METHOD AND APPARATUS TO HANDLE MULTI-CARRIER OPERATION IN CASE OF CELLULAR SERVICE COMMUNICATION AND PROXIMITY SERVICE COMMUNICATION

Abstract

A method and apparatus for power management in a cellular network for handling multi-carrier operation in case cellular communication services and proximity communication services occur simultaneously is proposed. A Power Headroom Report is sent by a User Equipment. The Power Headroom Report at least contains a power reduction measure reflecting a power reduction if the User Equipment performs proximity service communication.

Claims

1. A method for power management in a cellular network, comprising: sending a Power Headroom Report by a User Equipment, wherein the Power Headroom Report at least contains a power reduction measure reflecting a power reduction if the User Equipment performs proximity service communication.

2. A method for power management according to claim 1, wherein the Power Headroom Report contains an index indicating if the User Equipment applies power sharing between cellular services and proximity services.

3. A method for power management according to claim 1, wherein the lower limit for the configured maximum User Equipment power for serving a cell P.sub.CMAX,C is defined as
P.sub.CMAX.sub._.sub.L,c=MIN{P.sub.EMAX,c−ΔT.sub.C,c,P.sub.PowerClass−MAX(MPR.sub.c+A-MPR.sub.c,P-MPR.sub.c,P-pro_se)−ΔT.sub.C,c}.

4. A method for power management according to claim 1, wherein the power reduction in case of proximity service communication P-pro_se is defined in a lookup table for different combinations of at least one of band combinations of proximity service transmissions, operating frequency bands and resource allocation.

5. A method for power management according to claim 1, wherein the power reduction in case of proximity service communication P-pro_se is defined as a single value for maximum power reduction independent of the operating band.

6. A method for power management according to claim 1, wherein the lower limit for the configured maximum User Equipment power is defined as
P.sub.CMAX.sub._.sub.L=MIN{P.sub.EMAX−ΔT.sub.C,P.sub.PowerClass−MPR−A-MPR−P-MPR.sub.c−P-pro_se−ΔT.sub.C}.

7. A method for power management according to claim 1, wherein the power reduction in case of proximity service communication is included in the Power Management Maximum Power Reduction parameter for serving a cell P-MPR.sub.c.

8. A method for power management according to claim 1, wherein a reserved bit in the Power Headroom Report is used to indicate if power reduction due to proximity service transmission is applied to the corresponding Power Headroom Report.

9. A method for power management according to claim 1, wherein sending a Power Headroom Report is triggered if a timer expires or has expired and the power reduction due to proximity service communication for this cell has changed more than a specified threshold value.

10. A method for power management in a cellular network, comprising: receiving a Power Headroom Report by a Scheduler from at least one User Equipment, wherein the Power Headroom Report at least contains a power reduction measure reflecting a power reduction if the User Equipment performs proximity service communication.

11. A method for power management according to claim 10, wherein the Power Headroom Report contains an index indicating if the User Equipment applies power sharing between cellular services and proximity services.

12. A method for power management according to claim 1, wherein the lower limit for the configured maximum User Equipment power for serving a cell P.sub.CMAX,C is defined as
P.sub.CMAX.sub._.sub.L,c=MIN{P.sub.EMAX,c−ΔT.sub.C,c,P.sub.PowerClass−MAX(MPR.sub.c+A-MPR.sub.c,P-MPR.sub.c,P-pro_se)−ΔT.sub.C,c}.

13. A Scheduler in a cellular network, comprising: a receiver for receiving at least one Power Headroom Report, a scheduling entity for scheduling radio resources for at least one User Equipment, wherein the Power Headroom Report at least contains a power reduction measure reflecting a power reduction if the at least one User Equipment performs proximity service communication and the scheduling entity uses the information received about power reduction for scheduling the radio resources.

14. A User Equipment in a cellular network, wherein the User Equipment performs a method according to claim 1.

15. A Base Station in a cellular network, wherein the Base Station performs a method according to claim 10.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Some embodiments of apparatus and methods in accordance with embodiments of the present invention are now described, by way of examples only, and with reference to the accompanying drawings, in which:

[0029] FIG. 1 schematically depicts a cellular service communication scenario

[0030] FIG. 2 schematically depicts a first proximity service communication scenario

[0031] FIG. 3 schematically depicts a second proximity service communication scenario

[0032] FIG. 4 depicts a Power Headroom MAC control element as known in the art

[0033] FIG. 5 depicts an Extended Power Headroom MAC control element according to the invention

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0034] The description and drawings merely illustrate the principles of the invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be only for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof.

[0035] FIG. 1 schematically depicts a cellular service communication scenario. Even if two User Equipments UE1, UE2 are in close proximity and communicate with each other, their data path 1 in the user plane goes via the operator network eNB, SGW/PGW. The typical data path 1 for this type of communication as shown in FIG. 1 involves the eNodeBs eNB and the Serving Gateways/Packet data network Gateways SGW/PGW.

[0036] FIG. 2 schematically depicts a first proximity service communication scenario. If two or more User Equipments UE1, UE2 are in proximity to each other, they communicate by proximity service communication in direct mode with each other. For example, in LTE, the operator is able to move the data path 2 in the user plane off the access and core networks eNB, SGW/PGW onto direct links between the User Equipments UE1, UE2. The User Equipments communicate by a direct connection with each other. With regard to the data path 2, the eNodeBs eNB and the Serving Gateways/Packet data network Gateways SGW/PGW are not involved in a direct mode proximity service communication.

[0037] FIG. 3 schematically depicts a second proximity service communication scenario. If two or more User Equipments UE1, UE2 are in proximity to each other, they communicate locally-routed by proximity service communication with each other. Locally-routed means that the data path 3 in the user plane is routed via an eNodeB eNB, which is shared by both User Equipments UE1, UE2. The data path 3 does not include the core network, e.g. the Serving Gateways/Packet data network Gateways SGW/PGW are not involved in a locally routed proximity service communication.

[0038] Another mode of a proximity service communication scenario is that two User Equipments UE1, UE2 perform direct communication between each other. However the transmission grant for communication between the two User Equipments UE1, UE2 is allocated by the eNodeB eNB. This is a variation of locally routed proximity service communication, even though the data path for the proximity service communication is directly from one User Equipment UE1, UE2 to the other User Equipment UE2, UE1 and is not via the eNodeB eNB.

[0039] For proximity communication as depicted in FIGS. 2 and 3, a Power Headroom reporting procedure is defined in 3GPP TS 36.321-5.4.6.

[0040] The Power Headroom reporting procedure is used to provide the scheduling eNodeB eNB with information about the difference between the nominal User Equipment maximum transmit power and the estimated power for UL-SCH transmission per activated Serving Cell and also with information about the difference between the nominal User Equipment maximum power and the estimated power for UL-SCH and PUCCH transmission on PCell.

[0041] RRC controls Power Headroom reporting by configuring two timers periodicPHR-Timer and prohibitPHR-Timer, and by signaling dl-PathlossChange which sets the change in measured downlink pathloss and the required power backoff due to power management to trigger a Power Headroom Report.

[0042] A Power Headroom Report is triggered if any of the following events occur: [0043] prohibitPHR-Timer expires or has expired and the path loss has changed more than dl-PathlossChange dB for at least one activated Serving Cell which is used as a pathloss reference since the last transmission of a Power Headroom Report when the User Equipment has uplink resources for new transmission; [0044] periodicPHR-Timer expires; [0045] upon configuration or reconfiguration of the Power Headroom reporting functionality by upper layers, which is not used to disable the function; [0046] activation of an SCell with configured uplink; [0047] prohibitPHR-Timer expires or has expired, when the User Equipment has uplink resources for new transmission, and the following is true in this TTI for any of the actived Serving Cells with configured uplink: [0048] there are uplink resources allocated for transmission or there is a PUCCH transmission on this cell, and the required power backoff due to power management (as allowed by P-MPR.sub.c) for this cell has changed more than dl-PathlossChange dB since the last transmission of a Power Headroom Report when the User Equipment had uplink resources allocated for transmission or PUCCH transmission on this cell.

[0049] The User Equipment UE1, UE2 avoids triggering a Power Headroom Report when the required power backoff due to power management decreases only temporarily (e.g. for up to a few tens of milliseconds) and it should avoid reflecting such temporary decrease in the values of P.sub.CMAX,c/PH when a Power Headroom Report is triggered by other triggering conditions.

[0050] The estimated power of UL-SCH transmission depends on the transport block format, downlink pathloss estimation, allocated resources for the UL-SCH transmission, etc. P.sub.CMAX,c is defined as a value range where P.sub.CMAX,c is set at the User Equipment to be a value within the specified range. The value range depends on User Equipment power class, the maximum transmit power signalled by the network, P.sub.EMAX, maximum power reduction, MPR, additional maximum power reduction, A-MPR, and the transmission bandwidth.

[0051] P.sub.CMAX,c and the value range are defined in 3GPP TS 36.101 as follows:

[0052] The User Equipment sets its P.sub.CMAX,c. The configured maximum output power P.sub.CMAX,c on serving cell c is set within the following bounds:

P.sub.CMAX.sub._.sub.L,c≦P.sub.CMAX,c≦P.sub.CMAX.sub._.sub.H,c

[0053] For intra-band contiguous carrier aggregation:

P.sub.CMAX.sub._.sub.L,c=MIN{P.sub.EMAX,c−ΔT.sub.C,c,P.sub.PowerClass−MAX(MPRc+A-MPR.sub.c,P-MPR.sub.c)−ΔT.sub.C,c}

[0054] For inter-band non-contiguous carrier aggregation:

P.sub.CMAX.sub._.sub.L,c=MIN{P.sub.EMAX,c−ΔT.sub.C,c,P.sub.PowerClass−MAX(MPR.sub.c+A-MPR.sub.c+ΔT.sub.IB,c,P-MPR.sub.c)−ΔT.sub.C,c}

P.sub.CMAX.sub._.sub.H,cMIN{P.sub.EMAX,c,P.sub.PowerClass}

[0055] P.sub.EMAX,c is the value given by IE P-Max for serving cell c.

[0056] P.sub.PowerClass is the maximum User Equipment power specified in Table 6.2.2-1 of 3GPP TS 36.101 without taking into account the tolerance specified in the Table 6.2.2-1 of 3GPP TS 36.101.

[0057] ΔT.sub.IB,c is the additional tolerance for serving cell c as specified in Table 6.2.5A-3 of 3GPP TS 36.101.

[0058] For inter-band carrier aggregation, MPR.sub.c and A-MPR.sub.c apply per serving cell c. For intra-band contiguous carrier aggregation, MPR.sub.c=MPR and A-MPR.sub.c=A-MPR.

[0059] P-MPR.sub.c accounts for power management for serving cell c. For intra-band carrier aggregation, there is one power management term P-MPR for the User Equipment and P-MPR.sub.c=P-MPR.

[0060] ΔT.sub.C,c equals 1.5 dB when Note 2 in Table 6.2.2-1 of 3GPP TS 36.101 applies to the serving cell c.

[0061] ΔT.sub.C,c equals 0 dB when Note 2 in Table 6.2.2-1 of 3GPP TS 36.101 does not apply to the serving cell c.

[0062] For inter-band carrier aggregation with one uplink serving cell the total configured maximum output power P.sub.CMAX shall be set within the following bounds:

P.sub.CMAX.sub._.sub.L≦P.sub.CMAX≦P.sub.CMAX.sub._.sub.H

wherein

P.sub.CMAX.sub._.sub.L=P.sub.CMAX.sub._.sub.L,c, and

P.sub.CMAX.sub._.sub.H=P.sub.CMAX.sub._.sub.H,c.

[0063] The measured maximum output power P.sub.UMAX shall be within the following bounds:

P.sub.CMAX.sub._.sub.L−T(P.sub.CMAX.sub._.sub.L)≦P.sub.UMAX≦P.sub.CMAX.sub._.sub.H+T(P.sub.CMAX.sub._.sub.H)

[0064] In summary, the configured maximum output power P.sub.CMAX,c on serving cell depends on the frequency band combination used, A-MPR, MPR (addresses the regional band values which are specified in the standard) and P-MPR (accounts for power management when power backoff is applied).

[0065] FIG. 4 depicts an Extended Power Headroom MAC control element 4 according to 3GPP TS 36.321 for transmitting a Power Headroom Report. The Extended Power Headroom MAC Control Element 4 is defined as follows:

[0066] C.sub.i: this field indicates the presence of a Power Headroom field for the SCell with SCellIndex i. The C.sub.i field set to “1” indicates that a Power Headroom field for the SCell with SCellIndex i is reported. The C.sub.i field set to “0” indicates that a Power Headroom field for the SCell with SCellIndex i is not reported.

[0067] R: reserved bit, set to “0”;

[0068] V: this field indicates if the Power Headroom value is based on a real transmission or a reference format. For Type 1 Power Headroom, V=0 indicates real transmission on PUSCH and V=1 indicates that a PUSCH reference format is used. For Type 2 Power Headroom, V=0 indicates real transmission on PUCCH and V=1 indicates that a PUCCH reference format is used. Furthermore, for both Type 1 and Type 2 Power Headroom, V=0 indicates the presence of the associated P.sub.CMAX,c field, and V=1 indicates that the associated P.sub.CMAX,c field is omitted;

[0069] Power Headroom PH: this field indicates the power headroom level. The length of the field is 6 bits. Further, Type 1 or Type 2 Power Headroom and PCell/SCell are indicated.

[0070] P: this field indicates whether the User Equipment applies power backoff due to power management (as allowed by P-MPR.sub.c). The User Equipment shall set P=1 if the corresponding P.sub.CMAX,c field would have had a different value if no power backoff due to power management had been applied.

[0071] P.sub.CMAX,c: if present, this field indicates the P.sub.CMAX,c or {tilde over (P)}.sub.CMAX,c used for calculation of the preceding Power Headroom field.

[0072] FIG. 5 depicts an Extended Power Headroom MAC control element 5 according to one embodiment of the invention.

[0073] According to the invention, sufficient information on the available User Equipment UE1, UE2 transmission power is provided to the network, e.g. the Scheduler which is included in the eNodeB eNB or is a separate Scheduler for multiple eNodeBs eNB.

[0074] This is realized by signaling the nominal User Equipment maximum transmission power and/or the power reduction imposed due to the proximity service communication together with the Power Headroom Report. The Power Headroom report is provided to the Scheduler by the Extended Power Headroom MAC control element 5.

[0075] Therefore, the calculation of the Power Headroom report takes into account the power used in proximity service communication. The value range for the nominal User Equipment maximum transmission power which is communicated takes into account the possible power variation caused by proximity service communication. Therefore, the calculation of nominal User Equipment maximum transmission power and the power headroom reporting also reflects the power reduction due to proximity service communication.

[0076] In the Power Headroom Report, information to indicate whether the User Equipment applies power sharing between cellular service communication and proximity service communication is included. In other words, the User Equipment informs the network, i.e. the Scheduler if the calculated Power Headroom Report would have different values if the User Equipment did not perform proximity service communication and cellular service communication simultaneously at the time of the Power Headroom Report calculation.

[0077] In the Extended Power Headroom MAC control element according to FIG. 5, the “P” bit is used to indicate whether the power management due to power backoff is applied for Power Headroom Report calculation for the concerning service cell. In addition, the “R” (reserved) bits in Extended Power Headroom MAC control element is used for indicating if power reduction due to proximity service communication was considered when calculating the corresponding Power Headroom Report. These bits are indicated as “PR” in FIG. 5. If the “PR” bit is set to 1, the power reduction due to proximity service communication is applied for the corresponding Power Headroom. By the Extended Power Headroom MAC control element 5, the network, i.e. the Scheduler is informed of the power reduction caused by proximity service communication.

[0078] According to one embodiment, the value range for P.sub.CMAX,c is defined taking into account the possible proximity service communication.

[0079] Exemplarily, the value range for P.sub.CMAX,c is:

P.sub.CMAX.sub._.sub.L≦P.sub.CMAX,C≦P.sub.CMAX.sub._.sub.H

Wherein

[0080] For intra-band contiguous carrier aggregation, the lower bound for P.sub.CMAX,c is set as follows:

P.sub.CMAX.sub._.sub.L,c=MIN{P.sub.EMAX,c−ΔT.sub.C,c,P.sub.PowerClass−MAX(MPR.sub.c+A-MPR.sub.c,P-MPR.sub.c,P-pro_se)−ΔT.sub.C,c}, and

the higher bound for P.sub.CMAX,c is set as follows:

P.sub.CMAX.sub._.sub.H,c=MIN{P.sub.EMAX,c,P.sub.PowerClass}

[0081] P-pro_se defines the maximum power reduction due to proximity service communication in the corresponding band. In one embodiment, the value for P-pro_se is defined for different band combinations of proximity service communication, operating frequency bands and resource allocation. The embodiment is described for intra-band contiguous carrier aggregation. In one embodiment, similar definition is proposed for other band combinations as well as non-carrier aggregation scenarios.

[0082] In one embodiment, P-pro_se is defined as the total maximum power reduction due to the proximity service communication independent of the operating band of proximity service communication.

[0083] According to one embodiment, the lower bound for P.sub.CMAX,c is set as follows:

P.sub.CMAX.sub._.sub.L=MIN{P.sub.EMAX−ΔT.sub.C,P.sub.PowerClass−MPR−A-MPR−P-MPR.sub.c−P-pro_se−ΔT.sub.C}

[0084] According to one embodiment, the transmission power reduction is included within P-MPR.sub.c In this case, it is not necessary to define a separate parameter for the transmission power reduction due to proximity service communication. Rather the value range defined for P-MPR.sub.c is adapted to reflect the possible power reduction due to the proximity service communication. However, in such scenario, the network is not aware if the power reduction is caused by the power backoff resulting from legacy dual transmission on multiple radio networks or by to the proximity service communication.

[0085] According to one embodiment, a frequent Power Headroom Report and P.sub.CMAX,c transmission due to the reduction of power due to proximity service communication is controlled by a prohibitPHRPpro_se-Timer. A Power Headroom Report is triggered in addition to the triggering as described in 3GPP TS 36.321 if the following events occur: [0086] prohibitPHRPpro_se-Timer expires or has expired and the power reduction due to proximity service communication for this cell has changed more than a specified threshold value, ConfigPpro_seChange, since the last transmission of a Power Headroom Report.

[0087] The corresponding Power Headroom Report for the uplink transmission and the corresponding P.sub.CMAX,C are signaled to the network in the next available uplink transmission. The prohibitPHRPpro_se-Timer is restarted after transmission of Power Headroom Report and P.sub.CMAX,C.

[0088] According to one embodiment, a frequent Power Headroom Report and P.sub.CMAX,C transmission due to the reduction of power due to proximity service communication is controlled by a timer prohibitPHRP-Timer. A Power Headroom Report is triggered in addition to the triggering as described above, if the following events occur: [0089] prohibitPHR-Timer expires or has expired and the power reduction due to proximity service communication for this cell has changed more than a specified threshold value, dl-PathlossChange, since the last transmission of a Power Headroom Report.

[0090] prohibitPHR-Timer and dl-PathlossChange are used in known systems and are further used according to this embodiment to reflect power reduction due to proximity service communication.

[0091] The corresponding Power Headroom Report for the uplink transmission and the corresponding P.sub.CMAX,C are signalled to the network in the next available uplink transmission. prohibitPHR-Timer is restarted after the transmission of the Power Headroom Report and the P.sub.CMAX,C.

[0092] The functions of the various elements shown in the Figures, including any functional blocks, may be provided through the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software. When provided by a processor, the functions may be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which may be shared. Moreover, the functions may be provided, without limitation, by digital signal processor (DSP) hardware, network processor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), read only memory (ROM) for storing software, random access memory (RAM), and non volatile storage. Other hardware, conventional and/or custom, may also be included.