Systems and methods for reducing power consumption of a communications device using multiple elements in a receiver chain

Systems and methods according to embodiments of the present invention are provided for increasing the power efficiency of a communications device by allowing it to support dual-SIM functionality while issuing simultaneous wake ups for each SIM. Embodiments of the present invention leverage time sharing solutions to minimize the amount of circuitry needed in a communications device to issue wake ups while avoiding the drawbacks of other time sharing solutions that result in increased overhead due to requiring multiple transitions from an idle state to an active state.

FIELD OF THE INVENTION

This invention relates to mobile communications and more specifically to systems for reducing power consumption in mobile communications.

BACKGROUND OF THE INVENTION

Some communications devices (e.g., cellular phones) support two or more single subscriber identity modules (“SIMs” or “SIM cards”). SIMs are removable integrated circuits that securely store keys for subscriber identification, information regarding the cellular phone user (e.g., a unique cellular phone user number), a list of services for which the user has access, user passwords, and/or stored data for the user (e.g. a list of phone numbers). Thus, if a communications device supports two (or more) SIMs, the communications device can be configured to receive service (e.g., cellular service) from two (or more) different service providers, each service provider associated with a different SIM. For example, an owner of a communications device may receive service from a service provider for work-related phone service and service from a service provider for personal phone service. In some cases, each SIM is also associated with its own phone number specific to the service.

If a communications device is in idle mode, it can intermittently issue a “wake up” command at a predetermined period of time to check for incoming transmissions for a SIM. When a communications device supports dual SIMs, each of these SIMs is monitored for incoming transmissions (e.g., incoming cellular phone calls). Thus, if two or more SIMs are being monitored, the communications device consumes more battery power because it wakes up to check for incoming transmissions more often.

What is needed are systems and methods for reducing battery power consumption in a communications device having multiple SIMs.

DETAILED DESCRIPTION OF THE INVENTION

Some communications devices have a single receiver chain that is used by multiple SIMs. Thus, some communications devices equipped with only a single receiver chain use a time sharing method to check for incoming transmissions to each SIM using the shared receiver chain. For example, the communications device can wake up at a first time and check for incoming transmissions for the first SIM (e.g., for 100-200 ms) and then wake up at a second time and check for incoming transmissions for the second SIM (e.g., for an additional 100-200 ms). Thus, a communications device supporting multiple SIMs consumes more power while checking for incoming transmissions relative to a communications device supporting a single SIM.

The “waking up” process initiated by the communications device is associated with a battery power overhead required to transition the communications device from a lower-power idle state to an active (e.g., connected) state that supports the functionality associated with checking for incoming transmissions. Thus, by requiring the communications device to wake up additional times to support multiple SIMs, the battery power overhead caused by the waking up process is magnified. The battery power overhead is further increased by requiring the communications device to stay in the active state for a period of time (e.g., for 100-200 ms) as each SIM is checked for incoming transmissions. For example, in an embodiment, if the communication device supports two SIMs, the waking up overhead is approximately doubled, and, if the communications device supports three SIMs, the waking up overhead is approximately tripled.

To alleviate this unwanted overhead, embodiments of the present invention provide separate receiver chains in a communications device for each SIM. In an embodiment, the communications device wakes up and checks for incoming transmissions for each SIMs simultaneously, using a dedicated receiver chain for each SIM. Thus, embodiments of the present invention advantageously increase battery power efficiency by eliminating the need to implement a time sharing solution to monitor incoming transmissions to the communications device for all supported SIMs. By eliminating the need for this time sharing solution, the unwanted overhead described above is reduced because the communications device does not need to wake up more often than a communications device supporting only a single SIM. Rather, according to embodiments of the present invention, the communications device checks for incoming transmissions on all SIMs simultaneously.

Some communications devices include a “diversity receiver chain” for checking the performance of the communications device. For example, this diversity receiver chain can be used during a “connected mode” of a communications device (e.g., during a phone call) to monitor the performance of the phone call. Embodiments of the present invention utilize the diversity receiver chain as a separate receiver chain for an additional SIM so that incoming transmissions on both SIMs can be monitored simultaneously during a single wake up.

Further, embodiments of the present invention provide time sharing solutions to allow a communication device to conduct a transmission using one service without missing incoming transmissions on an idle service. For example, embodiments of the present invention enable a communications device to issue brief wake ups to an idle receiver associated with an idle service so that incoming calls are not missed while a call is in progress on an active service. Because the communications device is already in an active state when a transmission is in progress, these time sharing solutions avoid the unwanted overhead associated with the time sharing solutions discussed above, which require multiple wake ups for a communications device in idle mode. Further, the time sharing solutions provided by embodiments of the present invention leverage existing circuitry to issue wake ups to an inactive service while a transmission is in progress.

Thus, embodiments of the present invention advantageously increase the power efficiency of a communications device by allowing it to support dual-SIM functionality without the need to issue separate wake ups for each SIM. Further, embodiments of the present invention leverage time sharing solutions to minimize the amount of circuitry needed in a communications device while avoiding the drawbacks of other time sharing solutions that result in increased overhead due to requiring multiple transitions from an idle state to an active state.

A system100for reducing power consumption using main and diversity receiver chains of a communications device according to an embodiment of the present invention will now be explained with reference toFIG. 1A.FIG. 1Ais a diagram showing a transceiver102of a communications device (e.g., a cellular phone).FIG. 1Aalso shows a software (e.g., firmware) device controller104of the communications device.

InFIG. 1A, the communications device includes a transmitter receiver chain106(“transmitter”), a main receiver chain108(“main receiver”), and a diversity receiver chain110(“diversity receiver”). InFIG. 1A, main receiver (RX)108is shown as being coupled to main antenna109, and diversity receiver (RX)110is shown as being coupled to diversity antenna111. Additionally, transmitter (TX)106is shown as being coupled to transmitter antenna107. However, it should be understood that embodiments of the present invention can function with any number of antennas. For example, in an embodiment, main RX108, diversity RX110, and/or TX106can share one or more antennas. Control signals are sent to main receiver108, diversity receiver110, and transmitter106from transceiver controller112. Transceiver controller112includes, or is coupled to, at least one SIM. For example, transceiver controller112is coupled to SIM1114and SIM2116inFIG. 1A.

In an embodiment, transceiver controller112is a hardware controller. In an embodiment, transceiver controller112receives instructions from device controller104. In an embodiment, device controller104is firmware implemented on the same chip as the chip implementing the functionality of transceiver controller112. In another embodiment, device controller104is in communication with transceiver controller112but is implemented on a separate chip from the chip implementing the functionality of transceiver controller112.

Device controller104includes an RF device resource manager module118, which instructs the communications device to issue wake ups for both receiver chains simultaneously. RF device resource manager module118sends these instructions to the drivers for receivers108and110and the transmitter106. For example, TX chain device driver120receives instructions from RF device resource manager module118and relays these instructions to transceiver controller112, which sends control signals for controlling transmitter106. Transmitter106includes baseband processing module128, digital to analog converter (DAC)130, selection logic132, multiplier134, and transmit logic136.

RX chain device driver122receives instructions from RF device resource manager module118and relays these instructions to transceiver controller112, which sends control signals for controlling the receiver chains of main receiver108and diversity receiver110. Each receiver chain includes selection logic138, a multiplier140for down converting frequency to baseband, an analog to digital converter (ADC)142, and a baseband processing module144. In an embodiment, baseband processing module144is shared between main receiver108and diversity receiver110.

In some communications devices supporting a single SIM, functionality of the diversity receiver chain is often unused. For example, this diversity receiver chain can be used during a “connected mode” of a communications device (e.g., during a phone call) to monitor the performance of the phone call. Embodiments of the present invention advantageously leverage the unused diversity receiver chain to support functionality for multiple SIMs. For example, embodiments of the present invention utilize the diversity receiver chain as a separate receiver chain for an additional SIM so that incoming transmissions on both SIMs can be monitored simultaneously during a single wake up without requiring the incorporation of an additional PLL/VCO into transceiver102.

Because only one service is connected at a time during an active (e.g., connected) mode, the unused service can remain in idle mode while the connected service is in use. For example, if a call is in progress using SIM1114(which is connected to main receiver108), diversity receiver110can remain in idle mode because a user of the communications device will not need to be connected to two calls at the same time. While a call is in progress using SIM1114, RX PLL/VCO126is used to support functionality associated with receiving data, and TX PLL/VCO124is used to support functionality associated with sending data.

Likewise, if a call is in progress using SIM2116(which is connected to diversity receiver110), main receiver108can remain in idle mode. While a call is in progress using SIM2116, RX PLL/VCO126is used to support functionality associated with receiving data, and TX PLL/VCO124is used to support functionality associated with sending data.

Embodiments of the present invention allow the communications device to monitor incoming calls for both main receiver108and diversity receiver110by coupling TX PLL/VCO124to the diversity receiver chain. For example, during idle mode (i.e., when the communication device is not sending or receiving data), TX PLL/VCO124is not used for transmission because the communications device has no data to transmit. Thus, RX PLL/VCO126can be used for monitoring incoming calls for main receiver108, and TX PLL/VCO124can be used for monitoring incoming calls for diversity receiver110. By configuring TX PLL/VCO124to be used by the diversity receiver110during idle mode, two independent receiver chains are created without needing to incorporate an additional RX PLL/VCO into transceiver102.

As previously discussed, implementing these two independent receiver chains alleviates unwanted overhead because both receivers associated with the receiver chains can be issued wake up signals simultaneously. Simultaneously issuing wake up to both receivers avoids the need to transition the communications device from a lower-power idle state to an active (e.g., connected) state that supports the functionality associated with checking for incoming transmissions twice. Thus, embodiments of the present invention advantageously increase battery power efficiency by eliminating the need to implement a time sharing solution to monitor incoming transmissions to the communications device for all supported SIMs.

By eliminating the need for this time sharing solution, the unwanted overhead described above is reduced because the communications device does not need to wake up more often than a communications device supporting only a single SIM. Rather, according to embodiments of the present invention, the communications device checks for incoming transmissions on all SIMs simultaneously.

Different services can be associated with different transmission time due to the location of transmitters. For example, in a cellular telephone system, base stations (also known as “cellular sites” or “cells”) are associated with each service, and base station timing is not necessarily synchronized. At any given time, the nearest base station for one service may be very close, while the nearest base station for another service may be far away. This distance can impact the timing offset between the services because data has to travel farther to (and/or from) one base station when compared with the distance necessary to travel to (and/or from) the “close” base station.

Further, different base stations can transmit bursts of information to cellular telephones at different times, especially if the base stations are associated with different service providers. When a cellular telephone searches for a base station to connect to, the cellular telephone can briefly initiate a connection to each base station in range. Each base station can then send paging information to the cellular telephone to inform the cellular telephone at which times it sends transmission bursts. For example, a first base station and a second base station may be configured to send transmission bursts every 100 miliseconds, but the second base station may be configured to transmit bursts 50 miliseconds later than the bursts transmitted by the first base station. Embodiments of the present invention take this relative delay into account when selecting base stations.

In an embodiment, RF device resource manager118tracks and stores this timing information and uses it to determine a reference wake up time that minimizes the timing offset between these services. For example, RF device resource manager118can calculate a transmission time from each base station (e.g., relative to its own internal clock) based on the paging information received from each base station. Based on this calculated transmission time, RF device resource manager118can select base stations associated with each service such that the timing difference between the selected base stations is minimized. Thus, in an embodiment, the closest base station associated with any service is not necessarily selected. Rather, RF device resource manager118can be configured to instruct the communications device to select base stations for the services in a way that minimizes the relative difference in transmission time from each base station to the communications device.

By minimizing the timing offset between the services, the communications device is enabled to continually transmit wake ups to receivers associated with both services simultaneously. Because base stations are selected such that the transmission time is approximately the same for each service, variation in the transmission time from the base stations among services is eliminated as a factor when determining wake up rates for each service, and incoming transmissions can be checked for each service simultaneously without negatively impacting performance. As previously discussed, enabling a communications device to check for incoming transmissions simultaneously improves battery efficiency and reduces battery power overhead.

While embodiments of the present invention utilizing two receiver chains (e.g. a main receiver chain and a diversity receiver chain) are described above inFIG. 1A, it should be understood that embodiments of the present invention incorporating three or more receiver chains (e.g., depending on the number of supported SIMs) are envisioned. Further, embodiments of the present invention can be used to implement a hybrid solution incorporating separate receiver chains as well as time sharing. For example, if a communications device supports 4 SIMs and two receiver chains, a communications device may implement time sharing for two SIMs using each receiver chain. Thus, by implementing this time sharing solution, the communications device wakes up half as often (e.g., at a first time to check for incoming transmissions of SIMs1and2and at a second time to check for incoming transmissions of SIMs3and4), which improves battery power efficiency without requiring four receiver chains in the communications device.

Further, it should be understood that embodiments of the present invention can also be used to provide additional functionality in a communications device having only a single SIM. For example, in a communications device having only a single SIM, diversity receiver110can be used to support a different technology (e.g., WiFi or Bluetooth).

Additionally, it should be understood that embodiments of the present invention are applicable to any communications standard. For example, embodiments of the present invention are contemplated to function with a variety of mobile standards, including 3G, 4G, etc.

2.4 Time Sharing for Wake Up During Active Mode

FIG. 1Bis a diagram showing another embodiment of the present invention in which multiplexers (MUXes)125and127are incorporated into transceiver102. While MUXes125and127are described as “multiplexers,” it should be understood that MUXes125and127are not necessarily conventional multiplexers but rather can, in some embodiments, be hardware, software, and/or firmware modules that implement functionality of multiplexers and/or demultiplexers.

As previously discussed, SIM1114and SIM2116are each associated with a different service (e.g., cellular phone service from a cellular phone service provider). SIM1114is coupled to main receiver108through elements (e.g., multiplier140a) of the main receiver chain, and SIM2116is coupled to diversity receiver110through elements (e.g., multiplier140b) of the diversity receiver chain. At any given time, one service may be active (e.g., if a call is in progress for one phone number associated with one SIM) while the other service is idle. However, while one service is active, incoming transmissions can still be received for the idle service, and, thus, the idle service should periodically be issued a wake up to check for incoming calls even while transmissions are in progress for the active service. Embodiments of the present invention advantageously provide time sharing solutions to enable TX PLL/VCO124and RX PLL/VCO126to be used to issue brief wake ups to an idle receiver associated with an idle service so that incoming calls are not missed while a call is in progress on an active service. For example, herein, a “wake up” involves coupling the output of PLL/VCO (124or126) to the multiplier in the corresponding idle receiver chain, so as to enable reception of any incoming transmissions, while in idle mode.

For example, if a call is in progress for SIM1114, the main receiver chain is active (e.g., connected). RX PLL/VCO126is used for receiving data, and TX PLL/VCO124is used to transmit data. In this case, incoming calls can still be monitored for the unused service (associated with SIM2116and diversity receiver110) by connecting the output of TX PLL/VCO124to diversity receiver110for a very brief period of time (e.g., using time multiplexing via MUX125) to initiate a wake up. In an embodiment, these wake ups are periodically issued while the call is in progress (e.g., issued every 640 ms or every 1.28 s) to ensure that no incoming transmissions are missed. Because the amount of time needed to initiate a wake up is so brief (e.g., 100-200 ms), incoming calls can be monitored for the unused service with a negligible impact on transmission quality.

Likewise, if a call is in progress for SIM2116, diversity receiver110is active (e.g., connected), and main receiver108is idle. RX PLL/VCO126is used for receiving data, and TX PLL/VCO124is being used to transmit data. In this case, incoming calls are monitored for the unused service (associated with SIM1114and main receiver108) by utilizing a time-sharing solution for one of the PLL/VCOs124or126to initiate a wake up. For example, in an embodiment, the output of RX PLL/VCO126is briefly connected to the main receiver chain associated with main receiver108to issue a wake up to main receiver108. These wake ups are issued to main receiver108periodically while a call is in progress using diversity receiver110by implementing time division multiplexing using MUX127.

As described above, when a transmission is in progress for one service (e.g., a phone call is in progress for either SIM1114or SIM2116), TX PLL/VCO124is used to transmit data, and RX PLL/VCO126is used to receive data for the active service. InFIG. 1B, RX PLL/VCO126is shown as coupled, via MUX127, to main receiver108and diversity receiver110, and TX PLL/VCO124is shown as coupled, via MUX125, to transmitter106and diversity receiver110. Thus, because of the connections shown in.FIG. 1B, time division multiplexing is implemented for waking up diversity receiver110using TX PLL/VCO124, and time division multiplexing is implemented for waking up main receiver108using RX PLL/VCO126.

However, it should be understood that, according to embodiments of the present invention, time division multiplexing for main receiver108and diversity receiver110can be implemented using either (or both of) RX PLL/VCO126or TX PLL/VCO124. For example, in an embodiment, TX PLL/VCO124is also coupled to main receiver108via MUX125. Thus, when a call is in progress using diversity receiver110, wake ups can be periodically issued from TX PLL/VCO124, via MUX125, to main receiver108. In a similar fashion, wake ups can be time division multiplexed to diversity receiver110while main receiver108is active using RX PLL/VCO126and MUX127.

In an embodiment, multiplexers125and127receive a status signal (e.g., from transceiver controller112) that indicates a current state of the communications device (e.g., active, idle, wakeup needed, etc.). In an embodiment, this status signal is generated by RF device resource manager118and sent to multiplexer125from transceiver controller112. Based on the value of this status signal, multiplexers125and127transmit to an appropriate destination. For example, in an embodiment according toFIG. 1B, MUX125transmits data to transmitter106unless it receives a status signal indicating that a wake up should be issued to diversity receiver110. Likewise, MUX127receives data from the active service (either from main receiver108or diversity receiver110). When MUX127receives a status signal indicating that the idle service needs to be issued a wake up, MUX127transmits a brief wake up to the idle service and then resumes receiving data from the active service.

A method of calculating a wake up signal transmission time will now be described with reference toFIG. 2andFIG. 1A. In step200, a first plurality of transmitters (e.g., base stations) transmitting a first service from a first service provider is detected (e.g., by transceiver controller112and/or RF device resource manager118). For example, in an embodiment, these transmitters are base stations associated with the service provider servicing SIM1114.

In step202, a second plurality of transmitters transmitting a second service from a second service provider is detected. For example, in an embodiment, these transmitters are base stations associated with the service provider servicing SIM2116.

In step204, transceiver controller112and/or RF device manager118selects base stations from each of these groups of transmitters such that the relative difference in transmission time from each base station to the communications device is minimized. In other words, these base stations are selected such that a difference between the transmission time from the first transmitter to the communications device and a transmission time from the second transmitter to the communications device is minimized.

In step206, transceiver controller112and/or RF device manager118calculates a wake-up signal transmission time based on the transmission times of the selected transmitters. Because transmitters are selected such that the transmission times from the communications device to each transmitter is approximately the same for each service, incoming transmissions can be checked for each service simultaneously without negatively impacting performance. As previously discussed, enabling a communications device to check for incoming transmissions simultaneously improves battery efficiency and reduces battery power overhead.

A method for sending wake up signals in a communications device having first and second receivers will now be described with reference toFIG. 3andFIG. 1A. In step300, transceiver controller112and/or RF device resource manager118determines that wake up signals should be sent to each receiver (e.g., main receiver108and diversity receiver110). For example, if the communications device is idle, wake up signals are sent to main receiver108and diversity receiver110simultaneously at a certain interval. In an embodiment, this interval is determined using the method described inFIG. 2.

In step302, a first wake up signal is transmitted to the first receiver (e.g., main receiver108) via a first PLL (e.g., RX PLL/VCO126), and a second wake up signal is transmitted to the second receiver (e.g., diversity receiver110) via a second PLL (e.g., TX PLL/VCO124). By utilizing both phase PLL's124and126, wake up signals can be sent to both receivers108and110simultaneously, leading to an increase in battery efficiency and a reduction in overhead.

A method for sending a wake up signal to an idle receiver while an active receiver is conducting a transmission will now be described with reference toFIG. 4andFIG. 1B. In step200, a first PLL (e.g., RX PLL/VCO126) is instructed to receive data from a first receiver (e.g., main receiver108), and a second PLL (e.g., TX PLL/VCO124) is instructed to transmit data to a transmitter (e.g., transmitter106) while a transmission is in progress using the first receiver (e.g., while a call is in progress for SIM1114, which is connected to main receiver108).

In step402, transceiver controller112and/or RF device manager118determines that a wake up signal is to be sent to the second receiver (e.g., diversity receiver110). For example, a wake up signal is sent if transceiver controller112and/or RF device manager118determines that the wake up signal transmission time for diversity receiver110has been reached. This wake up signal transmission time may be determined, for example, by the process described inFIG. 2.

In step404, transceiver controller112and/or RF device manager118instructs the second PLL (e.g., TX PLL/VCO124) to transmit the wake up signal to the second receiver (e.g., diversity receiver110). In an embodiment, this wake up signal is sent to the second receiver using time division multiplexing, which can be performed, for example, by MUX125.

In step406, transceiver controller112and/or RF device manager118instructs the second PLL (e.g., TX PLL/VCO124) to continue transmitting data to the transmitter after the wake up signal has been sent. Thus, by leveraging existing circuitry (e.g., TX PLL/VCO124) to transmit brief, periodic wake up signals, embodiments of the present invention advantageously minimize the amount of circuitry needed in a communications device while continuing to support wake up functionality for both receivers108and110even while a one receiver is active (e.g., in connected mode).

The above systems and methods may be implemented as a computer program executing on a machine, as a computer program product, or as a tangible and/or non-transitory computer-readable medium having stored instructions. For example, the functions described herein could be embodied by computer program instructions that are executed by a computer processor or any one of the hardware devices listed above. The computer program instructions cause the processor to perform the signal processing functions described herein. The computer program instructions (e.g. software) can be stored in a tangible non-transitory computer usable medium, computer program medium, or any storage medium that can be accessed by a computer or processor. Such media include a memory device such as a RAM or ROM, or other type of computer storage medium such as a computer disk or CD ROM. Accordingly, any tangible non-transitory computer storage medium having computer program code that cause a processor to perform the signal processing functions described herein are within the scope and spirit of the present invention.