Contention resolution in random access procedure

Abstract

To provide a device, a method, and a computer-readable storage medium for contention resolution in a random access procedure.SOLUTION: A method includes causing a network device to send to a terminal device a random access request including a random access preamble for a random access procedure and an identifier of the network device, to receive from the terminal device control information indicating at least one of resources and timing information for communication between the network device and the terminal device regarding a control channel addressed to the identifier, and to determine a result of the random access procedure based at least in part on the control information.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly to an apparatus, method, and computer-readable storage medium for contention resolution in random access procedures. [Background technology]

[0002] Various wireless cellular communication systems have been implemented and are being implemented. To meet the increasing demand for communication services, mobile communication systems have been developed and are being developed. With rapid advances in technology, mobile communication systems have evolved to a level where they can provide high-speed data communication services that go beyond the initial voice-centric services.

[0003] A random access (RA) procedure refers to a procedure by which a terminal device establishes or re-establishes a connection with a network device, such as an Evolved NodeB (eNB) or a 5G gNodeB (gNB). A contention-based random access procedure may facilitate the possibility that multiple communication devices may be interested in attempting to access the network device by an RA procedure at the same or similar time. Once access is established and / or confirmed, the network device may allocate resources to the particular terminal device to assist in uplink communication with the network device. Summary of the Invention

[0004] Generally, the example embodiments of the present disclosure provide a solution for contention resolution in random access procedures.

[0005] In a first aspect, an apparatus is provided, the apparatus comprising at least one processor and at least one memory including computer program code configured to cause, by the at least one processor, the apparatus to: transmit a random access request to a second apparatus, the random access request including a random access preamble and an identifier of the apparatus for a random access procedure, receive control information from the second apparatus on a control channel addressed to the identifier, the control information indicating at least one of resources and timing information for communication between the apparatus and the second apparatus, and determine a result of the random access procedure based at least in part on the control information.

[0006] In a second aspect, an apparatus is provided, the apparatus comprising at least one processor and at least one memory including computer program code configured by the at least one processor to cause the apparatus to receive a random access request from a second apparatus, the random access request including a random access preamble and an identifier of the second apparatus for a random access procedure, determine in response to the random access request control information indicating at least one of resource and timing information for communication between the apparatus and the second apparatus, and transmit to the second apparatus the control information on a control channel addressed to the identifier.

[0007] In a third aspect, a method is provided, the method including: in an apparatus, transmitting a random access request to a second apparatus, the random access request including a random access preamble and an identifier of the apparatus for a random access procedure, receiving control information from the second apparatus on a control channel addressed to the identifier, the control information indicating at least one of resources and timing information for communication between the apparatus and the second apparatus, and determining a result of the random access procedure based at least in part on the control information.

[0008] In a fourth aspect, a method is provided, the method including: receiving, in an apparatus, a random access request from a second apparatus, the random access request including a random access preamble and an identifier of the second apparatus for a random access procedure, determining, in response to the random access request, control information indicating at least one of resource and timing information for communication between the apparatus and the second apparatus, and transmitting, to the second apparatus, the control information on a control channel addressed to the identifier.

[0009] In a fifth aspect, an apparatus is provided, the apparatus including: means for transmitting a random access request to a second apparatus, the random access request including a random access preamble and an identifier of the apparatus for a random access procedure, means for receiving control information from the second apparatus on a control channel addressed to the identifier, the control information indicating at least one of resources and timing information for communication between the apparatus and the second apparatus, and means for determining a result of the random access procedure based at least in part on the control information.

[0010] In a sixth aspect, an apparatus is provided, the apparatus including: means for receiving a random access request from a second apparatus, the random access request including a random access preamble and an identifier of the second apparatus for a random access procedure, means for determining, in response to the random access request, control information indicating at least one of resource and timing information for communication between the apparatus and the second apparatus, and means for transmitting, to the second apparatus, the control information on a control channel addressed to the identifier.

[0011] In a seventh aspect, there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least a method according to the third aspect.

[0012] In an eighth aspect, there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least a method according to the fourth aspect.

[0013] It should be understood that the Summary section is not intended to identify key or essential features of the embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become readily apparent through the following description.

[0014] Several example embodiments will now be described with reference to the accompanying drawings. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 illustrates an example communication network in which embodiments of the present disclosure may be implemented. [Diagram 2] 1A and 1B are a flowchart illustrating an example random access procedure. [Diagram 3] 1 is a flowchart illustrating a process for conflict resolution in an RA procedure according to some example embodiments of the present disclosure. [Figure 4] FIG. 2 is a schematic diagram illustrating a TAC MAC CE according to some exemplary embodiments of the present disclosure. [Diagram 5] 1 is a flowchart of a method according to some example embodiments of the present disclosure. [Figure 6] 1 is a flowchart of a method according to some example embodiments of the present disclosure. [Figure 7] FIG. 1 is a simplified block diagram of a device suitable for practicing embodiments of the present disclosure. [Figure 8] 1 is a block diagram of an example computer-readable medium according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Throughout the drawings, the same or similar reference numbers represent the same or similar elements.

[0017] The principles of the present disclosure will now be described with reference to some exemplary embodiments. It should be understood that these embodiments are described for illustrative purposes only, to help those skilled in the art understand and practice the present disclosure, without suggesting any limitation on the scope of the present disclosure. The present disclosure described herein can be implemented in various ways other than those described below.

[0018] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0019] In this disclosure, references to "one embodiment," "an embodiment," "an example embodiment," and the like indicate that the embodiment being described may include a particular feature, structure, or characteristic, but not all embodiments need include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with one embodiment, it is submitted that this affects such feature, structure, or characteristic in connection with other embodiments, whether or not expressly described, within the knowledge of one skilled in the art.

[0020] Although terms such as "first" and "second" may be used herein to describe various elements, it should be understood that these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, a first element could be referred to as a second element, and similarly, a second element could be referred to as a first element, without departing from the scope of the example embodiments. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0021] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the example embodiments. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly dictates otherwise. Furthermore, it will be understood that "comprises", "comprising", "has", "having", "includes" and / or "including", when used herein, specify the presence of stated features, elements, and / or components, etc., but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0022] As used in this application, the term "circuitry" means (a) Hardware-only circuit implementation (e.g., implementation using only analog and / or digital circuitry); (b) A combination of hardware circuitry and software, such as (where applicable), (i) A combination of analog and / or digital hardware circuitry(s) and software / firmware; and (ii) hardware processor(s) having software (including digital signal processor(s)), software, and any portion of memory(s) that work together to cause a device, such as a mobile phone or a server, to perform various functions; and (c) may refer to one or more or all of hardware circuitry(s) and / or processor(s), such as microprocessor(s) or portions of microprocessor(s), that require software (e.g., firmware) to operate but that may not be present when the software is not necessary for operation.

[0023] This definition of "circuitry" applies to all uses of the term in this application, including any claims. As a further example, as used in this application, the term "circuitry" also encompasses simply a hardware circuit or processor (or processors), or a portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware implementations. The term circuitry also encompasses, for example, baseband integrated circuits, processor integrated circuits for mobile devices, or similar integrated circuits in servers, cellular network devices, or other computing or network devices, if applicable to the particular claim element.

[0024] As used herein, the term "communication network" refers to a network conforming to any suitable communication standard, such as Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High Speed ​​Packet Access (HSPA), and Narrowband Internet of Things (NB-IoT). Furthermore, communication between terminal devices and network devices in a communication network may be performed according to any suitable generation of communication protocols, including, but not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, future fifth generation (5G) communication protocols, and / or any other protocols now known or developed in the future. The embodiments of the present disclosure may be applied in various communication systems. Given the rapid development of communication, it is natural that future communication technologies and systems in which the present disclosure may be embodied will also emerge. The scope of the present disclosure should not be considered to be limited only to the aforementioned systems.

[0025] As used herein, an apparatus may include a terminal device, a network device, or any other suitable device. As used herein, the term "network device" refers to a node in a communication network through which a terminal device accesses and receives services from the network. A network device may refer to a base station (BS) or an access point (AP), such as a Node B (NodeB or NB), evolved Node B (eNodeB or eNB), NR NB (also referred to as gNB), a remote radio unit (RRU), a radio header (RH), a remote radio head (RRH), a repeater, a low power node such as femto, pico, etc., depending on the terminology and technology applied.

[0026] The term "terminal device" refers to any end device that may be capable of wireless communication. By way of example and not limitation, a terminal device may also be referred to as a communication device, user equipment (UE), subscriber station (SS), mobile subscriber station, mobile station (MS), or access terminal (AT). The terminal device may include, but is not limited to, a mobile phone, a cellular phone, a smartphone, a voice-over-IP (VoIP) phone, a wireless local loop phone, a tablet, a wearable terminal device, a personal digital assistant (PDA), a portable computer, a desktop computer, an image capture terminal device such as a digital camera, a game terminal, a music storage and playback device, a vehicle-mounted wireless terminal device, a wireless endpoint, a mobile station, a laptop embedded device (LEE), a laptop mounted device (LME), a USB dongle, a smart device, a wireless customer equipment (CPE), an Internet of Things (IoT) device, a watch or other wearable device, a head mounted display (HMD), a vehicle, a drone, a medical device and medical application (e.g., remote surgery), an industrial device and industrial application (e.g., a robot and / or other wireless device operating in an industrial and / or automation processing chain context), a home electronic device, and a device operating in a commercial and / or industrial wireless network, etc. In the following description, the terms "terminal device", "communication device", "terminal", "user equipment", and "UE" may be used interchangeably.

[0027] FIG. 1 illustrates an example communication system 100 in which embodiments of the present disclosure can be implemented. The system 100 includes two devices: a network device 110 and a terminal device 120 served by the network device 110. The service area of ​​the network device 110 is referred to as a cell 102. It should be understood that the number of devices (both network devices and terminal devices) is for illustrative purposes only without implying any limitation. The system 100 may include any suitable number of network devices and terminal devices employed to implement embodiments of the present disclosure. Although not shown, it will be understood that one or more terminal devices may be located in the cell 102 and served by the network device 110.

[0028] Communications in the communications system 100 may be performed according to any suitable communications protocol(s), including, but not limited to, cellular communications protocols, such as first generation (1G), second generation (2G), third generation (3G), fourth generation (4G), and fifth generation (5G), wireless local network communications protocols, such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, and / or any other protocols now known or developed in the future. Communications may also utilize any suitable wireless communications technology, including, but not limited to, code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), frequency division duplex (FDD), time division duplex (TDD), multiple-input multiple-output (MIMO), orthogonal frequency division multiplexing (OFDM), cyclic prefix orthogonal frequency division multiplexing (CP-OFDM), discrete Fourier transform spread OFDM (DFT-s-OFDM), and / or any other technology now known or developed in the future.

[0029] In the communication system 100, once a connection is established, the network device 110 can communicate with the terminal device 120, and the terminal device 120 can also communicate data and control information to the network device 110. The link from the network device 110 to the terminal device 120 is referred to as the downlink (DL), and the link from the terminal device 120 to the network device 110 is referred to as the uplink (UL). In the DL, the network device 110 is the transmitting (TX) device (or transmitter) and the terminal device 120 is the receiving (RX) device (or receiver). In the UL, the terminal device 120 is the TX device (or transmitter) and the network device 110 is the RX device (or receiver).

[0030] Typically, to communicate with the network device 110, the terminal device 120 may initiate an RA procedure to establish or re-establish a connection with the network device 110.

[0031] There are several possible RA procedures that can be used, such as two-stage RA and four-stage RA. The RA procedure may be based on contention between multiple terminal devices. The four-stage contention-based RA procedure is an exemplary procedure, which is briefly introduced below with reference to FIG. 2A. In the RA procedure 200 of FIG. 2A, the terminal device selects and transmits a random access preamble (which may be referred to as "Msg1") to the network device (210). The network device further transmits a random access response RAR (which may be referred to as "Msg2") to the random access preamble (220). Upon receiving the random access response, the terminal device transmits a scheduled transmission (which may be referred to as "Msg3") to the network device (230). The network device transmits a contention resolution (which may be referred to as "Msg4") to the terminal device in response to contention across its serving terminal devices (240).

[0032] It has been agreed to use a two-stage procedure to achieve rapid random access. An example of a two-stage RA contention-based RA procedure is also briefly introduced below with reference to FIG. 2B. In the RA procedure 202 of FIG. 2B, the terminal device transmits a first message (which may be referred to as "MsgA") to the network device (250). The first message combines a random access preamble (e.g., Msg1) and uplink data (e.g., Msg3). In response to the first message, the network device transmits a second message (which may be referred to as "MsgB") to the terminal device (260). The second message combines a random access response (e.g., Msg2) and a contention resolution (e.g., Msg4).

[0033] Conventionally, for a four-stage RA procedure, an uplink timing alignment command (TAC) is provided via an RAR scheduled on a physical downlink control channel (PDCCH) addressed to the RA Radio Network Temporary Identifier (RNTI) for all random access preamble transmissions. Since the RAR is scheduled on a PDCCH addressed to the RA-RNTI, it is possible to use a special type of medium access control protocol data unit (MAC PDU) defined only to carry the RAR. Contention resolution is also provided in Msg4 in the four-stage RA procedure. For terminal devices in connected mode, it is scheduled on a PDCCH scrambled with the cell-RNTI (C-RNTI) that serves as contention resolution associated with either the UL grant (contention-based random access / CBRA) or the UL grant / DL assignment (contention-free random access / CFRA).

[0034] For the two-stage RA procedure, the first message (i.e., MsgA) is a signal to detect the UE, and the second message (i.e., MsgB) is for contention resolution for CBRA with possible payload. The first message will contain at least the equivalent information sent in Msg1 / Msg3 for the four-stage RA procedure. As a baseline, all triggers for the four-stage RA procedure are also applicable to the two-stage RA procedure, but further analysis is required on how timing advance and grant can be obtained for the first message. Contention resolution in the two-stage RA procedure will be done by including the UE identifier in the first message that is echoed in the second message.

[0035] For the two-stage RA procedure, it is assumed that the MsgB for connected mode UEs may be similar to the four-stage RA scheduled on the PDCCH addressed to the UE's C-RNTI. Furthermore, since connected mode UEs may also require a UL timing alignment value, it is assumed that a new Timing Advance Command (TAC) is defined which may consist of a 12-bit TAC indicating the absolute value of the timing adjustment (unlike the current 6-bit TAC MAC CE which indicates a relative adjustment to the current timing).

[0036] However, when a terminal device in connected mode performs a two-stage RA procedure by sending a first message to a network device, it is not easy to assume that contention resolution will be successful by decoding the PDCCH addressed to the C-RNTI, since the network device may, for example, have successfully scheduled the terminal device (e.g. DL data) after a failed Scheduling Request (SR) without knowing that the terminal device had performed an RA procedure. Furthermore, the requirements for the RA procedure also depend on the scenario whether the Timing Alignment Timer (TAT) is running or not, i.e. whether a TAC is mandatory for the terminal device or not. In contrast, in a four-stage procedure, the terminal device will always receive a TAC from the RAR / Msg2.

[0037] According to some example embodiments of the present disclosure, a solution for contention resolution in an RA procedure is proposed. The solution is related to an RA procedure in which a random access preamble and an identifier of a terminal device are transmitted together in an RA message such as MsgA. One example of such an RA procedure is a two-stage RA procedure. It will be understood that any other suitable RA procedure may also be applicable. According to the solution, an apparatus transmits a random access request to a further apparatus, the random access request including a random access preamble and an identifier of the apparatus for the random access procedure. The apparatus further also receives control information from the further apparatus on a control channel addressed to the identifier, the control information indicating at least one of resource and timing information for communication between the apparatus and the further apparatus. The apparatus then determines a result of the random access procedure based at least in part on the control information. In this way, the result of the RA procedure and contention resolution can be accurately determined even in the presence of other scheduling from a network device that does not respond to the RA procedure.

[0038] Some example embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. Reference is now made to FIG. 3, which illustrates a process 300 for conflict resolution in an RA procedure according to an example embodiment of the present disclosure. For discussion purposes, the process 300 is described with reference to FIG. 1. The process 300 may involve a terminal device 120 and a network device 110, as shown in FIG. 1. Although the process 300 is described as a terminal device 120 accessing the network device 110, it should be understood that the roles of the terminal device 120 and the network device 110 may be swapped. It should also be understood that the example embodiments described herein may be applied to two terminal devices, one of which is attempting to access the other.

[0039] In the process 300, the terminal device 120 sends a random access request to the network device 110 (305). The random access request includes a random access preamble and an identifier of the terminal device 120 for the random access procedure. This random access procedure may be a two-stage RA procedure as described above, and the random access request may be included in the first message, i.e., MsgA. Once the random access request is sent, the terminal device 120 may start a timer to monitor the PDCCH for contention resolution and to monitor contention resolution from the network device 110. For the purposes of discussion, this timer will hereafter be referred to as the CR timer.

[0040] In some example embodiments, terminal device 120 may be in a connected state with network device 110, i.e., terminal device 120 is in a connected mode. This means that terminal device 120 has completed an initial access to network device 110. The identifier of terminal device 120 may be, for example, the C-RNTI of terminal device 120. In this case, terminal device 120 may send MsgA with the C-RNTI MAC CE to network device 110.

[0041] The RA procedure may be triggered in any suitable manner, for example, the RA procedure may be initiated for beam failure recovery by a PDCCH command, by the MAC sublayer, or by the Radio Resource Control (RRC) sublayer.

[0042] Network device 110 receives a random access request from terminal device 120. If network device 110 determines that the contention-based random access for terminal device 120 is successful, network device 110 determines (310) control information to be sent to inform terminal device 120 that the random access is successful. The control information may indicate at least one of resources and timing information for communication between network device 110 and terminal device 120.

[0043] The control information may include a resource indication, e.g., a DL allocation or an UL grant. Alternatively or additionally, the control information may include a Timing Advance Command (TAC), e.g., to indicate an amount of timing adjustment to be used for timing alignment with the terminal device 120 in the uplink. The TAC may also be transmitted by using resources indicated by the DL allocation. The determination of the control information by the network device 110 is described in more detail below.

[0044] Furthermore, network device 110 transmits (315) the control information on a control channel addressed to the identifier of terminal device 120. For example, the control information may be transmitted in a PDCCH addressed to the C-RNTI of terminal device 120. Network device 110 may further transmit other control information and data to terminal device 120.

[0045] As such, terminal device 120 may receive the control information by monitoring a control channel addressed to this identifier. For example, terminal device 120 may receive the control information by monitoring a PDCCH addressed to this C-RNTI. Furthermore, terminal device 120 may determine (320) a result of the RA procedure based at least in part on the control information.

[0046] Here, a detailed description is given from the terminal device 120's point of view on how to determine the result of the RA procedure. Timing advance for uplink transmission is mandatory. The TAC as described above is used to inform the terminal device 120 of a relative or absolute timing advance value for timing adjustment. On the other hand, a timer called Timing Alignment Timer (TAT) may be kept by the terminal device 120. The TAT indicates the time when the terminal device 120 is currently in timing alignment with the network device 110 in the uplink. (in timing alignment with) It is used to indicate whether the TAT is running. If the TAT is running, it means that the terminal device 120 is currently in timing alignment with the network device 110 in the uplink. If the TAT is not running, it means that a TAC is required for the terminal device 120 to be forced. When a TAC is received from the network device 110, the TAT will be restarted or started.

[0047] In some example embodiments, the terminal device 120 may determine the result of the RA procedure based on control information received on a control channel. The terminal device 120 may determine whether a TAC is received from the network device 110 regardless of whether the TAT is active. The TAC may be received on a physical downlink shared channel (PDSCH), e.g., a TAC MAC CE, or on a PDCCH as a scheduling command.

[0048] In one example embodiment, the terminal device 120 may determine the result of the RA procedure based on a resource indication received in a control channel, for example, a PDCCH addressed to the C-RNTI of the terminal device 120. If the PDCCH transmission includes a DL assignment, the terminal device 120 may determine whether a TAC is received by using the DL resource indicated by the DL assignment. If the TAC is received, the terminal device 120 may determine that the RA procedure and the contention resolution are successful. When the TAC is received, the terminal device 120 may further restart the TAT (when the TAT is working) or start the TAT (when the TAT is not working). Alternatively, when the TAT is working, the terminal device 120 may ignore the received TAC so that the TAT is not restarted. Since the contention resolution is deemed successful, the terminal device 120 may stop or abort the CR timer.

[0049] The TAC may be included in a data unit, for example, a MAC protocol data unit (PDU). For example, based on the DL allocation, the terminal device 120 may decode a MAC PDU in a PDSCH. If the decoded MAC PDU includes a TAC MAC CE with an absolute timing value for timing adjustment, the terminal device 120 may determine that the RA procedure is successful. The terminal device 120 may also stop or abort the CR timer.

[0050] Referring to Figure 4, Figure 4 shows a schematic diagram 400 illustrating a TAC MAC CE 401 according to some exemplary embodiments of the present disclosure. As shown in Figure 4, the TAC MAC CE 401 occupies 12 bits, which means that the TAC MAC CE 401 indicates an absolute timing advance value for timing adjustment. It should be understood that the TAC MAC CE shown in Figure 4 is an example without any limitation.

[0051] In another example embodiment, the terminal device 120 may determine the result of the RA procedure based on timing information received in a PDCCH addressed to the C-RNTI of the terminal device 120. For example, if the TAC is directly conveyed by the PDCCH as a scheduling command or the scheduling command conveyed by the PDCCH indicates the TAC, the terminal device 120 may determine that the RA procedure is successful.

[0052] In such an embodiment, the outcome of the RA procedure and the conflict resolution can be determined in a simple manner, which is useful for a two-stage RA procedure.

[0053] For the above embodiment in which the TAC is used by the terminal device 120 as a criterion, if there is a case in which the TAC may be sent or indicated by the network device 110 without an RA procedure, the terminal device 120 may further determine whether the TAC is a response to the RA procedure. If the terminal device 120 determines that the TAC is a response to the RA procedure, the terminal device 120 may determine that the RA procedure is successful.

[0054] As an example, the TAC MAC CE may include a command indication indicating that the TAC MAC CE is sent in response to an RA procedure. Alternatively, such a command indication may not be included in the TAC MAC CE, but may instead be sent in association with the TAC MAC CE. In this way, erroneous determinations regarding the outcome of the RA procedure may be avoided.

[0055] In some example embodiments, terminal device 120 may determine the outcome of the RA procedure based on an activation state of a TAT maintained by terminal device 120 and control information on a control channel addressed to an identifier of terminal device 120. Terminal device 120 may determine whether the TAT is activated.

[0056] If the TAT is not running, this means that a TAC is mandatory for the terminal device 120, and the receipt of the TAC or another indication of timing advance may be used as a criterion for contention resolution. If the TAT is not running and a TAC is received, the terminal device 120 may determine that the RA procedure is successful. The TAC may be received on the PDSCH in the form of a TAC MAC CE, as described above, or on the PDCCH as a scheduling command.

[0057] As an example, the terminal device 120 may decode a MAC PDU in a PDSCH based on a DL allocation received on a PDCCH addressed to the C-RNTI of the terminal device 120. If the decoded MAC PDU includes a TAC MAC CE with an absolute timing value for the timing adjustment, the terminal device 120 may determine that the RA procedure is successful. The terminal device 120 may also stop or abort the CR timer.

[0058] The manner in which the terminal device 120 receives or determines the TAC is similar to the above embodiment in which the TAC is used as a reference regardless of the operating state of the TAT held by the terminal device 120. Therefore, details in this regard will not be repeated here.

[0059] It should be understood that if there are cases where a TAC may be sent or indicated by the network device 110 without an RA procedure, the terminal device 120 may further determine whether the TAC is a response to an RA procedure. If the terminal device 120 determines that the TAC is a response to an RA procedure, the terminal device 120 may determine that the RA procedure is successful.

[0060] If the TAT is working, it means that the terminal device 120 is in timing alignment with the network device 110 in the uplink, and TAC is not required for the terminal device 120. Thus, if the TAT is working and the control information received on the control channel indicates an uplink resource, the terminal device 120 may determine that the RA procedure is successful. For example, in the case where the TAT is working, if the PDCCH received by the terminal device 120 includes an UL grant, the terminal device 120 may determine that the RA procedure is successful.

[0061] It should be understood that the aspects described above with respect to the various exemplary embodiments can be combined. For example, if the TAT is active, a determination of whether a TAC is received or indicated may be used as a criterion for contention resolution in addition to an uplink resource indication (e.g., an UL grant).

[0062] For example embodiments in which the TAC is used as the basis for contention resolution, the TAT may be started or restarted upon receipt of the TAC, particularly the TAC MAC CE. In some example embodiments, the TAC may also be ignored if the TAT is running.

[0063] A detailed description is given on the terminal device 120 side of how to determine the result of the RA procedure. Returning now to FIG. 3, after receiving the random access request, the network device 110 may also determine 310 the control information to be sent to the terminal device 120.

[0064] A timer that is similar to the TAT maintained by the terminal device 120 may be maintained by the network device 110. Such a timer is used to indicate whether the terminal device 120 is currently in timing alignment with the network device 110 in the uplink. It should be understood that the network device 110 may maintain multiple such timers for each of the terminal devices in the serving cell 102.

[0065] In some example embodiments, network device 110 may transmit a TAC to terminal device 120 regardless of the running state of a timer for terminal device 120. For example, network device 110 may determine a TAC for terminal device 120. Network device 110 may transmit a TAC MAC CE on a PDSCH and include a DL allocation in a PDCCH addressed to the C-RNTI of terminal device 120 such that the PDSCH can be detected and decoded by terminal device 120. Alternatively or additionally, network device 110 may transmit the TAC in a PDCCH addressed to the C-RNTI of terminal device 120 as a scheduling command such that terminal device 120 may receive the TAC on the PDCCH directly without decoding the PDSCH.

[0066] In some example embodiments, network device 110 may determine the control information to be transmitted to terminal device 120 further based on a timer maintained for terminal device 120. If the timer for terminal device 120 is not running, network device 110 may determine a TAC for terminal device 120 and transmit a TAC for the PDCCH or PDSCH to terminal device 120, as described above.

[0067] When the timer for terminal device 120 is running, network device 110 may determine uplink resources for terminal device 120 and send an indication for the determined uplink resources. For example, network device 110 may send a UL grant for a PDCCH addressed to the C-RNTI of terminal device 120.

[0068] It should be understood that the aspects described above with respect to the various exemplary embodiments can be combined. For example, if the timer for the terminal device 120 is running, the network device 110 may further determine a TAC for the terminal device 120 and transmit the determined TAC to the terminal device 120.

[0069] The above example embodiments are described in a scenario in which a terminal device 120 is to access a network device 110. The embodiments of the present disclosure may be applied to a scenario involving two terminal devices or two network devices, one of which is to access the other.

[0070] Exemplary embodiments according to the present disclosure will now be described in more detail with reference to FIGS.

[0071] 5 illustrates a flowchart of an example method 500 according to some example embodiments of the present disclosure. The method 500 can be implemented in an apparatus, for example, a terminal device 120 as shown in FIG. 1. For purposes of discussion, the method 500 will be described with reference to FIG.

[0072] At block 510, the terminal device 120 sends a random access request to the network device 110, the random access request including a random access preamble and an identifier of the terminal device 120 for the random access procedure. At block 520, the terminal device 120 receives control information from the network device 110 on a control channel addressed to the identifier, the control information indicating at least one of resource and timing information for communication between the terminal device 120 and the network device 110. At block 530, the terminal device 120 determines a result of the random access procedure based at least in part on the control information.

[0073] In some example embodiments, determining a result of the random access procedure includes determining, in response to control information indicating a first resource for a first link from the network device 110 to the terminal device 120, whether a timing advance command for a timing adjustment amount is received by using the first resource, where the timing adjustment amount is used for timing alignment with the network device 110 on a second link from the terminal device 120 to the network device 110, and determining that the random access procedure is successful in response to determining that the timing advance command is received.

[0074] In some example embodiments, determining the result of the random access procedure includes determining that the random access procedure is successful in response to control information indicating a timing advance command for a timing adjustment amount used for timing alignment with the network device 110 on the second link from the terminal device 120 to the network device 110.

[0075] In some example embodiments, determining that the random access procedure is successful includes determining whether the timing advance command is a response to the random access request, and determining that the random access procedure is successful in response to determining that the timing advance command is a response to the random access request.

[0076] In some example embodiments, determining the result of the random access procedure includes determining the result of the random access procedure further based on determining whether a timer maintained by the terminal device 120 is running, the timer being configured to indicate whether the terminal device 120 is in timing alignment with the network device 110 in a second link from the terminal device 120 to the network device 110.

[0077] In some example embodiments, determining the outcome of the random access procedure is further based on determining that the timer has not run.

[0078] In some example embodiments, the method 500 further includes starting a timer in response to determining that a timing advance command is received.

[0079] In some example embodiments, determining a result of the random access procedure further based on the determination includes determining that the random access procedure is successful in response to determining that the timer is running and the control information indicates a second resource for the second link.

[0080] In some example embodiments, the identifier of the terminal device 120 includes a cell radio network temporary identifier of the terminal device 120 .

[0081] In some exemplary embodiments, terminal device 120 is in a connected state with network device 110 .

[0082] 6 illustrates a flowchart of an example method 600 according to some example embodiments of the present disclosure. The method 600 can be implemented in an apparatus, such as the network device 110 as shown in FIG. 1. For purposes of discussion, the method 600 will be described with reference to FIG.

[0083] At block 610, network device 110 receives a random access request from terminal device 120, the random access request including a random access preamble and an identifier of terminal device 120 for a random access procedure. At block 620, in response to the random access request, network device 110 determines control information indicating at least one of resource and timing information for communication between network device 110 and terminal device 120. At block 630, network device 110 transmits to terminal device 120 the control information on a control channel addressed to the identifier.

[0084] In some example embodiments, determining the control information includes determining a timing advance command for a timing adjustment amount, where the timing adjustment amount is used for timing alignment with the terminal device 120 on a second link from the terminal device 120 to the network device 110, determining the timing advance command, sending the timing advance command to the terminal device 120 by using a first resource for a first link from the network device 110 to the terminal device 120, and determining the control information based on the first resource.

[0085] In some example embodiments, determining the control information includes determining a timing advance command for a timing adjustment amount, the timing adjustment amount being used for timing alignment with the terminal device 120 in a second link from the terminal device 120 to the network device 110, and determining the control information based on the timing advance command.

[0086] In some example embodiments, the method 600 further includes indicating to the terminal device 120 that the timing advance command is a response to the random access request.

[0087] In some example embodiments, determining the control information includes determining the control information based on a determination of whether a timer maintained by the network device 110 is running, the timer being configured to indicate whether the network device 110 is in timing alignment with the terminal device 120 in a second link from the terminal device 120 to the network device 110.

[0088] In some example embodiments, the method 600 further includes determining the control information further based on determining that the timer is not running.

[0089] In some example embodiments, the method 600 further includes starting a timer after sending the timing advance command.

[0090] In some example embodiments, determining the control information based on the determination further includes determining, in response to determining that the timer is running, control information to indicate a second resource for the second link.

[0091] In some example embodiments, the identifier of the terminal device 120 includes a cell radio network temporary identifier of the terminal device 120 .

[0092] In some exemplary embodiments, terminal device 120 is in a connected state with network device 110 .

[0093] In some example embodiments, an apparatus capable of performing method 500 (e.g., terminal device 120) may include means for performing each step of method 500. The means may be implemented in any suitable form. For example, the means may be implemented in a circuit or a software module.

[0094] In some example embodiments, the apparatus includes: means for transmitting a random access request to a second device, the random access request including a random access preamble and an identifier of the device for a random access procedure; means for receiving control information from the second device on a control channel addressed to the identifier, the control information indicating at least one of resources and timing information for communication between the apparatus and the second device; and means for determining a result of the random access procedure based at least in part on the control information.

[0095] In some example embodiments, the means for determining a result of the random access procedure includes means for determining, in response to control information indicating a first resource for a first link from the second device to the device, whether a timing advance command for a timing adjustment amount is received by using the first resource, where the timing adjustment amount is used for timing alignment with the second device in the second link from the device to the second device, and means for determining that the random access procedure is successful in response to determining that the timing advance command is received.

[0096] In some example embodiments, the means for determining a result of the random access procedure includes means for determining that the random access procedure is successful in response to control information indicating a timing advance command for a timing adjustment amount used for timing alignment with the second device in a second link from the device to the second device.

[0097] In some example embodiments, the means for determining that the random access procedure is successful includes means for determining whether the timing advance command is a response to the random access request, and means for determining that the random access procedure is successful in response to determining that the timing advance command is a response to the random access request.

[0098] In some example embodiments, the means for determining a result of the random access procedure includes means for determining a result of the random access procedure further based on determining whether a timer maintained by the apparatus is running, the timer configured to indicate whether the apparatus is in timing alignment with a second apparatus in a second link from the apparatus to the second apparatus.

[0099] In some example embodiments, determining the outcome of the random access procedure is further based on determining that the timer has not run.

[0100] In some example embodiments, the apparatus further includes means for initiating a timer in response to determining that a timing advance command is received.

[0101] In some example embodiments, the means for determining a result of the random access procedure further based on the determination includes means for determining that the random access procedure is successful in response to determining that the timer is running and the control information indicates a second resource for the second link.

[0102] In some example embodiments, the identifier of the device includes a cell radio network temporary identifier of the device.

[0103] In some exemplary embodiments, the device is in communication with a second device.

[0104] In some example embodiments, the apparatus includes a terminal device and the second apparatus includes a network device.

[0105] In some example embodiments, an apparatus capable of performing method 600 (e.g., network device 110) may include means for performing each step of method 600. The means may be implemented in any suitable form. For example, the means may be implemented in circuitry or software modules.

[0106] In some example embodiments, the apparatus includes means for receiving a random access request from a second device at the apparatus, the random access request including a random access preamble and an identifier of the second device for a random access procedure; means for determining, in response to the random access request, control information indicating at least one of resource and timing information for communication between the apparatus and the second device; and means for transmitting the control information on a control channel addressed to the identifier to the second device.

[0107] In some example embodiments, the means for determining a result of the random access procedure includes means for determining, in response to control information indicating a first resource for a first link from the second device to the device, whether a timing advance command for a timing adjustment amount is received by using the first resource, where the timing adjustment amount is used for timing alignment with the second device in the second link from the device to the second device, and means for determining that the random access procedure is successful in response to determining that the timing advance command is received.

[0108] In some example embodiments, the means for determining a result of the random access procedure includes means for determining that the random access procedure is successful in response to control information indicating a timing advance command for a timing adjustment amount used for timing alignment with the second device in a second link from the device to the second device.

[0109] In some example embodiments, the means for determining that the random access procedure is successful includes means for determining whether the timing advance command is a response to the random access request, and means for determining that the random access procedure is successful in response to determining that the timing advance command is a response to the random access request.

[0110] In some example embodiments, the means for determining a result of the random access procedure includes means for determining a result of the random access procedure further based on determining whether a timer maintained by the apparatus is running, the timer configured to indicate whether the apparatus is in timing alignment with a second apparatus in a second link from the apparatus to the second apparatus.

[0111] In some example embodiments, determining the outcome of the random access procedure is further based on determining that the timer has not run.

[0112] Some example embodiments further include means for initiating a timer in response to determining that a timing advance command is received.

[0113] In some example embodiments, the means for determining a result of the random access procedure further based on the determination includes means for determining that the random access procedure is successful in response to determining that the timer is running and the control information indicates a second resource for the second link.

[0114] In some example embodiments, the identifier of the device includes a cell radio network temporary identifier of the device.

[0115] In some exemplary embodiments, the device is in communication with a second device.

[0116] In some example embodiments, the apparatus includes a terminal device and the second apparatus includes a network device.

[0117] 7 is a simplified block diagram of a device 700 suitable for implementing embodiments of the present disclosure. The device 700 may be provided to implement a communication device, such as the terminal device 120 or the network device 110 as shown in FIG. 1. As shown, the device 700 includes one or more processors 710, one or more memories 720 coupled to the processor 710, and one or more communication modules 740 coupled to the processor 710.

[0118] The communication module 740 is for bidirectional communication. The communication module 740 has at least one antenna to facilitate communication. The communication interface may represent any interface necessary for communication with other network elements.

[0119] Processor 710 may be of any type suitable for a local technology network, and may include, by way of non-limiting examples, one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), and processors based on multi-core processor architectures. Device 700 may have multiple processors, such as application specific integrated circuit chips slaved in time to a clock that synchronizes the main processor.

[0120] The memory 720 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read only memory (ROM) 724, electrically programmable read only memory (EPROM), flash memory, hard disks, compact disks (CDs), digital video disks (DVDs), and other magnetic and / or optical storage. Examples of volatile memories include, but are not limited to, random access memory (RAM) 722 and other volatile memories that do not persist during power down periods.

[0121] The computer program 730 includes computer executable instructions that are executed by an associated processor 710. The program 730 may be stored in the ROM 720. The processor 710 may load the program 730 into the RAM 720 to perform any suitable actions and operations.

[0122] The embodiments of the present disclosure may be implemented by a program 730, which may cause the device 700 to perform any process of the present disclosure, such as those discussed with reference to Figures 5-6. The embodiments of the present disclosure may also be implemented by hardware, or by a combination of software and hardware.

[0123] In some embodiments, the program 730 may be tangibly contained in a computer-readable medium, which may be included in the device 700 (such as in memory 720) or in other storage accessible to the device 700. The device 700 may load the program 730 from the computer-readable medium into RAM 722 for execution. The computer-readable medium may include any type of tangible non-volatile storage, such as ROM, EPROM, flash memory, hard disks, CDs, and DVDs. Figure 8 shows an example of a computer-readable medium 800 in the form of a CD or DVD. The computer-readable medium has the program 730 stored thereon.

[0124] In general, various embodiments of the present disclosure may be implemented in hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of the present disclosure are shown and described as block diagrams, flow charts, or using other pictorial representations, it should be understood that the blocks, apparatus, systems, techniques, or methods described herein may be implemented in, by way of non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controllers or other computing devices, or any combination thereof.

[0125] The present disclosure also provides at least one computer program tangibly stored in a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, that execute on a target real or virtual processor device to perform the method 500 or 600 as described above with reference to Figures 5-6. Generally, program modules include routines, programs, libraries, objects, classes, components, or data structures that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split among program modules as desired in various embodiments. The machine-executable instructions for the program modules may be executed in local or distributed devices. In a distributed device, the program modules may be located in both local and remote storage media.

[0126] Program codes for carrying out the methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, a special purpose computer, or other programmable data processing apparatus such that, when executed by the processor or controller, the functions / operations specified in the flowcharts and / or block diagrams are performed. The program code may run entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0127] In the context of the present disclosure, computer program code or associated data may be carried by any suitable carrier to enable a device, apparatus, or processor to perform the various processes and operations as described above. Examples of carriers include signals, computer readable media, etc.

[0128] The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. The computer-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer-readable storage medium may include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0129] Furthermore, although operations are shown in a particular order, this should not be understood as requiring such operations to be performed in the particular order or sequence shown, or that all of the operations shown must be performed to achieve a desired result. In certain circumstances, multitasking and parallel processing may be advantageous. Similarly, although some specific implementation details are included in the above discussion, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features that may be specific to certain embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination.

[0130] Although the present disclosure has been described in language specific to structural features and / or method acts, it is to be understood that the present disclosure as defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. At least one processor; at least one memory containing computer program code, The at least one memory and the computer program code are configured to cause the at least one processor to sending a random access request to a second device, the random access request including a random access preamble and an identifier of the device for a random access procedure; receiving, from the second device, control information on a control channel addressed to the identifier, the control information indicating at least one of resource and timing information for communication between the device and the second device; and determining an outcome of the random access procedure based at least in part on the control information; The apparatus is configured to cause

2. When determining the result of the random access procedure, the at least one memory and the computer program code are configured to cause the device, by the at least one processor, to: determining whether a timing advance command for a timing adjustment amount is received by using the first resource in response to the control information indicating a first resource for a first link from the second device to the device, the timing adjustment amount being used for timing alignment with the second device in a second link from the device to the second device; and in response to determining that the timing advance command is received, determining that the random access procedure is successful; The apparatus of claim 1 configured to:

3. When determining the result of the random access procedure, the at least one memory and the computer program code are configured to cause the device, by the at least one processor, to:

2. The apparatus of claim 1, configured to determine that the random access procedure is successful in response to the control information indicating a timing advance command for a timing adjustment amount used for timing alignment with the second device in a second link from the apparatus to the second device.

4. Upon determining that the random access procedure is successful, the at least one memory and the computer program code are configured to cause the at least one processor to determining whether the timing advance command is a response to the random access request; and in response to determining that the timing advance command is a response to the random access request, determining that the random access procedure is successful; 4. The apparatus of claim 2 or 3, configured to cause

5. When determining the result of the random access procedure, the at least one memory and the computer program code are configured to cause the device, by the at least one processor, to:

5. The apparatus of claim 1 , further configured to determine the result of the random access procedure based on a determination of whether a timer maintained by the apparatus is running, the timer configured to indicate whether the apparatus is in timing alignment with the second apparatus in a second link from the apparatus to the second apparatus.

6. The at least one memory and the computer program code are configured to cause the at least one processor to 6. The apparatus of claim 5, configured to cause the outcome of the random access procedure to be determined further based on determining that the timer has not run.

7. The at least one memory and the computer program code are further configured to cause the apparatus to: The apparatus of claim 6 , configured to start the timer in response to determining that the timing advance command is received.

8. When determining the result of the random access procedure further based on the determining, the at least one memory and the computer program code are configured to cause the apparatus, by the at least one processor, to:

6. The apparatus of claim 5, configured to cause the random access procedure to be determined to be successful in response to determining that the timer is running and that the control information indicates second resources for the second link.

9. The device of claim 1 , wherein the identifier of the device comprises a cell radio network temporary identifier of the device.

10. The device according to claim 1 , wherein the device is in a connected state with the second device.

11. The apparatus of claim 1 , wherein the apparatus comprises a terminal device and the second apparatus comprises a network device.

12. At least one processor; at least one memory containing computer program code, The at least one memory and the computer program code are configured to cause the at least one processor to receiving a random access request from a second device, the random access request including a random access preamble and an identifier of the second device for a random access procedure; determining, in response to the random access request, control information indicating at least one of resources and timing information for communication between the device and the second device; and transmitting to the second device the control information on a control channel addressed to the identifier; The apparatus is configured to cause

13. When determining the control information, the at least one memory and the computer program code cause the at least one processor to determining a timing advance command for a timing adjustment amount, the timing adjustment amount being used for timing alignment with the second device in a second link from the second device to the device; transmitting the timing advance command to the second device by using a first resource for a first link from the device to the second device; and determining the control information based on the first resource; The apparatus of claim 12 configured to cause

14. When determining the control information, the at least one memory and the computer program code cause the at least one processor to determining a timing advance command for a timing adjustment amount, the timing adjustment amount being used for timing alignment with the second device in a second link from the second device to the device; and determining the control information based on the timing advance command; The apparatus of claim 12 configured to cause

15. The at least one memory and the computer program code are further configured to cause the apparatus to:

15. The apparatus of claim 13 or 14, configured to cause the second device to indicate that the timing advance command is a response to the random access request.

16. When determining the control information, the at least one memory and the computer program code cause the at least one processor to 16. The apparatus of claim 12, further comprising: a control unit configured to determine the control information based on a determination of whether a timer maintained by the apparatus is running, the timer configured to indicate whether the apparatus is in timing alignment with the second apparatus in a second link from the second apparatus to the apparatus.

17. The at least one memory and the computer program code are configured to cause the at least one processor to The apparatus of claim 16 , configured to cause the control information to be determined further based on determining that the timer has not fired.

18. The at least one memory and the computer program code are further configured to cause the apparatus to: The apparatus of claim 17 , configured to start the timer after sending the timing advance command.

19. When determining the control information based on the determination, the at least one memory and the computer program code are configured to cause the device, by the at least one processor, to:

17. The apparatus of claim 16, configured to cause the control information to be determined to indicate second resources for the second link in response to determining that the timer is running.

20. 20. The apparatus of claim 12, wherein the identifier of the second device comprises a cell radio network temporary identifier of the second device.

21. 21. The device of any of claims 12 to 20, wherein the second device is in a connected state with the device.

22. 22. The apparatus of claim 12, wherein the apparatus comprises a network device and the second apparatus comprises a terminal device.

23. transmitting, at the device, a random access request to a second device, the random access request including a random access preamble and an identifier of the device for a random access procedure; receiving, from the second device, control information on a control channel addressed to the identifier, the control information indicating at least one of resources and timing information for communication between the device and the second device; determining a result of the random access procedure based at least in part on the control information; and A method comprising:

24. Determining the result of the random access procedure comprises: determining, in response to the control information indicating a first resource for a first link from the second device to the device, whether a timing advance command for a timing adjustment amount is received by using the first resource, the timing adjustment amount being used for timing alignment with the second device in a second link from the device to the second device; and 24. The method of claim 23, comprising: in response to determining that the timing advance command is received, determining that the random access procedure is successful.

25. Determining the result of the random access procedure comprises:

24. The method of claim 23, comprising determining that the random access procedure is successful in response to the control information indicating a timing advance command for a timing adjustment amount used for timing alignment with the second device in a second link from the device to the second device.

26. Determining that the random access procedure is successful comprises: determining whether the timing advance command is a response to the random access request; and in response to determining that the timing advance command is a response to the random access request, determining that the random access procedure is successful; 26. The method of claim 24 or 25, comprising:

27. Determining the result of the random access procedure comprises:

27. The method of claim 23, further comprising determining the result of the random access procedure based on determining whether a timer maintained by the device is running, the timer configured to indicate whether the device is in timing alignment with the second device in a second link from the device to the second device.

28. 28. The method of claim 27, wherein determining the outcome of the random access procedure is further based on determining that the timer is not running.

29. 30. The method of claim 28, further comprising starting the timer in response to determining that the timing advance command is received.

30. Determining the result of the random access procedure based further on the determining, 28. The method of claim 27, comprising determining that the random access procedure is successful in response to determining that the timer is running and the control information indicates second resources for the second link.

31. A method according to any of claims 23 to 30, wherein the identifier of the device comprises a cell radio network temporary identifier of the device.

32. 32. The method of any of claims 23 to 31, wherein the device is in a connected state with the second device.

33. 33. The method of any of claims 23 to 32, wherein the apparatus comprises a terminal device and the second apparatus comprises a network device.

34. receiving, at the apparatus, a random access request from a second apparatus, the random access request including a random access preamble and an identifier of the second apparatus for a random access procedure; determining, in response to the random access request, control information indicating at least one of resources and timing information for communication between the device and the second device; transmitting to the second device the control information on a control channel addressed to the identifier; A method comprising:

35. Determining the control information includes: determining a timing advance command for a timing adjustment amount, the timing adjustment amount being used for timing alignment with the second device in a second link from the second device to the device; transmitting the timing advance command to the second device by using a first resource for a first link from the device to the second device, and determining the control information based on the first resource; 35. The method of claim 34, comprising:

36. Determining the control information includes: determining a timing advance command for a timing adjustment amount, the timing adjustment amount being used for timing alignment with the second device in a second link from the second device to the device; and determining the control information based on the timing advance command; 35. The method of claim 34, comprising:

37. 37. The method of claim 35 or 36, further comprising indicating to the second device that the timing advance command is a response to the random access request.

38. Determining the control information includes:

38. The method of claim 34, comprising determining the control information based on a determination of whether a timer maintained by the device is running, the timer configured to indicate whether the device is in timing alignment with the second device in a second link from the second device to the device.

39. 40. The method of claim 38, further comprising determining the control information further based on determining that the timer is not running.

40. 40. The method of claim 39, further comprising starting the timer after sending the timing advance command.

41. 40. The method of claim 38, wherein determining the control information based on the determination further comprises determining the control information to indicate second resources for the second link in response to determining that the timer is running.

42. 42. A method according to any of claims 34 to 41, wherein the identifier of the second device comprises a cell radio network temporary identifier of the second device.

43. 43. The method of any of claims 34 to 42, wherein the second device is in communication with the device.

44. 44. The method of any of claims 34 to 43, wherein the apparatus comprises a network device and the second apparatus comprises a terminal device.

45. In the apparatus, means for transmitting a random access request to a second device, the random access request including a random access preamble and an identifier of the device for a random access procedure; means for receiving from the second device control information on a control channel addressed to the identifier, the control information indicating at least one of resource and timing information for communication between the device and the second device; and means for determining a result of the random access procedure based at least in part on the control information.

46. In an apparatus, a means for receiving a random access request from a second device, the random access request including a random access preamble and an identifier of the second device for a random access procedure; means for determining, in response to the random access request, control information indicating at least one of resources and timing information for communication between the device and the second device; means for transmitting to the second device the control information on a control channel addressed to the identifier; 13. An apparatus comprising:

47. A non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method of any of claims 23 to 33.

48. A non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method of any of claims 34 to 44.

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