WO2013127058A1

WO2013127058A1 - Preamble counter calculation scheme

Info

Publication number: WO2013127058A1
Application number: PCT/CN2012/071684
Authority: WO
Inventors: Wei Bai; Haiming Wang; Jussi Ojala; Jing HAN
Original assignee: Renesas Mobile Corporation
Priority date: 2012-02-27
Filing date: 2012-02-27
Publication date: 2013-09-06

Abstract

The present invention relates to methods, apparatuses and a computer program product for a preamble counter calculation scheme. The present invention includes transmitting a random access trigger order containing dedicated preamble and physical random access channel PRACH resource to a user equipment for a secondary cell, determining whether an expected random access preamble corresponding to the random access trigger order is received from the user equipment, and, if it is determined that the corresponding random access preamble is received, transmitting a command via dedicated physical downlink shared channel PDSCH including an absolute timing advance value to the user equipment.

Description

PREAMBLE COUNTER CALCULATION SCHEME

Field of the invention

The present invention relates to a preamble counter calculation scheme. More particularly, the present invention relates to methods, apparatuses and a computer program product for a preamble counter calculation scheme for random access on SCell.

Background

Long Term Evolution (LTE-) Advanced aims to provide significantly enhanced services by means of higher data rate and lower latency with reduced cost. Carrier Aggregation (CA) is one of the key technologies to greatly improve the data rate.

In 3GPP Release 10, there has been reached the agreement that there will be only intra-band CA for uplink (UL) and one timing advance (TA) for all the UL Component Carriers (CCs). However, in Release 11 and beyond, when taking inter-band carrier aggregation into consideration, as well as Radio Remote Head (RRH) and repeater case, multiple TA will be necessary. It was also agreed that a RACH procedure will be enabled on the Secondary Cell (SCeil) to let UE acquire the TA value on SCell.

It was further already agreed that contention based Random Access (RA) will not be supported on SCell. Thus, in order to perform RA procedure on SCell, there have to be considered only the three steps for non-contention based random access, as described in document [1]. These steps are shown in Fig. 1.

As shown in Fig. 1, in a first step Sll, the eNB assigns to the UE a non- contention Random Access Preamble. Then, in a step S12, the UE transmits the assigned non-contention Random Access Preamble to the eNB, and receives in a step S13 a Random Access Response. However, if cross carrier scheduling is configured, it is not clear how to transmit the Msg2 (layer 2 message) for the RA procedure on SCell, because it is possible that different UEs send the preamble with the same ID on the PRACH resource with the same RA-RNTI but on different carriers. In this case, eNB has to find a solution to let UE know whether the received Random Access Response (RAR) (Msg2) is for itself or not, because currently, UE only distinguish RAR by RA-RNTI and RAPID (random access preamble ID). In the 3GPP WG2 75bis and 76 meeting, it was discussed how to transmit the Msg2 for RACH procedure on SCell, in case cross carrier scheduling is configured. In the meeting, there were totally three options on the table:

- Address Msg2 with PDCCH in common search space (RA-RNTI) and transmit Msg2 on the scheduling SCell/PCell with modified RAR or modified RA-RNTI;

- Address Msg2 with PDCCH in common search space (RA-RNTI) and transmit Msg2 on PCell with modified RAR or modified RA-RNTI;

- Address Msg2 with PDCCH in UE specific search space (C-RNTI) and transmit Msg2 on any serving cells.

In 3GPP WG2 77 meeting, the second solution was excluded due to the RANI LS to not increase the total number of blind detections. And the agreed way forward is that companies who support the first solution or third solution should agree a simplest solution without open issue, and also a simplified MAC CR for each solution is preferred because companies raised concern on the specification and test complexity.

For the first solution, there are still some sub-options, e.g. modify the RA-RNTI calculation scheme to add a cell specific cell index, or use the padding bits of the RAR to carry the cell index, or use the T-C-RNTI to verify whether the received RAR is for UE itself or not. The expected simplest CR might be a proposal that for new UE, it will need to check the T-C-RNTI and see if it is same as its C-RNTI if the RAR for SCell is received. If they match, UE will regard it as its own RAR and if they don't match, it will discard the received RAR. For the third solution, if RA procedure is still adopted and the RAR window, RA failure definition is kept, there might be several open issues listed below

- The content of the dedicated RAR MAC CE;

- Whether the dedicated RAR MAC CE can be multiplexed with user data;

- Whether the legacy HARQ procedure (e.g. retransmission) can be applied for the TB including the dedicated RAR MAC CE;

- Whether RA Response window mechanism is still applied;

- When UE receives the dedicated RAR MAC CE, if the UE can consider Random Access procedure to be successfully completed.

For the RA procedure on SCell, the only purpose is to let UE acquire the TA value on SCell. However, with the current contention based RA procedure, because monitoring RAR on SIB-2 (System Information Block 2) linked SCell is excluded, UE has to receive the RAR on another cell. In this case, since the only identity of the RAR is the RA-RNTI which is derived from the PRACH index in a given CC, and the preamble ID which the UE has transmitted, it will cause ambiguity for the UE to know, which RAR is for itself. According to the present invention, there is proposed a simplified and effective solution to handle this case.

References: [1] 3GPP TS 36.300 Vll.0.0 (2011-12), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description, Stage 2, (Release 11), [2] 3GPP TS 36.321 V10.4.0 (2011-12), 3rd Generation Partnership Project;

Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Medium Access Control (MAC) protocol specification, (Release 10). [3] 3GPP TS 36.331 V10.4.0 (2011-12), 3rd Generation Partnership Project;

Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification, (Release 10).

Summary of the invention

According to exemplary aspects of the present invention, there are provided methods, apparatuses and a computer program product for a preamble counter calculation scheme for random access on SCell.

Various aspects of exemplary embodiments of the present invention are set out in the appended claims. According to an exemplary aspect of the present invention, there is provided a method, comprising :

transmitting, by a base station, a random access trigger order containing dedicated preamble and physical random access channel PRACH resource to a user equipment for a secondary cell,

determining, at the base station, whether an expected random access preamble corresponding to the random access trigger order is received from the user equipment,

if it is determined that the corresponding random access preamble is received, transmitting a command via dedicated physical downlink shared channel PDSCH including an absolute timing advance value to the user equipment.

According to another exemplary aspect of the present invention, there is provided a method, comprising :

receiving, at a user equipment, a random access trigger order from a base station for a specific secondary cell,

transmitting, by the user equipment, a random access preamble corresponding to the random access trigger order to the base station, increasing, at the user equipment, a counter every time the random access trigger order is received, for counting the number of receptions of the random access trigger order from the base station for the specific secondary cell, determining, at the user equipment, whether a command including an absolute timing advance value is received from the base station, and

if it is determined that the command is received, setting the counter to 0.

According to another exemplary aspect of the present invention, there is provided an apparatus, comprising :

at least one processor,

and at least one memory including computer program code,

the at least one memory and the computer program code arranged to, with the at least one processor, cause the apparatus at least to perform:

transmitting a random access trigger order containing dedicated preamble and physical random access channel PRACH resource to a user equipment for a secondary cell,

determining whether an expected random access preamble corresponding to the random access trigger order is received from the user equipment,

at least one processor,

and at least one memory including computer program code,

transmitting a random access preamble corresponding to the random access trigger order to the base station, increasing a counter every time the random access trigger order is received, for counting the number of receptions of the random access trigger order from the base station for the specific secondary cell,

determining whether a command including an absolute timing advance value is received from the base station, and

if it is determined that the command is received, setting the counter to 0.

means for transmitting a random access trigger order containing dedicated preamble and physical random access channel PRACH resource to a user equipment for a secondary cell,

means for determining whether an expected random access preamble corresponding to the random access trigger order is received from the user equipment,

means for transmitting, if it is determined that the corresponding random access preamble is received, a command via dedicated physical downlink shared channel PDSCH including an absolute timing advance value to the user equipment.

means for transmitting a random access preamble corresponding to the random access trigger order to the base station,

means for increasing a counter every time the random access trigger order is received, for counting the number of receptions of the random access trigger order from the base station for the specific secondary cell,

means for determining whether a command including an absolute timing advance value is received from the base station, and

means for setting the counter to 0, if it is determined that the command is received.

According to an exemplary aspect of the present invention, there is provided a computer program product comprising computer-executable computer program code which, when the program is run on a computer (e.g. a computer of an apparatus according to any one of the aforementioned apparatus-refated exemplary aspects of the present invention), is configured to cause the computer to carry out the method according to any one of the aforementioned method- related exemplary aspects of the present invention.

Such computer program product may comprise or be embodied as a (tangible) computer-readable (storage) medium or the like on which the computer- executable computer program code is stored, and/or the program may be directly loadable into an internal memory of the computer or a processor thereof.

Advantageous further developments or modifications of the aforementioned exemplary aspects of the present invention are set out in the dependent claims. The proposed way has the advantage that the impact to the current MAC specification is minimized and that it is easy to implement because the only change is due to the preamble-counter handling. Other parts cou!d be just duplicate with the legacy behavior. Brief Description of the Drawings

For a more complete understanding of exemplary embodiments of the present invention, reference is now made to the following description taken in connection with the accompanying drawings in which :

Fig. 1 is a diagram illustrating a legacy procedure of non-contention based random access;

Fig. 2 shows a principle flowchart of an example for a method according to certain embodiments of the present invention;

Fig. 3 shows a principle flowchart of another example for a method according to certain embodiments of the present invention; Fig. 4 shows a principle configuration of an example for an apparatus according to certain embodiments of the present invention;

Fig. 5 shows a principle configuration of another example for an apparatus according to certain embodiments of the present invention.

Description of exemplary embodiments

Exemplary aspects of the present invention will be described herein below. More specifically, exemplary aspects of the present are described hereinafter with reference to particular non-limiting examples and to what are presently considered to be conceivable embodiments of the present invention. A person skilled in the art will appreciate that the invention is by no means limited to these examples, and may be more broadly applied.

It is to be noted that the above description of the background as well as the following description of the present invention and its embodiments mainly refers to specifications being used as non-limiting examples for certain exemplary network configurations and deployments. Namely, the background, the present invention and its embodiments are mainly described in relation to 3GPP specifications being used as non-limiting examples for certain exemplary network configurations and deployments. In particular, a LTE-Advanced communication system is used as a non-limiting example for the applicability of thus described exemplary embodiments. As such, the description of exemplary embodiments given herein specifically refers to terminology which is directly related thereto. Such terminology is only used in the context of the presented non-limiting examples, and does naturally not limit the invention in any way. Rather, LTE or any other network configuration or system deployment, etc. may also be utilized as long as compliant with the features described herein.

Hereinafter, various embodiments and implementations of the present invention and its aspects or embodiments are described using several alternatives. It is generally noted that, according to certain needs and constraints, all of the described alternatives may be provided alone or in any conceivable combination (also including combinations of individual features of the various alternatives).

According to exemplary embodiments of the present invention, in general terms, there are provided mechanisms, measures and means for a preamble counter calculation scheme for random access on SCell.

According to exemplary embodiment of the present invention, it is proposed that, in order to acquire the TA value on SCell, UE should use the former part of the RA procedure to let eNB to measure the TA value for a given UE, and use the legacy TA command procedure to let eNB indicate to the UE the absolute TA value for the sTAG. That is, eNB will trigger RA on SCell via PDCCH order, once UE receives the RACH trigger, it should send the preamble to eNB accordingly (use the indicated preamble ID and PRACH resource), after that, UE will think the following procedure should follow the current TA command mechanism, i.e. eNB will send UE the TA command to tell the TA value for sTAG, and UE will apply the TA command and also start/restart the TAT.

It is noted that there might be a little difference compared to the current TA command mechanism that the current TA command is only a relative value that UE should adjust the running TA value by the received offset. But with the proposed solution, UE could also receive absolute TA value, and UE will add such TA value to the DL reception time to form the UL transmission timing of sTAG. Exemplary aspects of the present invention are about the handling of the parameter PREAMBLE JTRANSMISSIONJZOUNTER. Currently, the paramter PREAMBLE_TRANSMISSION_COUNTER is defined in document [2] .

According to exemplary aspects of the present invention, the random access procedure is as follows.

When the UE receives a PDCCH order to trigger random access on SCell, the UE should increase the corresponding PREAMBLE_TRANSMISSION_COUNTER by 1. Further, once the absolute TA command is received by UE for SCell within a sTAG, the UE should set the corresponding PREAMBLE_TRANSMISSION_COUNTER to 0 for all the SCell within the same sTAG. However, when the RA is triggered on PCell, all the PREAMBLE_TRANSMISSION_COUNTER for SCell should be set to 0.

Or in other words, the PREAMBLE_TRANSMISSION_COUNTER for SCell should be set as the number of the PDCCH order, i.e. counts the number of PDCCH orders, which is used to trigger RA on SCell, until it is reset again (i.e. set as the initial value).

In the following, a procedure of the above described proposed solution is given with respect to both an UE and an eNB.

The procedure with respect the eNB is shown in Fig. 2. Fig. 2 shows a principle flowchart of an example for a method according to certain embodiments of the present invention. As shown in Fig. 2, the method comprises transmitting, by a base station, a random access trigger order containing dedicated preamble and physical random access channel PRACH resource to a user equipment in a step S21, determining, at the base station, whether an expected random access preamble corresponding to the random access trigger order is received from the user equipment in a step S22, and, if it is determined in step S22 that the corresponding random access preamble is received (Y in step S22), transmitting, in a step S23, a command via dedicated physical downlink shared channel PDSCH including an absolute timing advance value to the user equipment. However, if it is determined in step S22 that the eNB has not successfully received the corresponding preamble from the UE, the procedure may return to step S21 and the eNB may re-trigger the RA by again sending a RA trigger order for SCell to the UE, but the eNB may not expect autonomous preamble retransmission which is the mechanism in legacy release (e.g. Rel-8/9/10). According to an exemplary embodiment of the present invention, the method as described above with respect to Fig. 2 is implemented in a communication network control element, in particular an evolved node B of an LTE or LTE-A based cellular communication network, wherein the random access trigger order and the command is transmitted to and the random access preamble is received from a communication element, like e.g. a user equipment, being controlled by the communication network control element.

In the following, a short overview of a RACH-ConfigCommon information element for SCell RACH configuration which is used to specify the generic random access parameters, as defined in document [3] is shown.

— ASN1START

RACH-ConfigCommon : := SEQUENCE {

preaitvblelnfo SEQUENCE {

numberOfRA-Preambles ENUMERATED {

n4, n8, nl2, nl6 ,n20, n2A, n28,

n32, n36, n40, n44, n48, n52, n56,

n60, n64},

preamblesGroupAConfig SEQUENCE {

sizeOfRA-PreamblesGroupA ENUMERATED {

ri4, n8, n!2, nl6 ,n20, n24, n28, n32, n36, n40, n44, n48, n52, n56, n60},

messageSizeGroupA ENUMERATED {b56, bl44, b208, b256}, messagePowerOffset.Grp.upB ENUMERATED {

minusinfinity , dBO, dBS, dB8, dB10, dB15, dBl8} ,

} OPTIONAL Need OP

},

po erRampingParameters SEQUENCE {

powerRampingStep ENUMERATED {dBO, dB2,dB4, dB6) ,

preamblelnitialReceivedTargetPo er ENUMERATED (

dBm-120, dBm-118, dBm-116, dBm-114, dBm-112, dBm-110, dBm-108, dBm-106, dBra-104, dBm-102, dBiti-100, dBm-98, dBm-96, dBm-94,

dBm-92, dBm-90)

Supervisionlnfo SEQUENCE {

preambleTransMaX ENUMERATED (

n3, Ώ4, n5, τιβ, nl, n8, nlO, n20, n50, nlOO, n200},

ra-ResponsewindowSize ENUMERATED {

sf2, sf3, s£4, sf5, sf6, sf7,

sfQ, sflOi,

mac-ContentionResolutiontimer ENUMERATED {

sf8, sfl6, sf24, sf32, sf40, sf48,

sf56, sfSi)

),

maxHARQ-Msg3Tx INTEGER (1..8) ,

— ASN1STOP According to exemplary embodiments of the present invention, the eIMB does not need to configure the parameters shown in italic in the overview. In particular, these parameters are

- preambleTransMax: maximum number of preamble transmission in TS 36.321 [2] . Value is an integer. Value n3 corresponds to 3, n4 corresponds to 4 and so on;

- ra-ResponseWindowSize: Duration of the RA response window in TS 36.321 [2]. Value in subframes. Value sf2 corresponds to 2 subframes, sf3 corresponds to 3 subframes and so on;

- mac ContentionResolutionTimer: Timer for contention resolution in TS 36.321 [2] . Value in subframes. Value sf8 corresponds to 8 subframes, sfl6 corresponds to 16 subframes and so on; and

- maxHARQ- sg3Tx: Maximum number of Msg3 HARQ transmissions in TS 36.321 [2], used for contention based random access. Value is an integer.

Thus, in summary, the eIMB doesn't need to configure the RAR window and RA failure related parameters to eIMB for RA on SCell.

For the UE, the procedure is shown in Fig. 3. Fig. 3 shows a principle flowchart of another example for a method according to certain embodiments of the present invention.

As shown in Fig . 3, receiving, at a user equipment, a random access trigger order from a base station for a specific secondary ceil in a step S31. Further, the method comprises transmitting, by the user equipment, a random access preamble corresponding to the random access trigger order to the base station in a step S32. That is, in a step S32, the UE sends the preamble according to the preamble ID and PRACH mask index, which is indicated in the signaling. This is the same procedure as in the legacy UE (cf. document [2], section 5.1.3 in this regard).

The method further comprises increasing, at the user equipment, a counter every time the random access trigger order is received, for counting the number of receptions of the random access trigger order from the base station for the specific secondary cell. That is, the UE increments the parameter PREAMBLE JTRANSMISSIOINLCOUNTER by 1 in a step S33. It is noted that the parameter PREAMBLE JTRANSMISSIOINLCOUNTER referred to in this exemplary embodiment is the PREAMBLE_TRANSMISSION_COUNTER for SCell.

Further, the method comprises determining, at the user equipment in a step S34, whether a command including an absolute timing advance value is received from the base station, and if it is determined that the command is received, setting the counter to 0 in a step S35. That is, if it is determined in step S34 that the absolute TA command has been received (Y in step S34), the parameter

PREAMBLE_TRANSMISSION_COUNTER is set to 0 in step S35 and the procedure is ended.

If it is determined in step S34 that the UE has not received the absolute TA command (N in step S34), the procedure is ended.

In this regard, it is noted that a case, in which the UE has not received the absolute TA command is, for example, a case in which the UE has again received the RA trigger on SCell without receiving the absolute TA command, as in step S31 described above. Then, as in step S32, the UE retransmits the preamble with the newly indicated preamble ID and PRACH mask index, regardless whether it is the same as the previous ID. This, however, is not illustrated in Fig. 3. Further, with respect to the steps shown in Fig. 3, it is noted that these steps do not have to be necessarily executed in the illustrated order, and that for example, steps S32 and S33 may be exchanged or step S32 may even be omitted.

Further, it is noted that the UE should also reset the PREAMBLE_TRANSMISSION_COUNTER for SCell to 0 if there is random access triggered on PCell. Thus, the main point according to the exemplary embodiment of the present invention is how to increase the counter (i.e. based on what condition the counter will be increased) and how to re-set the counter. According to the exemplary embodiment of the present invention, the counter is increased by reception of the RA trigger, which is different from the legacy procedure, where the UE will increase the counter if no RAR is received in the RAR window. Further, according to the exemplary embodiment of the present invention, the counter is reset upon reception of the absolute TA command, or if the RA is triggered on PCell, as described above.

The UE transmits the preamble with the power which is determined by the parameters which are configured by the eNB as well as the PREA BLE_TRANSMISSION_COUNTER, which is maintained by itself. This is the same as in the current preamble transmission mechanism as described in document [2].

According to an exemplary embodiment of the present invention, the method is implemented in a communication element, like e.g. a user equipment, located in an LTE or LTE-A based cellular communication network, wherein the random access trigger order and the command are received from a communication network control element and the random access preamble is transmitted to the network control element, in particular an evolved node B of the LTE or LTE-A based cellular communication network, controlling the communication element.

Fig. 4 shows a principle configuration of an example for an apparatus according to certain embodiments of the present invention. One option for implementing this example for an apparatus according to certain embodiments of the present invention would be a base station, like e.g. an eNB according to LTE/LTE-A.

Specifically, as shown in Fig. 4, the example for an apparatus 40, e.g. a base station, comprises at least one processor 41, at least one memory 42 including computer program code and an interface 43 which are connected by a bus 44 or the like. The at least one memory and the computer program code are arranged to, with the at least one processor, cause the apparatus at least to perform transmitting a random access trigger order to a user equipment, determining whether a random access preamble corresponding to the random access trigger order is received from the user equipment, and if it is determined that the corresponding random access preamble is received, transmitting a command including an absolute timing advance value to the user equipment.

According to another aspect of the present invention, if it is determined that the corresponding random access preamble is not received, the base staion retransmits the random access trigger order and/or does not expect autonomous retransmission of the same preamble.

According to an exemplary embodiment of the present invention the apparatus is comprised in a communication network control element, in particular an evolved node B of an LTE or LTE-A based cellular communication network, wherein the random access trigger order and the command is transmitted to and the random access preamble is received from a communication element, like e.g, a user equipment, being controlled by the communication network control element.

Fig. 5 shows a principle configuration of another example for an apparatus according to certain embodiments of the present invention. One option for implementing this example for an apparatus according to certain embodiments of the present invention would be a user equipment UE, like e.g. an UE according to LTE/ LTE- A.

Specifically, as shown in Fig. 5, the example for an apparatus 50, e.g. a UE, comprises at least one processor 51, at least one memory 52 including computer program code and an interface 53 which are connected by a bus 54 or the like. The at least one memory and the computer program code are arranged to, with the at least one processor, cause the apparatus at least to perform receiving a random access trigger order from a base station, transmitting a random access preamble corresponding to the random access trigger order to the base station, increasing a counter for counting the number of transmissions of the random access preamble, determining whether a command including an absolute timing advance value is received, and if it is determined that the command is received, setting the counter to 0. According to another aspect of the present invention, the at least one memory and the computer program code is further arranged to, with the at least one processor, cause the apparatus at least to perform determining, whether a random access order is received on a primary ceil, and if it is determined that the random access order is received on the primary cell, setting the counter to 0.

According to an exemplary embodiment of the present invention the apparatus is comprised in a communication element, like e.g. a user equipment located in an LTE or LTE-A based cellular communication network, wherein the random access trigger order and the command are received from a communication network control element and the random access preamble is transmitted to the network control element, in particular an evolved node B of the LTE or LTE-A based cellular communication network, controlling the communication element. In view of the above described exemplary embodiments of the present invention, it is an advantage of the present invention that an impact to the current MAC specification can be minimized and that it is easy to implement, because the only change has to be made with respect to the preamble counter handling. Other parts just correspond to the legacy behavior.

In the foregoing exemplary description of the apparatuses, i.e. the user equipment and the base station, only the units that are relevant for understanding the principles of the invention have been described using functional blocks. The apparatuses may comprise further units that are necessary for its respective operation as user equipment or base station, respectively. However, a description of these units is omitted in this specification. The arrangement of the functional blocks of the apparatuses is not construed to limit the invention, and the functions may be performed by one block or further split into sub-blocks. Further, the apparatuses, i.e. the user equipment and the respective base station, may be connected via a link 45/55. The link 45/55 may be a physical and/or logical coupling, which is implementation-independent (e.g. wired or wireless). When in the foregoing description it is stated that the apparatus, i.e. the user equipment or the base station (or some other means) is configured to perform some function, this is to be construed to be equivalent to a description stating that a (i.e. at least one) processor or corresponding circuitry, potentially in cooperation with computer program code stored in the memory of the respective apparatus, is configured to cause the apparatus to perform at least the thus mentioned function. Also, such function is to be construed to be equivalently implementable by specifically configured circuitry or means for performing the respective function (i.e. the expression "unit configured to" is construed to be equivalent to an expression such as "means for").

According to exemplarily embodiments of the present invention, a system may comprise any conceivable combination of the thus depicted devices/apparatuses and other network elements, which are arranged to cooperate as described above.

In general, it is to be noted that respective functional blocks or elements according to above-described aspects can be implemented by any known means, either in hardware and/or software, respectively, if it is only adapted to perform the described functions of the respective parts. The mentioned method steps can be realized in individual functional blocks or by individual devices, or one or more of the method steps can be realized in a single functional b!ock or by a single device. Generally, any procedural step or functionality is suitable to be implemented as software or by hardware without changing the idea of the present invention. Such software may be software code independent and can be specified using any known or future developed programming language, such as e.g. Java, C++, C, and Assembler, as long as the functionality defined by the method steps is preserved. Such hardware may be hardware type independent and can be implemented using any known or future developed hardware technology or any hybrids of these, such as MOS (Metal Oxide Semiconductor), CMOS (Complementary MOS), BiMOS (Bipolar MOS), BiCMOS (Bipolar CMOS), ECL (Emitter Coupled Logic), TTL (Transistor-Transistor Logic), etc., using for example ASIC (Application Specific IC (Integrated Circuit)) components, FPGA (Field-programmable Gate Arrays) components, CPLD (Complex Programmable Logic Device) components or DSP (Digital Signal Processor) components. A device/apparatus may be represented by a semiconductor chip, a chipset, system in package (SIP), or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of a device/apparatus or module, instead of being hardware implemented, be implemented as software in a (software) module such as a computer program or a computer program product comprising executable software code portions for execution/being run on a processor. A device may be regarded as a device/apparatus or as an assembly of more than one device/apparatus, whether functionally in cooperation with each other or functionally independently of each other but in a same device housing, for example. Apparatuses and/or means or parts thereof can be ^"implemented as ^"individual devices, but this does not exclude that they may be implemented in a distributed fashion throughout the system, as long as the functionality of the device is preserved. Such and similar principles are to be considered as known to a skilled person.

Software in the sense of the present description comprises software code as such comprising code means or portions or a computer program or a computer program product for performing the respective functions, as well as software (or a computer program or a computer program product) embodied on a tangible medium such as a computer-readable (storage) medium having stored thereon a respective data structure or code means/portions or embodied in a signal or in a chip, potentially during processing thereof.

The present invention also covers any conceivable combination of method steps and operations described above, and any conceivable combination of nodes, apparatuses, modules or elements described above, as long as the above- described concepts of methodology and structural arrangement are applicable. That is, for example, it is possible to perform the above mentioned timing advance procedure and the connectivity adjustment procedure either individually or in combination.

Even though the present invention and/or exemplary embodiments are described above with reference to the examples according to the accompanying drawings, it is to be understood that they are not restricted thereto. Rather, it is apparent to those skilled in the art that the present invention can be modified in many ways without departing from the scope of the inventive idea as disclosed herein.

Abbreviations:

CA Carrier Aggregation

CC Component Carrier

DL Downlink

LTE Long Term Evolution

LTE-A Long Term Evolution Advanced

MAC Media Access Control

PCC Primary Component Carrier

PDCCH Physical Downlink Control Channel

PRACH Physical Random Access Channel

RACH Random Access Channel

RAPID Random Access Preamble ID

RAR Random Access Response

RNTI Radio Network Temporary Identifier

RRC Radio Resource Control

SCC Secondary Component Carrier

STAG secondary TA Group

TA Timing Advance

TAT Time Alignment Timer

UE User Equipment

UL Uplink

Claims

WHAT IS CLAIMED IS:

1. A method, comprising:

transmitting a random access trigger order containing dedicated preamble and physical random access channel PRACH resource for a secondary cell,

determining whether an expected random access preamble corresponding to the random access trigger order is received,

if it is determined that the corresponding random access preamble is received, transmitting a command via dedicated physical downlink shared channel PDSCH including an absolute timing advance value.

2. The method according to claim 1, further comprising

if it is determined that the corresponding random access preamble is not received, retransmitting the random access trigger order and/or not expecting autonomous retransmission of the same preamble.

3. The method according to claim 1 or 2, wherein the method is implemented in a communication network control element, in particular an evolved node B of an LTE or LTE-A based cellular communication network, wherein the random access trigger order and the command is transmitted to and the random access preamble is received from a communication element being controlled by the communication network control element.

4. A method, comprising :

receiving a random access trigger order for a specific secondary cell, transmitting a random access preamble corresponding to the random access trigger order,

increasing a counter every time the random access trigger order is received, for counting the number of receptions of the random access trigger order for the specific secondary cell,

determining whether a command including an absolute timing advance value is received, and

if it is determined that the command is received, setting the counter to 0.

5. The method according to claim 4, further comprising

determining, whether a random access order is received on a primary cell, and

If it is determined that the random access order is received on the primary cell, setting the counter to 0,

6. The method according to claim 4 or 5, wherein the method is implemented in a communication element located in an LTE or LTE-A based cellular communication network, wherein the random access trigger order and the command are received from a communication network control element and the random access preamble is transmitted to the network control element, in particular an evolved node B of the LTE or LTE-A based cellular communication network, controlling the communication element.

7. An apparatus, comprising :

at least one processor,

and at least one memory including computer program code,

the at least one memory and the computer program code arranged to, with the at least one processor, cause the apparatus at least to perform :

8. The apparatus according to claim 7, wherein the at least one memory and the computer program code is further arranged to, with the at least one processor, cause the apparatus at least to perform

9. The apparatus according to claim 7 or 8, wherein the apparatus is comprised in a communication network control element, in particular an evolved node B of an LTE or LTE-A based cellular communication network, wherein the random access trigger order and the command is transmitted to and the random access preamble is received from a communication element being controlled by the communication network control element.

10. An apparatus, comprising :

at least one processor,

and at least one memory including computer program code,

if it is determined that the command is received, setting the counter to 0.

11. The apparatus according to claim 10, wherein the at least one memory and the computer program code is further arranged to, with the at least one processor, cause the apparatus at least to perform

determining, whether a random access order is received on a primary cell, and

if it is determined that the random access order is received on the primary cell, setting the counter to 0.

12. The apparatus according to claim 10 or 11, wherein the apparatus is comprised in a communication element located in an LTE or LTE-A based cellular communication network, wherein the random access trigger order and the command are received from a communication network control element and the random access preamble is transmitted to the network control element, in particular an evolved node B of the LTE or LTE-A based cellular communication network, controlling the communication element.

13. A computer program product comprising computer-executable computer program code which, when the program is run on a computer, is arranged to cause the computer to carry out the method according to any one of claims 1 to 6.

14. The computer program product according to claim 13, embodied as a computer-readable storage medium.

15. An apparatus, comprising :

means for transmitting a random access trigger order containing dedicated preamble and physical random access channel PRACH resource for a secondary cell,

means for determining whether an expected random access preamble corresponding to the random access trigger order is received,

means for transmitting, if it is determined that the corresponding random access preamble is received, a command via dedicated physical downlink shared channel PDSCH including an absolute timing advance value.

16. An apparatus, comprising :

means for transmitting a random access preamble corresponding to the random access trigger order,

means for increasing a counter every time the random access trigger order is received, for counting the number of receptions of the random access trigger order for the specific secondary cell,

means for determining whether a command including an absolute timing advance value is received, and