Apparatus and method for handling out-of-sync and radio link failure with fractional DPCH calls

Aspects of the present disclosure provide an apparatus and methods for operating the same that can improve out-of-sync and radio link failure handling in a W-CDMA network. A user equipment (UE) establishes a packet switched (PS) connection between the UE and a base station, wherein the PS connection includes a Fractional Dedicated Physical Channel (F-DPCH). The UE configures an in-sync threshold (Qin) and an out-of-sync threshold (Qout) for the F-DPCH, wherein values of the Qin and Qout are set higher than those of corresponding Qin and Qout of a Dedicated Physical Channel (DPCH). The UE further estimates a downlink (DL) Signal to Interference Ratio (SIR) based on one or more transmit power control (TPC) commands of the F-DPCH, and determines whether to release the PS connection based on a comparison of the estimated SIR and Qout of the F-DPCH.

TECHNICAL FIELD

Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to an apparatus and method for handling out-of-sync and radio link failure in W-CDMA networks.

BACKGROUND

In earlier generations of W-CDMA network, such as those described in the 3GPP technical specification 25.221, which was released in 1999 and commonly known as Release 99 or R99, each user (e.g., mobile terminal) has a separate and independent communication path to the network base station (known as Node B in UMTS) via a Dedicated Physical Channel (DPCH). As the W-CDMA technology evolved, new physical channels were added to improve system operation and to accommodate ever increasing number of users. For example, in HSPA networks, the Fractional Dedicated Physical Channel (F-DPCH) was added to reduce the consumption of downlink channelization codes among multiples users. Newer generation of user equipment (UE) typically supports communications on both R99 DPCH and F-DPCH. However, due to many differences between communication protocols on these channels, certain optimizations of various channel parameters at the UE are desirable.

SUMMARY

Aspects of the present disclosure provide an apparatus and methods for operating the same that can improve out-of-sync and radio link failure handling in a W-CDMA network supporting both R99 DPCH and F-DPCH.

One aspect of the disclosure provides a method for wireless communication operable at a user equipment (UE). The UE establishes a packet switched (PS) connection between the UE and a base station, wherein the PS connection includes a Fractional Dedicated Physical Channel (F-DPCH). The UE configures an in-sync threshold (Qin) and an out-of-sync threshold (Qout) for the F-DPCH, wherein values of the Qinand Qoutare set higher than those of corresponding Qinand Qoutof a Dedicated Physical Channel (DPCH). The UE further estimates a downlink (DL) Signal to Interference Ratio (SIR) based on one or more transmit power control (TPC) commands of the F-DPCH, and determines whether to release the PS connection based on a comparison of the estimated SIR and Qoutof the F-DPCH.

Another aspect of the disclosure provides an apparatus for wireless communication. The apparatus includes means for establishing a packet switched (PS) connection between the apparatus and a base station, wherein the PS connection includes a Fractional Dedicated Physical Channel (F-DPCH). The apparatus includes means for configuring an in-sync threshold (Qin) and an out-of-sync threshold (Qout) for the F-DPCH, wherein values of the Qinand Qoutare set higher than those of corresponding Qinand Qoutof a Dedicated Physical Channel (DPCH). The apparatus further includes means for estimating a downlink (DL) Signal-to-Interference Ratio (SIR) based on one or more transmit power control (TPC) commands of the F-DPCH and means for determining whether to release the PS connection based on a comparison of the estimated SIR and Qoutof the F-DPCH.

Another aspect of the disclosure provides a computer-readable storage medium. The computer-readable storage medium includes code for causing a user equipment (UE) to perform various functions. The UE establishes a packet switched (PS) connection between the UE and a base station, wherein the PS connection includes a Fractional Dedicated Physical Channel (F-DPCH). The UE configures an in-sync threshold (Qin) and an out-of-sync threshold (Qout) for the F-DPCH, wherein values of the Qinand Qoutare set higher than those of corresponding Qinand Qoutof a Dedicated Physical Channel (DPCH). The UE further estimates a downlink (DL) Signal-to-Interference Ratio (SIR) based on one or more transmit power control (TPC) commands of the F-DPCH, and determine whether to release the PS connection based on a comparison of the estimated SIR and Qoutof the F-DPCH.

Another aspect of the disclosure provides an apparatus for wireless communication. The apparatus includes at least one processor, a communication interface coupled to the at least one processor, and a memory coupled to the at least one processor. The at least one processor includes a number of components including first through fourth components. The first component is configured to establish a packet switched (PS) connection between the apparatus and a base station, wherein the PS connection includes a Fractional Dedicated Physical Channel (F-DPCH). The second component is configured to configure an in-sync threshold (Qin) and an out-of-sync threshold (Qout) for the F-DPCH, wherein values of the Qinand Qoutare set higher than those of corresponding Qin. and Qoutof a Dedicated Physical Channel (DPCH). The third component is configured to estimate a downlink (DL) Signal-to-Interference Ratio (SIR) based on one or more transmit power control (TPC) commands of the F-DPCH. The fourth component is configured to determine whether to release the PS connection based on a comparison of the estimated SIR and Qoutof the F-DPCH.

DETAILED DESCRIPTION

Aspects of the present disclosure provide an apparatus and methods for operating the same that can improve out-of-sync and radio link failure handling in a W-CDMA network supporting both R99 DPCH and F-DPCH. The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

The various concepts presented throughout this disclosure may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards. Referring now toFIG. 1, as an illustrative example without limitation, various aspects of the present disclosure are illustrated with reference to a Universal Mobile Telecommunications System (UMTS) system100. A UMTS network includes three interacting domains: a core network104, a radio access network (RAN) (e.g., the UMTS Terrestrial Radio Access Network (UTRAN)102), and a user equipment (UE)110. Among several options available for a UTRAN102, in this example, the illustrated UTRAN102may employ a W-CDMA air interface for enabling various wireless services including telephony, video, data, messaging, broadcasts, and/or other services. The UTRAN102may include a plurality of Radio Network Subsystems (RNSs) such as an RNS107, each controlled by a respective Radio Network Controller (RNC) such as an RNC106. Here, the UTRAN102may include any number of RNCs106and RNSs107in addition to the illustrated RNCs106and RNSs107. The RNC106is an apparatus responsible for, among other things, assigning, reconfiguring, and releasing radio resources within the RNS107. The RNC106may be interconnected to other RNCs (not shown) in the UTRAN102through various types of interfaces such as a direct physical connection, a virtual network, or the like using any suitable transport network.

The geographic region covered by the RNS107may 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 Node B 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 Bs108are shown in each RNS107; however, the RNSs107may include any number of wireless Node Bs. The Node Bs108provide wireless access points to a core network104for 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 user equipment (UE) in UMTS applications, but may also be referred to by those skilled in the art as a mobile station (MS), 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 (AT), 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 UE110may further include a universal subscriber identity module (USIM)111, which contains a user's subscription information to a network. For illustrative purposes, one UE110is shown in communication with a number of the Node Bs108. The downlink (DL), also called the forward link, refers to the communication link from a Node B108to a UE110and the uplink (UL), also called the reverse link, refers to the communication link from a UE110to a Node B108.

The core network104can interface with one or more access networks, such as the UTRAN102. As shown, the core network104is a UMTS 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 core networks other than UMTS networks.

The illustrated UMTS core network104includes 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 (GMSC). 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 core network104supports circuit-switched services with a MSC112and a GMSC114. In some applications, the GMSC114may be referred to as a media gateway (MGW). One or more RNCs, such as the RNC106, may be connected to the MSC112. The MSC112is an apparatus that controls call setup, call routing, and UE mobility functions. The MSC112also includes a visitor location register (VLR) that contains subscriber-related information for the duration that a UE is in the coverage area of the MSC112. The GMSC114provides a gateway through the MSC112for the UE to access a circuit-switched network116. The GMSC114includes a home location register (HLR)115containing 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 GMSC114queries the HLR115to determine the UE's location and forwards the call to the particular MSC serving that location.

The illustrated core network104also supports packet-switched data services with a serving GPRS support node (SGSN)118and a gateway GPRS support node (GGSN)120. General Packet Radio Service (GPRS) is designed to provide packet-data services at speeds higher than those available with standard circuit-switched data services. The GGSN120provides a connection for the UTRAN102to a packet-based network122. The packet-based network122may be the Internet, a private data network, or some other suitable packet-based network. The primary function of the GGSN120is to provide the UEs110with packet-based network connectivity. Data packets may be transferred between the GGSN120and the UEs110through the SGSN118, which performs primarily the same functions in the packet-based domain as the MSC112performs in the circuit-switched domain.

The UTRAN102is one example of a RAN that may be utilized in accordance with the present disclosure. Referring toFIG. 2, by way of example and without limitation, a simplified schematic illustration of a RAN200in a UTRAN architecture is illustrated. The system includes multiple cellular regions (cells), including cells202,204, and206, each of which may include one or more sectors. Cells may be defined geographically (e.g., by coverage area) and/or may be defined in accordance with a frequency, scrambling code, etc. That is, the illustrated geographically-defined cells202,204, and206may each be further divided into a plurality of cells, e.g., by utilizing different scrambling codes. For example, cell204amay utilize a first scrambling code, and cell204b, while in the same geographic region and served by the same Node B244, may be distinguished by utilizing a second scrambling code.

In a cell that is divided into sectors, the multiple sectors within a cell can be formed by groups of antennas with each antenna responsible for communication with UEs in a portion of the cell. For example, in cell202, antenna groups212,214, and216may each correspond to a different sector. In cell204, antenna groups218,220, and222may each correspond to a different sector. In cell206, antenna groups224,226, and228may each correspond to a different sector.

The cells202,204, and206may include several UEs that may be in communication with one or more sectors of each cell202,204, or206. For example, UEs230and232may be in communication with Node B242, UEs234and236may be in communication with Node B244, and UEs238and240may be in communication with Node B246. Here, each Node B242,244, and246may be configured to provide an access point to a core network204(seeFIG. 2) for all the UEs230,232,234,236,238, and240in the respective cells202,204, and206.

During a call with a source cell, or at any other time, the UE236may monitor various parameters of the source cell as well as various parameters of neighboring cells. Further, depending on the quality of these parameters, the UE236may maintain communication with one or more of the neighboring cells. During this time, the UE236may maintain an Active Set, that is, a list of cells to which the UE236is simultaneously connected (i.e., the UTRAN cells that are currently assigning a downlink dedicated physical channel (DPCH) or fractional downlink dedicated physical channel (F-DPCH) to the UE236may constitute the Active Set).FIG. 3is a conceptual diagram illustrating multiple F-DPCHs assigned to different UEs in the same DPCH slot. The use of F-DPCHs300, when using different timing offsets, allows the transmit power control (TPC) command stream for different users to be time multiplexed on the same channelization code.

The UTRAN air interface may be a spread spectrum Direct-Sequence Code Division Multiple Access (DS-CDMA) system, such as one utilizing the W-CDMA standards. The spread spectrum DS-CDMA spreads user data through multiplication by a sequence of pseudorandom bits called chips. The W-CDMA air interface for the UTRAN102is based on such DS-CDMA technology and additionally calls for a frequency division duplexing (FDD). FDD uses a different carrier frequency for the uplink (UL) and downlink (DL) between a Node B108and a UE110. 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 are equally applicable to a TD-SCDMA air interface or any other suitable air interface.

A high speed packet access (HSPA) air interface includes a series of enhancements to the 3G/W-CDMA air interface between the UE110and the UTRAN102, facilitating greater throughput and reduced latency for users. Among other modifications over prior standards, 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).

For example, in Release 5 of the 3GPP family of standards, HSDPA was introduced. HSDPA utilizes as its transport channel the high-speed downlink shared channel (HS-DSCH), which may be shared by several UEs. 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).

The HS-SCCH is a physical channel that may be utilized to carry downlink control information related to the transmission of HS-DSCH. Here, the HS-DSCH may be associated with one or more HS-SCCH. The UE may continuously monitor the HS-SCCH to determine when to read its data from the HS-DSCH and to determine the modulation scheme used on the assigned physical channel.

The HS-PDSCH is a physical channel that may be shared by several UEs and may carry downlink data for the high-speed downlink. The HS-PDSCH may support quadrature phase shift keying (QPSK), 16-quadrature amplitude modulation (16-QAM), and multi-code transmission.

The HS-DPCCH is an uplink physical channel that may carry feedback from the UE to assist the Node B in its scheduling algorithm. The feedback may include a channel quality indicator (CQI) and a positive or negative acknowledgement (ACK/NAK) of a previous HS-DSCH transmission.

One difference on the downlink between Release-5 HSDPA and the previously standardized circuit-switched air-interface is the absence of soft handover in HSDPA. This means that HSDPA channels are transmitted to the UE from a single cell called the HSDPA serving cell. As the user moves, or as one cell becomes preferable to another, the HSDPA serving cell may change. Still, the UE may be in soft handover on the associated DPCH, receiving the same information from plural cells.

In Release 5 HSDPA, at any instance a UE has one serving cell: the strongest cell in the active set as according to the UE measurements of Ec/I0. According to mobility procedures defined in Release 5 of 3GPP Technical Specification (TS) 25.331, the radio resource control (RRC) signaling messages for changing the HSPDA serving cell are transmitted from the current HSDPA serving cell (i.e., the source cell) and not the cell that the UE reports as being the stronger cell (i.e., the target cell).

3GPP Release 6 specifications introduced uplink enhancements referred to as Enhanced Uplink (EUL) or High Speed Uplink Packet Access (HSUPA). HSUPA utilizes as its transport channel the EUL Dedicated Channel (E-DCH). The E-DCH is transmitted in the uplink together with the Release 99 DCH. The control portion of the DCH, that is, the DPCCH, carries pilot bits and downlink power control commands on uplink transmissions. In the present disclosure, the DPCCH may be referred to as a control channel (e.g., a primary control channel) or a pilot channel (e.g., a primary pilot channel) in accordance with whether reference is being made to the channel's control aspects or its pilot aspects.

The E-DCH is implemented by physical channels including the E-DCH Dedicated Physical Data Channel (E-DPDCH) and the E-DCH Dedicated Physical Control Channel (E-DPCCH). In addition, HSUPA relies on additional physical channels including the E-DCH HARQ Indicator Channel (E-HICH), the E-DCH Absolute Grant Channel (E-AGCH), and the E-DCH Relative Grant Channel (E-RGCH).

In a wireless telecommunication system, the communication protocol architecture may take on various forms depending on the particular application. For example, in a 3GPP UMTS system, the signaling protocol stack is divided into a Non-Access Stratum (NAS) and an Access Stratum (AS). The NAS provides the upper layers, for signaling between the UE110and the core network104(referring toFIG. 1), and may include circuit switched and packet switched protocols. The AS provides the lower layers, for signaling between the UTRAN102and the UE110, and may include a user plane and a control plane. Here, the user plane or data plane carries user traffic, while the control plane carries control information (i.e., signaling).

Turning toFIG. 4, the AS is shown with three layers: Layer 1, Layer 2, and Layer 3. Layer 1 is the lowest layer and implements various physical layer signal processing functions. Layer 1 will be referred to herein as the physical layer406. The data link layer, called Layer 2408, is above the physical layer406and is responsible for the link between the UE210and Node B208over the physical layer406.

At Layer 3, the RRC layer416handles the control plane signaling between the UE210and the Node B208. RRC layer416includes a number of functional entities for routing higher layer messages, handling broadcasting and paging functions, establishing and configuring radio bearers, etc.

In the illustrated air interface, the L2 layer408is split into sublayers. In the control plane, the L2 layer408includes two sublayers: a medium access control (MAC) sublayer410and a radio link control (RLC) sublayer412. In the user plane, the L2 layer408additionally includes a packet data convergence protocol (PDCP) sublayer414. Although not shown, the UE may have several upper layers above the L2 layer408including 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.).

The PDCP sublayer414provides multiplexing between different radio bearers and logical channels. The PDCP sublayer414also provides header compression for upper layer data packets to reduce radio transmission overhead, security by ciphering the data packets, and handover support for UEs between Node Bs.

The RLC sublayer412generally supports an acknowledged mode (AM) (where an acknowledgment and retransmission process may be used for error correction), an unacknowledged mode (UM), and a transparent mode for data transfers, and provides segmentation and reassembly of upper layer data packets and reordering of data packets to compensate for out-of-order reception due to a hybrid automatic repeat request (HARQ) at the MAC layer. In the acknowledged mode, RLC peer entities such as an RNC and a UE may exchange various RLC protocol data units (PDUs) including RLC Data PDUs, RLC Status PDUs, and RLC Reset PDUs, among others. In the present disclosure, the term “packet” may refer to any RLC PDU exchanged between RLC peer entities.

The MAC sublayer410provides multiplexing between logical and transport channels. The MAC sublayer410is also responsible for allocating the various radio resources (e.g., resource blocks) in one cell among the UEs. The MAC sublayer410is also responsible for HARQ operations. The MAC sublayer410includes various MAC entities, including but not limited to a MAC-d entity and MAC-hs/ehs entity. The Radio Network Controller (RNC) houses protocol layers from MAC-d and above. For the high speed channels, the MAC-hs/ehs layer is housed in the Node B.

As part of regular call processing, a Node B can release a W-CDMA packet switched (PS) call or connection by sending an RRC Connection Release message (e.g., message240ofFIG. 2) to a UE. In one aspect of the disclosure, the UE and Node B may be the UE110and Node B108ofFIG. 1, respectively. Occasionally, the UE may miss the RRC Connection Release message because of HARQ level retransmission sub-block error rate (SBLER) or due to other network issues. Within a few seconds after the RRC Connection Release message was sent, the network may withdraw all dedicated resources assigned to the UE as part of call clearance of Channel Element (e.g., capacity resources for supporting radio access bearer (RAB) connections). As a result, associated DPCH or EUL resources will no longer be available for the UE. From this point onward, the UE relies on the F-DPCH to determine signal quality such as Signal-to-Interference Ratio Estimate (SIRE) measurements, which are used to determine out-of-sync (OOS) state and radio link (RL) failure state of the UE, to release its own call resources.

With respect to power control commands from the Node-B, a UE is considered out-of-sync (not synchronized) if the DL DPCCH quality or the quality of the TPC fields of the F-DPCH frame received from the serving HS-DSCH cell is worse than an OOS threshold Qoutfor a predetermined period (e.g., 160 ms as defined in 3GPP TS 25.101). A UE is considered in-sync (synchronized) if the quality of the DL DPCCH or the TPC fields of the F-DPCH frame received from the serving HS-DSCH cell over the predetermined period is better than an in-sync threshold Qin(see 3GPP TS 25.101 for more detail).

In general, radio link failure at UE side occurs when it experiences interference and/or poor signal strength leading to disconnection with a Node B. For example, it may be referred to as call drops (e.g., for voice calls), and the radio channel strength is too weak to continue with the applications. In aspects of the disclosure, a UE declares a radio link failure when signal quality from the Node B is below a certain threshold (OOS threshold) for a predetermined number of consecutive occasions or indications. For example, in a UMTS system, radio link failure occurs if after some number N313 of out-of-syncs (e.g., consecutive OOS) have been indicated (N313 being the label of a parameter whose value is the number), less than some number N315 of successive in-syncs are indicated before some number T313 of time periods expire (where the counting toward the number T313 starts from when the N313 consecutive out-of-syncs are indicated). When the timer for T313 expires. A radio link failure occurs.

For F-DPCH, the TPC SIR threshold (Qout) for out-of-sync state as well as TPC SIR threshold (Qin) for in-sync state may be set to the same low values as for the R99 DPCH on some UEs. For example, Qinand Qoutmay be set to −3 dB and −6.50 dB respectively, for both R99 DPCH and F-DPCH. However, the SIRE determined at the UE often cannot reach such low Qoutvalue (e.g., −6.50 dB), even though all dedicated resources have been removed by the network. As a result, the UE may stay in a “dangling” call state for an undesirably long time, e.g., more than a minute, which may cause significant packet switched (PS) activation delay for the next call.

Furthermore, F-DPCH SIR estimation has several limitations. One limitation is that, in F-DPCH, the UE relies on DL TPC symbols for SIR measurement. These TPC symbols are either up or down, in stochastic or random manner. Thus, the UE uses filtered absolute values of raw DL TPC symbols for F-DPCH SIR estimation (SIRE). This is different from R99 DPCH based SIR estimation, where the UE measures the SIR based on dedicated pilot symbols, which have a pattern that is already known to the UE based on the slot format provided at the beginning of the call. Thus, in R99 DPCH, the SIR is estimated based on filtered de-patterned dedicated pilots. Furthermore, F-DPCH is generally noisy due to quantization effects and inclusion of other noise. According to a generally known mathematical derivation, the F-DPCH SIRE is close to the maximum likelihood (ML) estimate when operating under good signal-to-noise ratio (SNR) conditions. However, in poor radio frequency (RF) conditions, the estimate may no longer be sufficiently accurate. This can be illustrated in the following example. Let y be the received filtered amplitude of TPC symbols of an F-DPCH, s and η be the true amplitude of the TPC symbol and the noise effects, respectively, and σ2be the noise variance.
|y|=|s+η|
E{|y|2}=E{|s|2}+σ2

Here, the expected value of the received TPC symbols is different from the expected value of the true TPC symbols by the noise variance. Therefore, it is desirable to correct excess power (bias) experienced in F-DPCH calls due to inaccurate TPC SIRE. There is also another F-DPCH related limitation. In HSPA, the UE may declare OOS based on failures of a cyclic redundancy check (CRC). However, for F-DPCH calls, all the signaling traffic appears in HS-PDSCH, and a UE cannot have CRC-based provision to declare OOS in call maintenance. Therefore, the value of Qoutfor F-DPCH calls need to account for this limitation.

In accordance with various aspects of the present disclosure, a UE implements one or more graceful call release schemes to handle DPCH and F-DPCH calls, which will be described fully below. In one aspect of the disclosure, a UE may configure Qinand Qoutvalues of F-DPCH to be several dB higher than the corresponding threshold values of the R99 DPCH. Suitable values of Qinand Qoutmay be determined based on simulation or actual network measurements. The difference in the Qinand Qoutvalues for the F-DPCH and the R99 DPCH serves to compensate for the quantization and other noise biases caused by limitations of the SIR estimation mechanism in F-DPCH. This mechanism allows the UE to gracefully release calls that have already been terminated by the network.

In another aspect of the disclosure, a UE may use another wrap up event (e.g., a safety clause) to release calls. For example, the UE may automatically or autonomously declare radio link failure and release call resources if the following two conditions are satisfied: (1) if the absolute DL SIRE is less than x dB (or, the SIRE lags the SIR target (SIRT) by a certain amount (e.g., y dB) or greater) for t amount of time, and (2) if UL TPC commands are such that a wind-up situation (i.e., UE sends all up TPC commands to the Node B) persists for the entire time duration t. In one aspect of the disclosure, the UE may automatically or autonomously declare radio link failure and release call resources when the absolute DL SIRE is less than about 6 dB (or the SIRE lags the SIRT by about 6 dB or more) for about 10 seconds.

In implementing the above F-DPCH call handling solutions, several considerations are taken into account. If the UE wishes to compensate for the F-DPCH SIR estimation error, there may be side effects. First, there may be undesirable impact on the outage based F-DPCH outer loop power control. Second, if Qoutis increased too much, call drop rates might increase. Therefore, in some aspects of the disclosure, the UE utilizes a wrap up event as a compromise between noise compensation of SIR estimation error to avoid a “dangling” call state and PDSCH power benefit which sometimes a UE can enjoy and to reduce excessive radio link failure declarations.

In yet another aspect of the disclosure, the UE may localize the condition (2) in the call release mechanism above by gating (e.g., AND-ing) a DL TPC rejection condition (3). In one aspect of the disclosure, condition (2) can occur if z % (e.g., about 90%) of DL TPC commands are rejected. This condition (3) may be used to account for the power control convergence speed difference in F-DPCH, UL Tx Power impact, etc. Therefore, with condition (3), an F-DPCH Qoutvalue higher than that of DPCH may be selected while undesirable frequent call drops may be avoided due to increased Qoutvalue for the F-DPCH.

In yet another aspect of the disclosure, a UE may declare a radio link failure if the number of DL TPC rejections is larger than z % (e.g., about 90%) and the SIRE lags (less than) SIRT by a certain threshold (which may be determined based on simulation or actual network measurements), or, the SIRE falls below an absolute value of x dB (e.g., about 6 dB) for t amount of time (e.g., about 10 seconds), as described above. In one aspect of the disclosure, the t value may be larger than values T314 and T315, which are defined in 3GPP TS 25.331, sections 8.3.1.13 and 8.3.1.13, associated with radio link failure.

Various combinations of the above described call release mechanisms may be used by the UEs depending on the specific system and network requirements.

FIG. 5is a conceptual block diagram of a UE500configured to gracefully handle R99 DPCH and F-DPCH call releases in a W-CDMA network in accordance with an aspect of the disclosure. The UE500may be any of the UEs illustrated inFIGS. 1, 2, and 7. The UE500includes a call processor502, which supports R99 DPCH and F-DPCH calls. The call processor502may be implemented using software, hardware, firmware, or a combination thereof. For example, in one aspect of the disclosure, software503for implementing the call processor502may be stored and executed by a hardware processor of the UE. The call processor502includes a call establisher504, a channel parameter configurator506, an SIR estimator508, and a call release determiner510. In one aspect of the disclosure, the call establisher504may implement procedures and functions for establishing an R99 DPCH call and/or F-DPCH call with a Node B. (e.g., see 3GPP TS 25.221 (Release 1999) for R99 DPCH call establishment and 3GPP TS 25.221 (Release 6) for F-DPCH call establishment.)

In one aspect of the disclosure, the channel parameter configurator506of the call processor502may configure various call parameters of R99 DPCH and F-DPCH calls or connections. In one example, the channel parameter configurator506may configure the Qinand Qoutvalues of F-DPCH to be several decibels (dB) higher than the respective values for R99 DPCH. In one aspect of the disclosure, the channel parameter configurator506may set the Qinand Qoutvalues of R99 DPCH to be −3 dB and −6.50 dB, respectively; and Qinand Qoutvalues of F-DPCH to be −1 dB and −4.50 dB, respectively. These values are merely exemplary and may vary in different system implementations based on simulation, actual network measurements, or various system requirements.

In one aspect of the disclosure, the SIR estimator508may estimate the DL SIR of R99 DPCH and F-DPCH. For example, the SIRE of an R99 DPCH may be determined based on DL dedicated pilot symbols (e.g., pilot302ofFIG. 3) received from a Node B. The SIRE of an F-DPCH may be determined based on DL TPC symbols (e.g., TPC304ofFIG. 3) received from the Node B. In other aspects of the disclosure, different methods may be used to estimate the SIR for R99 DPCH and F-DPCH.

In another aspect of the disclosure, the call release determiner510of the call processor502may be configured to determine when to release R99 DPCH and/or F-DPCH calls. In one aspect of the disclosure, the call release determiner510may declare OOS and release an R99 DPCH or F-DPCH call when the SIRE determined by the SIR estimator508is below the respective R99 DPCH and F-DPCH Qoutvalues set by the channel parameter configurator506. In one aspect of the disclosure, the call release determiner510may release an R99 DPCH or F-DPCH call or a packet switched connection in the absence of an RRC Connection Release message from the Node B or base station within a predetermined time. In one example, the predetermined time may be about 15 seconds.

In another aspect of the disclosure, the call release determiner510of the call processor502may use a wrap up event (e.g., safety clause) as described above to release R99 DPCH and F-DPCH calls. For example, the call release determiner510may declare radio link failure and release call resources if the following two conditions are satisfied: (1) if the absolute DL SIRE is less than x dB (e.g., about 6 dB) (or, the SIRE lags (less than) SIRT target (SIRT) by a certain amount (e.g., y dB or greater, about 6 dB) for t amount of time (e.g., about 10 seconds), and (2) if UL TPC commands are such that a wind-up situation (i.e., UE sends all up TPC commands to the Node B) persists for the entire time duration t.

In yet another aspect of the disclosure, the call release determiner510of the call processor502may declare radio link failure and release R99 DPCH and F-DPCH calls if the TPC rejection values appear to be larger than z % and the SIRE lags the SIRT by a certain threshold (which can be determined based on simulation or actual network measurements), or, the SIRE falls below an absolute value of x dB) for t amount of time, as described above.

FIG. 6is a conceptual diagram illustrating an example of a hardware implementation for an apparatus600employing a processing system614. In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements may be implemented with a processing system614that includes one or more processors604. For example, the apparatus600may be a user equipment (UE) as illustrated in any one or more ofFIGS. 1, 2, 5, and/or7. In another example, the apparatus600may be a radio network controller (RNC) as illustrated inFIG. 1. Examples of processors604include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. That is, the processor604, as utilized in an apparatus600, may be used to implement any one or more of the processes described below and illustrated inFIGS. 8-12.

In this example, the processing system614may be implemented with a bus architecture, represented generally by the bus602. The bus602may include any number of interconnecting buses and bridges depending on the specific application of the processing system614and the overall design constraints. The bus602links together various circuits including one or more processors (represented generally by the processor604), a memory605, and computer-readable media (represented generally by the computer-readable medium606). The bus602may 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 interface608provides an interface between the bus602and a transceiver610. The transceiver610provides a means for communicating with various other apparatus over a transmission medium. Depending upon the nature of the apparatus, a user interface612(e.g., keypad, display, speaker, microphone, joystick, touchscreen, touchpad) may also be provided.

In various aspects of the disclosure, the processor604may be used to implement the call processor502ofFIG. 5, and the computer-readable medium606may be used to store call processing software (e.g., software503) that when executed may configure the apparatus600to perform the various functions described throughout this disclosure as illustrated inFIGS. 8-12.

The processor604is responsible for managing the bus602and general processing, including the execution of software stored on the computer-readable medium606. The software, when executed by the processor604, causes the processing system614to perform the various functions described infra for any particular apparatus. The computer-readable medium606may also be used for storing data that is manipulated by the processor604when executing software.

FIG. 7is a block diagram of an exemplary Node B710in communication with an exemplary UE750, where the Node B710may be the Node B108inFIG. 1, and the UE750may be the UE110inFIG. 1. In other aspects of the disclosure, the UE750may be any of the UEs illustrated inFIGS. 1, 2, and 5. In the downlink communication, a transmit processor720may receive data from a data source712and control signals from a controller/processor740. The transmit processor720provides various signal processing functions for the data and control signals, as well as reference signals (e.g., pilot signals). For example, the transmit processor720may 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 processor744may be used by a controller/processor740to determine the coding, modulation, spreading, and/or scrambling schemes for the transmit processor720. These channel estimates may be derived from a reference signal transmitted by the UE750or from feedback from the UE750. The symbols generated by the transmit processor720are provided to a transmit frame processor730to create a frame structure. The transmit frame processor730creates this frame structure by multiplexing the symbols with information from the controller/processor740, resulting in a series of frames. The frames are then provided to a transmitter732, which provides various signal conditioning functions including amplifying, filtering, and modulating the frames onto a carrier for downlink transmission over the wireless medium through antenna734. The antenna734may include one or more antennas, for example, including beam steering bidirectional adaptive antenna arrays or other similar beam technologies.

At the UE750, a receiver754receives the downlink transmission through an antenna752and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver754is provided to a receive frame processor760, which parses each frame, and provides information from the frames to a channel processor794and the data, control, and reference signals to a receive processor770. The receive processor770then performs the inverse of the processing performed by the transmit processor720in the Node B710. More specifically, the receive processor770descrambles and despreads the symbols, and then determines the most likely signal constellation points transmitted by the Node B710based on the modulation scheme. These soft decisions may be based on channel estimates computed by the channel processor794. 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 sink772, which represents applications running in the UE750and/or various user interfaces (e.g., display). Control signals carried by successfully decoded frames will be provided to a controller/processor790. When frames are unsuccessfully decoded by the receiver processor770, the controller/processor790may 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 source778and control signals from the controller/processor790are provided to a transmit processor780. The data source778may represent applications running in the UE750and various user interfaces (e.g., keyboard). Similar to the functionality described in connection with the downlink transmission by the Node B710, the transmit processor780provides 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 processor794from a reference signal transmitted by the Node B710or from feedback contained in the midamble transmitted by the Node B710, may be used to select the appropriate coding, modulation, spreading, and/or scrambling schemes. The symbols produced by the transmit processor780will be provided to a transmit frame processor782to create a frame structure. The transmit frame processor782creates this frame structure by multiplexing the symbols with information from the controller/processor790, resulting in a series of frames. The frames are then provided to a transmitter756, 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 antenna752.

The uplink transmission is processed at the Node B710in a manner similar to that described in connection with the receiver function at the UE750. A receiver735receives the uplink transmission through the antenna734and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver735is provided to a receive frame processor736, which parses each frame, and provides information from the frames to the channel processor744and the data, control, and reference signals to a receive processor738. The receive processor738performs the inverse of the processing performed by the transmit processor780in the UE750. The data and control signals carried by the successfully decoded frames may then be provided to a data sink739and the controller/processor, respectively. If some of the frames were unsuccessfully decoded by the receive processor, the controller/processor740may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.

The controller/processors740and790may be used to direct the operation at the Node B710and the UE750, respectively. For example, the controller/processors740and790may provide various functions including timing, peripheral interfaces, voltage regulation, power management, and other control functions. The computer readable media of memories742and792may store data and software for the Node B710and the UE750, respectively. A scheduler/processor746at the Node B710may be used to allocate resources to the UEs and schedule downlink and/or uplink transmissions for the UEs.

FIG. 8is a flowchart illustrating a procedure800for gracefully handling R99 DPCH and F-DPCH call release at a UE in a W-CDMA network in accordance with an aspect of the disclosure. In various aspects of the disclosure, the procedure800may be performed by any of the UEs illustrated inFIGS. 1, 2, 5, and 7, which may be implemented using the apparatus600for example. At block802, a UE establishes a packet switched (PS) connection or call between the UE and a base station wherein the PS connection includes an F-DPCH. For example, the PS connection may be an F-DPCH call established between a UE110and a Node B108. At block804, the UE configures an in-sync threshold (Qin) and an out-of-sync threshold (Qout) for the F-DPCH. The values of the Qinand Qoutof F-DPCH are set higher than those of corresponding Qinand Qoutof DPCH. In one example, the Qinand Qoutof F-DPCH may be set to −3 dB and −6.50 dB respectively. At block806, the UE estimates DL SIR based on one or more TPC commands of the F-DPCH. At block808, the UE determines whether to release the PS connection or call based on a comparison of the estimated SIR and Qoutof the F-DPCH. For example, the UE may determine OOS and radio link failure based on the estimated SIR and Qoutas described above to decide when to release the PS connection or call.

FIG. 9is a flowchart illustrating a procedure900for declaring radio link failure at a UE in a W-CDMA network in accordance with an aspect of the disclosure. In various aspects of the disclosure, the procedure900may be performed by any of the UEs illustrated inFIGS. 1, 2, 5, and 7, which may be implemented using the apparatus600for example. At block902, if it is determined that DL SIRE is less than a first threshold for a predetermined period of time, the procedure continues to block904; otherwise, the procedure ends. For example, the first threshold may be x dB (e.g., 6 dB), and the period of time may be t seconds (e.g., about 10 seconds). At block904, if it is determined that the UE sends consecutive up TPC commands (wind-up) for the predetermined period of time, the procedure continues to block906; otherwise, the procedure ends. At block906, the UE declares radio link failure.

FIG. 10is a flowchart illustrating a procedure1000for declaring radio link failure at a UE in a W-CDMA network in accordance with an aspect of the disclosure. In various aspects of the disclosure, the procedure1000may be performed by any of the UEs illustrated inFIGS. 1, 2, 5, and 7, which may be implemented using the apparatus600for example. At block1002, if it is determined that DL SIRE is less than an SIRT by an amount greater than a first threshold for a predetermined period of time, the procedure1000continues to block1004; otherwise, the procedure1000ends. For example, the first threshold may be x dB (e.g., 6 dB), and the period of time may be t seconds (e.g., about 10 seconds). At block1004, if it is determined that the UE sends consecutive up TPC commands (wind-up) for the predetermined period of time, the procedure continues to block1006; otherwise, the procedure ends. At block1006, the UE declares radio link failure.

FIG. 11is a flowchart illustrating a procedure1100for declaring radio link failure at a UE in a W-CDMA network in accordance with an aspect of the disclosure. In various aspects of the disclosure, the procedure1100may be performed by any of the UEs illustrated inFIGS. 1, 2, 5, and 7, which may be implemented using the apparatus600for example. At block1102, if it is determined that DL SIRE is less than a first threshold for a predetermined period of time, the procedure continues to block1104; otherwise, the procedure ends. For example, the first threshold may be x dB (e.g., about 6 dB), and the period of time is t seconds (e.g., about 10 seconds). At block1104, if it is determined that the UE sends consecutive up TPC commands (wind-up) for the predetermined period of time, the procedure continues to block1106; otherwise, the procedure ends. At block1106, if it is determined that a number of DL TPC commands rejected by the UE is greater than a second threshold, the procedure continues to block1108; otherwise, the procedure ends. For example, the second threshold may be z % (e.g., about 90%). At block1108, the UE declares radio link failure.

FIG. 12is a flowchart illustrating a procedure1200for declaring radio link failure at a UE in a W-CDMA network in accordance with an aspect of the disclosure. In various aspects of the disclosure, the procedure1200may be performed by any of the UEs illustrated inFIGS. 1, 2, 5, and 7, which may be implemented using the apparatus600, for example. At block1202, if it is determined that a number of DL TPC commands rejected by the UE is greater than a first threshold, the procedure continues to blocks1204and/or1206; otherwise, the procedure ends. The first threshold may be z % (e.g., about 90%). At block1204, if it is determined that SIRE is less than SIRT by a second threshold for a predetermined period of time, the procedure continues to block1208; otherwise, the procedure ends. For example, the second threshold may be x dB (e.g., 6 dB), and the predetermined period of time may be t seconds (e.g., about 10 seconds). At block1206, if it is determined that SIRE is less than a third threshold for the predetermined period of time, the procedure continues to block1208. For example, the third threshold may be y dB (e.g., about 6 dB). At block1208, the UE declares radio link failure.

In various aspects of the disclosure, the methods and procedures illustrated inFIGS. 8-12may be performed in various orders different from those illustrated in the figures. In some aspects of the disclosure, some or all of the steps illustrated inFIGS. 8-12may be performed to handle DPCH and F-DPCH calls at any of the UEs illustrated inFIGS. 1, 2, 5, and/or7.

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.