Patent Description:
Embodiments pertain to wireless communications. Some embodiments relate to wireless networks including 3GPP (Third Generation Partnership Project) networks, 3GPP LTE (Long Term Evolution) networks, and 3GPP LTE-A (LTE Advanced) networks, although the scope of the embodiments is not limited in this respect. Some embodiments relate to packet-switched (PS) networks. Some embodiments relate to circuit-switched (CS) networks. Some embodiments relate to mobile devices that support operation in PS networks and/or CS networks.

A mobile network may support communication with mobile devices. In some cases, a mobile device may experience degradation in performance for any number of reasons. As an example, the mobile device may be out of coverage of base stations in the network. As another example, the network may experience congestion or other issues. In these and other scenarios, a performance of the device and/or a user experience may suffer.

Accordingly, there is a general need for methods and systems for improving performance in these and other scenarios,.

<CIT> is considered as relevant prior art.

The following description and the drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Portions and features of some embodiments may be included in, or substituted for, those of other embodiments.

<FIG> is a functional diagram of a 3GPP network in accordance with some embodiments. It should be noted that embodiments are not limited to the example 3GPP network shown in <FIG>, as other networks may be used in some embodiments. Such networks may or may not include some or all of the components shown in <FIG>, and may include additional components and/or alternative components in some cases.

The network comprises a radio access network (RAN) (e.g., as depicted, the E-UTRAN or evolved universal terrestrial radio access network) <NUM> and the core network <NUM> (e.g., shown as an evolved packet core (EPC)) coupled together through an S1 interface <NUM>. For convenience and brevity sake, only a portion of the core network <NUM>, as well as the RAN <NUM>, is shown.

The core network <NUM> includes a mobility management entity (MME) <NUM>, a serving gateway (serving GW) <NUM>, and packet data network gateway (PDN GW) <NUM>. The RAN <NUM> includes Evolved Node-B's (eNBs) <NUM> (which may operate as base stations) for communicating with User Equipment (UE) <NUM>. The eNBs <NUM> may include macro eNBs and low power (LP) eNBs.

In some embodiments, the UE <NUM> may exchange data signals, control signals and/or other signals with the eNB <NUM>. The signals may be exchanged, in some embodiments, according to one or more packet-switched (PS) techniques, including but not limited to Evolved Packet System (EPS) techniques. These embodiments will be described in more detail below.

The MME <NUM> is similar in function to the control plane of legacy Serving GPRS Support Nodes (SGSN). The MME <NUM> manages mobility aspects in access such as gateway selection and tracking area list management. The serving GW <NUM> terminates the interface toward the RAN <NUM>, and routes data packets between the RAN <NUM> and the core network <NUM>. In addition, it may be a local mobility anchor point for inter-eNB handovers and also may provide an anchor for inter-3GPP mobility. The serving GW <NUM> and the MME <NUM> may be implemented in one physical node or separate physical nodes. The PDN GW <NUM> terminates an SGi interface toward the packet data network (PDN). The PDN GW <NUM> routes data packets between the EPC <NUM> and the external PDN, and may be a key node for policy enforcement and charging data collection. It may also provide an anchor point for mobility with non-LTE accesses. The external PDN can be any kind of IP network, as well as an IP Multimedia Subsystem (IMS) domain. The PDN GW <NUM> and the serving GW <NUM> may be implemented in one physical node or separated physical nodes.

The eNBs <NUM> (macro and micro) terminate the air interface protocol and may be the first point of contact for a UE <NUM>. In some embodiments, an eNB <NUM> may fulfill various logical functions for the RAN <NUM> including but not limited to RNC (radio network, controller functions) such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management. In accordance with embodiments, UEs <NUM> may be configured to communicate Orthogonal Frequency Division Multiplexing (OFDM) communication signals with an eNB <NUM> over a multicarrier communication channel in accordance with an Orthogonal Frequency Division Multiple Access (OFDMA) communication technique. The OFDM signals may comprise a plurality of orthogonal subcarriers.

The S1 interface <NUM> is the interface that separates the RAN <NUM> and the EPC <NUM>. It is split into two parts: the S1-U, which carries traffic data between the eNBs <NUM> and the serving GW <NUM>, and the S1-MME, which is a signaling interface between the eNBs <NUM> and the MME <NUM>. The X2 interface is the interface between eNBs <NUM>. The X2 interface comprises two parts, the X2-C and X2-U. The X2-C is the control plane interface between the eNBs <NUM>, while the X2-U is the user plane interface between the eNBs <NUM>.

With cellular networks, LP cells are typically used to extend coverage to indoor areas where outdoor signals do not reach well, or to add network capacity in areas with very dense phone usage, such as train stations. As used herein, the term low power (LP) eNB refers to any suitable relatively low power eNB for implementing a narrower cell (narrower than a macro cell) such as a femtocell, a picocell, or a micro cell. Femtocell eNBs are typically provided by a mobile network operator to its residential or enterprise customers. A femtocell is typically the size of a residential gateway or smaller and generally connects to the user's broadband line. Once plugged in, the femtocell connects to the mobile operator's mobile network and provides extra coverage in a range of typically <NUM> to <NUM> meters for residential femtocells. Thus, a LP eNB might be a femtocell eNB since it is coupled through the PDN GW <NUM>. Similarly, a picocell is a wireless communication system typically covering a small area, such as in-building (offices, shopping malls, train stations, etc.), or more recently in-aircraft. A picocell eNB can generally connect through the X2 link to another eNB such as a macro eNB through its base station controller (BSC) functionality. Thus, LP eNB may be implemented with a picocell eNB since it is coupled to a macro eNB via an X2 interface. Picocell eNBs or other LP eNBs may incorporate some or all functionality of a macro eNB. In some cases, this may be referred to as an access point base station or enterprise femtocell.

In some embodiments, a downlink resource grid may be used for downlink transmissions from an eNB <NUM> to a UE <NUM>, while uplink transmission from the UE <NUM> to the eNB <NUM> may utilize similar techniques. The grid may be a time-frequency grid, called a resource grid or time-frequency resource grid, which is the physical resource in the downlink in each slot. Each column and each row of the resource grid correspond to one OFDM symbol and one OFDM subcarrier, respectively. The smallest time-frequency unit in a resource grid is denoted as a resource element (RE). Each resource grid comprises a number of resource blocks (RBs), which describe the mapping of certain physical channels to resource elements. Each resource block comprises a collection of resource elements in the frequency domain and may represent the smallest quanta of resources that currently can be allocated. With particular relevance to this disclosure, two of these physical downlink channels are the physical downlink shared channel and the physical down link control channel.

The physical downlink shared channel (PDSCH) carries user data and higher-layer signaling to a UE <NUM> (<FIG>). The physical downlink control channel (PDCCH) carries information about the transport format and resource allocations related to the PDSCH channel, among other things. It also informs the UE <NUM> about the transport format, resource allocation, and hybrid automatic repeat request (HARQ) information related to the uplink shared channel. Typically, downlink scheduling (e.g., assigning control and shared channel resource blocks to UEs <NUM> within a cell) may be performed at the eNB <NUM> based on channel quality information fed back from the UEs <NUM> to the eNB <NUM>, and then the downlink resource assignment information may be sent to a UE <NUM> on the control channel (PDCCH) used for (assigned to) the UE <NUM>.

The PDCCH uses CCEs (control channel elements) to convey the control information. Before being mapped to resource elements, the PDCCH complex-valued symbols are first organized into quadruplets, which are then permuted using a sub-block inter-leaver for rate matching. Each PDCCH is transmitted using one or more of these control channel elements (CCEs), where each CCE corresponds to nine sets of four physical resource elements known as resource element groups (REGs). Four QPSK symbols are mapped to each REG. The PDCCH can be transmitted using one or more CCEs, depending on the size of DCI and the channel condition. There may be four or more different PDCCH formats defined in LTE with different numbers of CCEs (e.g., aggregation level, L=<NUM>, <NUM>, <NUM>, or <NUM>).

Embodiments described herein may be implemented into a system using any suitably configured hardware and/or software.

<FIG> illustrates a block diagram of an example machine in accordance with some embodiments. The machine <NUM> is an example machine upon which any one or more of the techniques and/or methodologies discussed herein may be performed. The machine <NUM> may be a UE <NUM>, eNB <NUM>, access point (AP), station (STA), mobile device, base station, personal computer (PC), a tablet PC, a set-top box (STB), a personal digital assistant (PDA), a mobile telephone, a smart phone, a web appliance, a network router, switch or bridge, or any machine capable of executing instructions (sequential or otherwise) that specify actions to be taken by that machine.

Examples as described herein, may include, or may operate on, logic or a number of components, modules, or mechanisms.

The machine (e.g., computer system) <NUM> may include a hardware processor <NUM> (e.g., a central processing unit (CPU), a graphics processing unit (GPU), a hardware processor core, or any combination thereof), a main memory <NUM> and a static memory <NUM>, some or all of which may communicate with each other via an interlink (e.g., bus) <NUM>. The machine <NUM> may include an output controller <NUM>, such as a serial (e.g., universal serial bus (USB), parallel, or other wired or wireless (e.g., infrared (IR), near field communication (NFC), etc.) connection to communicate or control one or more peripheral devices (e.g., a printer, card reader, etc.).

In some embodiments, the machine readable medium may be or may include a non-transitory computer-readable storage medium.

The term "machine readable medium" may include any medium that is capable of storing, encoding, or carrying instructions for execution by the machine <NUM> and that cause the machine <NUM> to perform any one or more of the techniques of the present disclosure, or that is capable of storing, encoding or carrying data structures used by or associated with such instructions. Non-limiting machine readable medium examples may include solid-state memories, and optical and magnetic media. Specific examples of machine readable media may include: non-volatile memory, such as semiconductor memory devices (e.g., Electrically Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM)) and flash memory devices, magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; Random Access Memory (RAM); and CD-ROM and DVD-ROM disks. In some examples, machine readable media may include non-transitory machine readable media. In some examples, machine readable media may include machine readable media that is not a transitory propagating signal.

The instructions <NUM> may further be transmitted or received over a communications network <NUM> using a transmission medium via the network interface device <NUM> utilizing any one of a number of transfer protocols (e.g., frame relay, internet protocol (IP), transmission control protocol (TCP), user datagram protocol (UDP), hypertext transfer protocol (HTTP), etc.). Example communication networks may include a local area network (LAN), a wide area network (WAN), a packet data network (e.g., the Internet), mobile telephone networks (e.g., cellular networks), Plain Old Telephone (POTS) networks, and wireless data networks (e.g., Institute of Electrical and Electronics Engineers (IEEE) <NUM> family of standards known as Wi-Fi®, IEEE <NUM> family of standards known as WiMax®), IEEE <NUM>. <NUM> family of standards, a Long Term Evolution (LTE) family of standards, a Universal Mobile Telecommunications System (UMTS) family of standards, peer-to-peer (P2P) networks, among others. In an example, the network interface device <NUM> may include one or more physical jacks (e.g., Ethernet, coaxial, or phone jacks) or one or more antennas to connect to the communications network <NUM>. In an example, the network interface device <NUM> may include a plurality of antennas to wirelessly communicate using at least one of single-input multiple-output (SIMO), multiple-input multiple-output (MIMO), or multiple-input single-output (MISO) techniques. In some examples, the network interface device <NUM> may wirelessly communicate using Multiple User MIMO techniques. The term "transmission medium" shall be taken to include any intangible medium that is capable of storing, encoding or carrying instructions for execution by the machine <NUM>, and includes digital or analog communications signals or other intangible medium to facilitate communication of such software.

<FIG> is a block diagram of an Evolved Node-B (eNB) in accordance with some embodiments. It should be noted that in some embodiments, the eNB <NUM> may be a stationary non-mobile device. The eNB <NUM> may be suitable for use as an eNB <NUM> as depicted in <FIG>. The eNB <NUM> may include physical layer circuitry <NUM> and a transceiver <NUM>, one or both of which may enable transmission and reception of signals to and from the UE <NUM>, other eNBs, other UEs or other devices using one or more antennas <NUM>. As an example, the physical layer circuitry <NUM> may perform various encoding and decoding functions that may include formation of baseband signals for transmission and decoding of received signals. As another example, the transceiver <NUM> may perform various transmission and reception functions such as conversion of signals between a baseband range and a Radio Frequency (RF) range. Accordingly, the physical layer circuitry <NUM> and the transceiver <NUM> may be separate components or may be part of a combined component. In addition, some of the described functionality related to transmission and reception of signals may be performed by a combination that may include one, any or all of the physical layer circuitry <NUM>, the transceiver <NUM>, and other components or layers. The eNB <NUM> may also include medium access control layer (MAC) circuitry <NUM> for controlling access to the wireless medium. The eNB <NUM> may also include processing circuitry <NUM> and memory <NUM> arranged to perform the operations described herein. The eNB <NUM> may also include one or more interfaces <NUM><NUM>, which may enable communication with other components, including other eNBs <NUM> (<FIG>), components in the EPC <NUM> (<FIG>) or other network components. In addition, the interfaces <NUM> may enable communication with other components that may not be shown in <FIG>, including components external to the network. The interfaces <NUM> may be wired or wireless or a combination thereof. It should be noted that in some embodiments, an eNB or other base station may include some or all of the components shown in either <FIG> or <FIG> or both.

<FIG> is a block diagram of a User Equipment (UE) in accordance with some embodiments. The UE <NUM> may be suitable for use as a UE <NUM> as depicted in <FIG>. In some embodiments, the UE <NUM> may include application circuitry <NUM>, baseband circuitry <NUM>, Radio Frequency (RF) circuitry <NUM>, front-end module (FEM) circuitry <NUM> and one or more antennas <NUM>, coupled together at least as shown. In some embodiments, other circuitry or arrangements may include one or more elements and/or components of the application circuitry <NUM>, the baseband circuitry <NUM>, the RF circuitry <NUM> and/or the FEM circuitry <NUM>, and may also include other elements and/or components in some cases. As an example, "processing circuitry" may include one or more elements and/or components, some or all of which may be included in the application circuitry <NUM> and/or the baseband circuitry <NUM>. As another example, "transceiver circuitry" may include one or more elements and/or components, some or all of which may be included in the RF circuitry <NUM> and/or the FEM circuitry <NUM>. These examples are not limiting, however, as the processing circuitry and/or the transceiver circuitry may also include other elements and/or components in some cases. It should be noted that in some embodiments, a UE or other mobile device may include some or all of the components shown in either <FIG> or <FIG> or both.

The baseband circuitry <NUM> may include one or more baseband processors and/or control logic to process baseband signals received from a receive signal path of the RF circuitry <NUM> and to generate baseband signals for a transmit signal path of the RF circuitry <NUM>. Baseband processing circuitry <NUM> may interface with the application circuitry <NUM> for generation and processing of the baseband signals and for controlling operations of the RF circuitry <NUM>. For example, in some embodiments, the baseband circuitry <NUM> may include a second generation (<NUM>) baseband processor 404a, third generation (<NUM>) baseband processor 404b, fourth generation (<NUM>) baseband processor 404c, and/or other baseband processor(s) 404d for other existing generations, generations in development or to be developed in the future (e.g., fifth generation (<NUM>), <NUM>, etc.). The baseband circuitry <NUM> (e.g., one or more of baseband processors 404a-d) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry <NUM>. The radio control functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, etc. In some embodiments, modulation/demodulation circuitry of the baseband circuitry <NUM> may include Fast-Fourier Transform (FFT), precoding, and/or constellation mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry <NUM> may include convolution, tail-biting convolution, turbo, Viterbi, and/or Low Density Parity Check (LDPC) encoder/decoder functionality. Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments.

In some embodiments, the baseband circuitry <NUM> may include elements of a protocol stack such as, for example, elements of an evolved universal terrestrial radio access network (EUTRAN) protocol including, for example, physical (PHY), media access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), and/or radio resource control (RRC) elements. A central processing unit (CPU) 404e of the baseband circuitry <NUM> may be configured to run elements of the protocol stack for signaling of the PHY, MAC, RLC, PDCP and/or RRC layers. In some embodiments, the baseband circuitry may include one or more audio digital signal processor(s) (DSP) 404f. The audio DSP(s) 404f may be include elements for compression/decompression and echo cancellation and may include other suitable processing elements in other embodiments. Components of the baseband circuitry may be suitably combined in a single chip, a single chipset, or disposed on a same circuit board in some embodiments. In some embodiments, some or all of the constituent components of the baseband circuitry <NUM> and the application circuitry <NUM> may be implemented together such as, for example, on a system on a chip (SOC).

In some embodiments, the RF circuitry <NUM> may include a receive signal path and a transmit signal path. The receive signal path of the RF circuitry <NUM> may include mixer circuitry 406a, amplifier circuitry 406b and filter circuitry 406c. The transmit signal path of the RF circuitry <NUM> may include filter circuitry 406c and mixer circuitry 406a. RF circuitry <NUM> may also include synthesizer circuitry 406d for synthesizing a frequency for use by the mixer circuitry 406a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 406a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry <NUM> based on the synthesized frequency provided by synthesizer circuitry 406d. The amplifier circuitry 406b may be configured to amplify the down-converted signals and the filter circuitry 406c may be a low-pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitry <NUM> for further processing. In some embodiments, the output baseband signals may be zero-frequency baseband signals, although this is not a requirement. In some embodiments, mixer circuitry 406a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect. In some embodiments, the mixer circuitry 406a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 406d to generate RF output signals for the FEM circuitry <NUM>. The baseband signals may be provided by the baseband circuitry <NUM> and may be filtered by filter circuitry 406c. The filter circuitry 406c may include a low-pass filter (LPF), although the scope of the embodiments is not limited in this respect.

In some embodiments, the mixer circuitry 406a of the receive signal path and the mixer circuitry 406a of the transmit signal path may include two or more mixers and may be arranged for quadrature downconversion and/or upconversion respectively. In some embodiments, the mixer circuitry 406a of the receive signal path and the mixer circuitry 406a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry 406a of the receive signal path and the mixer circuitry 406a may be arranged for direct downconversion and/or direct upconversion, respectively. In some embodiments, the mixer circuitry 406a of the receive signal path and the mixer circuitry 406a of the transmit signal path may be configured for super-heterodyne operation.

In some dual-mode embodiments, a separate radio 1C circuitry may be provided for processing signals for each spectrum, although the scope of the embodiments is not limited in this respect.

In some embodiments, the synthesizer circuitry 406d may be a fractional-N synthesizer or a fractional N/N+<NUM> synthesizer, although the scope of the embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry 406d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider. The synthesizer circuitry 406d may be configured to synthesize an output frequency for use by the mixer circuitry 406a of the RF circuitry <NUM> based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 406d may be a fractional N/N+<NUM> synthesizer.

Synthesizer circuitry 406d of the RF circuitry <NUM> may include a divider, a delay-locked loop (DLL), a multiplexer and a phase accumulator. In some embodiments, the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide the input signal by either N or N+<NUM> (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip-flop. In these embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

In some embodiments, synthesizer circuitry 406d may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the earner frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a LO frequency (fLO). In some embodiments, the RF circuitry <NUM> may include an IQ/polar converter.

In some embodiments, the UE <NUM> may include additional elements such as, for example, memory/storage, display, camera, sensor, and/or input/output (I/O) interface.

The antennas <NUM>, <NUM>, <NUM> may comprise one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas or other types of antennas suitable for transmission of RF signals. In some multiple-input multiple-output (MIMO) embodiments, the antennas <NUM>, <NUM>, <NUM> may be effectively separated to take advantage of spatial diversity and the different channel characteristics that may result.

In some embodiments, the UE <NUM> and/or the eNB <NUM> may be a mobile device and may be a portable wireless communication device, such as a personal digital assistant (PDA), a laptop or portable computer with wireless communication capability, a web tablet, a wireless telephone, a smartphone, a wireless headset, a pager, an instant messaging device, a digital camera, an access point, a television, a wearable device such as a medical device (e.g., a heart rate monitor, a blood pressure monitor, etc.), or other device that may receive and/or transmit information wirelessly. In some embodiments, the UE <NUM> or eNB <NUM> may be configured to operate in accordance with 3GPP standards, although the scope of the embodiments is not limited in this respect. Mobile devices or other devices in some embodiments may be configured to operate according to other protocols or standards, including IEEE <NUM> or other IEEE standards. In some embodiments, the UE <NUM>, eNB <NUM> or other device may include one or more of a keyboard, a display, a non-volatile memory port, multiple antennas, a graphics processor, an application processor, speakers, and other mobile device elements. The display may be an LCD screen including a touch screen.

Although the UE <NUM> and the eNB <NUM> are each illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including digital signal processors (DSPs), and/or other hardware elements. For example, some elements may comprise one or more microprocessors, DSPs, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), radio-frequency integrated circuits (RFICs) and combinations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, the functional elements may refer to one or more processes operating on one or more processing elements.

Embodiments may be implemented in one or a combination of hardware, firmware and software. Embodiments may also be implemented as instructions stored on a computer-readable storage device, which may be read and executed by at least one processor to perform the operations described herein. A computer-readable storage device may include any non-transitory mechanism for storing information in a form readable by a machine (e.g., a computer). For example, a computer-readable storage device may include read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and other storage devices and media. Some embodiments may include one or more processors and may be configured with instructions stored on a computer-readable storage device.

It should be noted that in some embodiments, an apparatus used by the UE <NUM> and/or eNB <NUM> and/or machine <NUM> may include various components of the UE <NUM> and/or the eNB <NUM> and/or the machine <NUM> as shown in <FIG>. Accordingly, techniques and operations described herein that refer to the UE <NUM> (or <NUM>) may be applicable to an apparatus for a UE. In addition, techniques and operations described herein that refer to the eNB <NUM> (or <NUM>) may be applicable to an apparatus for an eNB.

In accordance with some embodiments, the UE <NUM> may operate in a failure state as part of a packet-switched (PS) communication session with a PS network, such as a 3GPP LTE network. The UE may determine that a circuit-switched (CS) communication session with a CS network is to be established. The UE may transmit, while operating in the failure state of the PS communication session, a CS registration message to a CS base station of the CS network as part of an establishment of the CS communication session. The UE may refrain from transmission, while operating in the failure state, of messages to the PS network for the establishment of the CS communication session. These embodiments are described in more detail below.

<FIG> illustrates the operation of a method of communication in accordance with some embodiments. It is important to note that embodiments of the method <NUM> may include additional or even fewer operations or processes in comparison to what is illustrated in <FIG>. In addition, embodiments of the method <NUM> are not necessarily limited to the chronological order that is shown in <FIG>. In describing the method <NUM>, reference may be made to <FIG> and <FIG>, although it is understood that the method <NUM> may be practiced with any other suitable systems, interfaces and components.

In addition, while the method <NUM> and other methods described herein may refer to eNBs <NUM> or UEs <NUM> operating in accordance with 3GPP standards, <NUM> standards and/or other standards, embodiments of those methods are not limited to just those eNBs <NUM> or UEs <NUM> and may also be practiced on other devices, such as a Wi-Fi access point (AP) or user station (STA). In addition, the method <NUM> and other methods described herein may be practiced by wireless devices configured to operate in other suitable types of wireless communication systems, including systems configured to operate according to various IEEE standards such as IEEE <NUM>. The method <NUM> may also refer to an apparatus for a UE <NUM> and/or eNB <NUM> and/or other device described above.

At operation <NUM> of the method <NUM>, the UE <NUM> may exchange data messages with an eNB <NUM> as part of a packet-switched (PS) communication session with a PS network. As a non-limiting example, the PS network may be and/or may include a 3GPP LTE network and the data messages may be transmitted and/or received over a wireless link. As another non-limiting example, the PS network may support a packet service such as Evolved Packet Service (EPS) and the PS communication session may include an EPS communication session. These examples are not limiting, however, as other suitable PS networks and/or packet services may be used, which may or may not be part of a standard. In addition, the UE <NUM> and the eNB <NUM> may also exchange (transmit and/or receive) control messages and/or other messages as part of the PS network.

At operation <NUM>, the UE <NUM> may determine whether the UE <NUM> is to operate in a failure state for the PS communication session. In some embodiments, the UE <NUM> may determine whether the UE <NUM> is to operate in the failure state or in a normal state (which may be a non-failure state, in some cases). At operation <NUM>, the UE <NUM> may transition to the failure state.

As an example, it may be determined whether the UE <NUM> is to operate in the failure state and/or normal state based at least partly on a network condition of the PS network, such as network congestion and/or other condition. As another example, it may be determined that the UE <NUM> is to operate in the failure state and/or normal state based at least partly on issues related to an air interface between the UE <NUM> and the eNB <NUM>, network coverage of the UE <NUM> and/or other performance measurement related to a wireless link between the UE <NUM> and the eNB <NUM>. As another example, it may be determined that the UE <NUM> is to operate in the failure state and/or normal state based at least partly on a network failure between the UE <NUM> and the network related to a failed registration attempt with the network. These examples are not limiting, however, as other factors may be used to determine whether die UE <NUM> is to operate in the failure state and/or normal state.

As a non-limiting example, in a first failure state, the UE <NUM> may be de-registered from the PS network and may intend to attach to the PS network. For instance, a DEREGISTERED. ATTEMPTING-TO-ATTACH state, which may be included in a 3GPP standard, may be used in some cases. As another non-limiting example, in a second failure state, the UE <NUM> may be registered with the PS network and may intend to update information related to the PS communication session. For instance, a REGISTERED. ATTEMPTING-TO-UPDATE state, which may be included in a 3GPP standard, may be used in some cases. These examples are not limiting, however, as other failure states may be used, which may or may not be part of a 3GPP standard and/or other standard.

In some embodiments, a group of one or more possible failure states may be used. For instance, such a group may include neither, either or both of these example failure states, in some cases, and may include other failure states in some cases. These examples are not limiting, however, as other failure states may be used, which may or may not be part of a 3GPP standard and/or other standard.

At operation <NUM>, the UE <NUM> may determine that a circuit-switched (CS) communication session is to be established. In some embodiments, it may be determined that the CS communication session is to be established with a CS network, which may or may not be exclusive to the PS network. As a non-limiting example, the determination that the CS communication session is to be established may be based at least partly on a service request generated, at the UE <NUM>, by a connection management (CM) sub-layer of the UE <NUM>. In some embodiments, the CS communication session may include a non-EPS communication session, although embodiments are not limited as such, and any suitable CS communication session may be used.

In some cases, the determination that the CS communication session is to be established may be performed while the UE <NUM> operates in the failure state. Various techniques that may be used as part of an establishment of the CS communication session in such scenarios are described herein.

At operation <NUM>, the UE <NUM> may determine an availability of one or more CS networks. Non-limiting examples of such CS networks may include UMTS, GERAN and/or other CS network which may or may not operate in accordance with a standard. In some embodiments, the determination of the availability of the CS network(s) may be based at least partly on a monitoring for transmissions by CS networks. For instance, the UE <NUM> may monitor for such transmissions by attempting to receive a signal (such as a beacon signal or other) from a CS network. Accordingly, the UE <NUM> may attempt to detect a presence of one or more CS base stations based at least partly on a monitoring, by die UE <NUM>, for CS network signals. In some embodiments, the UE <NUM> may attempt to determine an availability of at least one CS base station to support the CS communication session. In some cases, the UE <NUM> may not necessarily know which CS networks, if any, are operating within range of the UE <NUM> as part of operation <NUM>.

At operation <NUM>, the UE <NUM> may transmit a CS registration message to a CS base station of a CS network as part of an establishment of the CS communication session. In some embodiments, the UE <NUM> may transmit, when it is determined that a group of one or more CS base stations is available, a registration message for the CS connection to at least one of the CS base stations in die group. At operation <NUM>, the UE <NUM> may refrain from transmission of messages to the eNB <NUM> for the establishment of the CS communication session. In some cases, the UE <NUM> may refrain from transmission of messages to the PS network for the establishment of the CS communication session.

Although embodiments are not limited as such, either or both of operations <NUM> and <NUM> may be performed while the UE <NUM> operates in the failure state. In some embodiments, operations <NUM> and <NUM> may be included as part of a procedure that may be performed when the UE <NUM> is operating in the failure state and determines that the CS communication session is to be established. In some embodiments, the UE <NUM> may, while the UE operates in the failure state and when it is determined that a group of one or more CS base stations is available, transmit a registration message for the CS connection to at least one of the CS base stations in the group and/or refrain from transmission to the eNB of registration messages for the CS connection.

At operation <NUM>, the UE <NUM> may transmit, when the UE <NUM> is operating in a non-failure state for the PS communication session, a combined attachment message to the PS base station. In some embodiments, the combined attachment message may include status information for the PS communication session and may further include an indicator that the CS communication session is to be established. Accordingly, in some embodiments, operations performed by the UE <NUM> for the establishment of the CS communication session may depend on whether the UE <NUM> operates in the failure state or normal state (non-failure state). However, it should be noted that some embodiments of the method <NUM> may not include operation <NUM>.

At operation <NUM>, the UE <NUM> may initiate one or more failure state timers. At operation <NUM>, the UE <NUM> may refrain from resetting the failure state timer(s) based on the transmission of the CS registration message. As a non-limiting example, timers related to a 3GPP standard, such as a T3411 timer, a T3402 timer and/or other timer, may be used.

In some embodiments, a UE <NUM> anchor other mobile device may operate in a failure state. In some cases, a non-access stratum (NAS) layer or NAS module of the UE <NUM> may operate in the failure state. Non-limiting examples of such failure states may include an "EMM-REGISTERED ATTEMPTING-TO-UPDATE" state (or similar state), a "REGISTERED. ATTEMPING-TO-UPDATE" state (or similar state), an "EMM-DEREGISTERED. ATTEMPTING-TO-ATTACH" state (or similar state), a "DEREGISTERED. ATTEMPTING-TO-ATTACH" state (or similar state) and/or other failure state. Although not limited as such, the failure state may be included in a 3GPP standard and/or other standard. However, embodiments are not limited to usage of failure states that are included in a standard. The UE <NUM> may operate in the failure state for any suitable reason, including but not limited to temporary failures related to a network, registration, air interface and/or other aspect. It should also be noted that techniques and/or operations described herein may refer to one or more particular failure states (such as those above), but such references are not limiting. In some embodiments, such techniques and/or operations may be used in accordance with other failure states.

In some cases, the failure state may be related to operation of the UE <NUM> as part of a packet-switched (PS) network. As a non-limiting example, the UE <NUM> may be arranged to operate in a 3GPP LTE network. Accordingly, the PS network may support PS services such as an Evolved Packet System (EPS) service that may be included in a 3GPP standard and/or other standard. Embodiments are not limited to the EPS services, however, as other PS services that may or may not be included in a standard may be supported by the UE <NUM> in some embodiments.

In some embodiments, the UE <NUM> may support one or more circuit-switched (CS) services in addition to one or more PS services. Accordingly, the UE <NUM> may be and/or may be configured to operate as a multimode device in some cases. The CS services may include non-EPS services that may or may not be included in a standard such as a 3GPP standard and/or other standard.

In an example scenario, the UE <NUM> may receive a non-EPS service request. As a non-limiting example, a non-EPS service request may be received while the UE <NUM> operates in the failure state with respect to operation in die PS network. The UE <NUM> may operate in the failure state as a result of a failure related to an EPS service supported by the PS network, an air interface between the UE <NUM> and a base station of the PS network, a PS network issue and/or other failure. In some cases, the non-EPS service request may be received from and/or may be generated by a Connection Management (CM) sub-layer of the UE <NUM>.

In this example scenario, if the UE <NUM> attempts to initiate a registration procedure with the PS network for the requested non-EPS service request, a probability of a successful registration may not be high (or sufficiently high) in some cases. For instance, an issue that may have caused the UE <NUM> to enter the failure state with respect to the PS network may persist, in some cases, and registration attempts for the non-EPS service request may also fail. Examples of such registration procedures with the PS network may include, but are not limited to, an attach procedure while the UE <NUM> operates in the DEREGISTERED. ATTEMPTING-TO-ATTACH state, a Tracking Area Update (TAU) procedure while the UE <NUM> operates in the REGISTERED ATTEMPTING-TO-UPDATE state and/or other procedure. Accordingly, one or more registration failures of such a non-EPS service request with the PS network may cause a considerable amount of delay, in some cases. In addition, the approach of retrying a registration for the non-EPS service request while a failure state timer is running may cause network overloads, in some cases. For instance, multiple bursts of such registration requests may occur within a relatively short time span. The failure state timer may be a T3411 timer, a T3402 timer and/or other timer that may or not be included in a 3GPP standard and/or other standard.

In some embodiments, the UE <NUM> may be arranged to operate in an LTE RAT (PS network) and a non-LTE RAT (CS network), although embodiments are not limited to usage of the LTE RAT and non-LTE RAT as the PS network and CS network, respectively. Accordingly, reference to the LTE RAT and non-LTE RAT in scenarios described herein are not limiting, as other suitable PS networks and/or CS networks may be used, in some embodiments.

In some embodiments, the UE <NUM> may refrain from proceeding with additional registration procedures in an LTE RAT when the UE <NUM> receives a non-EPS service request from the CM sub-layer while the UE <NUM> operates in a DEREGISTERED. ATTEMPTING-TO-ATTACH or a REGISTERED. ATTEMPTING-TO-UPDATE state. The UE <NUM> may proceed with selecting a suitable cell in a non-LTE RAT (such as a UMTS, GERAN and/or other) and may proceed with one or more 3GPP procedures for non-EPS service requests for the non-LTE RAT.

In some embodiments, the UE <NUM> may skip (and/or may refrain from) attempting to communicate with the LTE RAT, for processing the non-EPS service request, over an unstable LTE air interface or when an unstable LTE network condition may be present. In addition, the UE <NUM> may also attempt to communicate with the non-LTE network for processing of the non-EPS service request, in some embodiments. In some cases, one or more benefits may be realized in terms of performance measures such as probability of successfully communicating the non-EPS service request, time spent in attempting to register and/or re-register for the non-EPS service request and/or other performance measures.

In some embodiments, the UE <NUM> may be configured to not skip (and/or may refrain from skipping) timers such as T3411 and/or T3402. Accordingly, in some cases, the LTE network may be protected against a burst of registration requests that may be caused (at least partly) by the UE <NUM> skipping such timers. The UE <NUM> not skipping such timers may reduce and/or eliminate a misuse of skipping such timers, in some cases.

In some embodiments, instead of the UE <NUM> re-attempting registration and/or subsequent Circuit Switched Fallback (CSFB) operations on the currently un-favorable LTE RAT (a condition of which may have caused the UE <NUM> to operate in the DEREGISTERED. ATTEMPTING-TO-ATTACH state, REGISTERED. ATTEMPTING-TO-UPDATE state and/or other failure state) the UE <NUM> may directly select a suitable non-LTE RAT cell and may proceed with processing of a non-EPS request from the CM sub-layer.

In some embodiments, the UE <NUM> may be arranged to operate in accordance with one or more 3GPP standards. While operating in a DEREGISTERED. ATTEMPTING-TO-ATTACH state, the UE <NUM> may use requests for non-EPS services (such as requests from the CM layer and/or other requests) to trigger a combined attach procedure if the T3346 timer is not running or may use the requests for non-EPS services to attempt to select a GERAN or UTRAN RAT. If die UE <NUM> finds a suitable GERAN or UTRAN cell and a CS fallback cancellation request was not received, the UE <NUM> may then proceed with one or more appropriate Mobility Management (MM) and/or Call Control (CC) specific procedures. The EPS Mobility Management (EMM) sub-layer may not indicate (and/or may refrain from indicating) the abort of the service request procedure to the MM sub-layer.

In some embodiments, the UE <NUM> may be arranged to operate in accordance with one or more 3GPP standards. While operating in a DEREGISTERED. ATTEMPTING-TO-ATTACH state, the UE <NUM> may use requests for non-EPS services (such as requests from the CM layer and/or other requests) to attempt to select a GERAN or UTRAN radio access technology (RAT). If the UE <NUM> finds a suitable GERAN or UTRAN cell and a CS fallback cancellation request was not received, the UE <NUM> may then proceed with one or more appropriate MM and/or CC specific procedures. The EMM sub-layer may not indicate (and/or may refrain from indicating) the abort of the service request procedure to the MM sub-layer.

In some embodiments, the UE <NUM> may be arranged to operate in accordance with one or more 3GPP standards. While operating in a REGISTERED. ATTEMPTING-TO-UPDATE state, the UE <NUM> may use requests for non-EPS services (such as requests from the CM layer and/or other requests) to trigger a combined tracking area updating (TAU) procedure if the T3346 timer is not running or may use the requests for the non-EPS services to attempt to select a GERAN or UTRAN RAT. If the UE <NUM> finds a suitable GERAN or UTRAN cell and a CS fallback cancellation request was not received, the UE <NUM> may then proceed with one or more appropriate MM and/or CC specific procedures. The EMM sub-layer may not indicate (and/or may refrain from indicating) the abort of the service request procedure to the MM sub-layer.

In some embodiments, the UE <NUM> may be arranged to operate in accordance with one or more 3GPP standards. While operating in a REGISTERED. ATTEMPTING-TO-UPDATE state, the UE <NUM> may use requests for non-EPS services (such as requests from the CM layer and/or other requests) to attempt to select a GERAN or UTRAN RAT. If the UE <NUM> finds a suitable GERAN or UTRAN cell and a CS fallback cancellation request was not received, the UE <NUM> may then proceed with one or more appropriate MM and/or CC specific procedures. The EMM sub-layer may not indicate (and/or may refrain from indicating) the abort of the service request procedure to the MM sub-layer.

<FIG> illustrates an example of a failure condition for a Long Term Evolution (LTE) network in accordance with some embodiments. Although the example failure condition <NUM> may illustrate some or all techniques, operations and/or concepts described herein, it is understood that embodiments are not limited by the example <NUM> in terms of number, type, size, arrangement and/or other aspects of elements shown in <FIG>. Such elements include, but are not limited to protocol layers, protocol modules, networks to which the UE <NUM> may communicate and/or others.

Referring to <FIG>. the UE <NUM> may be arranged to operate in an LTE network and in a non-LTE network. Embodiments are not limited to the LTE network and non-LTE network, however, as other suitable PS networks and/or CS networks may be used in some embodiments.

As shown at <NUM>, an issue such as interference on the air interface, a temporary network issue and/or other issue may cause the CS call to be impossible on the LTE network. However, it may be possible that due to conditions for the non-LTE network, as shown by <NUM>, the CS call may be possible on the non-LTE network.

<FIG> illustrates an example of a network failure scenario in accordance with some embodiments. <FIG> illustrates another example of a network failure scenario in accordance with some embodiments. <FIG> illustrates another example of a network failure scenario in accordance with some embodiments. <FIG> illustrates another example of a network failure scenario in accordance with some embodiments. It should be noted that the example scenarios illustrated in <FIG> may illustrate some or all concepts and/or techniques described herein, but embodiments are not limited by these examples in terms of message types, parameters, states, components, chronological ordering of messages and/or other aspects. Some embodiments may include one or more operations and/or states from one or more of <FIG>. Some embodiments may include additional operations and/or states not shown in scenarios like those in <FIG>. Some embodiments may include similar operations and/or states shown in scenarios like those in <FIG>. Some embodiments may include operations and/or states different from those shown in scenarios like those in <FIG>. In addition, <FIG> may illustrate techniques and/or operations using one or more particular failure states, such as REGISTERED. ATTEMPING-TO-UPDATE and/or DEREGISTERED. ATTEMPTING-TO-ATTACH, but such references are not limiting. In some embodiments, techniques and/or operations shown in <FIG> may be used in accordance with other failure states, such as an "EMM-REGISTERED. ATTEMPTING-TO-UPDATE" state, an "EMM-DEREGISTERED. ATTEMPTING-TO-ATTACH" state and/or other failure state. Although not limited as such, the failure state may be included in a 3GPP standard and/or other standard. However, embodiments are not limited to usage of failure states that are included in a standard. The UE <NUM> may operate in the failure state for any suitable reason, including but not limited to temporary failures related to a network, registration, air interface and/or other aspect.

Referring to <FIG>, the UE <NUM> may include a non-access stratum (NAS) <NUM> layer and/or module, an access stratum (AS) layer and/or module and a user/application <NUM> layer (which may include and/or be part of a connection management (CM) layer and/or module in some cases). In some embodiments, the UE <NUM> may include other modules and/or layers. In <FIG>, the UE <NUM> may include the same or similar modules and/or layers.

The example scenario <NUM> may illustrate events that may occur and/or operations that may be performed related to reception of a non-EPS service request from the CM sub-layer by the UE <NUM> while the UΣ. <NUM> operates in a DEREGISTERED. ATTEMPTING-TO-ATTACH state.

The example scenario <NUM> may illustrate events that may occur and/or operations that may be performed related to reception of a non-EPS service request from the CM sub-layer by the UE <NUM> before the UE <NUM> moves to the DEREGISTERED. ATTEMPTING-TO-ATTACH state. Accordingly, the non-EPS service request may be pending when the UE <NUM> moves to the failure state.

The example scenario <NUM> may illustrate events that may occur and/or operations that may be performed related to reception of a non-EPS service request from the CM sub-layer by the UE <NUM> while the UE <NUM> operates in a REGISTERED. ATTEMPTING-TO-UPDATE state.

Claim 1:
An apparatus for a User Equipment, UE, the apparatus comprising; transceiver circuitry; and
hardware processing circuitry, the hardware processing circuitry configured to:
configure the transceiver circuitry to transmit, as part of a packet-switched, PS, communication session, a data message to an Evolved Node-B, eNB, of a PS network;
determine that a circuit-switched, CS, communication session with a CS network is to be established; and
configure the transceiver circuitry to, when the UE is operating in a failure state of the PS communication session, transmit a CS registration message to a CS base station of the CS network as part of an establishment of the CS communication session and refrain from transmission of messages to the eNB for the establishment of the CS communication session; and
when the UE is operating in a non-failure state for the PS communication session, transmit a combined attachment message to the PS base station, wherein the combined attachment message includes status information for the PS communication session and further includes an indicator that the CS communication session is to be established,
wherein the failure state is one of a group that includes:
a first state in which the UE is de-registered from the PS network and intends to attach to the PS network; and
a second state in which the UE is registered with the PS network and intends to update information related to the PS communication session.