# Patent

## Title
Method and apparatus for efficient idle operation in a dual-SIM CDMA 1X mobile station

## Abstract

Methods and apparatus are provided for selecting identifying numbers associated with a mobile station (MS) having multiple subscriber identity modules (SIMs) such that the paging intervals for both identifying numbers are aligned. The MS having multiple SIMs may operate in a network via a particular radio access technology (RAT), such as Code Division Multiple Access (CDMA) 1×RTT (1 times Radio Transmission Technology). By having aligned paging intervals, the MS may wake up only once during the paging cycles for the various identifying numbers rather than waking up multiple times, thereby reducing power consumption of the MS during idle mode compared to a conventional MS with multiple SIMs, and thus multiple identifying numbers.

## Background
CROSS-REFERENCE TO RELATED APPLICATION(S)
This application is related to Ser. No. 12/903,034, entitled “Method and Apparatus for Efficient Idle Operation in a Dual SIM WCDMA Mobile Station,” filed concurrently herewith, which is expressly incorporated by reference herein in its entirety.
BACKGROUND
1. Field
Certain aspects of the present disclosure generally relate to wireless communications and, more particularly, to selecting identifying numbers associated with a mobile station (MS) having multiple subscriber identity modules (SIMs) such that the paging slots for both identifying numbers are aligned in an effort to reduce power consumption during an idle mode.
2. Background
Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. For example, one network may be a 3G (the third generation of mobile phone standards and technology) system, which may provide network service via any one of various 3G RATs including EVDO (Evolution-Data Optimized), 1×RTT (1 times Radio Transmission Technology, or simply 1×), W-CDMA (Wideband Code Division Multiple Access), UMTS-TDD (Universal Mobile Telecommunications System—Time Division Duplexing), HSPA (High Speed Packet Access), GPRS (General Packet Radio Service), and EDGE (Enhanced Data rates for Global Evolution). The 3G network is a wide area cellular telephone network that evolved to incorporate high-speed internet access and video telephony, in addition to voice calls. Furthermore, a 3G network may be more established and provide larger coverage areas than other network systems.
A wireless communication network may include a number of base stations that can support communication for a number of mobile stations. A mobile station (MS) may communicate with a base station (BS) via the downlink and uplink. The downlink (or forward link) refers to the communication link from the base station to the mobile station, and the uplink (or reverse link) refers to the communication link from the mobile station to the base station. A base station may transmit data and control information on the downlink to a mobile station and/or may receive data and control information on the uplink from the mobile station.
As mentioned above, CDMA 1× is one type of 3G RAT that may be used in providing network service. One of the CDMA2000 family of mobile technology standards, CDMA 1× uses the same RF bandwidth as IS-95: a duplex pair of 1.25 MHz radio channels. CDMA 1× almost doubles the capacity of IS-95 by adding 64 more traffic channels to the forward link, orthogonal to (in quadrature with) the original set of 64. The CDMA 1× standard enables up to 100 callers to share a single 1.25 MHz CDMA channel and provides a peak data rate of 153 kbps.
SUMMARY
In an aspect of the disclosure, a method for communicating in a radio access technology (RAT) network is provided. The method generally includes providing a first identifying number associated with a mobile station (MS), selecting a second identifying number such that a first paging interval for the first identifying number is aligned with a second paging interval for the second identifying number, and associating the second identifying number with the MS.
In an aspect of the disclosure, an apparatus for communicating in a network via a RAT is provided. The apparatus generally includes means for providing a first identifying number associated with a MS, means for selecting a second identifying number such that a first paging interval for the first identifying number is aligned with a second paging interval for the second identifying number, and means for associating the second identifying number with the MS.
In an aspect of the disclosure, an apparatus for communicating in a network via a RAT 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 typically configured to provide a first identifying number associated with a MS, to select a second identifying number such that a first paging interval for the first identifying number is aligned with a second paging interval for the second identifying number, and to associate the second identifying number with the MS.
In an aspect of the disclosure, a computer-program product for communicating in a network via a RAT is provided. The computer-program product generally includes a computer-readable medium having code for providing a first identifying number associated with a MS, for selecting a second identifying number such that a first paging interval for the first identifying number is aligned with a second paging interval for the second identifying number, and for associating the second identifying number with the MS.



BRIEF DESCRIPTION OF THE DRAWINGS
Aspects and embodiments of the disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout.
FIG. 1 is a block diagram conceptually illustrating an example of a wireless communication system in accordance with certain aspects of the present disclosure.
FIG. 2 is a block diagram conceptually illustrating an example of a base station (BS) in communication with a mobile station (MS) in a wireless communication system in accordance with certain aspects of the present disclosure.
FIG. 3 illustrates various intervals in a Code Division Multiple Access (CDMA) 1×RTT (1 times Radio Transmission Technology) paging cycle, in accordance with certain aspects of the present disclosure.
FIG. 4 illustrates the least significant 10 digits of an International Mobile Subscriber Identifier (IMSI), forming a short IMSI (IMSI_S), in accordance with certain aspects of the present disclosure.
FIG. 5 illustrates the paging intervals for two different IMSIs in a single mobile station (MS) being offset, in accordance with certain aspects of the present disclosure.
FIG. 6 is a functional block diagram conceptually illustrating example blocks executed to select identifying numbers associated with a mobile station (MS) having multiple subscriber identities such that the paging intervals for the multiple identifying numbers are aligned, in accordance with certain aspects of the present disclosure.
FIG. 7 illustrates the paging intervals for two different IMSIs in a single MS being completely aligned, in accordance with certain aspects of the present disclosure.



DETAILED DESCRIPTION
The detailed description set forth below, in connection with the appended drawings, is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.
An Example Wireless Communication System
The methods and apparatus of the present disclosure may be utilized in a broadband wireless communication system. The term “broadband wireless” refers to technology that provides wireless, voice, Internet, and/or data network access over a given area. The various concepts presented throughout this disclosure may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards. By way of example and without limitation, the aspects of the present disclosure illustrated in FIG. 1 are presented mainly with reference to a CDMA 1× system.
FIG. 1 illustrates an example of a wireless communication system 100. The wireless communication system 100 may be a broadband wireless communication system. The wireless communication system 100 may provide communication for a number of cells 102, each of which is serviced by a base station (BS) 104. A base station 104 may be a fixed station that communicates with mobile stations 106. The base station 104 may alternatively be referred to as a Node B, a base transceiver station (BTS), a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), or some other suitable terminology.
FIG. 1 depicts various mobile stations 106 dispersed throughout the system 100. The mobile stations 106 may be fixed (i.e., stationary) or mobile. A mobile station (MS) 106 may alternatively be referred to by those skilled in the art as a user terminal, a remote station, a subscriber station, a station (STA), user equipment (UE), a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal (AT), a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. Examples of a mobile station 106 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a notebook, a netbook, a smartbook, a wireless modem, a personal digital assistant (PDA), a satellite radio, a global positioning system (GPS) device, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a handheld device, or any other similar functioning device.
A variety of algorithms and methods may be used for transmissions in the wireless communication system 100 between the base stations 104 and the mobile stations 106. For example, signals may be sent and received between the base stations 104 and the mobile stations 106 in accordance with the CDMA 1× techniques. In these cases, the wireless communication system 100 may be referred to as a CDMA 1× system.
A communication link that facilitates transmission from a base station 104 to a mobile station 106 may be referred to as a downlink 108, and a communication link that facilitates transmission from a mobile station 106 to a base station 104 may be referred to as an uplink 110. Alternatively, a downlink 108 may be referred to as a forward link or a forward channel, and an uplink 110 may be referred to as a reverse link or a reverse channel.
A cell 102 may be divided into multiple sectors 112. A sector 112 is a physical coverage area within a cell 102. Base stations 104 within a wireless communication system 100 may utilize antennas that concentrate the flow of power within a particular sector 112 of the cell 102. Such antennas may be referred to as directional antennas.
FIG. 2 is a block diagram of a BS 104 in communication with a MS 106 in a network 200 operating according to a particular radio access technology (RAT). In the downlink communication, a transmit processor 220 may receive data from a data source 212 and control signals from a controller/processor 240. The transmit processor 220 provides various signal processing functions for the data and control signals, as well as reference signals (e.g., pilot signals). For example, the transmit processor 220 may provide cyclic redundancy check (CRC) codes for error detection, coding and interleaving to facilitate forward error correction (FEC), mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM), and the like), spreading with orthogonal variable spreading factors (OVSF), and multiplying with scrambling codes to produce a series of symbols. Channel estimates from a channel processor 244 may be used by a controller/processor 240 to determine the coding, modulation, spreading, and/or scrambling schemes for the transmit processor 220. These channel estimates may be derived from a reference signal transmitted by the MS 106. The symbols generated by the transmit processor 220 are provided to a transmit frame processor 230 to create a frame structure. The frames are then provided to a transmitter 232, which provides various signal conditioning functions including amplifying, filtering, and modulating the frames onto a carrier for downlink transmission over the wireless medium through antennas 234. The antennas 234 may be implemented with beam steering bidirectional adaptive antenna arrays or other similar beam technologies.
At the MS 106, a receiver 254 receives the downlink transmission through an antenna 252 and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver 254 is provided to a receive frame processor 260, which parses each frame, and may provides a portion to a channel processor 294 and the data, control, and reference signals to a receive processor 270. The receive processor 270 then performs the inverse of the processing performed by the transmit processor 220 in the BS 104. More specifically, the receive processor 270 descrambles and despreads the symbols, and then determines the most likely signal constellation points transmitted by the BS 104 based on the modulation scheme. These soft decisions may be based on channel estimates computed by the channel processor 294. The soft decisions are then decoded and deinterleaved to recover the data, control, and reference signals. The CRC codes are then checked to determine whether the frames were successfully decoded. The data carried by the successfully decoded frames will then be provided to a data sink 272, which represents applications running in the MS 106 and/or various user interfaces (e.g., display). Control signals carried by successfully decoded frames will be provided to a controller/processor 290. When frames are unsuccessfully decoded by the receiver processor 270, the controller/processor 290 may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.
In the uplink, data from a data source 278 and control signals from the controller/processor 290 are provided to a transmit processor 280. The data source 278 may represent applications running in the MS 106 and various user interfaces (e.g., keyboard). Similar to the functionality described in connection with the downlink transmission by the BS 104, the transmit processor 280 provides various signal processing functions including CRC codes, coding and interleaving to facilitate FEC, mapping to signal constellations, spreading with OVSFs, and scrambling to produce a series of symbols. Channel estimates, derived by the channel processor 294 from a reference signal transmitted by the BS 104, may be used to select the appropriate coding, modulation, spreading, and/or scrambling schemes. The symbols produced by the transmit processor 280 will be provided to a transmit frame processor 282 to create a frame structure. The frames are then provided to a transmitter 256, which provides various signal conditioning functions including amplification, filtering, and modulating the frames onto a carrier for uplink transmission over the wireless medium through the antenna 252.
The uplink transmission is processed at the BS 104 in a manner similar to that described in connection with the receiver function at the MS 106. A receiver 235 receives the uplink transmission through the antenna 234 and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver 235 is provided to a receive frame processor 236, which parses each frame, and provides a portion to the channel processor 244 and the data, control, and reference signals to a receive processor 238. The receive processor 238 performs the inverse of the processing performed by the transmit processor 280 in the MS 106. The data and control signals carried by the successfully decoded frames may then be provided to a data sink 239 and the controller/processor, respectively. If some of the frames were unsuccessfully decoded by the receive processor, the controller/processor 240 may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.
The controller/processors 240 and 290 may be used to direct the operation at the BS 104 and the MS 106, respectively. For example, the controller/processors 240 and 290 may provide various functions including timing, peripheral interfaces, voltage regulation, power management, and other control functions. The computer-readable media of memories 242 and 292 may store data and software for the BS 104 and the MS 106, respectively. A scheduler/processor 246 at the BS 104 may be used to allocate resources to the MSs and schedule downlink and/or uplink transmissions for the MSs.
An Example Method of Efficient Idle Operation in a Dual-Sim CDMA 1× Mobile Station
In CDMA 1×RTT (or simply CDMA 1×), a MS in idle slotted mode will listen to certain recurrent paging intervals. FIG. 3 illustrates various intervals in a CDMA 1× paging cycle. Within a paging cycle, the paging listening interval 302 may comprise an 80 ms PCH (Paging Channel) interval 304 preceded by a QPCH (Quick Paging Channel) interval 306 by 100 ms. Therefore, the MS may monitor paging messages for a 180 ms time interval per paging cycle. The MS may most likely start to monitor PCH at CDMA system time t, in units of 20 ms frame, calculated by:

t mod [64*(2SLOT—CYCLE—INDEX))=4*PGSLOT  (1)

The MS may most likely start to monitor the entire paging interval 302 (starting at QPCH) at system time t−5 in the above formula.

The above parameter SLOT_CYCLE_INDEX=0, 1, . . . , 7 can determine the length of a CDMA 1× paging cycle interval 308, namely 1.28 sec*2SLOT—CYCLE—INDEX. SLOT_CYCLE_INDEX is typically provisioned at the MS, but a BS may limit the maximum value by broadcasting the maximum of SLOT_CYCLE_INDEX in the System Parameter Message.
Each MS may have a different time offset (PGSLOT) to listen to a CDMA paging message. PGSLOT is a hashed function of the mobile station's IMSI (International Mobile Subscriber Identifier), a unique number associated with the MS and used to identify the MS on the network. Typically composed of 15 digits, an IMSI may comprise 3 digits specifying the Mobile Country Code (MCC), followed by either 2 (European standard) or 3 digits (North American standard) specifying the Mobile Network Code (MNC). The remaining digits may comprise the mobile station identification number (MSIN) within the network's customer base.
To calculate the PGSLOT, the least significant 10 digits (34 bits) of the IMSI form a short IMSI (IMSI_S) 400 as illustrated in FIG. 4. The IMSI_S 400 is divided into two fields: IMSI_S2 402 comprising 10 bits and IMSI_S1 404 comprising 24 bits. For example, one IMSI_S in certain countries such as the United States has at least 10 digits (e.g., 858-123-4567). In this case, IMSI_S2 comprises the first three digits 858, while IMSI_S1 comprises the last seven digits 1234567. As another example from other countries such as China, one IMSI may comprise the digits 57-12345678. In this case, IMSI_S2 comprises the first three digits 571, and IMSI_S1 comprises the last seven digits 2345678. For certain aspects, the IMSI_S 400 may be a phone number (i.e., a dialing telephone number) for the MS, while in other aspects, the IMSI_S and the phone number may be dissimilar.
To determine PGSLOT using a hashed function, HASH_KEY is equal to the 32 least significant bits of (IMSI_S1+224×IMSI_S2). L is defined as bits 0 to 15 of HASH_KEY, and H is defined as bits 16 to 31 of HASH_KEY. Therefore, PGSLOT is defined as:

PGSLOT=└2048×((40503×(L⊕H⊕DECORR))mod 216)/216┘  (2)

where DECORR=6×HASH_KEY [0 . . . 11], ⊕ is the exclusive bit-wise operation, └*┘ is the floor function, and HASH_KEY [0 . . . 11] is bits 0 to 11 of HASH_KEY.

In some countries, it is popular to operate a mobile station 106 with dual subscriber identity modules (SIMs). With two (or more) SIMs, a user can make and receive mobile calls with two (or more) different phone numbers due to the different IMSIs on each SIM. According to equation (2), PGSLOT may have 2048 different possible values: 0, 1, . . . , 2047.
In general, the MS with dual SIMs or IMSIs may monitor paging messages according to different paging intervals 302 because the different IMSIs frequently lead to different PGSLOT values. Consequently, if the MS has two IMSIs (e.g., two phone numbers), the MS may have to monitor for paging messages twice as long as a MS with only one IMSI (e.g., a single phone number).
As an example, FIG. 5 illustrates the paging cycle 500 for a first IMSI (IMSI 1) and the paging cycle 502 for a second IMSI (IMSI 2). In FIG. 5, the paging intervals 504 for IMSI 1 are offset a number of PGSLOTs from the paging intervals 506 for IMSI 2. Since in idle mode the MS may most likely wake up from the idle state during the paging intervals 504, 506 to listen for any paging messages, the power consumption of a MS with two IMSIs may be approximately double that of a MS with only a single IMSI during idle mode.
Accordingly, what is needed are techniques and apparatus for reducing the power consumption during idle mode for a MS with multiple IMSIs.
FIG. 6 is a functional block diagram conceptually illustrating example blocks 600 executed to select identifying numbers associated with a MS having multiple subscriber identities such that the paging intervals for the multiple identifying numbers are aligned. Operations illustrated by the blocks 600 may be executed, for example, at the processor(s) 270, 280, and/or 290 of the MS 106 from FIG. 2.
The operations may begin, at block 602, by providing a first identifying number (e.g., an IMSI or IMSI_S) associated with the MS. For certain aspects, at least a portion of the identifying number may match a phone number for the MS. At block 604, a second identifying number may be selected, such that a first paging interval for the first identifying number is aligned with a second paging interval for the second identifying number. For certain aspects, the second identifying number may be selected such that the first and second paging intervals may be completely aligned. Selection of the second identifying number may be performed, for example, by the MS 106, by the BS 104, or by the network. At block 606, the second identifying number may be associated with the MS.
Following the selection and association of the second identifying number, the MS may enter an idle state outside the aligned first and second paging intervals. During the idle state, at least a portion of the MS may be powered down in an effort to conserve battery power. In order to listen for a paging message, the MS may wake up from the idle state, powering up at least some of the components of the MS that were powered down during the idle state. By selecting the second identifying number such that the first and second paging intervals are aligned, the MS may wake up only once during a paging cycle to listen for paging messages for both identifying numbers. Consequently, the MS may spend more time in the idle state, and hence, power consumption may be reduced when compared to a conventional dual-SIM MS where the paging intervals for the first and second identifying numbers are more likely to be offset.
As an example of selecting the second identifying number such that the first and second paging intervals for the first and second identifying numbers are aligned, consider a dual-SIM CDMA 1× mobile phone that can be allocated with two IMSIs denoted X and Y. If X and Y are properly selected according to aspects of the present disclosure, then more power may be conserved in idle mode. The IMSI_S of X and Y may be denoted as X_S and Y_S, respectively. In order to obtain the same paging slot for listening to paging messages, the IMSI_S portion of the two IMSIs X and Y should satisfy:

PGSLOT(X—S)=PGSLOT(Y—S)  (3)

In equation (3), the PGSLOT (X_S) is the PGSLOT in equation (2) above with the IMSI_S equal to X_S, and the PGSLOT (Y_S) is the PGSLOT in equation (2) above with the IMSI_S equal to Y_S.

Typically, the first two or three digits are common for the two IMSI_Ss X_S and Y_S. For example, in the United States, this commonality occurs because the numbers often share the same 3-digit area code, while in other countries, such as China, the first two digits of the IMSI_S generally reflect a common mobile phone service provider. Consequently, with ten digits in the IMSI_S, there may be seven or eight digits that may be allocated freely. The hash function of equation (2) may most likely randomly distribute these seven- or eight-digit numbers into 2048 different values, but only one of the 2048 values will yield the same PGSLOT for both IMSI_Ss X_S and Y_S to meet equation (3). That implies, in turn, that there can be approximately 107/2048≈4900 or 108/2048≈49,000 second IMSI numbers available in a dual-SIM MS to meet equation (3) above. If the first digit of the remaining seven or eight digits of the IMSI_S cannot be zero, then there can be about 9·106/2048≈4400 or 9·107/2048≈44,000 second IMSI numbers available in a dual-SIM MS to meet equation (3) above. In other words, there are several possibilities for selecting Y such that the paging slots for X and Y (based on X_S and Y_S) are completely aligned.
By selecting a second identifying number in this manner, the paging intervals 504, 506 for both IMSI 1 and IMSI 2 may be completely aligned as illustrated in FIG. 7. During idle mode, the dual-SIM MS may wake up from an idle state to listen for a paging message for either IMSI 1 or IMSI 2 during the aligned paging intervals 504, 506, and the BS 104 may send a paging message during these intervals. By having only a single paging monitoring interval during the paging cycles 500, 502 for IMSI 1 and IMSI 2, the power consumption of a dual-SIM MS may be approximately equal to that of a single-SIM MS during the idle state (and approximately half that of a conventional dual-SIM MS with completely non-aligned paging intervals).
For certain aspects, PGSLOT (X_S) need not exactly equal PGSLOT (Y_S). There may most likely still be a power savings if the two paging slots for X_S and Y_S at least overlap. For example, instead of selecting identifying numbers that meet only one of 2048 values according to the hash function, certain aspects may involve selecting identifying numbers that meet more than one of the 2048 values (e.g., two of the 2048 values), as long as the values are chosen such that the resulting paging intervals will at least partially overlap to a suitable degree for acceptable power savings. In this manner, a greater number of possible IMSIs may be selected for at least partially aligning the paging intervals for the first and second IMSIs.
In one configuration, the apparatus for wireless communication (such as a MS with multiple subscriber identities) includes means for providing a first identifying number associated with the MS, means for selecting a second identifying number such that a first paging interval for the first identifying number is aligned with a second paging interval for the second identifying number, and means for associating the second identifying number with the MS. For certain aspects, the apparatus further comprises means for monitoring for a paging message for either the first or the second identifying number during the aligned first and second paging intervals. For certain aspects, the apparatus further comprises means for entering an idle state outside the aligned first and second paging intervals, wherein the means for monitoring for the paging message is configured to wake up from the idle state. In one aspect, the aforementioned means may be the processor(s) 270, 280, and/or 290 configured to perform the functions recited by the aforementioned means. In another aspect, the aforementioned means may be a module or any apparatus configured to perform the functions recited by the aforementioned means.
Several aspects of a telecommunications system have been presented with reference to a CDMA 1× system. As those skilled in the art will readily appreciate, various aspects described throughout this disclosure may be extended to other telecommunication systems, network architectures and communication standards. By way of example, various aspects may be extended to UMTS (Universal Mobile Telecommunications System) systems such as Wideband CDMA (W-CDMA), High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), High Speed Packet Access Plus (HSPA+) and Time-Division CDMA (TD-CDMA). Various aspects may also be extended to systems employing Long Term Evolution (LTE) (in FDD, TDD, or both modes), LTE-Advanced (LTE-A) (in FDD, TDD, or both modes), Time-Division Synchronized CDMA (TD-SCDMA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Ultra-Wideband (UWB), Bluetooth, and/or other suitable systems. The actual telecommunication standard, network architecture, and/or communication standard employed will depend on the specific application and the overall design constraints imposed on the system.
Several processors have been described in connection with various apparatuses and methods. These processors may be implemented using electronic hardware, computer software, or any combination thereof. Whether such processors are implemented as hardware or software will depend upon the particular application and overall design constraints imposed on the system. By way of example, a processor, any portion of a processor, or any combination of processors presented in this disclosure may be implemented with a microprocessor, microcontroller, digital signal processor (DSP), a field-programmable gate array (FPGA), a programmable logic device (PLD), a state machine, gated logic, discrete hardware circuits, and other suitable processing components configured to perform the various functions described throughout this disclosure. The functionality of a processor, any portion of a processor, or any combination of processors presented in this disclosure may be implemented with software being executed by a microprocessor, microcontroller, DSP, or other suitable platform.
Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside on a computer-readable medium. A computer-readable medium may include, by way of example, memory such as a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., compact disc (CD), digital versatile disc (DVD)), a smart card, a flash memory device (e.g., card, stick, key drive), random access memory (RAM), read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), a register, or a removable disk. Although memory is shown separate from the processors in the various aspects presented throughout this disclosure, the memory may be internal to the processors (e.g., cache or register).
Computer-readable media may be embodied in a computer-program product. By way of example, a computer-program product may include a computer-readable medium in packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system.
It is to be understood that the specific order or hierarchy of steps in the methods disclosed is an illustration of exemplary processes. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the methods may be rearranged. 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 unless specifically recited therein.
The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. A phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a; b; c; a and b; a and c; b and c; and a, b and c. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”

## Claims

1. A method for selecting identifying numbers associated with a mobile station communicating in a radio access Technology (RAT) network and having multiple subscriber identity modules (SIMs), the method comprising:
providing a first identifying number including a first short International Mobile Subscriber Identity (IMSI—S) associated with the mobile station (MS);
selecting, via a processor, a second identifying number including a second IMSI_S such that a first paging interval for the first identifying number is overlapping with but different from a second paging interval for the second identifying number, the first paging interval based at least in part on a first paging slot that is a function of the first IMSI_S; and
associating the second identifying number with the MS.

2. The method of claim 1, wherein the selecting the second identifying number is performed by the MS.

3. The method of claim 1, wherein the function is equal to └2048×((40503×(L⊕H⊕DDECORR))mod 216)/216┘, wherein └L*┘ is a floor function, ⊕ is an exclusive bit-wise operation, IMSI_S1 is the last seven digits of the first IMSI_S, IMSI_S2 is the first three digits of the first IMSI_S, HASH_KEY is defined as the 32 least significant bits of (IMSI_S1+224×IMSI_S2), L is defined as bits 0 to 15 of HASH_KEY, H is defined as bits 16 to 31 of HASH_KEY, HASH_KEY [0 . . . 11] is bits 0 to 11 of HASH_KEY, and DECORR=6×HASH_KEY [0 . . . 11].

4. The method of claim 1, wherein the second paging interval is based on a second paging slot, the second paging slot is the function of the second IMSI_S, and the selecting the second identifying number comprises selecting the second IMSI_S such that the first and second paging slots are equal.

5. The method of claim 1, wherein the RAT comprises Code Division Multiple Access (CDMA) 1×RTT (one times Radio Transmission Technology).

6. The method of claim 1, further comprising monitoring for a paging message for either the first or the second identifying number during the first and second paging intervals.

7. The method of claim 6, further comprising entering an idle state outside the first and second paging intervals, wherein the monitoring for the paging message comprises waking up from the idle state.

8. The method of claim 1, wherein the selecting of the second identifying number comprises selecting the second identifying number such that the first and second paging intervals overlap a predetermined amount to achieve a predetermined power savings.

9. An apparatus for selecting identifying numbers associated with a mobile station communicating in a network via a radio access technology (RAT) and having multiple subscriber identity modules (SIMs), the apparatus comprising:
means for providing a first identifying number including a first short International Mobile Subscriber Identity (IMSI_S) associated with the mobile station (MS);
means for selecting a second identifying number including a second IMSI_S such that a first paging interval for the first identifying number is overlapping with but different from a second paging interval for the second identifying number, the first paging interval based at least in part on a first paging slot that is a function of the first IMSI_S; and
means for associating the second identifying number with the MS.

10. The apparatus of claim 9, wherein the apparatus is the MS.

11. The apparatus of claim 9, wherein the function is equal to └2048×((40503×(L⊕H⊕DECORR))mod 216)/216┘, wherein └L*540 is a floor function, ⊕ is an exclusive bit-wise operation, IMSI_S1 is the last seven digits of the first IMSI_S, IMSI_S2 is the first three digits of the first IMSI_S, HASH_KEY is defined as the 32 least significant bits of (IMSI_S1+224×IMSI_S2), L is defined as bits 0 to 15 of HASH_KEY, H is defined as bits 16 to 31 of HASH_KEY, HASH_KEY [0 . . . 11] is bits 0 to 11 of HASH_KEY, and DECORR=6×HASH_KEY [0 . . . 11].

12. The apparatus of claim 9, wherein the second paging interval is based on a second paging slot, the second paging slot is the function of the second IMSI_S, and the means for selecting the second identifying number is configured to select the second IMSI_S such that the first and second paging slots are equal.

13. The apparatus of claim 9, wherein the RAT comprises Code Division Multiple Access (CDMA) 1×RTT (one times Radio Transmission Technology).

14. The apparatus of claim 9, further comprising means for monitoring for a paging message for either the first or the second identifying number during the first and second paging intervals.

15. The apparatus of claim 14, further comprising means for entering an idle state outside the first and second paging intervals, wherein the means for monitoring for the paging message is configured to wake up from the idle state.

16. The apparatus of claim 9, wherein the means for selecting the second identifying number is configured to select the second identifying number such that the first and second paging overlap a predetermined amount to achieve a predetermined power savings.

17. An apparatus for selecting identifying numbers associated with a mobile station communicating in a network via a radio access technology (RAT) and having multiple subscriber identity modules (SIMs), the apparatus comprising:
at least one processor adapted to:
provide a first identifying number including a first short International Mobile Subscriber Identity (IMSI_S) associated with the mobile station (MS);
select a second identifying number including a second IMSI_S such that a first paging interval for the first identifying number is overlapping with but different from a second paging interval for the second identifying number, the first paging interval based at least in part on a first paging slot that is a function of the first IMSI_S; and
associate the second identifying number with the MS; and

a memory coupled to the at least one processor.

18. The apparatus of claim 17, wherein the apparatus is the MS.

19. The apparatus of claim 17, wherein the function is equal to └2048×((40503×(L⊕H⊕DECORR))mod 216)/216┘, wherein └*┘ is a floor function, ⊕ is an exclusive bit-wise operation, IMSI_S1 is the last seven digits of the first IMSI_S, IMSI S2 is the first three digits of the first IMSI_S, HASH_KEY is defined as the 32 least significant bits of (IMSI_S1+224×IMSI_S2), L is defined as bits 0 to 15 of HASH_KEY, H is defined as bits 16 to 31 of HASH_KEY, HASH_KEY [0 . . . 11] is bits 0 to 11 of HASH_KEY, and DECORR=6×HASH_KEY [0 . . . 11].

20. The apparatus of claim 17, wherein the second paging interval is based on a second paging slot, the second paging slot is the function of the second IMSI_S, and the at least one processor is configured to select the second identifying number by selecting the second IMSI_S such that the first and second paging slots are equal.

21. The apparatus of claim 17, wherein the RAT comprises Code Division Multiple Access (CDMA) 1×RTT (one times Radio Transmission Technology).

22. The apparatus of claim 17, wherein the at least one processor is configured to monitor for a paging message for either the first or the second identifying number during the first and second paging intervals.

23. The apparatus of claim 22, wherein the at least one processor is configured to enter an idle state outside the first and second paging intervals, wherein the at least one processor is configured to monitor for the paging message by waking up from the idle state.

24. The apparatus of claim 17, wherein the at least one processor is configured to select the second identifying number such that the first and second paging intervals overlap a predetermined amount to achieve a predetermined power savings.

25. A computer-program product for selecting identifying numbers associated with a mobile station communicating in a network via a radio access technology (RAT) and having multiple subscriber identity modules (SIMs), the computer-program product comprising:
a non-transitory computer-readable medium comprising code for:
providing a first identifying number including a first International Mobile subscriber Identity (IMSI_S) associated with the mobile station (MS);
selecting a second identifying number including a second IMSI_S such that a first paging interval for the first identifying number is overlapping with but different from a second paging interval for the second identifying number, the first paging interval based at least in part on a first paging slot that is a function of the first IMSI_S; and
associating the second identifying number with the MS.

26. The computer-program product of claim 25, wherein the selecting the second identifying number is performed by the MS.

27. The computer-program product of claim 25, wherein the function is equal to └2048×((40503×(L⊕H⊕DECORR))mod 216)/216┘, wherein └*┘ is a floor function, ⊕ is an exclusive bit-wise operation, IMSI_S1 is the last seven digits of the first IMSI_S, IMSI_S2 is the first three digits of the first IMSI_S, HASH_KEY is defined as the 32 least significant bits of (IMSI_S1+224×IMSI_S2), L is defined as bits 0 to 15 of HASH_KEY, H is defined as bits 16 to 31 of HASH_KEY, HASH_KEY [0 . . . 11] is bits 0 to 11 of HASH_KEY, and DECORR=6×HASH_KEY [0 . . . 11].

28. The computer-program product of claim 25, wherein the second paging interval is based on a second paging slot, the second paging slot is the function of the second IMSI_S, and the selecting the second identifying number comprises selecting the second IMSI_S such that the first and second paging slots are equal.

29. The computer-program product of claim 25, wherein the RAT comprises Code Division Multiple Access (CDMA) 1×RTT (one times Radio Transmission Technology).

30. The computer-program product of claim 25, wherein the computer-readable medium comprises code for monitoring for a paging message for either the first or the second identifying number during the first and second paging intervals.

31. The computer-program product of claim 30, wherein the computer-readable medium comprises code for entering an idle state outside the first and second paging intervals, wherein the monitoring for the paging message comprises waking up from the idle state.

32. The computer-program product of claim 25, wherein the selecting the second identifying number comprises selecting the second identifying number such that the first and second paging overlap a predetermined amount to achieve a predetermined power savings.