for pilot or beacon signals in an attempt to discover one or more cells not currently serving the UE. Alternatively or additionally, reselection component104may query a fingerprinting database108to determine whether one or more cells110are associated with a cell currently serving the UE, and if so, may limit its scan to one or more frequencies or channels associated with the one or more associated cells.

Alternatively, a fingerprinting database querying component106, which may be associated with fingerprinting manager102, may perform the fingerprinting database query. Furthermore, fingerprinting database querying component106may be configured to query fingerprinting database108to determine whether a cell newly discovered by reselection component104has been previously entered into the fingerprinting database108.

In addition, as introduced above, fingerprinting manager102may include a fingerprinting database108, which may be configured to store information related to one or more cells(s)110. In an aspect, such information may include cell identifier(s)116that may include, but are not limited to, a PLMN, an Absolute Radio Frequency Channel Number (ARFCN), a cell identification number, a CSG ID, a HNB name, and/or any other cell identifying information. Furthermore, each cell110may include a list of one or more associated cells112, which may also be identified by the above-mentioned identifying information or cell identifiers116.

In an aspect, the list of one or more associated cells112may include a neighbor cell list of each cell110that is fingerprinted to each cell110. This list may be obtained from the network associated with each cell110, a network associated with the neighbor cells, directly from the neighbor cells, or from the UE's local search and measurement outcome when camped on the first cell before discovery or reselection and/or the second cell after discovery or reselection, though it may be obtained from another source at the UE and/or one of the cells110. Additionally, the cells in the neighbor cell list may be one or more CSG cells, and may be identified by their PLMN, Absolute Radio Frequency Channel Number (ARFCN), cell identification number, the CSG ID, and/or a homeNodeB name (HNB).

Additionally, fingerprinting database108may include one or more timestamps114that may correspond to each cell110and any associated cells112. In an aspect, fingerprinting database108may be configured to create and store a timestamp114when reselection component104discovers a cell, enters or updates that cell in an entry in fingerprinting database108, and/or reselects the serving cell of UE10to the newly discovered cell. Furthermore, in an aspect, timer manager118may start a timer upon the creation of the timestamp. In addition, timer manager118may be configured to monitor each timer such that, for example, if an association between a first cell and a second cell (e.g., first cell12and second cell16) is not reported or otherwise updated before the expiration of the timer, one or both of the first cell and second cell (or an indication of the association or fingerprint between the cells) may be determined to be out-of-date and discarded from the fingerprinting database108. In another aspect, a counter may be used by the UE to maintain a record of information about a cell and, if the counter reaches a threshold value, the UE may determine the cell to be out-of-date, and delete an entry associated with the cell in the fingerprinting database. For example, the counter may track a number of times the cell was discovered by the UE without a successful reselection to the cell by the UE.

Referring toFIG. 2, in one aspect, any of UE10, or the one or more network entities, such as first cell12and/or the optional second cell16(FIG. 1) may be represented by a specially programmed or configured computer device200. Computer device200includes a processor202for carrying out processing functions associated with one or more of the components and functions described herein. Processor202can include a single or multiple set of processors or multi-core processors. Moreover, processor202can be implemented as an integrated processing system and/or a distributed processing system. Additionally, processor202may be configured to concatenate data received over a frame or several frames during a communication.

Computer device200further includes a memory204, such as for storing data used herein and/or local versions of applications being executed by processor202. Memory204can include any type of memory usable by a computer, such as random access memory (RAM), read only memory (ROM), tapes, magnetic discs, optical discs, volatile memory, non-volatile memory, and any combination thereof

Further, computer device200includes a communications component206that provides for establishing and maintaining communications with one or more parties utilizing hardware, software, and services as described herein. Communications component206may carry communications between components on computer device200, as well as between computer device200and external devices, such as devices located across a communications network and/or devices serially or locally connected to computer device200. For example, communications component206may include one or more buses, and may further include transmit chain components and receive chain components associated with a transmitter and receiver, respectively, or a transceiver, operable for interfacing with external devices. In an additional aspect, communications component206may be configured to receive one or more pages and/or page indicators from one or more subscriber networks. In a further aspect, such a page or page indicator may correspond to the second subscription and may be received via the first communication technology type communication services.

Additionally, computer device200may further include a data store208, which can be any suitable combination of hardware and/or software, that provides for mass storage of information, databases, and programs employed in connection with aspects described herein. For example, data store208may be a data repository for applications not currently being executed by processor202.

In a mobile station implementation, such as for UE10ofFIG. 1, and/or a network entity implementation, such as a network entity associated with first cell12and/or second cell16, computer device200may include fingerprinting manager102(FIG. 1), such as in specially programmed computer readable instructions or code, firmware, hardware, or some combination thereof

Referring toFIG. 3, an example methodology3for maintaining a fingerprinting database for cell association to minimize battery power consumption due to exhaustive ASF is presented. In an aspect, methodology3may be performed by components associated with a UE (e.g., UE10) and/or a network component associated with a first or second cell (e.g., first cell12and/or second cell16). While, for purposes of simplicity of explanation, the methodology3is described below in relation to a UE, again, the methodology3may be performed by a network entity. Additionally, the methodology3is shown and described as a series of acts, it is to be understood and appreciated that the methodologies are not limited by the order of acts, as some acts may, in accordance with one or more aspects, occur in different orders and/or concurrently with other acts from that shown and described herein. For example, it is to be appreciated that a methodology could alternatively be represented as a series of interrelated states or events, such as in a state diagram. Moreover, not all illustrated acts may be required to implement a methodology in accordance with one or more aspects.

In an aspect, at block30, a UE (e.g., UE10,FIG. 1) may discover a second cell to which the UE may reselect from a first cell, which is currently serving the UE. In an aspect, the second cell is a CSG. In another aspect, the second cell may be discovered by the UE upon the UE reselecting from the first cell to the second cell. Additionally, at block32, the UE may query a fingerprinting database, and, through this querying, may determine, at block34, whether the second cell was previously recorded in the fingerprinting database. In an aspect, where the UE determines at block34that the second cell was not previously recorded, the UE may add the second cell (e.g., by adding one or more cell identifiers corresponding to the second cell) to the fingerprinting database and indicate an association between the first cell and the second cell in the fingerprinting database at block36. Furthermore, at block38, in an optional aspect, the UE may additionally add a timestamp associated with the second cell upon the discovery of the second cell, where the second cell was not previously recorded. In an aspect, the UE may add the second cell to the fingerprinting database and indicate an association between the first cell and the second cell in the fingerprinting database, as shown at block36, upon the UE reselecting to the second cell from the first cell, where the second cell was not previously recorded in the fingerprinting database. In addition, according to some examples of methodology3, where the second cell was previously recorded in the fingerprinting database, the UE may update a timestamp associated with the second cell (or the association between the second cell and the first cell) upon the discovery of the second cell. In an aspect, the UE may optionally update a timestamp associated with the second cell (or the association between the second cell and the first cell), as shown at block38, upon the UE reselecting to the second cell from the first cell, where the second cell was previously recorded in the fingerprinting database.

In an additional optional aspect of methodology3(this and below optional aspects not shown), the UE may start a timer upon discovery (or reselection) and/or storing/updating the second cell identifier(s) or the association between the first cell and the second cell in the fingerprinting database. In an aspect, the timer may be set based on a predetermined period of time. The predetermined period of time may be determined to have expired based on a timestamp and a current time reading. If the timer elapses, e.g., the predetermined period of time has expired, before the UE again updates the association and/or cell identifier, the UE may determine that the fingerprint of the second cell, e.g., the association between the first cell and the second cell in the fingerprinting database, is out-of-date. As a result, the UE may remove or delete one or more of the first and second cell entries in the fingerprinting database. Additionally or alternatively, the UE may delete a first cell entry in the fingerprinting database when the UE determines that the first cell is only associated with the second cell, upon removal of the second cell from the fingerprinting database.

In an aspect, a counter may be used by the UE to maintain a record of information about a cell and, if the counter reaches a threshold value, the UE may determine the cell to be out-of-date, and delete an entry associated with the cell in the fingerprinting database. For example, the counter may track a number of times the cell was discovered by the UE without a successful reselection to the cell by the UE.

Referring toFIG. 4, an example system4is displayed for managing improved cell reselection using a fingerprinting database. For example, system4can reside at least partially within one or more network entities and/or UEs. It is to be appreciated that system4is represented as including functional blocks, which can be functional blocks that represent functions implemented by a processor, software, or combination thereof (e.g., firmware). System4includes a logical grouping40of electrical components that can act in conjunction. For instance, logical grouping40can include an electrical component42for discovering a second cell to which a UE may reselect from a first cell, which is currently serving the UE. In an aspect, the second cell is a CSG. In another aspect, electrical component42may discover the second cell as a result of the UE reselecting from the first cell to the second cell. In an aspect, electrical component42may comprise reselection component104(FIG. 1). In addition, logical grouping40can include an electrical component44for querying a fingerprinting database. In an aspect, electrical component44may comprise fingerprint database querying component106(FIG. 1). In an additional aspect, logical grouping40can include an electrical component46for adding the second cell to the fingerprinting database and indicating an association between the first cell and the second cell in the fingerprinting database. In an aspect, electrical component46may comprise control components of UE10configured to control fingerprinting database108(FIG. 1) and/or processor202(FIG. 2), which may alternatively or additionally be configured to add, edit, and/or delete entries to fingerprinting database108. Furthermore, logical grouping40can include an electrical component48for updating or adding a timestamp (or starting a counter) in the fingerprinting database associated with discovering (or reselecting to) the second cell.

Additionally, system4can include a memory49that retains instructions for executing functions associated with the electrical components42,44,46, and48, and/or stores data used or obtained by the electrical components42,44,46, and48. While shown as being external to memory49, it is to be understood that one or more of the electrical components42,44,46, and48can exist within memory49. In one example, electrical components42,44,46, and48can comprise at least one processor, or each electrical component42,44,46, and48can be a corresponding module of at least one processor. Moreover, in an additional or alternative example, electrical components42,44,46, and48can be a computer program product including a computer readable medium, where each electrical component42,44,46, and48can be corresponding code.

FIG. 5is a block diagram illustrating an example of a hardware implementation for an apparatus500employing a processing system514for carrying out aspects of the present disclosure, such as methods for improved cell (e.g., CSG cell) scanning and discovery through maintenance of a fingerprinting database. In this example, the processing system514may be implemented with a bus architecture, represented generally by a bus502. The bus502may include any number of interconnecting buses and bridges depending on the specific application of the processing system514and the overall design constraints. The bus502links together various circuits including one or more processors, represented generally by the processor504, and computer-readable media, represented generally by the computer-readable medium506. The bus502may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further. A bus interface508provides an interface between the bus502and a transceiver510. The transceiver510provides a means for communicating with various other apparatus over a transmission medium. Depending upon the nature of the apparatus, a user interface512(e.g., keypad, display, speaker, microphone, joystick) may also be provided.

The processor504is responsible for managing the bus502and general processing, including the execution of software stored on the computer-readable medium506. The software, when executed by the processor504, causes the processing system514to perform the various functions described above for any particular apparatus. The computer-readable medium506may also be used for storing data that is manipulated by the processor504when executing software.

The various concepts presented throughout this disclosure may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards. By way of example and without limitation, the aspects of the present disclosure illustrated inFIG. 6are presented with reference to a UMTS system600employing a W-CDMA air interface, which may facilitate execution of one or methods contemplated by the present disclosure. A UMTS network includes three interacting domains: a Core Network (CN)604, a UMTS Terrestrial Radio Access Network (UTRAN)602, and User Equipment (UE)610. In an aspect, UE610may be UE10(FIG. 1), and UMTS602may comprise first and/or second cells12and/or16(FIG. 1) and/or network entities serving these or other cells. In this example, the UTRAN602provides various wireless services including telephony, video, data, messaging, broadcasts, and/or other services. The UTRAN602may include a plurality of Radio Network Subsystems (RNSs) such as an RNS607, each controlled by a respective Radio Network Controller (RNC) such as an RNC606. Here, the UTRAN602may include any number of RNCs606and RNSs607in addition to the RNCs606and RNSs607illustrated herein. The RNC606is an apparatus responsible for, among other things, assigning, reconfiguring, and releasing radio resources within the RNS607. The RNC606may be interconnected to other RNCs (not shown) in the UTRAN602through various types of interfaces such as a direct physical connection, a virtual network, or the like, using any suitable transport network.

Communication between a UE610and a NodeB608may be considered as including a physical (PHY) layer and a medium access control (MAC) layer. Further, communication between a UE610and an RNC606by way of a respective NodeB608may be considered as including a radio resource control (RRC) layer. In the instant specification, the PHY layer may be considered layer 1; the MAC layer may be considered layer 6; and the RRC layer may be considered layer 3. Information hereinbelow utilizes terminology introduced in the RRC Protocol Specification, 3GPP TS 65.331 v9.1.0, incorporated herein by reference.

The geographic region covered by the RNS607may be divided into a number of cells, with a radio transceiver apparatus serving each cell. A radio transceiver apparatus is commonly referred to as a NodeB in UMTS applications, but may also be referred to by those skilled in the art as a base station (BS), a base transceiver station (BTS), a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), or some other suitable terminology. For clarity, three Node Bs608are shown in each RNS607; however, the RNSs607may include any number of wireless Node Bs. The Node Bs608provide wireless access points to a CN604for any number of mobile apparatuses. Examples of a mobile apparatus include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a notebook, a netbook, a smartbook, a personal digital assistant (PDA), a satellite radio, a global positioning system (GPS) device, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, or any other similar functioning device. The mobile apparatus is commonly referred to as a UE in UMTS applications, but may also be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. In a UMTS system, the UE610may further include a universal subscriber identity module (USIM)611, which contains a user's subscription information to a network. For illustrative purposes, one UE610is shown in communication with a number of the Node Bs608. The DL, also called the forward link, refers to the communication link from a NodeB608to a UE610, and the UL, also called the reverse link, refers to the communication link from a UE610to a NodeB608.

The CN604interfaces with one or more access networks, such as the UTRAN602. As shown, the CN604is a GSM core network. However, as those skilled in the art will recognize, the various concepts presented throughout this disclosure may be implemented in a RAN, or other suitable access network, to provide UEs with access to types of CNs other than GSM networks.

The CN604includes a circuit-switched (CS) domain and a packet-switched (PS) domain. Some of the circuit-switched elements are a Mobile services Switching Centre (MSC), a Visitor location register (VLR) and a Gateway MSC. Packet-switched elements include a Serving GPRS Support Node (SGSN) and a Gateway GPRS Support Node (GGSN). Some network elements, like EIR, HLR, VLR and AuC may be shared by both of the circuit-switched and packet-switched domains. In the illustrated example, the CN604supports circuit-switched services with a MSC612and a GMSC614. In some applications, the GMSC614may be referred to as a media gateway (MGW). One or more RNCs, such as the RNC606, may be connected to the MSC612. The MSC612is an apparatus that controls call setup, call routing, and UE mobility functions. The MSC612also includes a VLR that contains subscriber-related information for the duration that a UE is in the coverage area of the MSC612. The GMSC614provides a gateway through the MSC612for the UE to access a circuit-switched network616. The GMSC614includes a home location register (HLR)615containing subscriber data, such as the data reflecting the details of the services to which a particular user has subscribed. The HLR is also associated with an authentication center (AuC) that contains subscriber-specific authentication data. When a call is received for a particular UE, the GMSC614queries the HLR615to determine the UE's location and forwards the call to the particular MSC serving that location.

The CN604also supports packet-data services with a serving GPRS support node (SGSN)618and a gateway GPRS support node (GGSN)620. GPRS, which stands for General Packet Radio Service, is designed to provide packet-data services at speeds higher than those available with standard circuit-switched data services. The GGSN620provides a connection for the UTRAN602to a packet-based network622. The packet-based network622may be the Internet, a private data network, or some other suitable packet-based network. The primary function of the GGSN620is to provide the UEs610with packet-based network connectivity. Data packets may be transferred between the GGSN620and the UEs610through the SGSN618, which performs primarily the same functions in the packet-based domain as the MSC612performs in the circuit-switched domain.

An air interface for UMTS may utilize a spread spectrum Direct-Sequence Code Division Multiple Access (DS-CDMA) system. The spread spectrum DS-CDMA spreads user data through multiplication by a sequence of pseudorandom bits called chips. The “wideband” W-CDMA air interface for UMTS is based on such direct sequence spread spectrum technology and additionally calls for a frequency division duplexing (FDD). FDD uses a different carrier frequency for the UL and DL between a NodeB608and a UE610. Another air interface for UMTS that utilizes DS-CDMA, and uses time division duplexing (TDD), is the TD-SCDMA air interface. Those skilled in the art will recognize that although various examples described herein may refer to a W-CDMA air interface, the underlying principles may be equally applicable to a TD-SCDMA air interface.

An HSPA air interface includes a series of enhancements to the 3G/W-CDMA air interface, facilitating greater throughput and reduced latency. Among other modifications over prior releases, HSPA utilizes hybrid automatic repeat request (HARQ), shared channel transmission, and adaptive modulation and coding. The standards that define HSPA include HSDPA (high speed downlink packet access) and HSUPA (high speed uplink packet access, also referred to as enhanced uplink, or EUL).

HSDPA utilizes as its transport channel the high-speed downlink shared channel (HS-DSCH). The HS-DSCH is implemented by three physical channels: the high-speed physical downlink shared channel (HS-PDSCH), the high-speed shared control channel (HS-SCCH), and the high-speed dedicated physical control channel (HS-DPCCH).

Among these physical channels, the HS-DPCCH carries the HARQ ACK/NACK signaling on the uplink to indicate whether a corresponding packet transmission was decoded successfully. That is, with respect to the downlink, the UE610provides feedback to the node B608over the HS-DPCCH to indicate whether it correctly decoded a packet on the downlink.

HS-DPCCH further includes feedback signaling from the UE610to assist the node B608in taking the right decision in terms of modulation and coding scheme and precoding weight selection, this feedback signaling including the CQI and PCI.

“HSPA Evolved” or HSPA+ is an evolution of the HSPA standard that includes MIMO and 64-QAM, enabling increased throughput and higher performance. That is, in an aspect of the disclosure, the node B608and/or the UE610may have multiple antennas supporting MIMO technology. The use of MIMO technology enables the node B608to exploit the spatial domain to support spatial multiplexing, beamforming, and transmit diversity.

Multiple Input Multiple Output (MIMO) is a term generally used to refer to multi-antenna technology, that is, multiple transmit antennas (multiple inputs to the channel) and multiple receive antennas (multiple outputs from the channel). MIMO systems generally enhance data transmission performance, enabling diversity gains to reduce multipath fading and increase transmission quality, and spatial multiplexing gains to increase data throughput.

Spatial multiplexing may be used to transmit different streams of data simultaneously on the same frequency. The data steams may be transmitted to a single UE610to increase the data rate or to multiple UEs610to increase the overall system capacity. This is achieved by spatially precoding each data stream and then transmitting each spatially precoded stream through a different transmit antenna on the downlink. The spatially precoded data streams arrive at the UE(s)610with different spatial signatures, which enables each of the UE(s)610to recover the one or more the data streams destined for that UE610. On the uplink, each UE610may transmit one or more spatially precoded data streams, which enables the node B608to identify the source of each spatially precoded data stream.

Spatial multiplexing may be used when channel conditions are good. When channel conditions are less favorable, beamforming may be used to focus the transmission energy in one or more directions, or to improve transmission based on characteristics of the channel. This may be achieved by spatially precoding a data stream for transmission through multiple antennas. To achieve good coverage at the edges of the cell, a single stream beamforming transmission may be used in combination with transmit diversity.

Generally, for MIMO systems utilizing n transmit antennas, n transport blocks may be transmitted simultaneously over the same carrier utilizing the same channelization code. Note that the different transport blocks sent over the n transmit antennas may have the same or different modulation and coding schemes from one another.

On the other hand, Single Input Multiple Output (SIMO) generally refers to a system utilizing a single transmit antenna (a single input to the channel) and multiple receive antennas (multiple outputs from the channel). Thus, in a SIMO system, a single transport block is sent over the respective carrier.

Referring toFIG. 7, an access network700in a UTRAN architecture is illustrated. The multiple access wireless communication system includes multiple cellular regions (cells), including cells702,704, and706, each of which may include one or more sectors. The multiple sectors can be formed by groups of antennas with each antenna responsible for communication with UEs in a portion of the cell. For example, in cell702, antenna groups712,714, and716may each correspond to a different sector. In cell704, antenna groups718,720, and722each correspond to a different sector. In cell706, antenna groups724,726, and728each correspond to a different sector. The cells702,704and706may include several wireless communication devices, e.g., User Equipment or UEs, which may be in communication with one or more sectors of each cell702,704or706. For example, UEs730and732may be in communication with NodeB742, UEs734and736may be in communication with NodeB744, and UEs738and740can be in communication with NodeB746. Here, each NodeB742,744,746is configured to provide an access point to a core network for all the UEs730,732,734,736,738,740in the respective cells702,704, and706.

As the UE734moves from the illustrated location in cell704into cell706, a serving cell change (SCC) or handover may occur in which communication with the UE734transitions from the cell704, which may be referred to as the source cell, to cell706, which may be referred to as the target cell. Management of the handover procedure may take place at the UE734, at the Node Bs corresponding to the respective cells, at a radio network controller606(FIG. 6), or at another suitable node in the wireless network. For example, during a call with the source cell704, or at any other time, the UE734may monitor various parameters of the source cell704as well as various parameters of neighboring cells such as cells706and702. Further, depending on the quality of these parameters, the UE734may maintain communication with one or more of the neighboring cells. During this time, the UE734may maintain an Active Set, that is, a list of cells that the UE734is simultaneously connected to (i.e., the UTRA cells that are currently assigning a downlink dedicated physical channel DPCH or fractional downlink dedicated physical channel F-DPCH to the UE734may constitute the Active Set).

The modulation and multiple access scheme employed by the access network700may vary depending on the particular telecommunications standard being deployed. By way of example, the standard may include Evolution-Data Optimized (EV-DO) or Ultra Mobile Broadband (UMB). EV-DO and UMB are air interface standards promulgated by the 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards and employs CDMA to provide broadband Internet access to mobile stations. The standard may alternately be Universal Terrestrial Radio Access (UTRA) employing Wideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA; Global System for Mobile Communications (GSM) employing TDMA; and Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, and Flash-OFDM employing OFDMA. UTRA, E-UTRA, UMTS, LTE, LTE Advanced, and GSM are described in documents from the 3GPP organization. CDMA2000 and UMB are described in documents from the 3GPP2 organization. The actual wireless communication standard and the multiple access technology employed will depend on the specific application and the overall design constraints imposed on the system.

The radio protocol architecture may take on various forms depending on the particular application. An example for an HSPA system will now be presented with reference toFIG. 8.FIG. 8is a conceptual diagram illustrating an example of the radio protocol architecture for the user and control planes.

Turning toFIG. 8, the radio protocol architecture for the UE and node B is shown with three layers: Layer 1, Layer 2, and Layer 3, where the UE may be the UE610ofFIG. 6and/or UE10ofFIG. 1and the node B may be the NodeB608ofFIG. 6. Layer 1 is the lowest lower and implements various physical layer signal processing functions. Layer 1 will be referred to herein as the physical layer806. Layer 2 (L2 layer)808is above the physical layer806and is responsible for the link between the UE and node B over the physical layer806.

In the user plane, the L2 layer808includes a media access control (MAC) sublayer810, a radio link control (RLC) sublayer812, and a packet data convergence protocol (PDCP)814sublayer, which are terminated at the node B on the network side. Although not shown, the UE may have several upper layers above the L2 layer808including a network layer (e.g., IP layer) that is terminated at a PDN gateway on the network side, and an application layer that is terminated at the other end of the connection (e.g., far end UE, server, etc.).

FIG. 9is a block diagram of a NodeB910in communication with a UE950, where the NodeB910may be the NodeB608inFIG. 6and/or first and/or second cells12and/or16ofFIG. 1, and the UE950may be the UE610inFIG. 6and/or UE10ofFIG. 1. In the downlink communication, a transmit processor920may receive data from a data source912and control signals from a controller/processor940. The transmit processor920provides various signal processing functions for the data and control signals, as well as reference signals (e.g., pilot signals). For example, the transmit processor920may provide cyclic redundancy check (CRC) codes for error detection, coding and interleaving to facilitate forward error correction (FEC), mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM), and the like), spreading with orthogonal variable spreading factors (OVSF), and multiplying with scrambling codes to produce a series of symbols. Channel estimates from a channel processor944may be used by a controller/processor940to determine the coding, modulation, spreading, and/or scrambling schemes for the transmit processor920. These channel estimates may be derived from a reference signal transmitted by the UE950or from feedback from the UE950. The symbols generated by the transmit processor920are provided to a transmit frame processor930to create a frame structure. The transmit frame processor930creates this frame structure by multiplexing the symbols with information from the controller/processor940, resulting in a series of frames. The frames are then provided to a transmitter932, which provides various signal conditioning functions including amplifying, filtering, and modulating the frames onto a carrier for downlink transmission over the wireless medium through antenna934. The antenna934may include one or more antennas, for example, including beam steering bidirectional adaptive antenna arrays or other similar beam technologies.

At the UE950, a receiver954receives the downlink transmission through an antenna952and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver954is provided to a receive frame processor960, which parses each frame, and provides information from the frames to a channel processor994and the data, control, and reference signals to a receive processor970. The receive processor970then performs the inverse of the processing performed by the transmit processor920in the NodeB910. More specifically, the receive processor970descrambles and despreads the symbols, and then determines the most likely signal constellation points transmitted by the NodeB910based on the modulation scheme. These soft decisions may be based on channel estimates computed by the channel processor994. The soft decisions are then decoded and deinterleaved to recover the data, control, and reference signals. The CRC codes are then checked to determine whether the frames were successfully decoded. The data carried by the successfully decoded frames will then be provided to a data sink972, which represents applications running in the UE950and/or various user interfaces (e.g., display). Control signals carried by successfully decoded frames will be provided to a controller/processor990. When frames are unsuccessfully decoded by the receiver processor970, the controller/processor990may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.

In the uplink, data from a data source978and control signals from the controller/processor990are provided to a transmit processor980. The data source978may represent applications running in the UE950and various user interfaces (e.g., keyboard). Similar to the functionality described in connection with the downlink transmission by the NodeB910, the transmit processor980provides various signal processing functions including CRC codes, coding and interleaving to facilitate FEC, mapping to signal constellations, spreading with OVSFs, and scrambling to produce a series of symbols. Channel estimates, derived by the channel processor994from a reference signal transmitted by the NodeB910or from feedback contained in the midamble transmitted by the NodeB910, may be used to select the appropriate coding, modulation, spreading, and/or scrambling schemes. The symbols produced by the transmit processor980will be provided to a transmit frame processor982to create a frame structure. The transmit frame processor982creates this frame structure by multiplexing the symbols with information from the controller/processor990, resulting in a series of frames. The frames are then provided to a transmitter956, which provides various signal conditioning functions including amplification, filtering, and modulating the frames onto a carrier for uplink transmission over the wireless medium through the antenna952.

The uplink transmission is processed at the NodeB910in a manner similar to that described in connection with the receiver function at the UE950. A receiver935receives the uplink transmission through the antenna934and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver935is provided to a receive frame processor936, which parses each frame, and provides information from the frames to the channel processor944and the data, control, and reference signals to a receive processor938. The receive processor938performs the inverse of the processing performed by the transmit processor980in the UE950. The data and control signals carried by the successfully decoded frames may then be provided to a data sink939and the controller/processor, respectively. If some of the frames were unsuccessfully decoded by the receive processor, the controller/processor940may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.

The controller/processors940and990may be used to direct the operation at the NodeB910and the UE950, respectively. For example, the controller/processors940and990may provide various functions including timing, peripheral interfaces, voltage regulation, power management, and other control functions. The computer readable media of memories942and992may store data and software for the NodeB910and the UE950, respectively. A scheduler/processor946at the NodeB910may be used to allocate resources to the UEs and schedule downlink and/or uplink transmissions for the UEs.

Several aspects of a telecommunications system have been presented with reference to a W-CDMA system. As those skilled in the art will readily appreciate, various aspects described throughout this disclosure may be extended to other telecommunication systems, network architectures and communication standards.