WO2018080620A1

WO2018080620A1 - Multiplexing a receive chain between entities of a device when error correcting technique is employed by an entity

Info

Publication number: WO2018080620A1
Application number: PCT/US2017/047716
Authority: WO
Inventors: Soumen Chakraborty
Original assignee: Intel IP Corporation
Priority date: 2016-10-28
Filing date: 2017-08-21
Publication date: 2018-05-03

Abstract

A device provided according to an aspect of the present disclosure contains a receive chain shared by two entities for receiving data units. The first entity uses an error correcting technique which requires only some of the encoded symbols for decoding the information symbols. Accordingly, when there is a requirement to allocate the shared receive chain to a second entity while a data unit is being received for the first entity via the receive chain, the receive chain is allocated to the second entity within the receive duration of the first data unit if the requisite number of encoded symbols can be received within the receive duration.

Description

MULTIPLEXING A RECEIVE CHAIN BETWEEN ENTITIES OF A DEVICE WHEN ERROR CORRECTING TECHNIQUE IS EMPLOYED BY AN ENTITY

Cross-Reference to Related Applications

[001] This application claims priority to Indian Patent Application Serial No. 201641037058, which was filed October 28, 2016, and is incorporated herein by reference in its entirety.

Background

[002] Technical Field

[003] Aspects of the present disclosure relate generally to communication in devices, and more specifically to multiplexing a receive chain between entities of a device when error correcting technique is employed by an entity (in the device).

[004] Related Art

[005] Devices are often used for communication with other devices. Wireless user equipment (UE) or wireless devices, are examples of such devices, and refer to instruments such as mobile phones using which users connect with mobile telephone networks on a wireless medium, as is well known in the relevant arts. In a common scenario, a UE interfaces with a base station of a mobile telephone network providing the corresponding user the facility of voice and data based services.

[006] A device may be viewed as hosting multiple entities which use respective channels for communication, or specifically for receiving the corresponding signal of interest. For example, in a dual-SIM (subscriber identity module) card phone, applications associated with each SIM card may be designed to receive data on a corresponding channel (band of frequencies). As another example, in a single SIM environment, while one application receives a signal of interest on one channel, another application may measure signal strength of a carrier on another channel.

[007] Devices are often designed with a limited number of receive chains for reasons such as cost and power-savings. Due to limited number of receive chains in a device, a receive chain may need to be shared between (or among) multiple entities. As is also well known in the relevant arts, a receive chain is used for decoding a received signal representing voice/data, and providing the decoded information to other internal blocks for further processing. [008] There are often situations when at least one of the entities receives data encoded using error correcting techniques. As is well known, an error correcting technique inserts additional redundant bits along with information bits into the data stream of interest such that the information bits can be recovered even if some of the bits are not received correctly.

[009] It may accordingly be appreciated that a receive chain may need to be multiplexed between entities when one or more entities employ error correcting techniques on respective channels. Aspects of the present disclosure are directed to such situations.

Brief Description of the views of Drawings

[010] Example aspects of the present disclosure will be described with reference to the accompanying drawings briefly described below.

[011] Figure 1 is a block diagram of an example environment in which several aspects of the present disclosure can be implemented.

[012] Figure 2 is a flow-chart illustrating the manner in which a receive chain is multiplexed between multiple entities when one of the entities uses error correcting techniques, according to an aspect of the present disclosure.

[013] Figure 3 is a block diagram illustrating the details of a user equipment (UE) in an aspect of the present disclosure.

[014] Figure 4 is a block diagram depicting a protocol stack implemented by a UE in an aspect of the present disclosure.

[015] Figure 5 is a timing diagram depicting the manner in which a receive chain is multiplexed when a non-noisy channel uses Fountain Codes for error correction, in an aspect of the present disclosure.

[016] Figure 6 is a timing diagram depicting the manner in which a receive chain is multiplexed when a noisy channel uses Fountain Codes for error correction, in an aspect of the present disclosure.

[017] In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.

Detailed Description

[018] 1. Overview

[019] A device provided according to an aspect of the present disclosure contains a receive chain shared by two entities for receiving data units. The device recovers the information symbols in a data unit received for a first entity, even though the receive chain is allocated to a second entity at least for some portion of receive duration (of the data unit). The information symbols are recovered by using an error correction technique used for encoding the information symbols in the data unit.

[020] Accordingly, the second entity can receive any required data without delay. At the same time such delay is avoided by taking advantage of the error correcting code and successfully recovering the required information symbols for the first entity.

[021] According to an aspect, the device may correspond to a wireless device and one entity may correspond to a first SIM (including any applications designed to process data received on the SIM), and the second entity may correspond to a second SIM (including the corresponding applications). Alternatively, each entity may correspond to a different application executing on a single-SIM wireless device.

[022] Several aspects of the invention are described below with reference to examples for illustration. It should be understood that numerous specific details, relationships, and methods are set forth to provide a full understanding of the invention. One skilled in the relevant arts, however, will readily recognize that the invention can be practiced without one or more of the specific details, or with other methods, etc. In other instances, well-known structures or operations are not shown in detail to avoid obscuring the features of the invention.

[023] 2. Example Environment

[024] Figure 1 is a block diagram representing an example environment in which several aspects of the present disclosure can be implemented. The example environment is shown containing only representative devices and systems for illustration. However, real world environments may contain more or fewer systems/devices. While Figure 1 depicts a cellular wireless environment for illustration, it should be appreciated that aspects of the present disclosure can be performed in other environments (e.g., in devices which communicate using wired medium).

[025] Figure 1 is shown containing a cell 100 of a cellular network. Cell 100 is shown containing base station (BS) 110 and user equipment (UE) 120, UE 130 and UE 140. Cell 100 and the devices therein may operate according to any standards/specifi cation for wireless mobile communications such as, for example, GSM 9Global System for Mobile Communications), LTE (Long Term Evolution), UMTS (Universal Mobile Telecommunications System), CDMA (Code Division Multiple Access), W-CDMA (Wideband CDMA), 5G, etc. Further, cell 100 and the devices therein may operate according to frequency division duplex (FDD) and/or time division duplex (TDD) modes specified by LTE also.

[026] Base station 110 is a fixed communications unit and provides the last-mile (or last hop) communications link to UEs in the cell 100. Although not shown in Figure 1, base station 110 may be connected to other devices/sy stems in the cellular network infrastructure to enable UEs in cell 100 to communicate with devices (e.g., other UEs) in other cells, with landline communications equipment in a conventional PSTN, public data networks such as the internet etc., as is well known in the relevant arts. In the context of LTE, base station 110 is referred to as EnodeB. Although noted as a base station, base station 110 can also correspond to a macrocell, microcell or a femtocell. Macro/micro/femtocells are special cellular base stations (operating over small cell areas) that are often deployed in small areas to add extra cell capacity. For example, such small cells can be deployed temporarily during sporting events and other occasions where a large number of cell phone users are expected to be concentrated in one spot.

[027] UE 120, UE 130 and UE 140 represent wireless devices such as mobile phones and tablets, and may be used for wireless communication such as voice calls, data exchange such as web browsing, receiving and sending emails, etc., representing the corresponding applications. However, as noted above, some aspects of the present disclosure can be implemented in devices which communicate using wired paths/medium also. At least some types of communication (e.g., data) may be encoded using error correcting techniques, and the corresponding receiving entity in a UE may need to employ the corresponding error correcting technique for recovering the encoded information (e.g., data) in the event of errors in some of the received data.

[028] One or more of UEs 120, 130 and 140 may be implemented to have only a limited number of receive chains as noted above. Accordingly, the UE may need to multiplex a(shared)receive chain for use by multiple entities in the UE, as also noted above, and the manner in which such multiplexing is performed when error correcting techniques are employed by entities in a UE is described next with respect to a flowchart.

[029] 3. Multiplexing a Receive Chain

[030] Figure 2 is a flowchart illustrating the manner in which a shared receive chain in a UE is multiplexed between multiple entities in the UE. The flowchart is described with respect to the environment of Figure 1, and in relation to UE 120, merely for illustration. However, various features described herein can be implemented in other environments and using other components as well, as will be apparent to one skilled in the relevant arts by reading the disclosure provided herein. Further, the steps in the flowchart are described in a specific sequence merely for illustration. Alternative aspects of the present disclosure using a different sequence of steps can also be implemented without departing from the scope and spirit of several aspects of the present invention, as will be apparent to one skilled in the relevant arts by reading the disclosure provided herein. The flowchart starts in step 201, in which control passes immediately to step 210.

[031] In step 210, UE 120 starts receiving for a first entity, a first data unit having a first number of information symbols and a second number of repair symbols according to an error correcting technique. In an aspect of the present disclosure, the error correcting technique corresponds to Fountain Codes according to which any I (K-prime, which can be equal to or slightly larger than K) of the N symbols are sufficient to recover the K information symbols with a high probability. Fountain codes (more specifically raptor code, which is a type of fountain code) are described in further detail in RFC 5053, entitled "Raptor Forward Error Correction Scheme for Object Delivery", published by the internet engineering task force (IETF).

[032] In the illustrative aspects of the present disclosure below (as well as in the instant flowchart), the first entity corresponds to SIM 360A (Figure 3, described below, and associated applications). However, in alternative aspects, the entities can alternatively correspond to respective applications of a single-SIM UE. Thus, in the duration the first entity continues to receive the first data unit, the shared receive chain is allocated to the first entity. Control then passes to step 220.

[033] In step 220, UE 120 identifies a situation requiring the receive chain to be used for a second entity, while the first data unit is being received using the shared receive chain. Such a situation may correspond to timed events or untimed events. A timed event refers to an activity that is required to be performed at a specific time instance, for the purpose of coordinating communication with external systems (typically base station 110). On the other hand an untimed event does not require such coordination with external systems, but can be performed at any suitable time instance, though typically within a desired time window. Control then passes to step 230. [034] In step 230, UE 120 determines whether the receive chain can be allocated to the second entity while retaining the ability to recover K information symbols of the first entity. Thus, in the context of Fountain Codes technique, a determination is made whether K' of the N symbols can possibly be reliably received, while accommodating allocation of the receive chain to the second entity. As may be readily appreciated, such a situation is readily satisfied if K' symbols have already been received. Some of the alternative scenarios in which the situation is satisfied, are also noted below. Control passes to step 250 if the information symbols can be recovered and to step 280 otherwise.

[035] In step 250, UE 120 allocates the receive chain to the second entity. Such allocation may entail tuning the receive chain to a frequency band corresponding to a channel on which the second entity is to receive the signals. It may be appreciated that the symbols transmitted by base stationl lO, in the duration of allocation of the receive chain to the second entity, are not received by the first entity. Control then passes to step 260.

[036] In step 260, the second entity processes the signal received on the receive chain. The processing depends on the implementation of the second entity. In one aspect of the present disclosure, the second entity merely recovers the symbols encoded in the received signal. Alternatively, the second entity may perform actions such as carrier strength estimation in a neighboring cell, etc.

[037] Control then passes to step 270, in which UE 120 may reallocate the receive chain to the first entity, such that the first entity continues processing the signal received on the receive chain in step 280. Assuming the total number of symbols received for the first entity (in steps 230 and 280 together) equals or exceeds the requisite number of symbols for recovering the information symbols, such information symbols are recovered in step 290, and processed further. In case Fountain Codes are employed, the K symbols can be recovered if at least I of the N symbols are received correctly. The flow chart ends in step 299.

[038] It may thus be appreciated that the second entity is conveniently allocated the shared receive chain within the duration in which data unit is being transmitted on the wireless medium (by the base station) for the first entity, when such allocation can be performed without reducing the probability of successful recovery of the K information symbols in the data unit.

[039] The features thus described can be implemented in various aspects of the present disclosure to address corresponding situations. The description is continued with respect to the details of an example implementation of UE 120.

[040] 4. User Equipment

[041] Figure 3 is a block diagram depicting the implementation details of a UE in an aspect of the present disclosure of the present disclosure. UE 120 is shown containing processing block 310, non-volatile memory 320, input/output (I/O) block 330, random access memory (RAM) 340, real-time clock (RTC) 350, Subscriber Identification Module (SIM)l 360A, Subscriber Identification Module (SIM)2 360B, transmit (TX) block 370, receive (RX) block 380, switch 390, and antenna 395. Some or all units of UE 120 may be powered by a battery (not shown). In another aspect of the present disclosure, UE 120 is mains-powered and contains corresponding components such regulators, filters, etc.

[042] The specific blocks of UE 120 are shown by way of illustration only, and UE 120 may contain more or fewer blocks depending on specific requirements. In an aspect of the present disclosure, UE 120 corresponds to a mobile phone supporting dual-SIM. The respective SIMs may subscribe to data and voice services according to one of several radio access technologies such as GSM, LTE (FDD as well as TDD), CDMA, WCDMA, 5G, etc, as also noted above. Further, the two SIMs can be directed to operation with the same type of radio access technology (e.g., LTE on both SIMs), or respectively different radio access technologies (e.g., LTE on one SIM and 4G on the other SIM, LTE on one SIM and CDMA on the other SIM, etc.).

[043] Each of SIM1 360A and SIM2 360B represents a subscriber identity module (SIM) that may be provided by a service provider. As is well known in the relevant arts, a SIM may store the international mobile subscriber identity (IMSI) number (also the phone number) used by a service provider to identify and authenticate a subscriber. Additionally, a SIM may store address book/telephone numbers of subscribers, security keys, temporary information related to the local network, a list of the services provided by the service provider, etc. Processing block 310 may read the IMSI number, security keys etc., in transmitting and receiving voice/data via TX block 370 and RX block 380 respectively. In an aspect of the present disclosure, SIM1 360A and SIM2 360B represent respective physical entities that share a RX chain (described below) in UE 120. Though not shown, the UE is equipped with two holders, each for housing a respective one of the two SIMs 360A and 360B. Typically, the SIM is 'inserted' into such housing before the UE can access the services provided by the network operator for subscriber configured on the SIM.

[044] RTC 350 operates as a clock, and provides the 'current' time to processing block 310. Additionally, RTC 350 may internally contain one or more timers.

[045] I/O block 330 provides interfaces for user interaction with UE 120, and includes input devices and output devices. The input devices may include a keypad and a pointing device (e.g., touch-pad). Output devices may include a display with touch-sensitive screen.

[046] Antenna 395 operates to receive from, and transmit to, a wireless medium, corresponding wireless signals (representing voice, data, etc.) according to one or more standards such as LTE. Switch 390 may be controlled by processing block 310 (connection not shown) to connect antenna 395 to one of blocks 370 and 380 as desired, depending on whether transmission or reception of wireless signals is required. Switch 390, antenna 395 and the corresponding connections of Figure 3 are shown merely by way of illustration. Instead of a single antenna 395, separate antennas, one for transmission and another for reception of wireless signals, can also be used. In addition, in the case wired-path based devices, switch 390 and antenna 395 can be replaced by appropriate components to meet the interface requirements of the corresponding communications medium. For example, assuming that a router is implemented to have an interface on a Ethernet network and another on Tokenring network, the router may be implemented with corresponding hardware interfaces (but with a shared receive path).

[047] TX block 370 receives, from processing block 310, digital signals representing information (voice, data, etc.) to be transmitted on a wireless medium (e.g., according to the corresponding standards/specifications), generates a modulated radio frequency (RF) signal (according to the standard), and transmits the RF signal via switch 390 and antenna 395. TX block 370 may contain RF circuitry (mixers/up-converters, local oscillators, filters, power amplifier, etc.) as well as baseband circuitry for modulating a carrier with the baseband information signal. Alternatively, TX block 370 may contain only the RF circuitry, with processing block 310 performing the modulation and other baseband operations (in conjunction with the RF circuitry).

[048] RX block 380 represents a receiver (or receive chain) that receives a wireless (RF) signal bearing voice/data and/or control information via switch 390, and antenna 395, demodulates the RF signal, and provides the extracted voice/data or control information to processing block 310. RX block 380 may contain RF circuitry (front-end filter, low-noise amplifier, mixer/down- converter, filters) as well as baseband processing circuitry for demodulating the down-converted signal. Alternatively, RX block 380 (the receive chain) may contain only the RF circuitry, with processing block 310 performing the baseband operations in conjunction with the RF circuitry. In implementations in which direct RF sampling is used, most of the operations of the receive chain as noted above may be performed by processing block 310, and only front-end filters, low- noise amplifier and analog to digital converter (ADC) may be required additional to processing block 310 for the receive chain operations.

[049] Hence, the receive chain may be viewed as the set of blocks (hardware plus firmware/software if any) that are required for receiving and demodulating transmitted data, and performing error correction (if applicable). Additionally, several other resources such as FFT (Fast Fourier Transform) module, dedicated memory resources used for receive operations, shared instances of software modules that are used in receive operations are also deemed to be included in a receive chain. While only one RX chain is shown in Figure 3, UE 120 may contain more than one RX chain. However, the total number of receive chains is generally limited due to consideration such as cost and power consumption.

[050] When multiple entities require simultaneous use of a receive chain, UE 120 may need to multiplex a same RX chain between (or among) multiple entities in UE 120. In the case of frequency division multiple access technologies (e.g., GSM, LTE FDD, etc.) on both SIMS, processing block 310 tunes (via control signal in path 318) RX block 380 to the corresponding frequency band (or channel) that is desired by the corresponding entity. Example frequency bands used by LTE FDD are the bands in exemplary frequency ranges 2110 - 2170 MHz and 1930 - 1990 MHz. Various other bands are also specified by the LTE standards. Typically, such tuning involves changing the frequency of the local oscillators in the receive chain and tuning front end filters to allow only the desired band, although other techniques can also be used instead.

[051] As an illustrative example, SIM1 360A may be used to receive voice/data in one frequency band (channel), while SIM2 360B may be used to receive control/status/voice/data in another (non-overlapping) frequency band. In the case of time division multiple access technologies (such as LTE TDD) on both SIMS, processing block 310 does not need to perform any frequency tuning, but merely allocates the use of the shared receive chain to the corresponding entity. In the case of other combinations of radio access technologies (like LTE on one SIM and CDMA on the other SIM) also, processing block 310 may need to perform tuning similar to that noted above. For other combinations of radio access technologies on the two SIMS, processing block 310 operates correspondingly to enable sharing of the receive chain between the two SIMs.

[052] Non-volatile memory 320 is a non-transitory machine readable medium, and stores instructions, which when executed by processing block 310, causes UE 120 to operate as described herein. In particular, the instructions enable UE 120 to operate as described with respect to the flowchart of Figure 2. The instructions may either be executed directly from nonvolatile memory 320 or be copied to RAM 340 for execution.

[053] RAM 340 is a volatile random access memory, and may be used for storing instructions and data.

[054] RAM 340 and non-volatile memory 320 (which may be implemented in the form of readonly memory/ROM/Flash) constitute computer program products or machine (or computer) readable medium, which are means for providing instructions to processing block 310. Processing block 310 may retrieve the instructions, and execute the instructions to provide several features of the present disclosure.

[055] Processing block 310 (or processor in general) may contain multiple processing units internally, with each processing unit potentially being designed for a specific task. Alternatively, processing block 310 may contain only a single general-purpose processing unit. Among other operations, processing block 310 enables multiple entities in UE 120 to perform corresponding receive operations by using the receive chain in a time-multiplexed fashion. Accordingly, processing block 310 may be implemented as separate processing cores, one each for each entity, which may correspond to a SIM card or an application.

[056] Alternatively, processing block 310 may represent a single processing unit executing multiple execution threads in software, each execution thread corresponding to an entity. Further, processing block 310 applies error correction techniques to recover received information that has been encoded using such techniques. In general, processing block 310 executes instructions stored in non-volatile memory 320 or RAM 340 to enable UE 120 to operate according to several aspects of the present disclosure, described in detail herein.

[057] Figure 4 illustrates an alternative view of the implementation of UE 120, and shows an example protocol stack implemented in UE 120. Protocol stack 400 is shown containing layers LI, L2, L3 and the application layer 470. The various layers in stack 400 may be implemented to generally conform to the ISO OSI (International Standards Organization Open Systems Interconnect) model, and are only briefly described below, since the corresponding implementations of the blocks would be well known to one skilled in the relevant arts on reading the disclosure herein. Further, only the relevant blocks of the protocol stack are shown in Figure 4, and typically more blocks (such as transport layer etc.) according to the ISO OSI model may be present, as also would be apparent to one skilled in the relevant arts.

[058] Layer 1 (LI) corresponds to PHY 410, which represents the electrical and physical interface between UE 120 and a transmission medium (here a wireless medium). PHY 410 receives data from MAC 420 and forwards the data to antenna 395 for transmission. PHY 410 receives data from antenna 395 and forwards the data to MAC 420 for further processing. PHY 410 includes TX block 370 and RX block 380. Additionally, according to an aspect of the present disclosure, PHY 410 receives indications on logical path 471 (which corresponds to physical path 318 of Figure 3) from application layer 470 specifying segment boundaries of an MBMS data stream, and also when K' (K prime) symbols out of N symbols in a segment of an MBMS data stream have been (or cannot be) successfully received, thereby allowing the receive chain in PHY 410 to be allocated to another entity, as illustrated below with examples.

[059] Layer 2 (L2) includes MAC (Medium Access Control layer) 420, Radio Link Control layer (RLC) 430 and Packet Data Convergence Protocol (PDCP) 440. MAC 420 performs operations such as mapping between logical channels and transport channels, error correction through HARQ (although not for MBMS data), priority handling between logical channels, etc. RLC 430 performs operations such as error correction through ARQ (although not for MBMS data), concatenation, segmentation and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, duplicate detection, etc. PDCP 440 performs operations such as header compression and decompression, ciphering and deciphering, etc.

[060] Layer 3 (L3) includes RRC (Radio Resource Control layer) 450 and NAS (Non-access Stratum protocol) 460. RRC 450 performs operations such as paging, establishment, maintenance and release of an RRC connection between UE 120 and base station 110, security functions including key management, QoS(Quality of Service) management functions, measurement reporting and control of the reporting, etc. NAS 460 performs operations such as support of mobility of UE 120, support of session management procedures to establish and maintain IP connectivity between UE 120 and a packet data network gateway, etc.

[061] Application layer 470 represents a communications component that allows software applications executing in UE 120 to communicate with software applications in other nodes (servers, etc.) via the other blocks shown in Figure 4. Thus, in corresponding situations, entity- 1 and entity-2 noted herein can be respective applications executing in application layer 470. In particular, application layer 470 performs forward error correction (FEC) for MBMS data received by UE 120 according to the techniques of Fountain Codes briefly described above. According to an aspect of the present disclosure, application layer 470 informs PHY 410 about the segment boundaries of a received MBMS video stream, and whether K' (K prime) symbols of the N symbols in an MBMS stream have been received or not. With respect to Figure 3, such informing (of having sufficient symbols for recovering information symbols of the present data unit) may cause processing block 310 to tune the receive chain to the frequency band of the other entity such that the other/second entity thereafter starts receiving the signal/data via PHY 410. The application may similarly control reallocation of the receive chain to the first entity.

[062] The description is continued with examples illustrating the manner in which a receive chain of UE 120 is multiplexed between entities when error correcting technique is employed by an entity.

[063] 5. Examples

[064] In the examples below, it is assumed that two entities are operational in UE 120, with one of the entities (entity- 1) operating to receive MBMS (Mobile Broadcast/Multicast Service) data broadcast/multicast by base station 110, while the other entity (entity-2) operates to execute timed or untimed events. Entity-1 and entity-2 may correspond respectively to SIM1 360A and SIM2 360B (or to the operations corresponding to SIM1 360A and SIM2 360B). Dual SIM allows UE 120 to make/receive voice and data for two subscriptions, one corresponding to SIM1 and the other corresponding to SIM2. Alternatively, entity-1 and entity-2 may correspond to application entities executed by processing block 310, as described below.

[065] MBMS may be used in LTE to broadcast/multicast streaming video. The streaming video data in MBMS is encoded using Raptor or Raptor-Q code, each of which is a type of a fountain code. As noted above and as is also well known in the relevant arts, Raptor/Raptor-Q codes is an encoding technique that encodes K information symbols into N encoded symbols such that knowledge of any K' or more of the N encoded symbols allows the K information symbols to be recovered with close to a probability of 1 as the number of symbols (Κ') received more than K exceeds K only very slightly.

[066] The video data transmitted by base station 110 according to MBMS may be split into segments, each of which may have a duration of 0.5 to 3 milliseconds. It is assumed for simplicity in the description below that the segment duration is 1 millisecond. Each segment contains K information symbols (which are sought to be recovered and used in a receiver such as UE 120), and N-K repair symbols. The number of repair symbols used by base station 110 in encoding may depend on factors such as, for example, the distance between base station 110 and the farthest UE in the set of UEs to which the MBMS is addressed. Again for simplicity, it is assumed in the examples below that K equals (N-K), and that only K (and not K') symbols need to be correctly received (i.e., received without error) by UE 120 for UE 120 to be able to successfully recover the K information symbols (as would be the case of optimal Fountain Codes). Further, in the examples below it is assumed that entity- 1 and entity-2 either correspond respectively to SIM1 360A and SIM2 360B (or operations corresponding to SIM1 360A and SIM2 360B) in a dual-SIM implementation of UE 120, or to two applications executing in UE 120 in a single-SIM implementation of UE 120.

[067] Figure 5 is an example timing diagram illustrating the manner in which the receive chain of UE 120 is multiplexed between entity-1 and entity-2. The example of Figure 5 assumes that the wireless communications channel (carrying MBMS data) between base station 110 and UE 120 has no or very little noise. The diagram depicts a data unit shown with reference to a receive duration between start time t51 and end time t56.

[068] Timing sequence 510 represents symbols of a segment transmitted by base station 110, and shows a segment containing 18 information symbols (cross hashed, and shown as occurring from start time instance t51 to time instance t54), and 18 repair symbols (hashed with horizontal lines, and shown as occurring from time instance t54 to end time instance t56), which together represent a first data unit destined for entity-1. Timing sequence 520 and 530 respectively represent the use of the receive chain of UE 120 by entity-1 and entity-2, as further described below.

[069] As depicted by timing sequence 520, entity-1 is allocated use of the receive chain from t51 to t52, and receives in that duration the first 6 of the K symbols (step 210). It is assumed that UE 120 identifies that the receive chain needs to be allocated to entity-2 for reception of a timed event even while receiving the symbols from t51-t52 (step 220). It is further assumed that the receive chain can be allocated to the second entity without detriment to recovering K information symbols for entity-1 (step 230). The decision that the receive chain can be allocated to entity-2 without detriment to entity-1 is taken by UE 120 based on the determination that there is still the possibility of receiving (K-6) symbols in the MBMS segment, and that the use by entity-2 of the receive chain is required only for a short duration.

[070] Accordingly, the receive chain is allocated (step 250) to entity-2 from t52 to t53. The timed event (which requires coordination with base station 110, and which cannot be deferred) in duration t52-t53 can be a reception by entity-2 of a paging message from base station 110, determination of a caller's identification, etc. As is well known in the relevant arts, paging refers to waking up the corresponding entity (here entity-2) from the idle state for reception of data from the base station. The information in a paging message may correspond to change of system information, earth quake or tsunami warnings, etc. Determination of caller identification refers to entering a connected state (from an idle state) to receive a caller's identification such as phone number. Thus, in interval t52-t53, entity-2 receives (step 260) the paging message or caller-ID from base station 110. Entity-1 is unable to receive the three symbols of the video stream transmitted by base station 110 in interval t52-t53.

[071] From t53-t54, the receive chain is re-allocated (step 270) to entity-1, and entity-1 receives all 9 of the K symbols transmitted by base station 110 between t53 and t54, and also 3 of the repair symbols between t54 and t55. Since K symbols (18 in the example) of the total of N symbols in the segment have been received by entity-1 at the end of t54, the receive chain is allocated (step 250) to entity-2 for the duration t55-t56. Such allocation is also an instance of UE 120 determining that the receive chain needs to be allocated to entity-2 (step 220), as well as that the receive chain can be allocated to the entity-2 without detriment to recovering K information symbols for entity-1 (step 230). In this instance, K symbols of the segment t51-t56 have already been received and the K information symbols can be recovered from the K received symbols. Since a next segment does not start until t56, UE 120 determines that the receive chain can be allocated to entity-2 for some other pending activity. In the example, such activity is reception by entity-2 of untimed events.

[072] Accordingly, entity-2 uses the receive chain to receive (step 260) an untimed event in interval t55-t56. Examples of untimed events include neighbor cell measurements, autonomous gaps for CSG(Closed Subscriber Group) measurements, measurements for self-optimizing network (SON),and setting the receive chain in power-save state if there is no untimed event for entity-2. Neighbor cell measurement refers to determination of strength of carrier signal of a neighboring cell for purposes such as deciding which other cell to move to (in instances in which UE 120 is moving). An autonomic gap refers to a measurement gap created by a UE on its own rather than having the base station (or eNodeB) configure the gap. Measurements for CSG involve measurement of signal strength of certain CSG cells and reporting the strengths to the eNodeB to be able to trigger handover. Alternatively, CSG measurement reports can also be for ANR (Automatic Neighbor Relation). Measurements for SON generally refer to measurements directed to enable optimization of performance of a cell (e.g., cell 100 of Figure 1) after installation and during normal operation. Such SON measurements can help cell 100 to self-optimize by analyzing the performance and accordingly changing the operation of cell lOO.At t56, the receive chain is reallocated (step 270) to entity-1 for start of reception of the symbols of the next segment of the video stream.

[073] In the example of Figure 5, due to the good signal strength of the MBMS signal, UE 120 is able to decide that the receive chain can be allocated to the entity-2 without detriment to recovering K information symbols for entity-1 (step 230). However, if such allocation cannot be made without detriment to cannot entity-2, then UE 120 continues to allocate the receive chain for use by entity-1 (step 280) to receive the MBMS video stream.

[074] Figure 6 is another example timing diagram illustrating the manner in which the receive chain of UE 120 is multiplexed between entity-1 and entity-2. The example of Figure 6 assumes that the wireless communications channel (carrying MBMS data) between base station 110 and UE 120 is noisy. Timing sequence 610 represents symbols of a segment transmitted by base station 110, and shows a segment containing 18 information symbols (cross hashed, and shown as occurring from time instance t61 to t62), and 18 repair symbols (hashed with horizontal lines, and shown as occurring from time instance t62 to t64), which together represent a first data unit destined for entity-1. Timing sequences 620 and 630 respectively represent the use of the receive chain of UE 120 by entity-1 and entity-2, as further described below.

[075] As depicted by timing sequence 620, entity-1 is allocated use of the receive chain from t61 to t63, and receives in that duration 6 of the 18 information symbols and 1 repair symbol (step 210). Symbols that are not hashed represent symbols that are not received reliably by the receive chain due to the noisy channel. At t63, UE 120 determines that even K of the total N symbols of the segment cannot be received by t64 (since only 7 symbols have been received by t63, and only 11 symbols of the total of N symbols of the segment remain to be received). Hence, UE 120 determines that the receive chain can be allocated to the second entity without detriment (step 230), in the sense that K symbols cannot possibly be received and it is wasteful to continue allocation of the receive chain to entity-1 till t64. Hence, UE 120 allocates the receive chain for use by entity-2 (step 250).

[076] From t63-t64, entity-2 uses the receive chain to receive (step 260) untimed events. As noted above, the untimed events can include neighbor cell measurements, autonomous gaps for CSG(Closed Subscriber Group) measurements, measurements for self-optimizing network (SON) , and setting the receive chain in power-save state if there is no untimed event for entity- 2. UE 120 re-allocates (step 270) the receive chain to entity-1, which may then receive (step 280) a symbols of a next segment and recover the K symbols (step 290).

[077] In the examples above, UE 120 is shown as allocating the receive chain to entity-2 for receiving untimed events when/if either K symbols of a segment have been received (implying successful recovery of K symbols of a segment) or when/if UE 120 determines that there is no possibility of receiving even K symbols of a segment (implying loss of at least some portion of the segment). However, if the deadline to receive an untimed event is about to expire, UE 120 may allocate the receive chain to entity-2 to receive the untimed event even if such allocation adversely affects the MBMS reception by entity-1 (i.e., even if K symbols can be received by entity-1).

[078] If a timed event for entity-2 occurs after successful receipt of K symbols of a segment (and before end of the segment) or if there is no possibility of receiving even K symbols of a segment, then UE 120 always allocates the receive chain to entity-2 till at least the end of the segment.

[079] If the MBMS channel on which entity-1 receives MBMS data is better than a threshold (THl) (i.e., signal-to-noise ratio of the MBMS data is above THl), then UE 120 prioritizes a timed event for entity-2 over the MBMS reception by entity-1 (and therefore allocates the receive channel to entity-2), as illustrated in interval t52-t53 of Figure 5.

[080] On the other hand, if the MBMS channel on which entity-1 receives MBMS data is worse than threshold THl and a timed event is scheduled to occur either before successful receipt of K symbols of the segment by entity-1, or before determination by UE120 that successful receipt of even K symbols of the segment is not possible, then UE 120 alternately allocates the receive chain for MBMS reception by entity- 1 and the timed event by entity -2.

[081] Further, while entity-1 and entity-2 have been generally noted above to correspond to either SIM1 360A and SIM2 360B, or to corresponding applications executed by UE 120, in an aspect of the present disclosure, the situations/contexts of MBMS and paging reception, MBMS and caller ID identification, MBMS and neighbor cell measurements correspond to the context when entity-1 and entity-2 are respectively to SIM1 360A and SIM2 360B. The situation/context of MBMS and measurement using autonomous gaps (for CSG cells or SON) corresponds to the context when entity-1 and entity-2 are respective applications executed by UE 120.

[082] Thus, in general, UE 120 prioritizes the MBMS reception by entity-1 and reception of timed events by entity-2, by multiplexing the receiver chain between entity-1 and entity-2 based on the criticality of the two activities (MBMS reception and timed/untimed event reception), indications from the error correction running in application layer 470 and channel conditions of the MBMS service, and thus is a balance between the MBMS reception performance by entity-1 and the timed/untimed event reception by entity-2.

[083] 6. Conclusion

[084] References throughout this specification to "one aspect of the present disclosure", "an aspect of the present disclosure", or similar language means that a particular feature, structure, or characteristic described in connection with the aspect of the present disclosure is included in at least one aspect of the present disclosure of the present invention. Thus, appearances of the phrases "in one aspect of the present disclosure", "in an aspect of the present disclosure" and similar language throughout this specification may, but do not necessarily, all refer to the same aspect of the present disclosure.

[085] Thus, example 1 is a device containing a receive chain, which is required to be multiplexed between two entities, for example since the receive chain can be used only by one of the two entities at any given time. The device receives, for a first entity via the receive chain, a first set of encoded symbols of a first data unit. The device receives the first data unit in a receive duration on a wireless medium. The device allocates the receive chain to a second entity at a first time instance of the receive duration and recovers information symbols from the first set of encoded symbols based on an error correction technique. [086] In example 2, the device of example 1 receives the first data unit containing multiple encoded symbols, with encoded symbols containing information symbols and repair symbols encoded according to the error correction technique. Due to the presence of such repair symbols, the device may recover the information symbols from those of the information symbols received for the first entity in the receive duration.

[087] In example 3, the error correcting technique is designed to require at least a first number of symbols of the multiple encoded symbols to recover the information symbols. Accordingly the device allocates the receive chain to the second entity if the receive chain can be allocated to the second entity in the receive duration while retaining the ability to receive at least the first number of symbols of the multiple encoded symbols.

[088] In example 4, the error correcting technique is based on Fountain Codes.

[089] In example 5, the device of example 1 or 3 reallocates the receive chain to the first entity at a second time instance within the receive duration, and recovers the information symbols based on the symbols received between the start time of the receive duration and the first time instance, and also between the second time instance and the end time of the receive duration.

[090] In example 6, the device of examples 3 or 5, allocates the receive chain to the second entity if the first number of symbols are received before the first time instance.

[091] In example 7, the device of examples 3, 5 or 6 receives a second data unit in a second receive duration, and allocates the receive chain to the second entity if the first number of symbols would not be received for the first entity by the end of the second receive duration, for example, due to a noisy channel.

[092] In example 8, the device of examples 1-7 corresponds to a wireless device.

[093]While various aspects of the present disclosure have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above-described aspects of the present disclosure, but should be defined only in accordance with the following claims and their equivalents.

Claims

I/We Claim:

1. A device comprising:

a receive chain;

a processing block configured to:

receive, for a first entity via the receive chain, a first set of encoded symbols of a first data unit,

wherein the device receives the first data unit in a receive duration; allocate the receive chain to a second entity at a first time instance of the receive duration; and

recover the plurality of information symbols from the first set of encoded symbols based on an error correction technique, the plurality of information symbols being encoded in the first data unit according to the error correction technique.

2. The device of claim 1, wherein the first data unit contains a plurality of encoded symbols,

the plurality of encoded symbols containing the plurality of information symbols and a plurality of repair symbols encoded according to the error correction technique,

the first set of encoded symbols also being contained in the plurality of encoded symbols.

3. The device of claim 1 or 2, wherein the error correcting technique requires at least a first number of symbols of the plurality of encoded symbols to recover the plurality of information symbols, the processing block further configured to:

determine whether the receive chain can be allocated to the second entity in the receive duration while retaining the ability to receive at least the first number of symbols of the plurality of encoded symbols,

wherein the allocation is performed if the receive chain can be allocated to the second entity in the receive duration while retaining the ability to receive at least the first number of symbols of the plurality of encoded symbols.

4. The device of any of claims 1-3, wherein the error correcting technique is based on Fountain Codes, wherein the first number of symbols is equal to or slightly greater than the number of symbols in the plurality of information symbols, wherein said device is a wireless device which receives the first set of encoded symbols on a wireless medium, and wherein the first entity and the second entity correspond to a respective subscriber identity module (SIM) of two SIMs.

5. The device of any of claim 1 -4, wherein the processing block is further configured to: reallocate the receive chain to the first entity at a second time instance within the receive duration,

wherein a first subset of encoded symbols are received via the receive chain for the first entity in a duration between the start time of the receive duration and the first time instance, and a second subset of encoded symbols are received via the receive chain for the first entity in a duration between the second time of the receive duration and the end time of the receive duration,

wherein the first set of encoded symbols comprise the first subset of encoded symbols and the second subset of encoded symbols.

6. The device of any of claims 1-5, wherein the determining comprises checking whether the first number of symbols are received before the first time instance,

wherein the receive chain is allocated to the second entity the first number of symbols are received before the first time instance.

7. The device of any of claims 1 -6, wherein the device receives a second data unit in a second receive duration, wherein the processing block is further configured to:

determine at a third time instance of the second receive duration whether the first number of symbols would be received for the first entity by the end of the second receive duration; and allocate the receive chain to the second entity if the first number of symbols would not be received for the first entity by the end of the second receive duration.

8. A method performed in a device, the method comprising:

receiving, for a first entity via a receive chain, a first set of encoded symbols of a first data unit,

wherein the device receives the first data unit in a receive duration; allocating the receive chain to a second entity at a first time instance of the receive duration; and

recovering the plurality of information symbols from the first set of encoded symbols based on an error correction technique, the plurality of information symbols being encoded in the first data unit according to the error correction technique.

9. The method of claim 8, wherein the first data unit contains a plurality of encoded symbols,

10. The method of claim 8 or 9, wherein the error correcting technique requires at least a first number of symbols of the plurality of encoded symbols to recover the plurality of information symbols, the method further comprising:

determining whether the receive chain can be allocated to the second entity in the receive duration while retaining the ability to receive at least the first number of symbols of the plurality of encoded symbols,

11. The method of any of claims 8-10, wherein the error correcting technique is based on Fountain Codes, wherein the first number of symbols is equal to or slightly greater than the number of symbols in the plurality of information symbols, wherein said device is a wireless device which receives the first set of encoded symbols on a wireless medium, and wherein the first entity and the second entity correspond to a respective subscriber identity module (SIM) of two SIMs.

12. The method of any of claim 8-11, further comprising:

reallocating the receive chain to the first entity at a second time instance within the receive duration,

13. The method of any of claims 8-12, wherein the checking further checks whether the first SIM has been denied registration by the first mobile network, wherein the wireless device is deemed to be in the coverage hole if the first SIM has been denied registration by the first mobile network.

14. The method of any of claims 8-13, wherein the wireless device is designed to operate according to LTE (Long Term Evolution) for each of the first SIM and any other SIM , wherein the limited service includes making emergency calls from the wireless device, and receiving alerts provided by Earthquake and Tsunami Warning System (ETWS), Public Warning System (PWS) and Commercial Mobile Alert System (CMAS).

15. A non-transitory machine readable medium storing one or more sequences of instructions for operating a wireless device, wherein execution of the one or more instructions by one or more processors contained in the wireless device enables the wireless device to perform the actions of:

identifying a situation requiring selection of a cell to camp on for a first SIM configured to operate using a first mobile network of a first network operator, the first SIM being contained in the plurality of SIMs;

checking whether the wireless device is in a coverage hole of the first mobile network; if the wireless device is not in the coverage hole, camp the first SIM in a first cell of the first mobile network;

if the wireless device is in the coverage hole, determining whether any other SIM of the plurality of SIMs is already camped on a cell with support for at least limited service;

if the any other SIM is already camped on a cell with support for at least limited service, suspending selection of the cell for the first SIM; and

if the any other SIM is not already camped on a cell with support for at least limited service, camping on any acceptable cell for limited service.

16. The non-transitory machine readable medium of claim 15, wherein the cell with support for at least limited service is one of a suitable cell and an acceptable cell.

17. The non-transitory machine readable medium of claim 15 or 16, wherein the first SIM is camped on a third cell prior to the identifying, such that the selection comprises a reselection.

18. The non-transitory machine readable medium of any of claims 15-17, further comprising instructions for:

checking periodically whether the first SIM is camped in a suitable cell, wherein the situation comprises a determination that the first SIM is not camped in a suitable cell.

19. The non-transitory machine readable medium of any of claims 15-18, wherein the checking further checks whether the first SIM has been denied registration by the first mobile network, wherein the wireless device is deemed to be in the coverage hole if the first SIM has been denied registration by the first mobile network.

20. The non-transitory machine readable medium of any of claims 15-19, wherein the wireless device is designed to operate according to LTE (Long Term Evolution) for each of the first SIM and any other SIM, wherein the limited service includes making emergency calls from the wireless device, and receiving alerts provided by Earthquake and Tsunami Warning System (ETWS), Public Warning System (PWS) and Commercial Mobile Alert System (CMAS

21. A device comprising:

means for receiving, for a first entity via the receive chain, a first set of encoded symbols of a first data unit, wherein the device receives the first data unit in a receive duration;

means for allocating the receive chain to a second entity at a first time instance of the receive duration; and

means for recovering the plurality of information symbols from the first set of encoded symbols based on an error correction technique, the plurality of information symbols being encoded in the first data unit according to the error correction technique.

22. The device of claim 21, wherein the first data unit contains a plurality of encoded symbols,

23. The device of claim 21 or 22, wherein the error correcting technique requires at least a first number of symbols of the plurality of encoded symbols to recover the plurality of information symbols, the device further comprising means for:

wherein means for allocating performs the allocation if the receive chain can be allocated to the second entity in the receive duration while retaining the ability to receive at least the first number of symbols of the plurality of encoded symbols.

24. The device of any of claims 21-23, wherein the error correcting technique is based on Fountain Codes, wherein the first number of symbols is equal to or slightly greater than the number of symbols in the plurality of information symbols, wherein said device is a wireless device which receives the first set of encoded symbols on a wireless medium, and wherein the first entity and the second entity correspond to a respective subscriber identity module (SIM) of two SIMs.

25. The device of any of claims 21 -24, wherein the device further comprises:

means for reallocating the receive chain to the first entity at a second time instance within the receive duration,