WO2016093754A1

WO2016093754A1 - Improved random access

Info

Publication number: WO2016093754A1
Application number: PCT/SE2014/051485
Authority: WO
Inventors: Caner KILINC; Johnny KAROUT; Min Wang; Mats Nordberg
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2014-12-11
Filing date: 2014-12-11
Publication date: 2016-06-16

Abstract

According to an example of a method performed by a wireless communication device when communicating with a wireless network, the method comprises initiating (201)a random access, RA, procedure by selecting a first preamble sequence at random from a set of preamble sequences and transmitting the first preamble sequence to the wireless network. Following the transmission of the first preamble sequence, receiving (203) information from the wireless network that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure occurring in relation to the RA procedure. The method further comprises determining (205) that the failure has occurred in relation to the RA procedure and, as a consequence of the determination that the failure has occurred, continuing (207) the communication with the wireless network using the specified resources associated with uplink transmission.

Description

IMPROVED RANDOM ACCESS

TECHNICAL FIELD

Embodiments herein relate to a wireless communication device and a network node in a wireless network and more specifically to a random access procedure involving such entities.

BACKGROUND

In a wireless network such as a third generation partnership project (3GPP) wireless network that operates according to a standard such as evolved universal terrestrial radio access network (E-UTRAN) and other 3GPP standards, a fundamental requirement for a wireless communication device (typically referred to as user equipment (UE) in many 3GPP specifications) is that of being able to operate a procedure of setting up a connection with the wireless network. Such a procedure involves a so-called random access (RA) procedure in which a preamble sequence is transmitted to the wireless network. The transmission of the preamble sequence may be triggered in various ways, a basic trigger being a power-on of the wireless communication device.

A first step in such a RA procedure is to select a preamble sequence among a predetermined number of preamble sequences and then transmit the selected preamble sequence to the wireless network via a physical random access channel (PRACH). The wireless communication device also needs to provide an identity to the wireless network so that the wireless network can address the wireless communication device in a subsequent response step. If the wireless communication device does not receive any response to the preamble sequence transmission from the wireless network, the wireless communication device ramps up its transmission power and transmits the preamble sequence again. The wireless network responds to the transmission of the preamble sequence with a response message via a downlink shared channel (DL-SCH). In this response message, the wireless network provides, to the wireless communication device, a temporary cell- radio network identifier (TC-RNTI) and a timing advance (TA) value for the wireless communication device to use in compensating for the round trip delay caused by the spatial distance between the wireless communication device and the wireless network node with which it communicates. The wireless network further will assign other specific resources that will enable the wireless communication device to continue in the setting up of the connection with the wireless network via an uplink shared channel (UL-SCH).

Using the UL-SCH, the wireless communication device transmits a radio resource control (RRC) connection request message to the wireless network. At this phase, the wireless communication device is identified by the temporary identity that was assigned as described above. The RRC connection request message also comprises a value that represents an identity of the wireless communication device. This value may be a temporary mobile subscriber identity (TMSI) or a random value. The TMSI is used if the wireless communication device has previously been connected to the wireless network whereas, if the random value is used, the wireless communication device is connecting for the very first time to the wireless network. The random value and the TMSI value is an aid for distinguishing between wireless communication devices when the same TC-RNTI has been assigned to more than one wireless communication device, which may occur in case of so called preamble sequence collisions. If such a collision occurs, the wireless network might not respond to the RRC connection request from the wireless communication device.

The wireless network responds to a successfully received RRC connection request message with a contention resolution message to the wireless communication device. This contention resolution message is addressed towards the TMSI value or to the random value and the TC-RNTI is promoted to a non-temporary C-RNTI which will be used for the further communication between the wireless communication device and the wireless network.

When two or more wireless communication devices attempt to use the same RACH preamble sequence at the same time, then a preamble collision will occur. In such a case, the RRC connection might be successfully established for at most one of the wireless communication devices, while the process is unsuccessful for the other wireless communication devices. These unsuccessful wireless communication devices will typically need to reinitiate the RA procedure from the beginning. Therefore, each wireless communication device will re-attempt to connect to the wireless network by selecting a new RACH preamble sequence randomly and then transmitting a new random access request. In order to reduce the risk for collision, the wireless network may signal wireless communication devices that they have to back-off a certain time, i.e. wait , before accessing RACH again. The actual time the wireless communication device should back- off is chosen by the wireless communication device according to information signaled by the wireless network in a response to the random access request. Re-attempting to set up connections with the wireless network, as a consequence of preamble sequence collisions, will increase random access signaling delay in the wireless network. This will degrade the performance of the wireless network and delay sensitive real time communication such as voice over internet protocol (VoIP), real time video, etc. This leads to an undesired negative user experience. In well-known scenarios such as in a sport stadium or a concert arena, a wireless network is typically very highly loaded.

Therefore, re-attempting connections by selecting preamble sequences might take too long time for users of wireless communication devices who are to use real time services provided in the wireless network.

International patent application publication WO2013/1 10331 describes a RA procedure comprising an initial so-called contention-based RA procedure, where a wireless communication device among a plurality of other wireless communication devices connects to a wireless network as summarized above where preamble sequences collide and where a plurality of re-connection attempts are made. After this contention-based procedure has resolved, the wireless communication device is provided with a fixed preamble sequence for use in future RA procedures.

SUMMARY In order to at least mitigate at least some of the drawbacks as discussed above, different aspects/embodiments of the invention are provided.

One aspect provides a method performed by a wireless communication device when communicating with a wireless network. The method comprises initiating a random access, RA, procedure by selecting a first preamble sequence at random from a set of preamble sequences and transmitting the first preamble sequence to the wireless network. Following the transmission of the first preamble sequence, receiving information from the wireless network that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure occurring in relation to the RA procedure. The method further comprises determining that the failure has occurred in relation to the RA procedure and, as a consequence of the determination that the failure has occurred, continuing the communication with the wireless network using the specified resources associated with uplink transmission. In some embodiments, the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies at least one other preamble sequence that is different from the first preamble sequence. In some embodiments, the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies at least one time-frequency resource for transmission on the uplink.

In some embodiments, the transmission of the first preamble sequence to the wireless network comprises transmitting, on a random access channel, RACH, the first preamble sequence. Further, receiving information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure may comprise receiving, on a downlink shared channel, DL-SCH, a response to the transmission of the first preamble sequence, which comprises the information that specifies the resources associated with uplink transmission for continued communication with the wireless network in case of a failure.

In some embodiments, the determination that a failure has occurred in relation to the RA procedure comprises determining that no response to the transmission of the first preamble sequence has been received from the wireless network within a predetermined time interval.

In some embodiments, the reception of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure may comprise receiving, on a downlink shared channel, DL-SCH, a RRC connection setup message comprising the information that specifies the resources associated with uplink transmission for continued communication with the wireless network in case of a failure.

In some embodiments, the determination that a failure has occurred in relation to the RA procedure comprises determining that the failure has occurred upon recognizing that a received RRC connection setup message is not intended for the wireless communication device. In some embodiments, the reception of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises receiving, in a system information block, SIB, on a broadcast control channel, BCCH, the information that specifies at least one other preamble sequence that is different from the first preamble sequence.

Another aspect provides a method performed by a network node in a wireless network when communicating with a wireless communication device in a random access, RA, procedure. The method comprises determining information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure occurring in relation to the RA procedure. The method further comprises transmitting, to the wireless communication device, the information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure. In some embodiments, the information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure is determined by a selection of at least one preamble sequence from all available unused preamble sequences.

In some embodiments, the transmission of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises transmitting, in a system information block, SIB, on a broadcast control channel, BCCH, the selected at least one preamble sequence from all available unused preamble sequences.

In some embodiments, the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies at least one time-frequency resource for transmission on the uplink.

That is, embodiments herein enable a wireless communication device to obtain and use resources associated with uplink transmission, such as an available unused preamble or other time-frequency resource, during a RA procedure. By using these resources, risks of failures in connection with the RA procedure, such as a preamble sequence collision, are at least reduced and thus reducing the need for access re-attempts that otherwise would be necessary.

In other words, during the RA procedure, a failure such as a preamble collision is determined at an early stage (e.g. after a first message exchange via RACH and DL- SCH), and different preamble sequences or other time-frequency resources (during RRC message exchanges) can be used so that the wireless communication device that is suffering from an initial failure can avoid further unnecessary RA attempts and thereby minimizes the delay in the RA procedure.

Further aspects provide, wireless communication devices, a network nodes, computer programs and carriers comprising such computer programs that correspond to the aspects as summarized above.

The effects and advantages of these further aspects correspond to those summarized above in connection with the methods performed by the wireless communication device and the wireless network. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 schematically illustrates a wireless network 100,

figure 2 is a flow chart of a method performed by a wireless communication device, figure 3 is a flow chart of a method performed by a network node,

figure 4a is a flow chart of a method performed by a wireless communication device, figure 4b is a flow chart of a method performed by a network node,

figure 4c is a signalling diagram associated with the methods of figures 4a and 4b, figure 4d is a flow chart of a method performed by a wireless communication device, figure 4e is a signalling diagram associated with the methods of figures 4a, 4b and 4d, figure 5 schematically illustrates a wireless communication device,

figure 6 schematically illustrates a wireless communication device,

figure 7 schematically illustrates a network node, and

figure 8 schematically illustrates a network node.

DETAILED DESCRIPTION Figure 1 illustrates schematically an exemplifying wireless network 100 in which embodiments herein may be implemented. The wireless network 100 may be any 3GPP wireless network, such as a Universal Mobile Telecommunication System (UMTS) Wideband Code Division Multiple Access (WCDMA) network, a Global System for Mobile communication (GSM), or the like. The wireless communication system 100 may be an evolution of any one of the aforementioned systems or a combination thereof, including a Long Term Evolution (LTE) wireless network.

The wireless network 100 may comprise a number of different nodes distributed in a radio access network 102 and a core network 103.

Nodes in the wireless network 100 may be denoted "network node" and, for example, refer to a Base Station (BS), a Base Transceiver Station (BTS), a Radio Base Station (RBS), a Remote Radio Unit (RRU), an access point, a NodeB in 3G networks, evolved NodeB (eNodeB or eNB) in LTE networks, or the like. In UMTS Terrestrial Radio Access Network (UTRAN) networks, a node may also be a Radio Network Controller (RNC). Furthermore, in GSM EDGE Radio Access Network, GERAN, where EDGE is short for Enhanced Data rates for GSM Evolution, the term "network node" may also refer to a Base Station Controller (BSC).

As figure 1 shows, a node 105 may be connected to other nodes in the system, exemplified here by a node 104 in the radio access network 102 and connected to a node 107, which may represent any entity in the core network 103 and further nodes, such as node 110 in another network 109. It is to be noted, however, that any details regarding communication with such entities is outside the scope of the present disclosure.

A number of wireless communication devices may be operating in connection with the wireless network 100. One such wireless communication device 106 is shown being in connection with the wireless network 100 via a radio interface 11 1 with the node 104 in the radio access network 102. The wireless communication device 106, and typically many other wireless communication devices (one of which, wireless communication device 108, is shown in figure 1), are located in cells (not illustrated) that are under the control of, e.g., an eNodeB, which may be represented by the node 104. As used herein, the term "wireless communication device" may refer to a user equipment, UE, a subscriber unit, mobile phone, a cellular phone, a Personal Digital Assistant, PDA, equipped with radio communication capabilities, a smartphone, a laptop or personal computer, PC, equipped with an internal or external mobile broadband modem, a tablet PC with radio communication capabilities, a portable electronic radio communication device or the like. As will be described in some detail in the following, focus will be made on communication between the wireless communication device 106 and a network node such as the eNodeB 104.

Turning now to figure 2 a random access procedure will be described in terms of a number of actions performed by a wireless communication device, such as any of the wireless communication devices 106, 108 illustrated in figure 1 , which operates in connection with a wireless network.

As illustrated in figure 2, the method performed by the wireless communication device when communicating with a wireless network comprises actions as follows:

Action 201

The random access procedure is initiated by selecting a first preamble sequence at random from a set of preamble sequences and transmitting the first preamble sequence to the wireless network.

Action 203

Following the transmission of the first preamble sequence in action 201 information is received, from the wireless network, that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure occurring in relation to the RA procedure.

This information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure may comprise information that specifies at least one other preamble sequence that is different from the first preamble sequence.

Alternatively, the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies at least one time-frequency resource for transmission on the uplink.

Action 205

A determination is made that the failure has occurred in relation to the RA procedure.

For example, the determination that a failure has occurred in relation to the RA procedure, may comprise determining that the failure has occurred upon recognizing that a received RRC connection setup message is not intended for the wireless communication device. In other examples of the failure determination, for example where the transmission in action 201 of the first preamble sequence to the wireless network comprises a

transmission of the first preamble sequence on a RACH, then the determination that a failure has occurred in relation to the RA procedure may comprise determining that no response to the transmission of the first preamble sequence has been received from the wireless network within a predetermined time interval. This predetermined time interval may in some examples be defined in terms of a number of times an attempt has been made to transmit a preamble on RACH.

In other examples, where a RRC connection request message has been transmitted on an UL-SCH, the determination that a failure has occurred in relation to the RA procedure, may comprise determining that no RRC connection setup message in response to the transmission of the RRC connection request message has been received from the wireless network within a predetermined time interval.

Action 207

As a consequence of the determination that the failure has occurred, the communication with the wireless network is continued using the specified resources associated with uplink transmission.

For example, the continued communication with the wireless network may comprise selecting a second preamble sequence from among the at least one other preamble sequence, and transmitting this second preamble sequence to the wireless network. In such examples, the information may comprises information that specifies a plurality of other preamble sequences that are different from the first preamble sequence and then the selection of a second preamble sequence may be performed at random from among this plurality of other preamble sequences. In the examples where the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies at least one time-frequency resource for transmission on the uplink, the continued communication with the wireless network may comprise transmitting, using the specified at least one time-frequency resource on an uplink shared channel, UL-SCH, a radio resource control, RRC, connection request message.

With reference to actions 201 and 203, the transmission, in action 201 , of the first preamble sequence to the wireless network may in some examples comprise transmitting the first preamble sequence, on a random access channel, RACH. In such examples, the reception, in action 203, of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure may comprise receiving, on a downlink shared channel, DL-SCH, a response to the transmission of the first preamble sequence, said response comprising the information that specifies the resources associated with uplink transmission for continued

communication with the wireless network in case of a failure.

The reception, in action 203, of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure may comprise receiving, on a downlink shared channel, DL-SCH, a RRC connection setup message comprising the information that specifies the resources associated with uplink transmission for continued communication with the wireless network in case of a failure.

With reference to action 203, in some examples, the reception of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises receiving, in a system information block, SIB, on a broadcast control channel, BCCH, the information that specifies at least one other preamble sequence that is different from the first preamble sequence.

Turning now to figure 3 a random access procedure will be described in terms of a number of actions performed by a network node in a wireless network, such as any of the nodes 104, 105 illustrated in figure 1 , which operates in connection with a wireless communication device.

As illustrated in figure 3, the method performed by the network node when communicating with a wireless communication device comprises actions as follows: Action 301

A determination is made of information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure occurring in relation to the RA procedure.

For example, the information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure may be determined by selecting at least one preamble sequence from all available unused preamble sequences

In other examples, the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure may comprise information that specifies at least one time-frequency resource for transmission on the uplink. In these examples, the specified at least one time-frequency resource may relate to transmission by the wireless communication device on an UL-SCH of a RRC connection request message.

In some embodiments, the wireless network may detect a failure related to the transmission of the first preamble sequence from the wireless communication device. Upon the detection of the failure, the wireless network may perform the determination action 301.

In some embodiments, the wireless network may select the at least one preamble sequence from another preamble group, which is reserved by the network for preamble collision avoidance purpose.

Action 303

The information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure is transmitted to the wireless communication device. In some embodiments, the information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of failure is transmitted on a downlink shared channel, DL-SCH, in a response to a transmission of a first preamble sequence, by the wireless

communication device. In some embodiments, the information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of failure is transmitted on a downlink shared channel, DL-SCH, in a RRC connection setup message.

In some embodiments, where the information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of failure is a selected at least one preamble sequence, is transmitted in a system information block, SIB, on a broadcast control channel, BCCH.

Turning now to figure 4a and figure 4b, an example of a random access procedure will be described in terms of a number of actions performed by a wireless communication 5 device 406 that operates in connection with a network node 404 in a wireless network.

Figure 4c illustrates signals that are communicated between the wireless communication device 406 and the network node 404. Figure 4c also illustrates signals communicated between the network node 404 and a second wireless communication device 408. The wireless communication devices 406, 408 and the network node 404 may correspond to 10 the wireless communication devices 106, 108 and the node 104, respectively, in the wireless network 100 of figure 1.

As illustrated in figure 4a and in figure 4b, the methods performed by the wireless communication device 406 and the network node 404 when communicating with each other in the wireless network comprises actions and signals as follows:

15 Action 410

A preamble sequence is selected by the wireless communication device 406 among a predetermined number of preamble sequences.

Action 412

The selected preamble sequence is transmitted to the wireless network in a first message 20 401 via a RACH.

Concurrently, the second wireless communication device 408 has selected the same preamble sequence as the wireless communication device 406 and transmitted this in a message 403 via the RACH.

Action 450

25 The network node 404 receives and identifies only the message 403 from the second wireless communication device 408.

Action 452 and action 454

The network node 404 responds to the transmission of the preamble sequence with transmission of a response message 405 via a DL-SCH, which both wireless

30 communication device 406 and wireless communication device 408 can receive. This response message 405 from the network node 404 may comprise information that has been determined in an action 452 and that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure occurring in relation to the RA procedure. The information is in this example at least one preamble sequence that has been selected from all available preamble sequences. (Alternatively, as will be described below, the information that has been determined in an action 452 may be provided to the wireless communication devices 406,408 in a later message.)

Action 414

The wireless communication device 406 as well as the second wireless communication device 408 receive the message 405 containing the information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure occurring in relation to the RA procedure initiated by the first preamble sequence. As mentioned above, the information is in this example at least one preamble sequence that has been selected from all available preamble sequences.

Action 416

Using the UL-SCH, the wireless communication device 406 as well as the second wireless communication device 408 transmit a respective RRC connection request message 407,409 to the network node 404. As mentioned above, the RRC respective connection request messages 407,409 comprise a value that represents an identity of the respective wireless communication device 406,408. As mentioned, this value may be a TMSI or a random value.

Action 456

The network node 404 receives only the RRC connection request message 409 transmitted by the second wireless communication device 408.

Action 458

The network node 404 responds to received RRC connection request message with a contention resolution message, i.e. a RRC connection setup message 41 1 that comprises a wireless communication device identity via information in a medium access control (MAC) element of a MAC protocol data unit (PDU) that carries the message 41 1. Because the network node 404 identified only the message 403 from the second wireless communication device 408, this RRC connection setup message 411 is intended for the second wireless communication device 408. As a consequence, the second wireless communication device 408 will receive the RRC connection setup message 41 1 as it would expect and thus be enabled to continue any desired communication with the network node 404, as indicated in figure 4c by signals 421.

Unless already transmitted in action 454, this RRC connection setup message 41 1 may comprise the information that has been determined in action 452 and that specifies at least one preamble sequence that has been selected from all available preamble sequences.

Action 418

The wireless communication device 406, on the other hand, when receiving the RRC connection setup message 41 1 which is intended to the second wireless communication device 408 will realize that a failure has occurred in the RA. In other words, the wireless communication device 406 recognizes that the received RRC connection setup message 41 1 is not intended for the wireless communication device 406 because the information in the MAC control element of the MAC PDU that carries the message 411 comprises an identity of another wireless communication device.

Action 420

As a consequence of having determined, in action 418, that a failure has occurred, the wireless communication device 406 selects a second preamble sequence from among the at least one preamble sequence provided from the network node 404 in the response message 405 or, alternatively, in the RRC connection setup message 41 1.

Action 422

Having selected, in action 420, a second preamble sequence, the wireless communication device 406 continues communication with the network node 404 by transmitting, via the RACH, a repeated first message 413. However, this repeated first message 413 comprises the second preamble sequence.

The wireless communication device may ignore any back-off execution, i.e., continue transmission with the specified resources directly after the termination of the failed RA procedure even if information has been received from the wireless network to wait for a period of time before making an attempt at transmitting a preamble on RACH. Since the second preamble sequence has been determined by the network node 404 to be available, i.e. not used by any other wireless communication device for transmission on the RACH, the wireless communication device 406 continues the communication by receiving a response message 415 via a DL-SCH. Following this, RRC signaling takes place where a RRC connection request message 417 and a RRC connection setup message 419 are communicated between the wireless communication device 406 and the network node 404, whereupon any desired communication may continue.

Turning now to figure 4d and figure 4e and with continued reference to figure 4a and figure 4b, another example of a random access procedure will be described. The example in figure 4d comprises actions 410 to 418 performed by the wireless communication device 406 and actions 450 to 458 is performed by the network node 404 as illustrated in figures 4a and 4b, respectively.

However, with regard to actions 452, 454 and 458 in this example, instead of providing at least another preamble sequence, the information that specifies resources associated with uplink transmission by the wireless communication device for continued

communication with the wireless network in case of a failure occurring in relation to the RA procedure is here in the example of figures 4d and 4e in the form of at least one time- frequency resource on an UL-SCH for transmitting a RRC connection request message.

In some embodiments, additional at least one TC RNTI values or additional TC-RNTI and TA values may be provided in the RRC connection setup message 411 (via a MAC PDU control element), and used as discussed below in connection with figures 4d and 4e, if such kind of information is not provided in message 405 that has been determined in action 452.

Action 460

As a consequence of having determined, in action 418, that a failure has occurred, the wireless communication device 406 transmits a RRC connection request message 423 to the network node 404 using the specified time-frequency resource on the UL-SCH. That is, in contrast to the example above, since the specified uplink resources are not one or more unused preamble sequence, no attempt is made to transmit a preamble on the RACH.

In some embodiments, the information that was received in the RRC connection setup message 41 1 in action 458 or in message 405, that has been determined in action 452 may further specify additional at least one TC-RNTI values or additional TC-RNTI and TA values for the wireless communication device 406 to use. In such embodiments, the continued communication with the wireless network comprises making use of such additional TC-RNTI value, at an adjusted transmit timing according to the additional TA value (if an additional TA value is received together with an additional TC-RNTI value). However, the transmission of the RRC connection request message 423 may alternatively comprise a value that represents an identifier of the wireless communication device. This value may be a TMSI or a random value.

Action 462

The wireless communication device 406 continues the communication by receiving a response from the network node 404 in the form of a RRC conn setup message 425 via a DL-SCH.

Turning now to figure 5, example embodiments of a wireless communication device 500 will be described in some detail.

The wireless communication device 500, which may be one of the wireless

communication devices discussed above in connection with figures 1-4, is for

communication with a wireless network, such as the wireless network 100. The wireless communication device 500 comprises radio frequency circuitry 506, a processor 502 and a memory 504. The memory 504 contains instructions executable by the processor 502 whereby the wireless communication device 500 is operative to:

- initiate a random access, RA, procedure by selecting a first preamble sequence at random from a set of preamble sequences and transmitting the first preamble sequence to the wireless network,

- following the transmission of the first preamble sequence, receive, from the wireless network, information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure occurring in relation to the RA procedure,

- determine that the failure has occurred in relation to the RA procedure and, as a consequence of the determination that the failure has occurred,

- continue the communication with the wireless network using the specified resources associated with uplink transmission. The instructions that are executable by the processor 502 may be software in the form of a computer program 541. The computer program 541 may be contained in or by a carrier 542, which may provide the computer program 541 to the memory 504 and processor 502. The carrier 542 may be in any suitable form including an electronic signal, an optical signal, a radio signal or a computer readable storage medium.

In some embodiments, the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies at least one other preamble sequence that is different from the first preamble sequence.

In some embodiments, the continued communication with the wireless network comprises selecting a second preamble sequence from among the at least one other preamble sequence, and transmitting the second preamble sequence to the wireless network. In some embodiments, the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies a plurality of other preamble sequences that are different from the first preamble sequence and the selection of a second preamble sequence is performed at random from among the plurality of other preamble sequences. In some embodiments, the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies at least one time-frequency resource for transmission on the uplink.

In some embodiments, the continued communication with the wireless network comprises:

- transmitting, using the specified at least one time-frequency resource on an uplink shared channel, UL-SCH, a radio resource control, RRC, connection request message.

In some embodiments, the transmission of the first preamble sequence to the wireless network comprises:

- transmitting, on a random access channel, RACH, the first preamble sequence, and the reception of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises:

- receiving, on a downlink shared channel, DL-SCH, a response to the

transmission of the first preamble sequence, said response comprising the information that specifies the resources associated with uplink transmission for continued

communication with the wireless network in case of a failure.

In some embodiments, the determination that a failure has occurred in relation to the RA procedure, comprises:

- determining that no response to the transmission of the first preamble sequence has been received from the wireless network within a predetermined time interval.

In some embodiments, the reception of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises:

- receiving, on a downlink shared channel, DL-SCH, a RRC connection setup message comprising the information that specifies the resources associated with uplink transmission for continued communication with the wireless network in case of a failure.

In some embodiments, the determination that a failure has occurred in relation to the RA procedure comprises:

- if an identifier comprised in the received RRC connection setup message is not equal to the identity of the wireless communication device, determining that the failure has occurred.

- determining that no RRC connection setup message in response to a

transmission of a RRC connection request message has been received from the wireless network within a predetermined time interval.

- receiving, in a system information block, SIB, on a broadcast control channel, BCCH, the information that specifies at least one other preamble sequence that is different from the first preamble sequence.

Turning now to figure 6, example embodiments of a wireless communication device 600 will be described in some detail. The wireless communication device 600, which may be one of the wireless

communication devices discussed above in connection with figures 1-4, is for

communication with a wireless network, such as the wireless network 100. The wireless communication device 600 comprises:

- an initiating module 602 configured to initiate a random access, RA, procedure by selecting a first preamble sequence at random from a set of preamble sequences and transmitting the first preamble sequence to the wireless network,

- a receiving module 604 configured to, following the transmission of the first preamble sequence, receive, from the wireless network, information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure occurring in relation to the RA procedure,

- a determining module 606 configured to determine that the failure has occurred in relation to the RA procedure and,

- a continue communicating module 608 configured to, as a consequence of the determination in the determining module 606 that the failure has occurred, continue the communication with the wireless network using the specified resources associated with uplink transmission.

The wireless communication device 600 may comprise further modules that are configured to perform in a similar manner as, e.g., the wireless communication device 500 described above in connection with figure 5.

Turning now to figure 7, example embodiments of a network node 700 will be described in some detail.

The network node 700, which may be one of the network nodes discussed above in connection with figures 1-4, is for use in a wireless network for communication with a wireless communication device. The network node 700 comprises input/output circuitry 706, a processor 702 and a memory 704. The memory 704 contains instructions executable by the processor 702 whereby the network node 700 is operative to:

- determine information that specifies resources associated with uplink

transmission by the wireless communication device for continued communication with the wireless network in case of a failure occurring in relation to the RA procedure, and

- transmit, to the wireless communication device, the information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure. The instructions that are executable by the processor 702 may be software in the form of a computer program 741. The computer program 741 may be contained in or by a carrier 742, which may provide the computer program 741 to the memory 704 and processor 702. The carrier 742 may be in any suitable form including an electronic signal, an optical signal, a radio signal or a computer readable storage medium.

In some embodiments, the information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure is determined by:

- selecting at least one preamble sequence from all available unused preamble sequences.

In some embodiments, the transmission of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises:

- transmitting, in a system information block, SIB, on a broadcast control channel, BCCH, the selected at least one preamble sequence from all available unused preamble sequences.

In some embodiments, the specified at least one time-frequency resource relates to transmission by the wireless communication device, on an uplink shared channel, UL- SCH, of a radio resource control, RRC, connection request message.

Turning now to figure 8, example embodiments of a network node 800 will be described in some detail.

The network node 800, which may be one of the network nodes discussed above in connection with figures 1-4, is for use in a wireless network for communication with a wireless communication device. The network node 800 comprises:

- a determining module 802 configured to determine information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure occurring in relation to the RA procedure, and

- a transmitting module 804 configured to transmit, to the wireless communication device, the information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure.

The network node 800 may comprise further modules that are configured to perform in a similar manner as, e.g., the network node 700 described above in connection with figure 7.

As used herein, the term "processing module" may refer to a processing circuit, a processing unit, a processor, an Application Specific integrated Circuit (ASIC), a Field- Programmable Gate Array (FPGA) or the like. As an example, a processor, an ASIC, an FPGA or the like may comprise one or more processor kernels. In some examples, the processing module may be embodied by a software module or hardware module. Any such module may be a determining means, estimating means, capturing means, associating means, comparing means, identification means, selecting means, receiving means, transmitting means or the like as disclosed herein. As an example, the expression "means" may be a module, such as a determining module, selecting module, etc.

As used herein, the expression "configured to" may mean that a processing circuit is configured to, or adapted to, by means of software configuration and/or hardware configuration, perform one or more of the actions described herein.

As used herein, the term "memory" may refer to a hard disk, a magnetic storage medium, a portable computer diskette or disc, flash memory, random access memory (RAM) or the like. Furthermore, the term "memory" may refer to an internal register memory of a processor or the like. As used herein, the term "computer readable medium" may be a Universal Serial Bus (USB) memory, a DVD-disc, a Blu-ray disc, a software module that is received as a stream of data, a Flash memory, a hard drive, a memory card, such as a MemoryStick, a Multimedia Card (MMC), etc.

As used herein, the term "computer readable code units" may be text of a computer program, parts of or an entire binary file representing a computer program in a compiled format or anything there between. As used herein, the terms "number", "value" may be any kind of digit, such as binary, real, imaginary or rational number or the like. Moreover, "number", "value" may be one or more characters, such as a letter or a string of letters, "number", "value" may also be represented by a bit string. As used herein, the expression "in some embodiments" has been used to indicate that the features of the embodiment described may be combined with any other embodiment disclosed herein.

Even though embodiments of the various aspects have been described, many different alterations, modifications and the like thereof will become apparent for those skilled in the art. The described embodiments are therefore not intended to limit the scope of the present disclosure.

Claims

1. A method performed by a wireless communication device (106, 406, 500, 600) when communicating with a wireless network (100), the method comprising:

- initiating (201) a random access, RA, procedure by selecting a first preamble sequence at random from a set of preamble sequences and transmitting the first preamble sequence to the wireless network,

- following the transmission of the first preamble sequence, receiving (203), from the wireless network, information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure occurring in relation to the RA procedure,

- determining (205) that the failure has occurred in relation to the RA procedure and, as a consequence of the determination that the failure has occurred,

- continuing (207) the communication with the wireless network using the specified resources associated with uplink transmission.

2. The method of claim 1 , wherein the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies at least one other preamble sequence that is different from the first preamble sequence.

3. The method of claim 2, wherein the continued communication with the wireless network comprises:

- selecting (420) a second preamble sequence from among the at least one other preamble sequence, and

- transmitting (422) the second preamble sequence to the wireless network.

4. The method of claim 3, wherein the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies a plurality of other preamble sequences that are different from the first preamble sequence and wherein the selection of a second preamble sequence is performed at random from among the plurality of other preamble sequences.

5. The method of claim 1 , wherein the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies at least one time-frequency resource for transmission on the uplink.

6. The method of claim 5, wherein the continued communication with the wireless network comprises:

- transmitting (460), using the specified at least one time-frequency resource on an uplink shared channel, UL-SCH, a radio resource control, RRC, connection request message (423).

7. The method of any of claims 1 to 6, wherein the transmission of the first preamble sequence to the wireless network comprises:

- transmitting (412), on a random access channel, RACH, the first preamble sequence, and

wherein the reception of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises:

- receiving (414), on a downlink shared channel, DL-SCH, a response to the transmission of the first preamble sequence, said response comprising the information that specifies the resources associated with uplink transmission for continued

communication with the wireless network in case of a failure.

8. The method of any of claims 1 to 6, wherein the determination that a failure has occurred in relation to the RA procedure, comprises:

9. The method of any of claims 1 to 6, wherein the reception of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises:

- receiving (418), on a downlink shared channel, DL-SCH, a RRC connection setup message (41 1) comprising the information that specifies the resources associated with uplink transmission for continued communication with the wireless network in case of a failure.

10. The method of claim 9, wherein the determination that a failure has occurred in relation to the RA procedure comprises:

- determining that the failure has occurred upon recognizing that the received RRC connection setup message is not intended for the wireless communication device.

1 1. The method of any of claims 1 to 6, wherein the determination that a failure has occurred in relation to the RA procedure, comprises:

- determining that no RRC connection setup message in response to a transmission of a RRC connection request message (416) has been received from the wireless network within a predetermined time interval.

12. The method of any of claims 2 to 4, wherein the reception of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises:

13. A method performed by a network node (104, 105, 404, 700, 800) in a wireless network (100) when communicating with a wireless communication device (106, 406, 500,

5 600) in a random access, RA, procedure, the method comprising:

- determining (301 , 452) information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure occurring in relation to the RA procedure, and

- transmitting (303), to the wireless communication device, the information that0 specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure.

14. The method of claim 13, wherein the information that specifies resources associated with uplink transmission by the wireless communication device for continued

communication with the wireless network in case of a failure is determined by:

5 - selecting at least one preamble sequence from all available unused preamble sequences.

15. The method of claim 14, wherein the transmission of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises:

0 - transmitting, in a system information block, SIB, on a broadcast control channel, BCCH, the selected at least one preamble sequence from all available unused preamble sequences.

16. The method of claim 13, wherein the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies at least one time-frequency resource for transmission on the uplink.

17. The method of claim 16, wherein the specified at least one time-frequency resource relates to transmission by the wireless communication device, on an uplink shared channel, UL-SCH, of a radio resource control, RRC, connection request message (423).

18. A wireless communication device (106, 406, 500, 600) for communication with a wireless network (100), the wireless communication device comprising radio frequency circuitry (506), a processor (502) and a memory (504), said memory containing instructions executable by said processor whereby said wireless communication device is operative to:

- continue the communication with the wireless network using the specified resources associated with uplink transmission.

19. The wireless communication device of claim 18, wherein the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies at least one other preamble sequence that is different from the first preamble sequence.

20. The wireless communication device of claim 19, wherein the continued communication with the wireless network comprises selecting a second preamble sequence from among the at least one other preamble sequence and transmitting the second preamble sequence to the wireless network.

5 21. The wireless communication device of claim 20, wherein the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies a plurality of other preamble sequences that are different from the first preamble sequence and wherein the selection of a second preamble sequence is performed at random from 10 among the plurality of other preamble sequences.

22. The wireless communication device of claim 18, wherein the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies at least one time-frequency resource for transmission on the uplink.

15 23. The wireless communication device of claim 22, wherein the continued

communication with the wireless network comprises:

20 24. The wireless communication device of any of claims 18 to 23, wherein the

transmission of the first preamble sequence to the wireless network comprises:

- transmitting, on a random access channel, RACH, the first preamble sequence, and wherein the reception of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure

25 comprises: - receiving, on a downlink shared channel, DL-SCH, a response to the transmission of the first preamble sequence, said response comprising the information that specifies the resources associated with uplink transmission for continued

communication with the wireless network in case of a failure.

5 25. The wireless communication device of any of claims 18 to 23, wherein the

determination that a failure has occurred in relation to the RA procedure, comprises:

26. The wireless communication device of any of claims 18 to 23, wherein the reception of 10 information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises:

15 27. The wireless communication device of claim 26, wherein the determination that a

failure has occurred in relation to the RA procedure comprises:

28. The wireless communication device of any of claims 18 to 23, wherein the

20 determination that a failure has occurred in relation to the RA procedure, comprises:

- determining that no RRC connection setup message in response to a transmission of a RRC connection request message has been received from the wireless network within a predetermined time interval.

29. The wireless communication device of any of claims 19 to 21 , wherein the reception of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises:

- receiving, in a system information block, SIB, on a broadcast control channel, 5 BCCH, the information that specifies at least one other preamble sequence that is different from the first preamble sequence.

30. A wireless communication device (106, 406, 500, 600) for communication with a wireless network (100), the wireless communication device comprising means adapted to:

- initiate a random access, RA, procedure by selecting a first preamble sequence at 10 random from a set of preamble sequences and transmitting the first preamble sequence to the wireless network,

- following the transmission of the first preamble sequence, receive, from the wireless network, information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure occurring in

15 relation to the RA procedure,

20 31. The wireless communication device of claim 30, wherein the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies at least one other preamble sequence that is different from the first preamble sequence.

32. The wireless communication device of claim 31 , wherein the continued

25 communication with the wireless network comprises selecting a second preamble sequence from among the at least one other preamble sequence, and transmitting the second preamble sequence to the wireless network.

33. The wireless communication device of claim 32, wherein the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies a plurality of other preamble sequences that are different from the first preamble sequence and wherein the selection of a second preamble sequence is performed at random from among the plurality of other preamble sequences.

34. The wireless communication device of claim 30, wherein the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies at least one time-frequency resource for transmission on the uplink.

35. The wireless communication device of claim 34, wherein the continued

communication with the wireless network comprises:

36. The wireless communication device of any of claims 30 to 35, wherein the

transmission of the first preamble sequence to the wireless network comprises:

- transmitting, on a random access channel, RACH, the first preamble sequence, and wherein the reception of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises:

- receiving, on a downlink shared channel, DL-SCH, a response to the

communication with the wireless network in case of a failure.

37. The wireless communication device of any of claims 30 to 35, wherein the

38. The wireless communication device of any of claims 30 to 35, wherein the reception of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises:

39. The wireless communication device of claim 38, wherein the determination that a failure has occurred in relation to the RA procedure comprises:

40. The wireless communication device of any of claims 30 to 35 wherein the

- determining that no RRC connection setup message in response to a

41. The wireless communication device of any of claims 31 to 33, wherein the reception of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises: - receiving, in a system information block, SIB, on a broadcast control channel, BCCH, the information that specifies at least one other preamble sequence that is different from the first preamble sequence.

42. A network node (104, 105, 404, 700, 800) for use in a wireless network (100) for 5 communication with a wireless communication device (106, 406, 500, 600), the network node comprising input/output circuitry (706), a processor (702) and a memory (704), said memory containing instructions executable by said processor whereby said network node is operative to:

- determine information that specifies resources associated with uplink transmission 10 by the wireless communication device for continued communication with the wireless network in case of a failure occurring in relation to the RA procedure, and

- transmit, to the wireless communication device, the information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure.

15 43. The network node of claim 42, wherein the information that specifies resources

associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure is determined by:

20 44. The network node of claim 43, wherein the transmission of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises:

- transmitting, in a system information block, SIB, on a broadcast control channel, BCCH, the selected at least one preamble sequence from all available unused preamble

25 sequences.

45. The network node of claim 42, wherein the information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises information that specifies at least one time- frequency resource for transmission on the uplink.

46. The network node of claim 45, wherein the specified at least one time-frequency resource relates to transmission by the wireless communication device, on an uplink shared channel, UL-SCH, of a radio resource control, RRC, connection request message.

47. A network node (104, 105, 404, 700, 800) for use in a wireless network (100) for communication with a wireless communication device (106, 406, 500, 600), the network node comprising means adapted to:

- determine information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure occurring in relation to the RA procedure, and

48. The network node of claim 47, wherein the information that specifies resources associated with uplink transmission by the wireless communication device for continued communication with the wireless network in case of a failure is determined by:

49. The network node of claim 48, wherein the transmission of information that specifies resources associated with uplink transmission for continued communication with the wireless network in case of a failure comprises:

50. The network node of claim 47, wherein the information that specifies resources associated with uplink transmission for continued communication with the wireless

5 network in case of a failure comprises information that specifies at least one time- frequency resource for transmission on the uplink.

51. The network node of claim 50, wherein the specified at least one time-frequency resource relates to transmission by the wireless communication device, on an uplink shared channel, UL-SCH, of a radio resource control, RRC, connection request message.

10 52. A computer program (541), comprising instructions which, when executed on at least one processor (502) in a wireless communication device (106, 406, 500), cause the wireless communication device to carry out the method according to any one of claims 1 to 12.

53. A computer program (741), comprising instructions which, when executed on at least 15 one processor (702) in a network node (104, 105, 404, 700), cause the network node to carry out the method according to any one of claims 13 to 17.

54. A carrier (542, 742) comprising the computer program of claim 52 or claim 53, wherein the carrier is one of an electronic signal, an optical signal, a radio signal and a computer readable storage medium.

20