WO2013113146A1

WO2013113146A1 - Method and apparatus for controlling uplink transmission

Info

Publication number: WO2013113146A1
Application number: PCT/CN2012/070777
Authority: WO
Inventors: Wei Bai; Haiming Wang; Brian Martin; Jing HAN
Original assignee: Renesas Mobile Corporation
Priority date: 2012-01-30
Filing date: 2012-01-30
Publication date: 2013-08-08

Abstract

A method is provided that includes determining whether a group of carriers (sTAG) that includes one or more secondary cells and that has the same timing advance (TA) value has a valid timing reference and a valid TA value. The method of this embodiment also includes causing uplink transmission to be suspended in an instance in which at least one of the timing reference or the TA value is invalid for the sTAG. Corresponding apparatus and computer program products are also provided.

Description

METHOD AND APPARATUS FOR CONTROLLING UPLINK TRANSMISSION

TECHNOLOGICAL FIELD

[0001] An example embodiment of the present invention relates generally to wireless communications and, more particularly, to controlling uplink transmission based upon a timing reference and a timing advance value.

BACKGROUND

[0002] Long term evolution (LTE)- advanced (LTE-A) systems intend to provide enhanced services by achieving a higher data rate and lower latency. In order to provide for a higher data rate, an LTE-A system may utilize carrier aggregation. Carrier aggregation allows the expansion of the effective bandwidth delivered to a user terminal through the concurrent utilization of radio resources across multiple carriers. In this way, multiple component carriers are aggregated to form a larger overall transmission bandwidth. The component carriers include a primary cell (pCell) that is regarded as the anchor carrier for a mobile terminal and is utilized for basic functions, such as radio link failure monitoring. If more than one component carrier is configured for a mobile terminal, the additional component carriers are referred to as secondary cells (sCells).

[0003] In Release 10, the third generation partnership project (3 GPP) determined that there would be only intra-band carrier aggregation for the uplink and one timing advance ( ) for all of the uplink component carriers. The TA compensates for the propagation delays as the signal travels between the mobile terminal and a base station. In this regard, the base station may assign a TA to the mobile terminal based on the distance between the mobile terminal and the base station. However, in LTE-A Release 11, multiple TAs would be required so as to take into account inter-band carrier aggregation as well as instances involving a radio remote head (RRH) and repeater. Release 11 also determines that a random access channel (RACH) procedure may be enabled with a secondary cell to allow the mobile terminal to acquire the TA value via the secondary cell.

[0004] In order to manage the TAs of a mobile terminal more efficiently, particularly in an instance in which the mobile terminal has multiple TAs, a TA group has been established. In this regard, a TA group is a group of carriers that share the same TA value and the same timing reference. The TA group that includes the pCell is referred to as pTAG, while the TA group that includes only sCells is referred to as sTAG.

[0005] In an LTE system, in order to cause uplink transmissions to be received by an evolved Node B (eNB) at the same time, a mobile terminal will need both a timing reference and a TA value so as to define the uplink transmission timing. It has been determined that the system information block (SIB)-2 linked secondary cell in which random access (RA) is performed is to be taken as the timing reference for the sTAG, More particularly, it is the time at which the RA is triggered on a secondary cell that defines the timing reference, rather than the time at which the RA is successful. In this regard, the transmission of the preamble will require a timing reference and for the first RA procedure of an sTAG, there will otherwise be no prior timing reference.

[0006] However, there are instances in which the timing reference and/or the TA value may potentially be invalid, thereby jeopardizing uplink transmissions from the mobile terminal. In this regard, in an instance in which the sCell that is utilized as the timing reference may be deactivated while the other sCells remain active, the timing reference utilized by the other sCells that remain active may have questionable, if any, validity.

[0007] Additionally, a mobile terminal will generally not transmit uplink data if the user equipment is not in an uplink synchronization (sync) state and a downlink sync state. In an LTE system, the uplink sync state depends on whether the time alignment timer (TAT) is running. In an instance in which the mobile terminal has initially accessed the network, but has not successfully performed the random access, the mobile terminal will not have a valid TA so that the time alignment timer will not be running and the user equipment will, in turn, not be in an uplink sync state. Additionally, in an instance in which an eNB does not provide the mobile terminal with the TA command before time alignment timer expires, the mobile terminal will also not be in an uplink sync state. In contrast to the uplink sync state, the downlink sync state of the mobile terminal of an LTE system will depend upon whether a radio link failure (RLF) condition is fulfilled. However, at least some LTE systems may not take into consideration the possibility that the timing reference or the TA value may be invalid even if the time alignment timer is running and, as such, may not direct the behavior of the mobile terminal in such a situation. BRIEF SUMMARY

[0008] A method, apparatus and computer program product are provided according to an example embodiment in order to determine whether the timing reference and the timing advance value are invalid and, if so, to suspend an uplink transmission for a group of carriers (sTAG) that includes one or more secondary cells. As such, a method, apparatus and computer program product of an example embodiment may suspend the uplink transmissions for the secondary cells of an sTAG and thereby avoid unsuccessful uplink transmissions that would have otherwise unnecessarily consumed network resources until a valid timing reference and valid timing advance value are again defined for the sTAG.

[0009] In one embodiment, a method is provided that includes determining whether a group of carriers (sTAG) that includes one or more secondary cells and that has the same timing advance (TA) value has a valid timing reference and a valid TA value. The method of this embodiment also includes causing uplink transmission to be suspended in an instance in which at least one of the timing reference or the TA value is invalid for the sTAG.

[0010] In another embodiment, an apparatus is provided that includes at least one processor and at least one memory including computer program code with the at least one memory and the computer program code being configured to, with the processor, cause the apparatus to at least determine whether a group of carriers (sTAG) that includes one or more secondary cells and that has the same timing advance (TA) value has a valid timing reference and a valid TA value. The at least one memory and the computer program code are also configured to, with the processor, cause the apparatus to cause uplink transmission to be suspended in an instance in which at least one of the timing reference or the TA value is invalid for the sTAG.

[0011] In a further embodiment, a computer program product includes at least one non-transitory computer-readable storage medium having computer-readable program

instructions stored therein with the computer-readable program instructions including program insttuctions configured to determine whether a group of carriers (sTAG) that includes one or more secondary cells and that has the same timing advance (TA) value has a valid timing reference and a valid TA value. The computer-readable program instructions of this embodiment also include program instructions configured to cause uplink transmission to be suspended in an instance in which at least one of the timing reference or the TA value is invalid for the sTAG.

[0012] In yet another embodiment, an apparatus is provided that includes means for determining whether a group of carriers (sTAG) that includes one or more secondary cells and that has the same timing advance (TA) value has a valid timing reference and a valid TA value. The apparatus of this embodiment also includes means for causing uplink transmission to be suspended in an instance in which at least one of the timing reference or the TA value is invalid for the sTAG.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Having thus described certain embodiments of the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

[0014] FIG. 1 is a block diagram of an apparatus that may be specifically configured in accordance with an example embodiment of the present invention;

[0015] FIG. 2 is a flowchart illustrating operations performed in accordance with one example embodiment of the present invention; and

[0016] FIGs. 3a and 3b are a flowchart illustrating the operations performed in accordance with another example embodiment of the present invention. DETAILED DESCRIPTION

[0017] The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

[0018] As used in this application, the term "circuitry" refers to all of the following:

(a)hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and (b) to combinations of circuits and software (and/or firmware), such as (as applicable): (i) to a combination of processors) or (ii) to portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) to circuits, such as a microprocessors) or a portion of a microprocessor(s), that

require software or firmware for operation, even if the software or firmware is not

physically present.

[0019] This definition of "circuitry" applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware. The term "circuitry" would also cover, for example and if applicable to the particular claim element, a baseband integrated circuit or application specific integrated circuit for a mobile phone or a similar integrated circuit in server, a cellular network device, or other network device.

[0020] A mobile terminal may be configured to communicate with a network via a base station, such as a node B, an evolved node B (eNB), a relay node, an access point or the like. Various types of mobile terminals may be configured in accordance with an example embodiment including, for example, a mobile communication device such as, for example, a mobile telephone, portable digital assistant (PDA), pager, laptop computer, tablet computer, or any of numerous other hand held or portable communication devices, computation devices, content generation devices, content consumption devices, or combinations thereof. The mobile terminal may be configured to communicate with various different networks including, for example, an LTE network, an LTE-A network, a Global Systems for Mobile communications (GSM) network, a Code Division Multiple Access (CDMA) network, e.g., a Wideband CDMA (WCDMA) network, a CDMA2000 network or the like, a General Packet Radio Service (GPRS) network or other type of network.

[0021] The mobile terminal may be configured to communicate with the network via an uplink that supports the transmission of data or other signals from the mobile terminal to the network and via a downlink that supports the transmission of data and other signals from the network to the mobile terminal. In order to insure that the data and other signals transmitted by the mobile terminal to the network are properly received by the network from a temporal standpoint, a timing reference and a timing advance (TA) value are defined. In one embodiment, TA groups have been defined with a TA group being a group of carriers that share the same TA value and the same timing reference. In this regard, a TA group that includes a primary cell is referred to as a pTAG, while a TA group that includes only secondary cells is referred to as an sTAG.

[0022] In order to ensure that an uplink transmission from a mobile terminal to the network has the proper timing, the method, apparatus and computer program product of an example embodiment determines the validity of both the timing reference and the TA value and suspends the uplink transmission in an instance in which either the timing reference or the TA value is invalid. In this regard, an apparatus 10 that may be embodied by or otherwise associated with a mobile terminal and that may be particularly configured in order to determine the validity of the timing reference and the TA value and to suspend uplink transmissions in an instance in which either the timing reference or the TA value is invalid is shown in FIG. 1 and described below. However, it should be noted that the components, devices or elements described below may not be mandatory and thus some may be omitted in certain embodiments. Additionally, some embodiments may include further or different components, devices or elements beyond those shown and described herein.

[0023] As shown in FIG. 1, the apparatus 10 may include or otherwise be in communication with a processing system including, for example, processing circuitry that is configurable to perform actions in accordance with example embodiments described herein. The processing circuitry may be configured to perform data processing, application execution and/or other processing and management services according to an example embodiment of the present invention. In some embodiments, the apparatus or the processing circuitry may be embodied as a chip or chip set. In other words, the apparatus or the processing circuitry may comprise one or more physical packages (e.g., chips) including materials, components and/or wires on a structural assembly (e.g., a baseboard). The structural assembly may provide physical strength, conservation of size, and/or limitation of electrical interaction for component circuitry included thereon. The apparatus or the processing circuitry may therefore, in some cases, be configured to implement an embodiment of the present invention on a single chip or as a single "system on a chip." As such, in some cases, a chip or chipset may constitute means for performing one or more o erations for providing the functionalities described herein.

[0024] In an example embodiment, the processing circuitry may include a processor 12 and memory 14 that may be in communication with or otherwise control a communication interface 16 and, in some cases, a user interface 18. As such, the processing circuitry may be embodied as a circuit chip (e.g., an integrated circuit chip) configured (e.g., with hardware, software or a combination of hardware and software) to perform operations described herein. However, in some embodiments taken in the context of the mobile terminal, the processing circuitry may be embodied as a portion of mobile terminal.

[0025] The user interface 18 (if implemented in embodiments of the apparatus 10 embodied by the mobile terminal) may be in communication with the processing circuitry to receive an indication of a user input at the user interface and/or to provide an audible, visual, mechanical or other output to the user. As such, the user interface may include, for example, a keyboard, a mouse, a joystick, a display, a touch screen, a microphone, a speaker, and/or other input/output mechanisms, ha one embodiment, the user interface includes user interface circuitry configured to facilitate at least some functions of the user equipment by receiving user input and providing output.

[0026] The communication interface 16 may include one or more interface mechanisms for enabling communication with other devices and/or networks. In some cases, the

communication interface may be any means such as a device or circuitry embodied in either hardware, or a combination of hardware and software that is configured to receive and/or transmit data from to a network and/or any other device or module in communication with the processing circuitry, such as between the mobile terminal and the access point. In this regard, the communication interface may include, for example, an antenna (or multiple antennas) and supporting hardware and/or software for enabling communications with a wireless

communication network and/or a communication modem or other hardware/software for supporting communication via cable, digital subscriber line (DSL), universal serial bus (USB), Ethernet or other methods.

[0027] In an example embodiment, the memory 14 may include one or more non-transitory memory devices such as, for example, volatile and/or non-volatile memory that may be either fixed or removable. The memory may be configured to store information, data, applications, instructions or the like for enabling the apparatus 10 to carry out various functions in accordance with example embodiments of the present invention. For example, the memory could be configured to buffer input data for processing by the processor 12. Additionally or alternatively, the memory could be configured to store instructions for execution by the processor. As yet another alternative, the memory may include one of a plurality of databases that may store a variety of files, contents or data sets. Among the contents of the memory, applications may be stored for execution by the processor in order to carry out the functionality associated with each respective application. In some cases, the memory may be in communication with the processor via a bus for passing information among components of the apparatus.

[0028] The processor 12 may be embodied in a number of different ways. For example, the processor may be embodied as various processing means such as one or more of a

microprocessor or other processing element, a coprocessor, a controller or various other computing or processing devices including integrated circuits such as, for example, an ASIC (application specific integrated circuit), an FPGA (field programmable gate array), or the like. In an example embodiment, the processor may be configured to execute instructions stored in the memory 14 or otherwise accessible to the processor. As such, whether configured by hardware or by a combination of hardware and software, the processor may represent an entity (e.g., physically embodied in circuitry - in the form of processing circuitry) capable of performing operations according to embodiments of the present invention while configured accordingly.

Thus, for example, when the processor is embodied as an ASIC, FPGA or the like, the processor may be specifically configured hardware for conducting the operations described herein.

Alternatively, as another example, when the processor is embodied as an executor of software instructions, the instructions may specifically configure the processor to perform the operations described herein.

[0029] FIGS, 2, 3a and 3b are flowcharts illustrating the operations performed by a method, apparatus and computer program product, such as apparatus 10 of FIG. 1 , from the perspective of the mobile terminal in accordance with one embodiment of the present invention. It will be understood that each block of the flowchart, and combinations of blocks in the flowchart, may be implemented by various means, such as hardware, firmware, processor, circuitry and/or other device associated with execution of software including one or more computer program instructions. For example, one or more of the procedures described above may be embodied by computer program instructions. In this regard, the computer program instructions which embody the procedures described above may be stored by a non-transitory memory 14 of an apparatus employing an embodiment of the present invention and executed by a processor 12 in the apparatus. As will be appreciated, any such computer program instructions may be loaded onto a computer or other programmable apparatus (e.g., hardware) to produce a machine, such that the resulting computer or other programmable apparatus provides for implementation of the functions specified in the flowchart blocks. These computer program instructions may also be stored in a non-transitory computer-readable storage memory that may direct a computer or other programmable apparatus to function in a particular manner, such that the instructions stored in the computer-readable storage memory produce an article of manufacture, the execution of which implements the function specified in the flowchart blocks. The computer program instructions may also be loaded onto a computer or other programmable apparatus to cause a series of operations to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide operations for implementing the functions specified in the flowchart blocks. As such, the operations of FIGs. 2, 3a and 3b, when executed, convert a computer or processing circuitry into a particular machine configured to perform an exam le embodiment of the present invention, Accordingly, the operations of FIGs. 2, 3a and 3b define an algorithm for configuring a computer or processing circuitry, e.g., processor, to perform an example embodiment. In some cases, a general purpose computer may be provided with an instance of the processor which performs the algorithm of FIGs. 2, 3a and 3b to transform the general purpose computer into a particular machine configured to perform an example embodiment.

[0030] Accordingly, blocks of the flowcharts support combinations of means for performing the specified functions and combinations of operations for performing the specified functions. It will also be understood that one or more blocks of the flowchart, and combinations of blocks in the flowchart, can be implemented by special purpose hardware-based computer systems which perform the specified functions, or combinations of special purpose hardware and computer instructions.

[0031] In some embodiments, certain ones of the operations above may be modified or further amplified as described below. It should be appreciated that each of the modifications, optional additions or amplifications below may be included with the operations above either alone or in combination with any others among the features described herein.

[0032] Referring now to FIG. 2, the operations performed by an apparatus 10, such as depicted in FIG. 1, in order to detennine the validity of a timing reference and a TA value and to suspend an uplink transmission in an instance in which either the timing reference and the TA value is invalid is depicted. As shown in operation 20 of FIG. 2, the apparatus may include means, such as the processor 12 or the like, for determining whether a group of carriers (sTAG) that includes one or more secondary cells and that has the same TA value has a valid timing reference and a valid TA value. In one embodiment, the sTAG may only include secondary cells. The apparatus of one embodiment may also include means, such as the processor, the communications interface 16 or the like, for causing uplink transmission to be suspended in an instance in which at least one of the timing reference or the TA values is invalid for the sTAG. See operation 22, Thus, in an instance in which the timing reference is invalid for the sTAG, uplink transmission may be suspended even if the TA value is valid. Conversely, in an instance in which the TA value is invalid, the uplink transmission may be suspended for the sTAG even if the timing reference is valid. The suspension of the uplink transmission is different than the expiration of a time alignment timer (TAT) so the mobile terminal may not necessarily release the type 0 sounding reference signals (SRS) or flush the hybrid automatic request (HARQ) buffer upon the suspension of the uplink transmission.

[0033] Once the uplink transmission has been suspended, the apparatus 10, such as a processor 12 or the like, may continue to monitor the timing reference and the TA value of the sTAG and once the sTAG is determined to have a valid timing reference and a valid TA value, uplink transmission may be resumed. In this regard, the apparatus may include means, such as the processor, the communications interface 16 or the like, for causing uplink transmissions to be conducted, such as by being resumed in an instance in which the uplink transmission has been previously suspended, in an instance in which each of the timing reference and the TA value are valid for the sTAG. See operation 24.

[0034] The method, apparatus and computer program product of an example embodiment may define the validity of the timing reference and/or the validity of the TA value based upon one or more measures, parameters, conditions or the like. In this regard, one example definition of the validity of the timing reference and the validity of the TA value is described below in conjunction with FIG. 3 in which a valid timing reference may be evaluated to determine if the timing reference satisfies three conditions and a valid TA value may be evaluated to determine if the TA value satisfies two conditions. However, the method, apparatus and computer program product of other embodiments may include only a subset of the conditions described below in conjunction with the embodiment of FIG. 3 in order to define the validity of a timing reference and/or the validity of the TA value. Still further, the method, apparatus and computer program product of other embodiments may define the validity of the timing reference and/or the TA value based upon additional or different conditions. Further, the conditions that are evaluated in regard to the timing reference and/or the TA value may be evaluated in different orders than that set forth in Figure 3 in other embodiments.

[0035] By way of example, however, the apparatus 10 of one embodiment will now be described in conjunction with the operations set forth by FIGs. 3a and 3b. In this embodiment, the apparatus may include means, such as the processor 12 or the like, for determining whether the sTAG has a valid timing reference by determining the timing reference to be invalid in an instance in which no random access (RA) is triggered on any of the secondary cells of the sTAG, such as a newly configured sTAG. See operation 30 of FIG. 3a. In an instance in which no RA is triggered on any of the secondary cells of the sTAG, the timing reference may be considered to be invalid and the uplink transmission may be suspended. See operation 40 of FIG. 3b. However, in an instance in which RA has been triggered on one or more of the secondary cells of the sTAG, the apparatus may evaluate other conditions relevant to the validity of the timing reference and/or the TA value.

[0036] With referenced operation 32 of FIG. 3a, the apparatus 10 of one embodiment may also include means, such as the processor 12 or the like, for determining whether the sTAG has a valid timing reference by determining the timing reference to be invalid in an instance in which the secondary cell that serves as a timing reference is deactivated. In an instance in which the secondary cell that serves as a timing reference is deactivated, the uplink transmission may be suspended. However, in an instance in which the secondary cell that serves as a timing reference is activated, the apparatus of one embodiment may consider additional conditions for determining the validity of the timing reference and/or the TA value.

[0037] With respect to operation 34 of FIG. 3a, for example, the apparatus 10 of one embodiment may include means, such as the processor 12 or the like, for determining whether the sTAG has a valid timing reference by determining the timing reference to be invalid in an instance in which the channel quality of the secondary cell that serves as the timing reference fails to satisfy a predefined criteria. In an instance in which the channel quality of a secondary cell that serves as a timing reference fails to satisfy the predefined criteria, the uplink transmission may be suspended. However, in an instance in which the channel quality of the secondary cell that serves as the timing reference satisfies the predefined criteria and the secondary cell that serves as a timing reference has been previously determined to be active and an RA has been triggered on at least one of the secondary cells of the sTAG, the apparatus of this embodiment may determine that the sTAG has a valid timing reference.

[0038] Either prior to determining the validity of the timing reference, concurrent with the determination of the validity of the timing reference or following the determination of the validity of the timing reference as shown in the embodiment of FIG. 3a, the apparatus 10 of one embodiment may determine the validity of the TA value. In regards to the embodiment of FIG. 3, for example, the apparatus may include means, such as a processor 12 or the like, for determining whether the sTAG, such as a newly configured sTAG, has a valid TA value by determining the TA value to be invalid in an instance in which an indication of the TA value, such as provided by a TA command, e.g., Msg2, or a random access response (RAR), has not been received for the sTAG. See operation 36. In an instance in which no indication of the TA value has been received for the sTAG, uplink transmission may be suspended. However, in an instance in which an indication of the TA value has been received for the sTAG, the apparatus of one embodiment may consider other conditions that are indicative of the validity of the TA value. As shown in operation 38 of FIG. 3a, for example, the apparatus may include means, such as the processor or the like, for determining whether the sTAG has a valid TA value by determining the TA value to be invalid in an instance in which the RA has been triggered on a secondary cell of the sTAG other than the secondary cell that serves as the timing reference without an indication of the TA value, such as provided by a TA command, e.g., Msg2, by a RAR or a media access control (MAC) control element, regardless of whether or not the time alignment timer (TAT) is running. In an instance in which the RA has been triggered on a secondary cell of the sTAG other than the secondary cell that serves as a timing reference without an indication of the TA value, the uplink transmission may be suspended. However in this embodiment, in an instance in which the RA has been triggered on a secondary cell of the sTAG other than the secondary cell that serves as a timing reference or in an instance in which a TA command has been received regardless of whether the RA has been triggered on a secondary cell of the sTAG other than the secondary cell that serves as a timing reference, the apparatus of this embodiment may determine the TA value to be valid. Once both the timing reference and the TA value have been determined to be valid, uplink transmission from a mobile terminal to the network may continue, or resume if previously suspended. See operation 42 of FIG. 3b.

[0039] By way of example, in an instance in which a mobile terminal receives an RA trigger for a secondary cell other than the secondary cell that serves as the timing reference for the sTAG, the mobile terminal may suspend uplink transmission for all of the secondary cells of the sTAG, regardless of whether the time alignment timer for the sTAG is running or not. As another example, in an instance in which the secondary cell that serves as a timing reference for the sTAG is deactivated, the mobile terminal of one embodiment may suspend uplink transmissions for all of the secondary cells of the sTAG. In a further example, in an instance in which the TA value is valid, the mobile terminal may resume uplink transmissions once the secondary cell that serves as the timing reference for the sTAG is activated from a prior deactivated state. In yet another example, in an instance in which the timing reference is valid, a mobile terminal that receives an indication of the TA value, such as by receipt of a TA command, e.g., Msg2, or a RAR, for the sTAG may be configured to resume uplink

transmissions,

[0040] By determining the validity of the timing reference and the TA value prior to commencing or continuing with uplink transmission, the method, apparatus and computer program product of an example embodiment may ensure the uplink data and other signals is only transmitted in an instance in which the timing is appropriate so as to avoid or at least reduce instances of uplink interference. Additionally, the method, apparatus and computer program product of an example embodiment may ensure that the mobile terminal has the same understanding of its sync state as the network, such as the base station or the like, by ensuring that both the timing reference and the TA value are valid.

[0041] Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although the foregoing descriptions and the associated drawings describe example embodiments in the context of certain example combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and/or functions than those explicitly described above are also contemplated as maybe set forth in some of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

What is Claimed is:

1. A method comprising:

determining whether a group of carriers (sTAG) that includes one or more secondary cells and that has the same timing advance (TA) value has a valid timing reference and a valid TA value; and

causing uplink transmission to be suspended in an instance in which at least one of the timing reference or the TA value is invalid for the sTAG.

2. A method according to Claim 1 further comprising causing uplink transmission to be resumed in an instance in which both of the timing reference and the TA value are valid for the sTAG.

3. A method according to any one of Claims 1 or 2 wherein determining whether the sTAG has a valid timing reference comprises determining the timing reference to be invalid in an instance in which random access (RA) is not triggered on any of the secondary cells of the sTAG.

4. A method according to any one of Claims 1 to 3 wherein determining whether the sTAG has a valid timing reference comprises determining the timing reference to be invalid in an instance in which the secondary cell that serves as the timing reference is deactivated.

5. A method according to any one of Claims 1 to 4 wherein determining whether the sTAG has a valid timing reference comprises detennining the timing reference to be invalid in an instance in which a channel quality of the secondary cell that serves as the timing reference fails to satisfy a predefined criteria.

6. A method according to any one of Claims 1 to 5 wherein determining whether the sTAG has a valid TA value comprises determining the TA value to be invalid in an instance in which an indication of the TA value has not been received for the sTAG.

7. A method according to any one of Claims 1 to 6 wherein determining whether the sTAG has a valid TA value comprises determining the TA value to be invalid in an instance in which random access (RA) has been triggered on a secondary cell of the sTAG other than the secondary cell that serves as the timing reference without an indication of the TA value.

8. An apparatus comprising at least one processor and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the processor, cause the apparatus to at least:

determine whether a group of carriers (sTAG) that includes one or more secondary cells and that has the same timing advance (TA) value has a valid timing reference and a valid TA value; and

cause uplink transmission to be suspended in an instance in which at least one of the timing reference or the TA value is invalid for the sTAG.

9. An apparatus according to Claim 8 wherein the at least one memory and the computer program code are also configured to, with the processor, cause the apparatus to cause uplink transmission to be resumed in an instance in which both of the timing reference and the TA value are valid for the sTAG.

10. An apparatus according to any one of Claims 8 or 9 wherein the at least one memory and the computer program code are configured to, with the processor, cause the apparatus to detennine whether the sTAG has a valid timing reference by determining the timing reference to be invalid in an instance in which random access (RA) is not triggered on any of the secondary cells of the sTAG.

11. An apparatus according to any one of Claims 8 to 10 wherein the at least one memory and the computer program code are configured to, with the processor, cause the apparatus to determine whether the sTAG has a valid timing reference by determining the timing reference to be invalid in an instance in which the secondary cell that serves as the timing reference is deactivated.

12. An apparatus according to any one of Claims 8 to 11 wherein the at least one memory and the computer program code are configured to, with the processor, cause the apparatus to determine whether the sTAG has a valid timing reference by determining the timing reference to be invalid in an instance in which a channel quality of the secondary cell that serves as the timing reference fails to satisfy a predefined criteria.

13. An apparatus according to any one of Claims 8 to 12 wherein the at least one memory and the computer program code are configured to, with the processor, cause the apparatus to determine whether the sTAG has a valid TA value by determining the TA value to be invalid in an instance in which an indication of the TA value has not been received for the sTAG.

1 . An apparatus according to any one of Claims 8 to 13 wherein the at least one memory and the computer program code are configured to, with the processor, cause the apparatus to determine whether the sTAG has a valid TA value by determining the TA value to be invalid in an instance in which random access (RA) has been triggered on a secondary cell of the sTAG other than the secondary cell that serves as the timing reference without an indication of the TA value.

15. An apparatus according to any one of Claims 8 to 14 wherein the apparatus is embodied by a mobile telephone.

16. An apparatus according to any one of Claims 8 to 15 further comprising user interface circuitry configured to facilitate user control of at least some functions of the mobile telephone through use of a display.

17. An apparatus comprising:

means for determining whether a group of carriers (sTAG) that includes one or more secondary cells and that has the same timing advance (TA) value has a valid timing reference and a valid TA value; and

means for causing uplink transmission to be suspended in an instance in which at least one of the timing reference or the TA value is invalid for the sTAG.

18. An apparatus according to Claim 17 further comprising means for causing uplink transmission to be resumed in an instance in which both of the timing reference and the TA value are valid for the sTAG.

19. An apparatus according to any one of Claims 17 or 18 wherein the means for determining whether the sTAG has a valid timing reference comprises means for determining the timing reference to be invalid in an instance in which random access (RA) is not triggered on any of the secondary cells of the sTAG.

20. An apparatus according to any one of Claims 17 to 19 wherein the means for determining whether the sTAG has a valid timing reference comprises means for determining the timing reference to be invalid in an instance in which the secondary cell that serves as the timing reference is deactivated.

21. An apparatus according to any one of Claims 17 to 20 wherein the means for determining whether the sTAG has a valid timing reference comprises means for determining the timing reference to be invalid in an instance in which a channel quality of the secondary cell that serves as the timing reference fails to satisfy a predefined criteria.

22. An apparatus according to any one of Claims 17 to 21 wherein the means for determining whether the sTAG has a valid TA value comprises means for determining the TA value to be invalid in an instance in which an indication of the TA value has not been received for the sTAG.

23. An apparatus according to any one of Claims 17 to 22 wherein the means for determining whether the sTAG has a valid TA value comprises means for determining the TA value to be invalid in an instance in which random access (RA) has been triggered on a secondary cell of the sTAG other than the secondary cell that serves as the timing reference without an indication of the TA value.

24. A computer program product comprising at least one non-transitory

computer-readable storage medium having computer-readable program instructions stored therein with the computer-readable program instructions comprising program instructions configured to:

25. A computer program product according to Claim 24 wherein the computer-readable program instructions further comprise program instructions configured to cause uplink transmission to be resumed in an instance in which both of the timing reference and the TA value are valid for the sTAG.

26. A computer program product according to any one of Claims 24 or 25 wherein the program instructions configured to determine whether the sTAG has a valid timing reference comprise program instructions configured to determine the timing reference to be invalid in an instance in which random access (RA) is not triggered on any of the secondary cells of the sTAG.

27. A computer program product according to any one of Claims 24 to 26 wherein the program instructions configured to determine whether the sTAG has a valid timing reference comprise program instructions configured to determine the timing reference to be invalid in an instance in which the secondary cell that serves as the timing reference is deactivated.

28. A computer program product according to any one of Claims 24 to 27 wherein the program instructions configured to determine whether the sTAG has a valid timing reference comprise program instructions configured to determine the timing reference to be invalid in an instance in which a channel quality of the secondary cell that serves as the timing reference fails to satisfy a predefined criteria.

29. A computer program product according to any one of Claims 24 to 28 wherein the program instructions configured to determine whether the sTAG has a valid TA value comprise program instructions configured to determine the TA value to be invalid in an instance in which an indication of the TA value has not been received for the sTAG.

30. A computer program product according to any one of Claims 24 to 29 wherein the program instructions configured to deteraiine whether the sTAG has a valid TA value comprise program instructions configured to determine the TA value to be invalid in an instance in which random access (RA) has been triggered on a secondary cell of the sTAG other than the secondary cell that serves as the timing reference without an indication of the TA value.