WO2017033091A1

WO2017033091A1 - Activation delay for pucch scell based on ul response

Info

Publication number: WO2017033091A1
Application number: PCT/IB2016/054891
Authority: WO
Inventors: Lars Dalsgaard; Li Zhang
Original assignee: Nokia Solutions and Networks Oy
Current assignee: Nokia Solutions and Networks Oy
Priority date: 2015-08-24
Filing date: 2016-08-15
Publication date: 2017-03-02
Anticipated expiration: 2018-02-24

Abstract

This invention relates generally to primary and secondary cells for carrier aggregation and, provides a method, an apparatus, a communication system, a computer program and a computer readable medium storing a computer program related thereto. The method comprises sending from a base station an activation command to a user equipment for activating a secondary cell with a physical uplink control channel for use by the user equipment; sending after an activation delay a physical downlink control channel order message to the user equipment on a physical downlink control channel for the secondary cell; and receiving, responsive to the physical downlink control channel order message, a random access response from the user equipment on the physical uplink control channel for the secondary cell.

Description

Activation Delay for PUCCH SCell Based on UL Response

TECHNICAL FIELD

[0001] This invention relates generally to primary and secondary cells for carrier aggregation and, more specifically, relates to secondary cells for carrier aggregation. BACKGROUND

[0002] This section is intended to provide a background or context to the invention disclosed below. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise explicitly indicated herein, what is described in this section is not prior art to the description in this application and is not admitted to be prior art by inclusion in this section. Abbreviations that may be used in the specification and/or drawings are defined below.

[0003] In the last few RAN4 meetings, some companies have provided papers addressing the issue of activation delay of a PUCCH SCell without valid UL timing. See the following: R4-151975, Considerations on dual PUCCH, Nokia Networks; R4-141492, RRM requirements of PUCCH SCell, NTT DoCoMo; R4- 153089, RRM requirements of PUCCH on SCell, NTT DOCOMO INC.; R4- 153056, Considerations on activation of SCell with PUCCH Nokia Networks. In RAN4#75 in Fukuoka, the topic was discussed and the WF was agreed upon. See R4- 153902, WF on PUCCH SCell activation, NTT DOCOMO INC.

[0004] However, as the current CA activation delay requirements in 3GPP TS 36.133 do not cover SCell activation delay when the PUCCH SCell does not have valid UL timing, leaving the UE requirements open, the conventional techniques could be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] In the attached Drawing Figures:

[0006] FIG. 1 is a block diagram of an exemplary system in which exemplary embodiments may be practiced;

[0007] FIG. 2 is an example of a number of LTE frames in time;

[0008] FIG. 3 is a logic flow diagram performed by a base station for activation delay for PUCCH SCell based on UL response, and illustrates the operation of an exemplary method, a result of execution of computer program instructions stored on a computer readable memory, functions performed by logic implemented in hardware, and/or interconnected means for performing functions in accordance with exemplary embodiment; and

[0009] FIG. 4 is a logic flow diagram performed by a user equipment for activation delay for PUCCH SCell based on UL response, and illustrates the operation of an exemplary method, a result of execution of computer program instructions stored on a computer readable memory, functions performed by logic implemented in hardware, and/or interconnected means for performing functions in accordance with exemplary embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

[0010] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. All of the embodiments described in this Detailed Description are exemplary embodiments provided to enable persons skilled in the art to make or use the invention and not to limit the scope of the invention.

[0011] The exemplary embodiments herein describe techniques for activation delay for PUCCH SCell based on UL Response. Additional description of these techniques is presented after a system is described into which some exemplary embodiments may be used.

[0012] Turning to FIG. 1, this figure shows a block diagram of an exemplary system in which exemplary embodiments may be practiced. In FIG. 1, UE 110 is in wireless communication with a wireless network 100 and specifically with a primary cell (PCell) formed by eNB 170-1 and a secondary cell (SCell) formed by eNB 170-2. Although shown separately, as the eNBs 170-1 and 170-2, this is solely for ease of description, and the eNBs 170-1 and 170-2 may be the same eNB or co-located. For instance, there could be three cells for a single eNB carrier frequency and associated bandwidth, each cell covering one-third of a 360 degree area so that the single eNB's coverage area covers an approximate oval or circle. Furthermore, each cell can correspond to a single carrier and an eNB may use multiple carriers. So if there are three 120 degree cells per carrier and two carriers, then the eNB has a total of six cells. So, a single eNB 170 could form both the PCell and the SCell. Depending on implementation, these could also be considered two eNBs (one for the three 120 degree cells and each carrier) or even six eNBs (one for each 120 degree cell and each carrier). Multiple eNBs can communicate, e.g., via an X2 interface and use the communication for coordination.

[0013] A user equipment 110 (e.g., 110-1) includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected through one or more buses 127. Each of the one or more transceivers 130 includes a receiver, Rx, 132 and a transmitter, Tx, 133. The one or more buses 127 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like. The one or more transceivers 130 are connected to one or more antennas 128. The one or more memories 125 include computer program code 123. The UE 110 includes an Activation Delay (AD) module 140, comprising one of or both parts 140-1 and/or 140-2, which may be implemented in a number of ways. The AD module 140 may be implemented in hardware as AD module 140-1, such as being implemented as part of the one or more processors 120. The AD module 140-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the AD module 140 may be implemented as AD module 140-2, which is implemented as computer program code 123 and is executed by the one or more processors 120. For instance, the one or more memories 125 and the computer program code 123 may be configured to, with the one or more processors 120, cause the user equipment 110 to perform one or more of the operations as described herein.

[0014] The UE 110 communicates with the eNBs 170-1 and 170-2 via a corresponding wireless link 111-1 or 111-2, respectively. The eNBs 170-1 and 170-2 are expected to be similar. Therefore, only one possible implementation of an eNB will be described in reference to FIG. 1. An eNB 170 (e.g., eNB 170-1) is a base station that provides access by wireless devices such as the UEs 110 to the wireless network 100. The eNB 170 includes one or more processors 152, one or more memories 155, one or more network interfaces (N/W I/F(s)) 161, and one or more transceivers 160 interconnected through one or more buses 157. Each of the one or more transceivers 160 includes a receiver, Rx, 162 and a transmitter, Tx, 163. The one or more transceivers 160 are connected to one or more antennas 158. The one or more memories 155 include computer program code 153. The eNB 170 includes an Activation Delay (AD) module 150, comprising one of or both parts 150-1 and/or 150-2, which may be implemented in a number of ways. The AD module 150 may be implemented in hardware as AD module 150-1, such as being implemented as part of the one or more processors 152. The AD module 150-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the AD module 150 may be implemented as AD module 150-2, which is implemented as computer program code 153 and is executed by the one or more processors 152. For instance, the one or more memories 155 and the computer program code 153 are configured to, with the one or more processors 152, cause the eNB 170 to perform one or more of the operations as described herein. The one or more network interfaces 161 communicate over a network such as via the links 176 and 131. Two or more eNBs 170 communicate using, e.g., link 176. The link 176 may be wired or wireless or both and may implement, e.g., an X2 interface.

[0015] The one or more buses 157 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, wireless channels, and the like. For example, the one or more transceivers 160 may be implemented as a remote radio head (RRH) 195, with the other elements of the eNB 170 being physically in a different location from the RRH, and the one or more buses 157 could be implemented in part as fiber optic cable to connect the other elements of the eNB 170 to the RRH 195.

[0016] The wireless network 100 may include a network control element (NCE) 190 that may include MME/SGW functionality, and which provides connectivity with a further network, such as a telephone network and/or a data communications network (e.g., the Internet). The eNB 170 is coupled via a link 131 to the NCE 190. The link 131 may be implemented as, e.g., an SI interface. The NCE 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces (NAV I/F(s)) 180, interconnected through one or more buses 185. The one or more memories 171 include computer program code 173. The one or more memories 171 and the computer program code 173 are configured to, with the one or more processors 175, cause the NCE 190 to perform one or more operations.

[0017] The wireless network 100 may implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization involves platform virtualization, often combined with resource virtualization. Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to software containers on a single system. Note that the virtualized entities that result from the network virtualization are still implemented, at some level, using hardware such as processors 152 or 175 and memories 155 and 171, and also such virtualized entities create technical effects. Note that not all (or even no) eNBs 170 need to implement virtualization and thus RRHs 195 might not be used by one or more of the eNBs 170.

[0018] The computer readable memories 125, 155, and 171 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The processors 120, 152, and 175 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multi-core processor architecture, as non-limiting examples.

[0019] In general, the various embodiments of the user equipment 110 can include, but are not limited to, cellular telephones such as smart phones, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, tablets with wireless communication capabilities, as well as portable units or terminals that incorporate combinations of such functions.

[0020] Concerning the techniques described herein for activation delay for PUCCH SCell based on UL response, it is helpful at this time to describe additional information regarding convention techniques. In particular, SCell with PUCCH was discussed during the RAN2#90 meeting in Fukuoka. The following decisions were made in RAN2 and captured in the running CR (R2- 152855, Running 36.300 CR to capture agreements on carrier aggregation enhancements, Nokia Corporation (Rapporteur)):

[0021] · Upon activation of a PUCCH SCell without valid UL timing, the UE waits for network to initiate random access via a PDCCH order. [0022] One fundamental difference when introducing SCell with PUCCH is that this basic assumption of having a valid UL timing upon activation, in the cell in which the UE is to transmit the SCell CSI report, may no longer be true. Instead, for a PUCCH SCell we may experience two situations:

[0023] · The UE does have valid UL timing on the activated PUCCH SCell; or

[0024] · The UE does not have valid UL timing on the activated PUCCH SCell.

[0025] One observation that is made is that the UE may be configured with SCell with PUCCH for which the UE has no valid UL timing. Based on the RAN2 agreements in R2- 152855, it is possible that for a UE, which has valid UL timing on activated PUCCH SCell, the SCell activation delay requirements would most likely be similar as for a non-PUCCH SCell although UE behavior needs to be changed.

[0026] Another observation that is made is that for a UE having valid UL timing on activated PUCCH SCell, the existing SCell activation delay requirements could be re-used as baseline.

Changes are most likely needed, as the UE is expected to have the behavior of transmitting the OoR CQI reporting between n+8 and the time point when the SCell is activated, which may not be possible.

[0027] The other case to consider is when the UE does not have valid UL timing on the activated PUCCH SCell. In such a situation, the UE cannot transmit in UL and current agreement R2- 152855 states that the UE shall wait for the PDCCH order. That is, the UE cannot transmit CSI reports according to the current activation requirements. Another observation that is made is that if UE has no valid UL timing in the activated SCell with PUCCH, the UE cannot transmit in the SCell.

[0028] It is unclear what would be the UE requirements when UE has no valid UL timing on the activated PUCCH SCell, and this needs to be discussed in RAN4.

[0029] In R2-152855, it is already stated that for this case:

[0030] · Upon activation of a PUCCH SCell without valid UL timing, the UE waits for network to initiate random access via PDCCH order.

[0031] This indicates that when the UE has no valid UL timing on a PUCCH SCell for which the UE receives an activation command, the UE shall wait for network to send a PDCCH order on the newly activated PUCCH SCell.

[0032] Based on this discussion, it is necessary to develop PUCCH SCell activation delay requirements by re-using existing activation delay requirements when the UE has valid UL timing on the activated PUCCH SCell. For the case when the UE does not have valid UL timing on the activated PUCCH SCell, it is necessary to develop new activation delay requirements based on the RAN2 running CR in R2-152855.

[0033] Other technologies have some relationship with this situation. For instance, dual connectivity (DC). However, in DC the PSCell (which also has UL) is always activated and never deactivated. Therefore, there is no need to have the same activation delay requirements for when the network has sent the MAC activation command, which is when the UE required to be ready on the activated SCell. In addition, the UE does not (is not required to) wait for PDCCH Order on the configured PSCell.

[0034] In carrier aggregation (CA), the PUCCH is carried on PCell, until now when 3GPP is introducing the PUCCH SCell (i.e., where PUCCH is carried on the SCell). That is, the problem does not exist in current CA.

[0035] It is believed the techniques presented herein overcome these problems. An overview will be provided first, and then a more in depth description will be provided.

[0036] As an overview, it is proposed herein to define the UE PUCCH SCell activation delay requirements, for the case when the UE does not have valid UL timing on the activated PUCCH SCell, based on the UL response from the UE on the PUCCH SCell.

[0037] This UL response would be due to scheduling, which could be due to PDCCH Order, e.g., when the RA burst is received from the UE. An additional option would be that delay would be based/defined on when the UE sends first CSI report in UL (after UL timing has been aligned) and this delay is then relaxed by adding PRACH procedure delay (e.g., non-contention based RA triggered by PDCCH order). For the other case when UE has UL timing, the new delay requirement would be based on when the UE is capable of transmitting its first valid CSI report on the activated PUCCH SCell.

[0038] The delay should then be referring to the point when the UE receives the activation command and when the eNB receives the UL (e.g., RA burst or CSI report) from the UE on the PUCCH SCell.

[0039] Additionally, it is proposed also to define a minimum requirement for the UE related to what is the longest delay expected on the UE side from when receiving the MAC activation command for the PUCCH SCell (e.g., on the PCell) and until the UE can receive the PDCCH on the (PUCCH) SCell. Also related is a consideration as to when is the earliest point in time when the network can schedule the UE on the activated (PUCCH) SCell - e.g., PDCCH Order - and expect that the UE is able to receive the scheduling/PDCCH correctly.

[0040] Now that an overview has been provided, a more detailed description of the various embodiments is as follows. Support of this feature is based on stating the UE requirement which is based on UE expected behavior and requirement specification. For a PUCCH SCell, in which the UE does not have valid UL timing, the UE 110 cannot transmit the CSI reports as is currently the expected behavior from the UE when an SCell is activated. Difference from legacy SCell activation is that in legacy SCell activation, the UL for SCell is transmitted on the PCell. Meanwhile, for a PUCCH SCell, the UL for the SCell is transmitted on the PUCCH SCell. When the UE does not have valid UL timing in the PUCCH SCell, the UE is not allowed to transmit in the PUCCH SCell.

[0041] RAN2 decided that the UE shall wait for PDCCH Order in the PUCCH SCell, when the PUCCH SCell is activated, if the UE does not have valid UL timing in the cell. There will of course not be any restriction on when (or if) the network shall send the PDCCH Order to the UE. However, there would be a need for a UE requirement concerning what is the earliest (or actually the latest) point in time when the network can send a PDCCH Order to the UE. Another UE requirement concerns what is the latest point in time from receiving the SCell activation command on UE side and until that the UE shall be able to receive PDCCH - and therefore the PDCCH Order - on the activated SCell. This point is referred to as point 'y' and is indicated in FIG. 2 as 'Earliest point when eNB expect UE monitoring PDCCH' (see block 220).

[0042] Referring to FIG. 2 in more detail, this figure is an example of a number of LTE frames in time. Five LTE frames 205-1, -2, -3, -4, and -5 are shown. Each frame 205 (10 ms in duration) has 10 subframes 210-0 through 210-9, each of which is 1 (one) ms in duration. Block 215 illustrates that the activation command is received in subframe 210-0 of frame 205-1, e.g., on PCell for activating the PUCCH SCell (in which the UE 110 has no valid UL timing). Block 220 indicates that the earliest point when the eNB 170 expects the UE 110 to be monitoring PDCCH (y) is subframe 210-0 of frame 205-2. Block 225 indicates that the UE 110 shall be able to transmit the RA preamble if PDCCH is received in subframe 210-4 of frame 205-1. Block 230 indicates that the latest point is subframe 210-0 of frame 205-3 when the UE 110 shall be able to receive PDCCH and the latest point the eNB 170 can expect the UE 110 to be able to correctly receive PDCCH (y). Block 235 indicates that at subframe 210-4 of frame 205-3, the UE 110 shall be able to transmit the RA preamble (PDCCH is possible to receive the latest four (4) TTIs prior to this point).

[0043] FIG. 2 and following requirement and UE behavior are based, e.g., on the current E-

UTRAN behavior, which should not be seen as a limiting factor. Two main topics are covered here: 1) minimum time when the UE shall be able to correctly receive PDCCH on the activated PUCCH SCell (e.g., what is the latest point in time after activation that the eNB (PUCCH SCell eNB) can expect the UE 110 to correctly receive the PUCCH SCell PDCCH) - time 'y' ; and 2) what is the (relative) maximum UE activation delay of the PUCCH SCell.

[0044] When the PUCCH SCell is activated and the MAC message is received on UE side in TTI=n, the UE has time to activate the SCell in case the SCell is not active (i.e., on UE side the RF chain is not active and needs to be turned on). For this, the UE would first have 4 TTIs for MAC processing and reply to network (HARQ) (subframes 210-1 through 210-4 of frame 205-1) after that the UE has 5 TTIs for activating the RF - if needed (subframes 210-5 through 210-9 of frame 205-1). Hereafter (subframe 210-0 of frame 205-2) is the earliest time where the UE could/should be able (is expected) to receive the PDCCH on the PUCCH SCell. See block 220. This is then defined as the earliest point when the network can expect UE to be schedulable on the activated SCell. If the UE receives a PDCCH Order, the UL RA burst shall be transmitted (see block 225) in z TTIs later (e.g., as in legacy requirement) which is then the earliest point.

[0045] The latest point in time (now using the assumption that the activated PUCCH SCell is known) (see block 230) when the UE shall be able to receive the PDCCH on the activated PUCCH SCell would be in 20 TTIs after receiving the activation command in TTI=n (i.e., PDCCH reception requirement is in TTI n+20). UL RA burst shall be transmitted in n+24TTIs after receiving the MAC activation command (assuming z=4). See block 235.

[0046] The delay requirement is then relaxed according to the time when the UE receives the PDCCH Order from the network on the PUCCH SCell. An example to illustrate this is as follows. The PDCCH order is in fact received on the PUCCH SCell in TTI n+40 and then the UE shall be able to transmit the UL RA burst in n+40+z -> in TTI n+44 (assuming z=4). That is, the UE requirement would in this case be n+44. In other words, the UE shall be able to transmit UL RA at n+x+z, where x is the time when UE receives PDCCH order, and eNB can assume UE is able to receive the PDCCH order if x is larger than y (assuming RA is sent z TTIs after receiving the PDCCH order). Here, y is the latest point in time from receiving the SCell activation command on UE side (in TTI n) and until that the UE shall be able to receive PDCCH.

[0047] Alternatively, the UE requirement is linked to when the UE is fact receiving the PDCCH order on the PUCCH SCell.

[0048] The detailed numbers used here are only examples and would of course possibly be different in field applications.

[0049] Referring to FIG. 3, a logic flow diagram is shown that is performed by a base station for activation delay for PUCCH SCell based on UL response. This figure illustrates the operation of an exemplary method, a result of execution of computer program instructions stored on a computer readable memory, functions performed by logic implemented in hardware, and/or interconnected means for performing functions in accordance with exemplary embodiment. The blocks in FIG. 3 are assumed to be performed by eNB 170, e.g., under control in part of the Activation Delay (AD) module 150. Note that the eNB 170 might be separated into eNBs 170-1 (PCell) and 170-2 (SCell). If so, there could be coordination between the two eNBs 170-1 and 170-2 (e.g., so that the activation delay can be a known entity).

[0050] In block 310, the eNB 170 performs sending from a base station an activation command to a user equipment for activating a secondary cell with a physical uplink control channel for use by the user equipment. In block 320, the eNB 170 performs sending after an activation delay a physical downlink control channel order message to the user equipment on a physical downlink control channel for the secondary cell. In block 330, the eNB 170 performs receiving, responsive to the physical downlink control channel order message, a random access response from the user equipment on the physical uplink control channel for the secondary cell.

[0051] Note that the eNBs 170 for the PCell and SCell could be "separate" eNBs (even if co- located). If this is the case, there could be some coordination between the two eNBs. For example, block 310 could be performed by the PCell, and some communication (e.g., via an indication) could be performed so that the SCell can determine that the sending of the activation command has been performed. The SCell would then perform block 320 (e.g., and 330) responsive to the fact that the sending of the activation command has been performed.

[0052] Turning to FIG. 4, FIG. 4 is a logic flow diagram performed by a user equipment for activation delay for PUCCH SCell based on UL response. FIG. 4 further illustrates the operation of an exemplary method, a result of execution of computer program instructions stored on a computer readable memory, functions performed by logic implemented in hardware, and/or interconnected means for performing functions in accordance with exemplary embodiment. The blocks in FIG. 4 are assumed to be performed by UE 110, e.g., under control in part of the Activation Delay (AD) module 140.

[0053] In block 410, the UE 110 performs receiving, at a user equipment and from a base station, an activation command for activating a secondary cell with a physical uplink control channel for use by the user equipment. The UE 110, in block 420, performs receiving after an activation delay a physical downlink control channel order message on a physical downlink control channel for the secondary cell. In block 430, the UE 110 performs sending, responsive to the physical downlink control channel order message, from the user equipment a random access response on the physical uplink control channel for the secondary cell.

[0054] One exemplary advantage of this approach is that it is flexible for both UE and network while still being well defined. That is, there is a clear requirement (e.g., a technical effect) related to UE behavior for activation delay concerning the PUCCH SCell. Additionally, this approach is using existing signaling while enabling (e.g., another technical effect) clear definition and testable/predictable UE behavior. This proposal is aligned with existing activation delay procedures and UE requirements.

[0055] It is noted that Appendix A, entitled "R4- 154482, Considerations on activation delay of PUCCH SCell without valid UL timing", by Nokia Networks, forms part of this application and is incorporated in its entirety herein.

[0056] As an example for a UE with UL timing in the activated PUCCH SCell, the UE shall not transmit any CSI feedback to eNB until the UE has obtained valid CSI report.

[0057] The following examples are presented as possible implementations. Example 1. A method, comprising: sending from a base station an activation command to a user equipment for activating a secondary cell with a physical uplink control channel for use by the user equipment; sending after an activation delay a physical downlink control channel order message to the user equipment on a physical downlink control channel for the secondary cell; and receiving, responsive to the physical downlink control channel order message, a random access response from the user equipment on the physical uplink control channel for the secondary cell. See also FIG. 3 and the text describing the same.

[0058] Example 2. The method of example 1, wherein sending an activation command is performed using a physical downlink control channel on a primary cell for the user equipment. Example 3. The method of any of examples 1 or 2, wherein the activation delay is at least from an earliest point the base station expects the user equipment to be monitoring the physical downlink control channel for the secondary cell after the user equipment receives the activation command for the secondary cell to a latest point the base station expects the user equipment as being able to correctly receive the physical downlink control channel for the secondary cell. Example 4. The method of any of examples 1 to 3, wherein the sending the activation command occurs in TTI n, the sending of the physical downlink control channel order message occurs in TTI x, TTI y is a latest point in time from receiving by the user equipment the activation command and until the user equipment is able to receive physical downlink control channel on the secondary cell, and the base station assumes the user equipment is able to receive the physical downlink control channel order message if x is larger than y.

[0059] Example 5. The method of example 4, wherein the base station receives the random access response in TTI n+x+z, where z is a predetermined number of TTIs. Example 6. The method of example 5, wherein the predetermined number of TTIs meet a legacy requirement.

[0060] Example 7. An apparatus comprising one or more processors one or more memories including computer program code, the one or more memories and the computer program code configured, with the one or more processors, to cause the apparatus to perform the method of any of examples 1 to 6.

[0061] Example 8. An apparatus, comprising: means for sending from a base station an activation command to a user equipment for activating a secondary cell with a physical uplink control channel for use by the user equipment; means for sending after an activation delay a physical downlink control channel order message to the user equipment on a physical downlink control channel for the secondary cell; and means for receiving, responsive to the physical downlink control channel order message, a random access response from the user equipment on the physical uplink control channel for the secondary cell.

[0062] Example 9. The apparatus of example 8, wherein the means for sending an activation command uses a physical downlink control channel on a primary cell for the user equipment.

Example 10. The apparatus of any of examples 8 or 9, wherein the activation delay is at least from an earliest point the base station expects the user equipment to be monitoring the physical downlink control channel for the secondary cell after the user equipment receives the activation command for the secondary cell to a latest point the base station expects the user equipment as being able to correctly receive the physical downlink control channel for the secondary cell.

[0063] Example 11. The apparatus of any of examples 8 to 10, wherein the sending the activation command occurs in TTI n, the sending of the physical downlink control channel order message occurs in TTI x, TTI y is a latest point in time from receiving by the user equipment the activation command and until the user equipment is able to receive physical downlink control channel on the secondary cell, and the base station assumes the user equipment is able to receive the physical downlink control channel order message if x is larger than y. Example 12. The apparatus of example 11, wherein the base station receives the random access response in TTI n+x+z, where z is a predetermined number of TTIs. Example 13. The apparatus of example 12, wherein the predetermined number of TTIs meet a legacy requirement.

[0064] Example 14. A method, comprising: receiving, at a user equipment and from a base station, an activation command for activating a secondary cell with a physical uplink control channel for the user equipment; receiving after an activation delay a physical downlink control channel order message on a physical downlink control channel for the secondary cell; and sending, responsive to the physical downlink control channel order message, from the user equipment a random access response on the physical uplink control channel for the secondary cell. See also FIG. 4 and the text describing the same.

[0065] Example 15. The method of example 14, wherein receiving an activation command is performed using a physical downlink control channel on a primary cell for the user equipment. Example 16. The method of any of examples 14 or 15, wherein the activation delay is at least from an earliest point the base station expects the user equipment to be monitoring the physical downlink control channel for the secondary cell after the user equipment receives the activation command for the secondary cell to a latest point the base station expects the user equipment as being able to correctly receive the physical downlink control channel for the secondary cell.

[0066] Example 17. The method of any of examples 14 to 16, wherein the receiving the activation command occurs in TTI n, the sending of the physical downlink control channel order message occurs in TTI x, TTI y is a latest point in time from receiving by the user equipment the activation command and until the user equipment is able to receive physical downlink control channel on the secondary cell, and the base station assumes the user equipment is able to receive the physical downlink control channel order message if x is larger than y. Example 18. The method of example 17, wherein the user equipment sends the random access response in TTI n+x+z, where z is a predetermined number of TTIs. Example 19. The method of example 18, wherein the predetermined number of TTIs meet a legacy requirement.

[0067] Example 20. An apparatus comprising one or more processors one or more memories including computer program code, the one or more memories and the computer program code configured, with the one or more processors, to cause the apparatus to perform the method of any of examples 14 to 19.

[0068] Example 21. An apparatus, comprising: means for receiving, at a user equipment and from a base station, an activation command for activating a secondary cell with a physical uplink control channel for the user equipment; means for receiving after an activation delay a physical downlink control channel order message on a physical downlink control channel for the secondary cell; and means for sending, responsive to the physical downlink control channel order message, from the user equipment a random access response on the physical uplink control channel for the secondary cell.

[0069] Example 22. The apparatus of example 21, wherein the means for receiving an activation command uses a physical downlink control channel on a primary cell for the user equipment. Example 23. The apparatus of any of examples 21 or 22, wherein the activation delay is at least from an earliest point the base station expects the user equipment to be monitoring the physical downlink control channel for the secondary cell after the user equipment receives the activation command for the secondary cell to a latest point the base station expects the user equipment as being able to correctly receive the physical downlink control channel for the secondary cell.

[0070] Example 24. The apparatus of any of examples 23 to 23, wherein the receiving the activation command occurs in TTI n, the sending of the physical downlink control channel order message occurs in TTI x, TTI y is a latest point in time from receiving by the user equipment the activation command and until the user equipment is able to receive physical downlink control channel on the secondary cell, and the base station assumes the user equipment is able to receive the physical downlink control channel order message if x is larger than y. Example 25. The apparatus of example 24, wherein the user equipment sends the random access response in TTI n+x+z, where z is a predetermined number of TTIs. Example 26. The apparatus of example 25, wherein the predetermined number of TTIs meet a legacy requirement.

[0071] Example 27. A communication system comprising the apparatus in accordance with any one of the examples 8 to 13 and the apparatus in accordance with any one of the examples 21 to 26.

[0072] Example 28. A computer program comprising program code for executing the method according to any of examples 1 to 6 or 14 to 19. Example 29. The computer program according to example 28, wherein the computer program is a computer program product comprising a computer-readable medium bearing computer program code stored therein for use with a computer.

[0073] Embodiments herein may be implemented in software (executed by one or more processors), hardware (e.g., an application specific integrated circuit), or a combination of software and hardware. In an example embodiment, the software (e.g., application logic, an instruction set) is maintained on any one of various conventional computer-readable media. In the context of this document, a "computer-readable medium" may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer, with one example of a computer described and depicted, e.g., in FIG. 1. A computer-readable medium may comprise a computer- readable storage medium (e.g., memories 125, 155, 171 or other device) that may be any media or means that can contain or store the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. A computer-readable storage medium does not comprise propagating signals. [0074] If desired, the different functions discussed herein may be performed in a different order and/or concurrently with each other. Furthermore, if desired, one or more of the above- described functions may be optional or may be combined.

[0075] Although various aspects are set out above, other aspects comprise other combinations of features from the described embodiments, and not solely the combinations described above.

[0076] It is also noted herein that while the above describes example embodiments of the invention, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention.

[0077] The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:

3GPP third generation partnership project

AD activation delay

CA carrier aggregation

CR change request

CSI channel state information

CQI channel quality indicator

DC dual connectivity

DL downlink (from base station to UE)

eNB or eNodeB evolved Node B (e.g., LTE base station)

E-UTRAN Evolved UMTS terrestrial radio access network

HARQ hybrid automatic repeat request

LTE long term evolution

MAC medium access control

MME mobility management entity

ms milliseconds

NCE network control entity

OoR out of range

PCell primary cell

PDCCH physical downlink control channel

PRACH physical random access channel

PUCCH physical uplink control channel

RA random access

RAN2 RAN working group 2

RAN4 RAN working group 4

Rel release RF radio frequency

SCell secondary cell

SGW serving gateway

TS technical standard

TTI transmission time interval

UE user equipment (e.g., a wireless, portable device)

UL uplink (from UE to base station)

UMTS universal mobile telecommunications system

Claims

Claims:

1. A method, comprising:

sending from a base station an activation command to a user equipment for activating a secondary cell with a physical uplink control channel for use by the user equipment;

sending after an activation delay a physical downlink control channel order message to the user equipment on a physical downlink control channel for the secondary cell; and

receiving, responsive to the physical downlink control channel order message, a random access response from the user equipment on the physical uplink control channel for the secondary cell.

2. The method of claim 1, wherein sending an activation command is performed using a physical downlink control channel on a primary cell for the user equipment.

3. The method of any of claims 1 or 2, wherein the activation delay is at least from an earliest point the base station expects the user equipment to be monitoring the physical downlink control channel for the secondary cell after the user equipment receives the activation command for the secondary cell to a latest point the base station expects the user equipment as being able to correctly receive the physical downlink control channel for the secondary cell.

4. The method of any of claims 1 to 3, wherein the sending the activation command occurs in TTI n, the sending of the physical downlink control channel order message occurs in TTI x, TTI y is a latest point in time from receiving by the user equipment the activation command and until the user equipment is able to receive physical downlink control channel on the secondary cell, and the base station assumes the user equipment is able to receive the physical downlink control channel order message if x is larger than y.

5. The method of claim 4, wherein the base station receives the random access response in TTI n+x+z, where z is a predetermined number of TTIs.

6. The method of claim 5, wherein the predetermined number of TTIs meet a legacy requirement.

7. An apparatus comprising one or more processors one or more memories including computer program code, the one or more memories and the computer program code configured, with the one or more processors, to cause the apparatus to perform the method of any of claims 1 to 6.

8. An apparatus, comprising:

means for sending from a base station an activation command to a user equipment for activating a secondary cell with a physical uplink control channel for use by the user equipment;

means for sending after an activation delay a physical downlink control channel order message to the user equipment on a physical downlink control channel for the secondary cell; and

means for receiving, responsive to the physical downlink control channel order message, a random access response from the user equipment on the physical uplink control channel for the secondary cell.

9. The apparatus of claim 8, wherein the means for sending an activation command uses a physical downlink control channel on a primary cell for the user equipment.

10. The apparatus of any of claims 8 or 9, wherein the activation delay is at least from an earliest point the base station expects the user equipment to be monitoring the physical downlink control channel for the secondary cell after the user equipment receives the activation command for the secondary cell to a latest point the base station expects the user equipment as being able to correctly receive the physical downlink control channel for the secondary cell.

11. The apparatus of any of claims 8 to 10, wherein the sending the activation command occurs in TTI n, the sending of the physical downlink control channel order message occurs in TTI x, TTI y is a latest point in time from receiving by the user equipment the activation command and until the user equipment is able to receive physical downlink control channel on the secondary cell, and the base station assumes the user equipment is able to receive the physical downlink control channel order message if x is larger than y.

12. The apparatus of claims 11, wherein the base station receives the random access response in TTI n+x+z, where z is a predetermined number of TTIs.

13. The apparatus of claims 12, wherein the predetermined number of TTIs meet a legacy requirement.

14. A method, comprising:

receiving, at a user equipment and from a base station, an activation command for activating a secondary cell with a physical uplink control channel for the user equipment;

receiving after an activation delay a physical downlink control channel order message on a physical downlink control channel for the secondary cell; and

sending, responsive to the physical downlink control channel order message, from the user equipment a random access response on the physical uplink control channel for the secondary cell.

15. The method of claim 14, wherein receiving an activation command is performed using a physical downlink control channel on a primary cell for the user equipment.

16. The method of any of claims 14 or 15, wherein the activation delay is at least from an earliest point the base station expects the user equipment to be monitoring the physical downlink control channel for the secondary cell after the user equipment receives the activation command for the secondary cell to a latest point the base station expects the user equipment as being able to correctly receive the physical downlink control channel for the secondary cell.

17. The method of any of claims 14 to 16, wherein the receiving the activation command occurs in TTI n, the sending of the physical downlink control channel order message occurs in TTI x, TTI y is a latest point in time from receiving by the user equipment the activation command and until the user equipment is able to receive physical downlink control channel on the secondary cell, and the base station assumes the user equipment is able to receive the physical downlink control channel order message if x is larger than y.

18. The method of claim 17, wherein the user equipment sends the random access response in TTI n+x+z, where z is a predetermined number of TTIs.

19. The method of claim 18, wherein the predetermined number of TTIs meet a legacy requirement.

20. An apparatus comprising one or more processors one or more memories including computer program code, the one or more memories and the computer program code configured, with the one or more processors, to cause the apparatus to perform the method of any of claims 14 to 19.

21. An apparatus, comprising:

means for receiving, at a user equipment and from a base station, an activation command for activating a secondary cell with a physical uplink control channel for the user equipment;

means for receiving after an activation delay a physical downlink control channel order message on a physical downlink control channel for the secondary cell; and

means for sending, responsive to the physical downlink control channel order message, from the user equipment a random access response on the physical uplink control channel for the secondary cell.

22. The apparatus of claims 21, wherein the means for receiving an activation command uses a physical downlink control channel on a primary cell for the user equipment.

23. The apparatus of any of claims 21 or 22, wherein the activation delay is at least from an earliest point the base station expects the user equipment to be monitoring the physical downlink control channel for the secondary cell after the user equipment receives the activation command for the secondary cell to a latest point the base station expects the user equipment as being able to correctly receive the physical downlink control channel for the secondary cell.

24. The apparatus of any of claims 23 to 23, wherein the receiving the activation command occurs in TTI n, the sending of the physical downlink control channel order message occurs in TTI x, TTI y is a latest point in time from receiving by the user equipment the activation command and until the user equipment is able to receive physical downlink control channel on the secondary cell, and the base station assumes the user equipment is able to receive the physical downlink control channel order message if x is larger than y.

25. The apparatus of claim 24, wherein the user equipment sends the random access response in TTI n+x+z, where z is a predetermined number of TTIs.

26. The apparatus of claim 25, wherein the predetermined number of TTIs meet a legacy requirement.

27. A communication system comprising the apparatus in accordance with any one of the claims 8 to 13 and the apparatus in accordance with any one of the claims 21 to 26.

28. A computer program comprising program code for executing the method according to any of claims 1 to 6 or 14 to 19.

29. The computer program according to claim 28, wherein the computer program is a computer program product comprising a computer-readable medium bearing computer program code stored therein for use with a computer.