Methods and apparatus to reduce a time to transfer multiple PDN contexts during inter-radio access technology handoff

Aspects of the present disclosure provide apparatus and methods to reduce the time taken to perform multiple packet data network (PDN) context transfers during inter-radio access technology (IRAT) scenarios. Certain aspects provide methods and apparatus for wireless communication by a device capable of communicating in at least a first and second RAT networks. The device may have multiple PDN contexts established in the first RAT network. As part of a transition to the second RAT network, the mobile device may transmit a single signaling message that indicates at least two of the PDN contexts to be transferred. In some aspects, the single signaling message may also indicate a new PDN context to be established as part of the transition.

BACKGROUND

Certain aspects of the present disclosure generally relate to wireless communications and, more particularly, to reducing a time taken to perform multiple packet data network (PDN) context transfers during an inter-radio access technology (IRAT) handoff.

Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. The forward communication link and the reverse communication link may be established via a single-input single-output, multiple-input single-output or a multiple-input multiple-output system.

A wireless multiple-access communication system can support a time division duplex (TDD) and frequency division duplex (FDD) systems. In a TDD system, the forward and reverse link transmissions are on the same frequency region so that the reciprocity principle allows the estimation of the forward link channel from the reverse link channel. This enables the access point to extract transmit beamforming gain on the forward link when multiple antennas are available at the access point.

The 3GPP LTE represents a major advance in cellular technology and it is a next step forward in cellular 3rdgeneration (3G) services as a natural evolution of Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UMTS). The LTE provides for an uplink speed of up to 75 megabits per second (Mbps) and a downlink speed of up to 300 Mbps, and brings many technical benefits to cellular networks. The LTE is designed to meet carrier needs for high-speed data and media transport as well as high-capacity voice support. The bandwidth may be scalable from 1.25 MHz to 20 MHz. This suits the requirements of different network operators that have different bandwidth allocations, and also allows operators to provide different services based on spectrum. The LTE is also expected to improve spectral efficiency in 3G networks, allowing carriers to provide more data and voice services over a given bandwidth.

Physical layer (PHY) of the LTE standard is a highly efficient means of conveying both data and control information between an enhanced base station (eNodeB) and mobile user equipment (UE). The LTE PHY employs advanced technologies that are new to cellular applications. These include Orthogonal Frequency Division Multiplexing (OFDM) and Multiple Input Multiple Output (MIMO) data transmission. In addition, the LTE PHY uses OFDMA on the downlink and Single Carrier-Frequency Division Multiple Access (SC-FDMA) on the uplink. OFDMA allows data to be directed to or from multiple users on a subcarrier-by-subcarrier basis for a specified number of symbol periods.

SUMMARY

Certain aspects of the present disclosure provide a method for wireless communication by a device capable of communicating in at least first and second radio access technology (RAT) networks. The method generally includes communicating in the first RAT network with connectivity with a plurality of packet data network (PDN) contexts and as part of a transition to the second RAT network, and sending a single signaling message that indicates at least two of the plurality of PDN contexts.

Certain aspects of the present disclosure provide a method for wireless communication with a device capable of communicating in at least first and second radio access technology (RAT) networks. The method generally includes receiving, as part of a transition of the device from the first RAT network to the second RAT network, a single signaling message from the device that indicates multiple PDN contexts with which the device was communicating in the first RAT network, and processing the single signaling message to transfer the multiple PDN contexts from the first RAT network to the second RAT network.

Certain aspects of the present disclosure provide an apparatus for wireless communication capable of communicating in at least first and second radio access technology (RAT) networks. The apparatus generally includes means for communicating in the first RAT network with connectivity with a plurality of packet data network (PDN) contexts and means for sending a single signaling message that indicates at least two of the plurality of PDN contexts, as part of a transition to the second RAT network.

Certain aspects of the present disclosure provide an apparatus for wireless communication with a device capable of communicating in at least first and second radio access technology (RAT) networks. The apparatus generally includes means for receiving, as part of a transition of the device from the first RAT network to the second RAT network, a single signaling message from the device that indicates multiple PDN contexts with which the device was communicating in the first RAT network and means for processing the single signaling message to transfer the multiple PDN contexts from the first RAT network to the second RAT network.

In an aspect of the disclosure, an apparatus for wireless communications is provided. The apparatus generally includes at least one processor and a memory coupled to the at least one processor. The at least one processor is generally configured to communicate in the first RAT network with connectivity with a plurality of packet data network (PDN) contexts, and as part of a transition to the second RAT network, send a single signaling message that indicates at least two of the plurality of PDN contexts.

In an aspect of the disclosure, an apparatus for wireless communications is provided. The apparatus generally includes at least one processor and a memory coupled to the at least one processor. The at least one processor is generally configured to receive, as part of a transition of the device from the first RAT network to the second RAT network, a single signaling message from the device that indicates multiple PDN contexts with which the device was communicating in the first RAT network, and process the single signaling message to transfer the multiple PDN contexts from the first RAT network to the second RAT network.

Certain aspects of the present disclosure provide a computer-program product for wireless communications by a device capable of communicating in at least first and second radio access technology (RAT) networks. The computer-program product generally includes a non-transitory computer-readable medium having code stored thereon. The code is generally executable by one or more processors for communicating in a first RAT network with connectivity with a plurality of packet data network (PDN) contexts and, as part of a transition to the second RAT network, sending a single signaling message that indicates at least two of the plurality of PDN contexts.

Certain aspects of the present disclosure provide a computer-program product for wireless communications with a device capable of communicating in at least first and second radio access technology (RAT) networks. The computer-program product generally includes a non-transitory computer-readable medium having code stored thereon. The code is generally executable by one or more processors for receiving, as part of a transition of the device from the first RAT network to a second RAT network, a single signaling message from a device that indicates multiple PDN contexts with which the device was communicating in the first RAT network and processing the single signaling message to transfer the multiple PDN contexts from the first RAT network to the second RAT network.

DETAILED DESCRIPTION

Aspects of the present disclosure generally relate to minimizing the time taken to perform multiple PDN context transfers when a multi-mode mobile device moves from one RAT network to another RAT network. As will be described in more detail below, the mobile device may, as part of a transition from a first RAT network to a second RAT network, send a single signaling message that indicates multiple PDN contexts that may need to be transferred to the second RAT.

According to aspects, the second RAT network may receive, as part of a transition of the device to the second RAT network, a single signaling message from the mobile device that indicates multiple PDN contexts with which the device was communicating in the first RAT network. The second network may process the single signaling message to transfer the multiple contexts from the first RAT to the second RAT. As will be described in more detail below, the network may transfer multiple PDN contexts in parallel or one at a time. Employing a single signaling message rather than a separate signaling message for each context may reduce a call setup time.

An Example Wireless Communication System

An access point (“AP”) may comprise, be implemented as, or known as NodeB, Radio Network Controller (“RNC”), eNodeB (“eNB”), Base Station Controller (“BSC”), Base Transceiver Station (“BTS”), Base Station (“BS”), Transceiver Function (“TF”), Radio Router, Radio Transceiver, Basic Service Set (“BSS”), Extended Service Set (“ESS”), Radio Base Station (“RBS”), or some other terminology.

Referring toFIG. 1, a multiple access wireless communication system according to one aspect of the present disclosure is illustrated. An access point100(AP) may include multiple antenna groups, one group including antennas104and106, another group including antennas108and110, and an additional group including antennas112and114. InFIG. 1, only two antennas are shown for each antenna group, however, more or fewer antennas may be utilized for each antenna group. Access terminal116(AT) may be in communication with antennas112and114, where antennas112and114transmit information to access terminal116over forward link120and receive information from access terminal116over reverse link118. Access terminal122may be in communication with antennas106and108, where antennas106and108transmit information to access terminal122over forward link126and receive information from access terminal122over reverse link124. In a FDD system, communication links118,120,124and126may use different frequency for communication. For example, forward link120may use a different frequency than that used by reverse link118.

Each group of antennas and/or the area in which they are designed to communicate is often referred to as a sector of the access point. In one aspect of the present disclosure each antenna group may be designed to communicate to access terminals in a sector of the areas covered by access point100.

In communication over forward links120and126, the transmitting antennas of access point100may utilize beamforming in order to improve the signal-to-noise ratio of forward links for the different access terminals116and124. Also, an access point using beamforming to transmit to access terminals scattered randomly through its coverage causes less interference to access terminals in neighboring cells than an access point transmitting through a single antenna to all its access terminals.

FIG. 2illustrates a block diagram of an aspect of a transmitter system210(also known as the access point) and a receiver system250(also known as the access terminal) in a multiple-input multiple-output (MIMO) system200. At the transmitter system210, traffic data for a number of data streams is provided from a data source212to a transmit (TX) data processor214.

At receiver system250, the transmitted modulated signals may be received by NRantennas252athrough252rand the received signal from each antenna252may be provided to a respective receiver (RCVR)254athrough254r. Each receiver254may condition (e.g., filters, amplifies, and downconverts) a respective received signal, digitize the conditioned signal to provide samples, and further process the samples to provide a corresponding “received” symbol stream.

A processor270periodically determines which pre-coding matrix to use. Processor270formulates a reverse link message comprising a matrix index portion and a rank value portion. The reverse link message may comprise various types of information regarding the communication link and/or the received data stream. The reverse link message is then processed by a TX data processor238, which also receives traffic data for a number of data streams from a data source236, modulated by a modulator280, conditioned by transmitters254athrough254r, and transmitted back to transmitter system210.

FIG. 3illustrates various components that may be utilized in a wireless device302that may be employed within the wireless communication system fromFIG. 1. The wireless device302is an example of a device that may be configured to implement the various methods described herein. The wireless device302may be an access point100fromFIG. 1or any of access terminals116,122.

The wireless device302may include a processor304which controls operation of the wireless device302. The processor304may also be referred to as a central processing unit (CPU). Memory306, which may include both read-only memory (ROM) and random access memory (RAM), provides instructions and data to the processor304. A portion of the memory306may also include non-volatile random access memory (NVRAM). The processor304typically performs logical and arithmetic operations based on program instructions stored within the memory306. The instructions in the memory306may be executable to implement the methods described herein.

The wireless device302may also include a housing308that may include a transmitter310and a receiver312to allow transmission and reception of data between the wireless device302and a remote location. The transmitter310and receiver312may be combined into a transceiver314. A single or a plurality of transmit antennas316may be attached to the housing308and electrically coupled to the transceiver314. The wireless device302may also include (not shown) multiple transmitters, multiple receivers, and multiple transceivers.

The wireless device302may also include a signal detector318that may be used in an effort to detect and quantify the level of signals received by the transceiver314. The signal detector318may detect such signals as total energy, energy per subcarrier per symbol, power spectral density and other signals. The wireless device302may also include a digital signal processor (DSP)320for use in processing signals.

The various components of the wireless device302may be coupled together by a bus system322, which may include a power bus, a control signal bus, and a status signal bus in addition to a data bus.

FIG. 4illustrates an example network architecture400, according to aspects of the present disclosure. A multi-mode user-equipment402, such as UE116and/or122ofFIG. 1, may communicate with one or more RATs. UE402may communicate with, a Long Term Evolution (LTE) network and an enhanced High Rate Packet Data (eHRPD) network. UE402may communicate with, for example, LTE eNB404and eHRPD radio access network (RAN)406.

LTE eNB404and eHRPD RAN406may use an EPC (3GPP) core network for Internet Protocol (IP) services. Mobility Management Entity (MME)408and HRPD serving gateway (HSGW)410may communicate with a Packet Data Network (PDN) Gateway412. MME408for LTE and HSGW410for eHRPD may assign an IP address to UE402after receiving it from the PDN Gateway412. MME408, HSGW410, and PDN Gateway412may be considered part of the Evolved Packet Core (EPC).

A multi-mode mobile device may perform multiple Packet Data Network (PDN) context transfers during inter-RAT (IRAT) scenarios. Traditionally, single shot signaling techniques to transfer multiple PDN contexts are not available. For example, as will be described with reference toFIGS. 5-6, a mobile device capable of supporting LTE and Evolved High Rate Packet Data (eHRPD) technologies may perform multiple-PDN context transfers during an inter-RAT scenario, which may lead to delays in PDN context transfers and may degrade a user's experience.

FIG. 5illustrates an example500of transferring multiple PDN contexts during handover from an LTE network502to an eHRPD network504. As illustrated, a multi-mode mobile device may communicate in the LTE network502and have connectivity with a number of PDN contexts. The mobile device may be connected to, for example, an IP Multimedia Subsystem (IMS) PDN, Internet PDN, and/or Administrative PDN (e.g., Provisioning PDN).

At508, the mobile device may handover from the LTE network502to the eHRPD network504. Currently, the mobile device may have to exchange a Point-to-Point Protocol Vendor-Specific Network Control Protocol (PPP/VSNCP) signaling message to transfer each PDN context from LTE to eHRPD. More specifically, the mobile device may transmit a separate VSNCP configuration request message to an HRPD Serving Gateway (HSGW)506for each PDN context established in the LTE network502. Transmitting multiple PPP/VSNCP signaling messages may lead to delays in PDN context transfers. HSGW506may transmit a configuration acknowledgment message for each PDN context before each PDN context is set up in the eHRPD network504.

FIG. 6illustrates an example600of transferring multiple PDN contexts during handover from an eHRPD network602to an LTE network604. As illustrated, a multi-mode mobile device may communicate in the eHRPD network602with connectivity with multiple PDN contexts. For example, the mobile device may be connected to an IMS PDN, Internet PDN, and/or Administrative PDN.

At608, the mobile device may handover from the eHRPD network602to the LTE network604. Similar to the scenario illustrated inFIG. 5, the mobile device may have to exchange multiple signaling messages to transfer the multiple PDN contexts.

While connected to the LTE network604, the mobile device may transmit several Network Access Stratum (NAS) signaling messages to a Mobility Management Entity/PDN Gateway (MME/PGW)606to transfer PDN contexts from the eHRPD602network. The specific signaling messages depicted inFIG. 6are illustrative of an example set of messages exchanged between a mobile device and the MME/PGW606to transfer multiple PDN contexts.

The mobile device may have to wait until the completion of the Attach Request before other PDN contexts may be transferred. This may degrade user experience, for example, in cases where other PDN contexts belong to an Internet Access Point Name (APN). If there are delays during the attach PDN setup completion due to, for example, LTE radio conditions, then the Internet APN and setup for other APNs may be delayed further or disconnected. The mobile device may have to make a priority call based on which application needs service first and, accordingly, which subsequent PDN is activated second, third, fourth, and so on.

Accordingly, aspects of the present disclosure provide techniques to reduce and/or minimize the time taken to perform multiple PDN context transfers during IRAT scenarios. As will be described in more detail below, single-shot signaling may be used to bundle multiple PDN context transfer requests. A network may receive the single-shot signaling message and may transfer multiple PDN contexts. The single-shot signaling message may indicate a number of the PDN contexts to be transferred as part of the transition.

FIG. 7illustrates example operations700, which may be performed by a mobile device capable of communicating in at least first and second RAT networks, according to aspects of the present disclosure. The operations700may be performed, for example, by a multi-mode mobile device, such as UE402ofFIG. 4.

At702, the mobile device may communicate in the first RAT network with connectivity with a plurality of packet data network (PDN) contexts. As part of a transition to the second RAT network, at704, the mobile device may send a single signaling message that indicates at least two of the plurality of PDN contexts.

FIG. 8illustrates example operations800, which may be performed by a RAT network, according to aspects of the present disclosure. The operations800may be performed, for example, by HSGW410or MME408ofFIG. 4.

At802, the network may receive, as part of a transition of the device from the first RAT network to the second RAT network, a single signaling message from the device that indicates multiple PDN contexts with which the device was communicating in the first RAT network. At804, the network may process the single signaling message to transfer the multiple PDN contexts from the first RAT network to the second RAT network.

FIG. 9illustrates an example900of IRAT improvement when a mobile device performs a handover from an LTE network902to an eHRPD network904, according to aspects of the present disclosure. The mobile device may communicate with multiple PDN contexts in the LTE network902, including an IMS PDN, Internet PDN, and/or Administrative PDN.

At908, the mobile device may handover from the LTE network902to the eHRPD network904. To facilitate IRAT improvement (e.g., optimization), the mobile device may transmit a single Vendor-Specific Network Control Protocol (VSNCP) Configuration Request Message910, wherein the message may indicate two or more PDN contexts that may be transferred to the eHRPD network904. Accordingly, the mobile device may transmit a single signaling message which includes a handover attach request message with a plurality of PDN connectivity requests. As illustrated inFIG. 9, the mobile device may transmit a single VSNCP singling message that indicates transfer of the IMS, Internet, and Administrative PDN contexts to the eHRPD network.

The HSGW906may receive the single signaling message that includes a handover attach request message with a plurality of PDN connectivity requests. According to aspects, the single signaling message may include a parameter which indicates a number the number of PDN contexts to be transferred from the LTE network902to the eHRPD network904.

At912, the HSGW906may transmit a VSNCP Configuration Acknowledgment for transferring multiple PDN contexts. According to aspects, at least two of the PDNs may be activated together. As illustrated inFIG. 9, the IMS PDN, Internet PDN, and Administrative PDN may be activated together (e.g., in parallel).

FIG. 10illustrates an example1000of IRAT improvement when a mobile device performs a handover from an eHRPD network1002to an LTE network1004, according to aspects of the present disclosure. The mobile device may communicate with multiple PDN contexts in the eHRPD network1002, including, for example, an IMS PDN, Internet PDN, and Administrative PDN.

At1008, the mobile device may handover from the eHRPD network1002to the LTE network1004. To facilitate IRAT improvement, the mobile device may transfer the IMS, Internet, and Administrative PDN contexts to the LTE network1004. According to aspects, the mobile device may transmit a single NAS signaling message to the MME/PGW1006.

The single signaling message may include a Handover Attach Request, a parameter indicating the number of PDN contexts attempting to be transferred to the LTE network1004, and/or parameters specific to the transfer for each PDN context. The MME/PGW1006may receive the single signaling message and may activate multiple PDNs together. For example, the IMS PDN, Internet PDN, and Administrative PDN may be activated in parallel.

FIG. 11illustrates an example1100of IRAT improvement when a mobile device moves from an eHRPD network1102to an LTE network1104, according to aspects of the present disclosure. The mobile device may be communicating with multiple PDN contexts in the eHRPD network1102, including, for example, an IMS PDN, Internet PDN, and Administrative PDN. At1108, the mobile device may handover from the eHRPD network1102to the LTE network1104.

The MME/PGW1106may receive a single Handover Attach Request message from the mobile device. As described above with reference toFIG. 10, the Handover Attach Request message may include connectivity requests for more than one PDN context transfer.

According to aspects, the MME/PGW1106may receive the single signaling message and activate each PDN individually. Activating each PDN context individually may provide the network with flexibility, for example, in situations when the network may be unable to activate two or more transferred PDN contexts at the same time (e.g., in parallel). In these cases, after receiving the single Handover Attach Request message, MME/PGW1106may activate transferred PDN contexts separately. As illustrated, the IMS PDN context may be transferred first, followed by the Internet PDN context and Administrative PDN context.

FIG. 12illustrates an example1200of IRAT improvement when a mobile device moves from an eHRPD network1202to an LTE network1204, according to aspects of the present disclosure. The mobile device may be communicating in the eHRPD network1202with connectivity with an Internet PDN and Administrative PDN. At1208, the mobile device may handover from the eHRPD network1202to the LTE network1204. As part of the handover, the mobile device may transmit a single signaling message that indicates at least two PDN contexts to be transferred. According to aspects, the single signaling message may further indicate that a new PDN context is to be activated as part of the transition.

For example, the mobile device may attempt to transfer the active Internet PDN and Administrative PDN contexts and may set up a new IMS PDN context. Each of the plurality of PDN contexts and the new PDN context (e.g., IMS PDN) may be activated together. According to aspects, at least two of the PDN contexts, including the new PDN context to be established and the plurality of PDN contexts already established, may be activated together.

As illustrated inFIG. 12, the mobile device may transmit an Initial Attach Request Message to the MME/PGW1206. According to aspects, the Initial Attach Request Message may include a connectivity request for a PDN context that the mobile device had not established in the eHRPD network1202. For example, the Initial Attach Request Message may include a PDN connectivity request for setting up a new IMS PDN context. The signaling messages shown for setting up the new IMS PDN context in the LTE network1204are illustrative of an example set of signaling messages. According to aspects, fewer signaling messages may be exchanged while setting up a context in the LTE network1204.

According to aspects, after the IMS PDN context is established, the mobile device may transmit a single signaling message containing a handover attach request message with a plurality of PDN connectivity requests. The single signaling message may include a count parameter indicating the number of PDN contexts attempting to be transferred to the LTE network1204. The handover attach message may include PDN connectivity requests for the Internet PDN and Administrative PDN. The MME1206may activate the Internet PDN and Administrative PDN contexts in parallel.

As described herein, a mobile device may be communicating in a first RAT network with established connectivity with a plurality of PDN contexts. As part of a transition to a second RAT network, the mobile device may send a single signaling message that indicates at least two of the PDN contexts to be transferred. In some aspects, a signaling message may be employed to indicate an IMS PDN context to be transferred. Thereafter, a single signaling message may be employed to indicate at least two other PDN contexts (e.g., Internet PDN, Administrative PDN) to be transferred.

According to aspects, at least one of the first and second RAT networks may be an LTE network and at least one of the first and second RAT networks may be an eHRPD network. Aspects of the present disclosure may be extended between LTE and UMTS Packet Data Protocol (PDP) context transfers. For example, according to aspects, at least one of the first and second RATs may include at one of an eHRPD network or a UMTS network.

In certain aspects, the single signaling message may comprise a handover attach request message with a plurality of PDN connectivity requests. As described above, each PDN may be activated individually. Alternatively, at least two of the PDNs may be activated together, which may facilitate IRAT improvement.

Various techniques are described herein with reference to an LTE and eHRPD network as a specific, but not limiting, example of a network in which the techniques may be used. However, those skilled in the art will appreciate that the techniques may be applied more generally in various types of wireless networks.

Although several scenarios refer to transferring an IMS, Internet, and Administrative (e.g., Provisioning) PDN context from a first RAT to a second RAT, those skilled in the art will appreciate that the techniques described herein may be applied to transferring any type of PDN context. PDN contexts may include, for example, carrier-specific PDNs, operator-specific, and/or GPS PDN, as well as any other PDN context. For example, the plurality of PDN contexts to be transferred may include at least two of an IP Multimedia Subsystem (IMS), provisioning, operator-specific, carrier-specific, or GPS PDN contexts. Such services may be orthogonal to each other.