Patent Application
20160278105
1. Field
The present disclosure relates generally to methods and apparatus for reducing call setup delay for a wireless device, and more specifically to reducing call set up delay for a CDMA 1× Mobile Terminated (MT) call in a Simultaneous Voice and Long Term Evolution (SVLTE) device.
2. Background
Simultaneous Voice and Long Term Evolution (SVLTE) is a protocol and technical standard that allows a mobile wireless device, such as a mobile station (MS), mobile terminal, or user equipment (UE), to use both voice and data networks simultaneously. For example, SVLTE allows simultaneous use of CDMA 3G (e.g., CDMA 1×) for voice and LTE (4G.) for data, with the LTE and CDMA 1× domains being simultaneously managed in an SVLTE device.
When a mobile terminated (MT) call (i.e., a call received on a mobile device (MS or UE)) in CDMA 1× is setup, there is a set up delay (i.e., a Call Setup Delay) that occurs. The delay results from a number of steps that occur during the call setup. These steps include (1) the procedure of a base transceiver station (BTS) transmitting a page to the mobile station (MS) and the MS successfully receiving the page; (2) the MS updating an Overhead Message and accessing the network (i.e., sending a Page Response); and (3) the traffic channel (TCH) setup. It is noted that the first of these steps is referred to as the “Paging Delay,” and is unique to an MT call and adds further delay over the second and third steps, which are essentially common to and equal for both MT and mobile originated (MO) calls. The delay due to the second and third steps can then be referred to as the MO Call Setup Delay, which is common to both MT and MO calls. Thus, in general, the MT Call Setup Delay can be estimated according to the following relationship: MT Call Setup Delay=Paging Delay+MO Call Setup Delay.
The Paging Delay in MT calls is dependent on the slot cycle index (SCI) for the Paging Channel in the system. In CDMA 1×, for example, the Paging Channel (i.e., a shared channel that all MS's listen for various information including pages), is divided into “slots”. To conserve power, MS's that are idle will only “wake up” and listen for messages on the Paging Channel during their assigned slots. The SCI determines how frequently the MS's assigned slot occurs in a network. For example, if the SCI=0, the MS wakes up every 1.28 seconds, if the SCI=1, the MS wakes up every 2.56 seconds, and so on up to a typical maximum value of 7 (i.e., 163.84 seconds). It is evident then that the larger the SCI value, the more power that will be conserved in the MS, but the longer it will take to page the MS for an incoming call. Furthermore, it is noted that, on average, the Paging Delay is roughly half of the SCI. This means that the average Paging Delay is approximately 2.56 seconds for a network running with an SCI=2, with the worst case being 5.12 seconds, which is considered long.
It is further noted that for SVLTE devices, the paging process for MT calls follows the traditional CDMA 1× call set up procedure described above, including CDMA 1× paging, and the setting of the SCI index. Thus, given the tradeoff between call setup delay times and power conservation in a MS employing SVLTE, there is therefore a need in the art for methods and apparatus for such devices that afford good power conservation through the use of a longer SCI value, while at the same time further reducing the Paging Delay time.
According to an aspect, a method for reducing a call setup time in a wireless communication system is disclosed. The method includes establishing attachment and registration of a mobile terminal with a first radio access network and a second radio access network, and receiving a call page in a mobile terminal from the first radio access network for a mobile terminated call via a second radio access network. Additionally, the method includes modifying a normal mode of operation of a predefined operation in the mobile terminal wherein messaging between the mobile terminal and the second network processes normally performed according to the predefined operation are not performed in the mobile terminal. The method further includes sending a page response message to the first radio access network in response to the call page, and then establishing the mobile terminated call between the mobile terminal and the first radio access network according to predefined procedures particular to the first radio access network for mobile terminated call set up.
In another aspect, an apparatus for reducing a call setup time in a wireless communication system is disclosed. The apparatus features means for establishing attachment and registration of a mobile terminal with a first radio access network and a second radio access network, and means for receiving a call page in a mobile terminal from the first radio access network for a mobile terminated call via a second radio access network. Further, the apparatus includes means for modifying a normal mode of operation of a predefined operation in the mobile terminal wherein messaging between the mobile terminal and the second network processes normally performed according to the predefined operation are not performed in the mobile terminal. Moreover, the apparatus includes means for sending a page response message to the first radio access network in response to the call page, and means for establishing the mobile terminated call between the mobile terminal and the first radio access network according to predefined procedures particular to the first radio access network for mobile terminated call set up.
According to still another aspect, an apparatus for reducing a call setup time in a wireless communication system is disclosed. The apparatus features at least one processor that is configured for establishing the attachment and registration of a mobile terminal with a first radio access network and a second radio access network, an receiving a call page in a mobile terminal from the first radio access network for a mobile terminated call via a second radio access network. The at least one processor is further configured for modifying a normal mode of operation of a predefined operation in the mobile terminal wherein messaging between the mobile terminal and the second network processes normally performed according to the predefined operation are not performed in the mobile terminal. Additionally, the at least one processor is configured for sending a page response message to the first radio access network in response to the call page, and establishing the mobile terminated call between the mobile terminal and the first radio access network according to predefined procedures particular to the first radio access network for mobile terminated call set up.
The present disclosure recognizes that for 3GPP and 3GPP2 specifications, a technology termed “Circuit Switched FallBack” (CSFB) was specified whereby voice and messaging (e.g., SMS) services are delivered to LTE devices through the use of another circuit-switched network, such as CDMA 1× or GSM. For example, in 1×CSFB when a User equipment (UE) or mobile terminal is camped on an LTE network, it needs to “fall back” to the Circuit Switched (CS) domain when a voice call is initiated or received. CS fallback from LTE (i.e., evolved UMTS Terrestrial Radio Access (E-UTRAN)) to CDMA 1× enables the delivery of CS-domain services by reuse of the CDMA 1× infrastructure when the UE is served by E-UTRAN. In 1×CSFB, the paging procedure is performed in the LTE domain, and is known to be much faster than in the CDMA 1× domain. Even if a re-page is required, for example, the additional delay is still much less than the paging delay in the CDMA 1× domain, with delays typically being less than one second. Accordingly, the present disclosure provides methods and apparatus that utilize at least a portion of a paging procedure in the LTE domain in an SVLTE device to reduce the Call Setup Delay for MT calls, while also using a portion of 1×CSFB procedure, thus allowing a greater SCI value in the CDMA 1× domain for greater power conservation.
As will be explained in more detail below, according to one aspect the present methods and apparatus achieve a reduction in Call Setup Delay for an SVLTE UE by modifying the normal SVLTE call paging and set up operation using traditional CDMA 1× processes, to become a modified or “hybrid” operation that employs part of the normal SVLTE call set (i.e., CDMA 1× call paging and call set up), as well as using 1×CSFB processes employing LTE processes that will reduce the call set up time when establishing a 1×MT call. This hybrid approach is based on assumption that the network supports 1×CSFB procedures such that the 1×CSFB can be capitalized upon. According to another aspect of the present methods and apparatus, further beneficial reduction of Call Setup Delay can be achieved by configuring the hybrid process to skip further normal CSFB call set up processes during certain situations, such as after Radio Resource Control set up has already been effected for a UE.
In other aspects, it is noted that further power reduction in a UE may be realized through use of the disclosed hybrid procedures through increasing the SCI index value or even eliminating the use of an SCI index.
For purposes of the following discussion, it is noted that the word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any example described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other examples. Additionally the terms “CDMA 1×”, “1×RTT”, and “1×” may be used interchangeably herein to denote any one of the various iteration of CDMA2000 1× standards or technologies.
Turning to
The environment 100 further includes an E-UTRAN eNodeB 108 that effectuates wireless access for the UE 102 to an LTE radio access network via the LTE-Uu interface (109). The E-UTRAN 108 is in network communication with core network (CN) elements in the LTE evolved packet core (EPC) including a Mobility Management Entity (MME) 110 via the S1-MME interface 112 and Serving and PDN Gateways (S-GW/P-GW) 114 via an S1 interface (S1-U 116). According to the EPC model, MME 110 also is in communication with S-GW/P-GW via an S11 interface 117. The core network is responsible for the overall control of the LTE UE and establishment of various bearers (i.e., a set of network parameters that define how UE data is treated when it travels across the network (e.g., providing a specific data rate for particular data, etc.)).
The MME 110, in particular, is the control node that processes the signaling between the UE 102 and the core network, but also processes signaling to other networks, such as a CDMA 1× network. The signaling between an LTE network and a CDMA 1× network is effectuated via an S102 tunnel or interface, as indicated in
Furthermore,
When an MT call occurs, the 1×MSC 210 sends a paging request 214 to the 1×CS IWS node 208. The 1×CS IWS node 208 forwards a 1×RTT CS paging request 216 via an S102 tunnel to the MME 206. It is noted that LTE uses the S102 tunnel or interface to transparently pass 1× signaling between the cdma2000 1× system and UE's.
If the UE 202 is in an idle state, it is noted that the MME 206 will perform a network initiated Service Request procedure in order to bring the UE 202 to an active state prior to tunneling of the 1×RTT CS paging request toward the UE 202. This process includes the a page where the core network is packet switched (218) and then a Radio Resource Control (RRC) connection is established between MME 206 and UE 202 as indicated by arrow 220.
MME 206 forwards a 1×RTT CS paging request to the UE through first an UL/DL (uplink/downlink) S1 cdma2000 tunneling 222 from MME 206 to the E-UTRAN 204 and then a UL/DL information transfer 224 from the E-UTRAN or eNodeB 204 to the UE 202. If the UE 202 accepts CS paging for the CS Fallback for 1×RTT, the UE 202 sends an Extended Service Request 226 (also known as a CS Fallback Indicator) to the MME 206.
Next, the MME 206 will indicate to the E-UTRAN 204 to move the UE 202 to 1×RTT. The MME 206 may cause the E-UTRAN 204 to trigger a move of the UE 202 to 1×RTT. Furthermore, although not shown in
Next, the MME 206 sends an S1 UE message 227 for UE Context Modification (UE capabilities, CS Fallback Indicator) to indicate to the E-UTRAN 204 to move the UE 202 to 1×RTT domain or context. The E-UTRAN 204 triggers RRC connection release as shown at block 228 with redirection to the 1×CS system. The E-UTRAN 204 then sends an S1 UE Context Release Request (Cause) message 230 to the MME 206. Message 230 indicates that the S1 UE Context Release was caused by CS Fallback to 1×RTT. The MME 206 sets the UE context to a suspended status and a Suspend Request message 232 sends to serving gateway (S-GW) 233 that requests the suspension of EPS bearers for the UE 202. The S1-UE bearers are released for all EPS bearers by the MME 206 and all Guaranteed Bit Rate (GBR) bearers are deactivated. The non-GBR bearers are preserved and are marked as suspended in a serving gateway (S-GW) 233. In response, the S-GW 233 responds to the Suspend Request message 232 with an acknowledgement message 234, and marks the UE 202 as suspended. When downlink data arrives at the S-GW, the S-GW should not send a downlink data notification message to the MME 206 if the UE 202 is marked as suspended.
The S1 UE Context in the E-UTRAN 204 is released as specified in the 3GPP specification as indicated at block 236. The UE 202 then tunes to 1×RTT and acknowledges the page by transmitting a 1×RTT CS Page Response message 238 to the 1×RTT MSC 210 over the 1× Access Channel. Subsequently the UE 202 performs the procedure for MT call establishment as specified in 3GPP2 specification. After the 1× voice call ends, the UE 202 will revert to an inactive state and the MMSS is triggered to reselect a best system (i.e., LTE). The UE 202 will return to LTE and perform tracking area (TA) updates. The UE 202 also may request 1×CSFB parameters from the E-UTRAN 204 and perform S102 preregistration.
According to an aspect of the present disclosure, methods and apparatus provide a hybrid procedure of normal operation of SVLTE devices (or similarly functioning devices) whereby the normal monitoring of 1× and LTE pages is modified. In particular, the monitoring of 1× paging may be disabled in a UE where the UE only will monitor the LTE connection for pages from the 1×RTT MSC. It is noted that this hybrid procedure is based on the assumption that CSFB capabilities are extant in the radio access networks with which the UE communicates. Thus, the CSFB procedure, or at least a portion of the procedure, may be utilized in this hybrid approach.
Whether the UE is already connected and or was in idle mode requiring the further RRC connection establishment process, the MME 206 sends the 1×RTT CS Paging message (i.e., processes 222 and 224). It is noted here that, because of the presently disclosed hybrid process, the ESR and Context Release Procedures can be skipped. Thus, the attendant processes 226, 227, 228, 230, 232, 234, and 236 for ESR and Context Release are not shown in
According to an aspect, the hybrid methodology of
It is noted that
Accordingly, the method 400 first includes establishing attachment and registration of a user equipment with a first network (e.g., 1×RTT CDMA) and with a second network (e.g., LTE) as shown in block 402. After the combined attachment in block 402, the method 400 includes receiving at least one page request from the first network for a MT call (i.e., a call terminated at the UE) via the second network (e.g., an LTE network) as shown in block 404. It is noted that the switching domain of the page request message may be that of the second network (e.g., PS in the case of LTE) as illustrated in
As the hybrid mode or disabled normal mode is effectuated in the UE, after the CS Paging (e.g., 222, 224), the UE may then be configured to send or issue a page response message to the first network via the second network as illustrated by block 408 (e.g., UE 202 issues a 1×RTT CS Page Response Message (e.g., 238) tunneled via the E-UTRAN 204, the MME 206, the S102 interface, and the IWS 208 to the 1×RTT MSC 210 in a 1×CSFB Optimized approach). It is noted that, in an alternative not shown, rather than sending the page response via tunneling via the LTE network, the UE 202 may instead send the page response directly to the 1× network over the CDMA access channel. It is further noted here that in the case of
In yet another aspect, it is noted that the further processes of the CSFB procedure may be skipped when the SVLTE UE is in an Idle Mode for a UE operating according to the presently disclosed hybrid process. This aspect is illustrated in
As described above, after an SVLTE UE has registered to LTE domain for a combined attach to E-EUTRAN and 1×RTT CS (e.g., process 212 in
From a practical standpoint, it is noted that although higher SCI's are possible to use, consideration would likely need to be made when the UE should need to switch back to normal mode (normal SCI value), such as when the LTE network is unavailable or is degraded to a point that paging for the 1× network needs to be returned to the 1×PCH. Accordingly the UE can be configured with a fall back mechanism or process for going back to monitoring both 1× and LTE domain simultaneously for certain conditions. In an aspect, this process includes first determining that for predetermined qualitative and/or quantitative conditions, such as LTE unavailability or LTE degradation, the UE will switch back to the normal SCI index. A quantitative measure that can be used in making this determination, for example, is the Reference Signal Received Power (RSRP), which in LTE is the linear average of reference signal power across a specified bandwidth. Thus, in one example if the RSRP is greater or stronger than a certain predefined threshold level, the UE can utilize a longer SCI value (or no SCI value), whereas if the RSRP is at or below the predefined level the UE can be switched back to the normal SCI index value.
Of further note, if the RSRP is close to the threshold, frequent back and forth oscillation between a longer SCI and a normal SCI may occur. In such case, hysteresis can be incorporated into the process to mitigate frequent back and forth switching when the determined RSRP is close to the predefined threshold value. According to an aspect, at least two different thresholds may be established; one for when a UE is moving from good to poor coverage and the other when the UE is moving from poor to good coverage. As an example of this use of different RSRP thresholds,
As illustrated in
Alternatively, when the UE moves from good LTE coverage to poor LTE coverage, another RSRP value designated as “Threshold_Normal_SCI” may be set such that as the RSRP equals or is below (i.e., less than) this value, the operation of the UE will fall back to a normal SCI value, such as SCI=2, for example. As will be appreciated by those skilled in the art, there is hysteresis in this process where the UE will not switch from a long SCI value to a normal SCI value until the RSRP value has deteriorated such that it is below the Threshold_Normal_SCI value, even though the RSRP has greatly dropped below the Threshold_Long_SCI value; and the UE will not switch from a normal SCI value to a longer SCI value until the RSRP improves such that it is greater than the Threshold_Long_SCI value even though the RSRP value has already substantially increased over the Threshold_Normal_SCI value.
If the UE is not using the long SCI as determined at block 804, a determination is made at block 810 whether the measure is greater than a second predetermined threshold (e.g., Threshold_Long_SCI), the affirmative indicating an improving network quality. If the condition of block 810 is affirmative, then the SCI value is set to the long SCI value as indicated at block 812 and flow proceeds back to block 802. Alternatively at block 810, the measure does not indicate improvement or enough improvement as determined by the second threshold, then the SCI value will remain the normal SCI value and flow proceeds back to block 802.
One skilled in the art will appreciate that the condition of block 804 is simply making a determination between two possible states, i.e., whether a UE using a long SCI and a UE using a normal SCI. It is also contemplated, however, that more than two states could be considered to provide a higher degree of granularity of decision making, as well as allowing the setting of multiple different SCI's dependent on different ranges of the determined measure of the serving network.
Each stack 902, 904 may include data processing and RF chains to transmit and receive data via the different RATs. Devices 902 and 904 are illustrated with processing (i.e., 908, 912, 920, 926) and RF (i.e., 910, 914, 916, 918922, 928, 930, and 932) chains for purposes of illustrating the capability of communication according to at least two distinct RATs. It is noted, however, that the configuration of
In the configuration of
In operation, the UE 900 may implement any of the processes or operations illustrated in
Apparatus 1000 may include a means or module 1004 for establishing attachment and registration of the user equipment with a first network and a second network. In a particular aspect, the first network may be a 1×CDMA network and the second network an LTE network. In a further aspect, means 1004 could be implemented by processor(s) 934 in
The apparatus 1000 further includes a means or module 1006 for receiving at least one page request from the first network for a User Equipment Terminated call (i.e., an MT call). In an aspect, the MT call may be a 1×RTT call according to the 3GPP2 specification, although it is not necessarily limited to such. In a further aspect, means 1006 may be implemented by processor 934, as well as stacks 902 or 904, or any equivalent thereof capable of performing the functions. In a particular aspect, the stack 902 configured as an LTE stack may be included as part of means 1006 to receive the paging message from an MME 206 as shown by processes 218 or 502 in
Further, apparatus 1000 includes means 1008 for disabling or modifying normal CSFB operation to skip at least ESR and Context Release processes in normal CSFB operations. In an aspect, means 1008 may be implemented by processor 934 as one example, and may also include components of stacks 902 or 904, or implemented by any equivalent structures capable of modifying or disabling CSFB. Furthermore, means 1008 may be configured or structured to effect the operations or processes of block 406 in method 400, for example. Means 1008 may also operate independently of the other means in apparatus 1000 by disabling or modifying CSFB operation either concomitantly or separately from the other functions performed by the other means or modules.
Apparatus 1000 also includes means 1010 for issuing a page response message to the first network via the second network. In one example, the page response message is a 1×RTT CS Page Response Message (e.g., 238 in
When means 1010 issues a page response, apparatus 1000 then utilizes means 1012 for setting up a UE terminated call (i.e., MT call) using the first network. The first network, in one example, is a 1×CDMA network, and the call set up would be effectuated according to the standard 3GPP2 specification provisions for MT calls, accordingly. Means 1012 may be implemented with by the processor(s) 934 in
In another optional aspect, apparatus 1000 may include also includes a general processor 1014 (or application specific processor in another aspect), which may perform any or all of the various functions of the various means of apparatus 1000 in association with a memory device 1016 used to store instructions executable by the processor 1014 to implement one or more various functions. It is noted that any of the means or modules in apparatus 1000 may be implemented with hardware, software, firmware, or any combination thereof, and may further be implemented separately as shown, or alternatively in an integral unit such as in a processor 1014 or a similarly equivalent device.
Still further, apparatus 1000 may include an optional means 1018 for either measuring network parameters or receiving measure parameters from other network devices. For example, means 1018 may determine (or receive measurements of) the RSRP of an LTE network, which are then used for setting or modifying the SCI index value when a UE associated with the apparatus 1000 is operating in the above-described hybrid mode. Means 1012 may be implemented with by the processor(s) 934 in
Associated with means 1018 is an optional means 1020 for setting or modifying the SCI index value of a UE in which apparatus 1000 is employed. In particular, means 1020 may be configured to implement various processes disclosed in methods 700 and 800. Means 1020 may be implemented with by the processor(s) 934 in
It is understood that the specific order or hierarchy of steps in the processes disclosed is merely an example of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged while remaining within the scope of the present disclosure. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.
Those of skill in the art will understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.
Those of skill will further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.
The previous description of the disclosed examples is provided to enable any person skilled in the art to make or use the presently disclosed methods and apparatus. Various modifications to these examples will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other examples without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the examples shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
