METHODS AND APPARATUSES RELATING TO UPLINK

TRANSMISSIONS

Field

This specification relates generally to uplink transmissions of user equipment within a mobile telecommunications radio access network.

Background

One of the aims with future E-UTRA (Advanced LTE) networks (such as 5G networks) is to achieve ultra-reliable low-latency communications (URLLC) with over-the-air latencies of 1 millisecond or less. Even for applications which do not demand such low-latency requirements, for instance traditional mobile broadband (MBB) applications, it is in general beneficial to achieve low-latency in order to provide a better end-user experience. One way in which low latencies may be achieved is the use of multiple-connectivity in which a user equipment (UE) performs multiple uplink transmissions within multiple cells simultaneously in a particular transmission time interval.

Summary

In a first aspect, this specification describes a method comprising adapting at least one of a modulation and coding scheme, MCS, and a number of resource blocks for at least one of plural uplink transmissions allocated to a user equipment for a common transmission time interval such that a total transmission power utilised by the user equipment when performing the plural uplink transmissions during the common transmission time interval satisfies a maximum constraint.

The method may comprise adapting the at least one of the MCS and the number of resource blocks in response to determining that a sum of transmission powers indicated by plural uplink transmission allocation messages exceeds the maximum constraint, each of the plural uplink transmission allocation messages relating to a different cell. The method may further comprise, in response to determining that the sum of the

transmission powers indicated by the plural uplink transmission allocation messages does not exceed the maximum constraint, utilising MCSs and numbers of resource blocks specified in the uplink allocation messages when performing the plural uplink

transmissions. The method may comprise adapting the at least one of the MCS and the number of resource blocks for each of plural uplink transmissions allocated to the user equipment.

The method may comprise indicating to an access point whether the MCS or number of resource blocks for an uplink transmission allocated by the access point has been adapted. The method may further comprise indicating to the access point the adapted MCS or the adapted number of resource blocks. The method may further comprise the user equipment indicating to the access point identities of the adapted number of resource blocks which are being utilised for the uplink transmission.

The method may comprise determining by the user equipment a split of the user equipment's transmission power between the uplink transmissions, and adapting the at least one of the MCS and the number of resource blocks based on the determined split of the transmission power.

The method may further comprise, for at least one of the plural uplink transmissions, utilising the number of resource blocks specified in a received uplink allocation message and adapting the MCS from that specified in the uplink allocation message. The method may further comprise adapting the MCS thereby to achieve a larger transport block size. The method may comprise adapting the MCS to an MCS within a range of possible MCSs that is bounded by the MCS indicated in the uplink allocation message and a lowest available MCS. The split of the transmission power may be determined in accordance with:

where: Pj is the transmission power for the uplink transmission to aj ^th cell,

Wj is the assigned bandwidth allocated for the j ^th cell,

l/dj is the SINR per unit transmit power per Hz for hej ^th cell, and

λ is a variable that is calculated such that a sum of the transmission powers Pj over all cells is equal to the maximum constraint of the transmission power of the user equipment.

The method may comprise for at least one of the plural uplink transmissions, utilising the MCS specified in an uplink allocation message and adapting the number of resource blocks from that specified in the uplink allocation message. The method may comprise determining the split of the transmission power of the user equipment based on a rate of transmission per unit power for each of the uplink transmissions. Determining the split of the transmission power of the user equipment based on the rate of transmission per unit power for each of the uplink transmissions may comprise allocating a portion of the uplink transmission power to the uplink transmissions in descending order based on the transmission rate per unit power of the respective uplink transmissions. The method may comprise allocating the portion of the uplink transmission power to the uplink

transmissions in descending order based on the transmission rate per unit power of the respective uplink transmissions until the maximum constraint on the transmission power has been reached.

The method may comprise adapting the MCS and the number of resource blocks from the MCS and the number of resource blocks specified in the uplink allocation message. The MCS and number of resource blocks may be adapted in accordance with a solution to the following optimization problem:

M

max w, log ( 1 H '— )

pJ ^w J i V ^w i ^d i)

such that: ∑ _{= 1} Pj≤P,

0 < wj≤ Wj Vj, and

Pj≥ O. V _j ,

where: Pj is the transmission power for the uplink transmission to aj ^th cell,

Wj is the assigned bandwidth allocated for the j ^th cell,

Wj is the bandwidth decided by the UE for the j ^th cell, and

i/dj is the SINR per unit transmit power per Hz for thej ^w cell, P is the maximum UE transmit power, and

M is the number of cells that have allocated uplinks to the UE.

In a second aspect, this specification describes apparatus configured to perform any method according to the first aspect.

In a third aspect, this specification describes computer-readable instructions which, when executed by computing apparatus, cause the computing apparatus to perform any method according to the first aspect.

In a fourth aspect, this specification describes apparatus comprising at least one processor, and at least one memory including computer program code, which when executed by the at least one processor, causes the apparatus to adapt at least one of a modulation and coding scheme, MCS, and a number of resource blocks for at least one of plural uplink transmissions allocated to a user equipment for a common transmission time interval such that a total transmission power utilised by the user equipment when performing the plural uplink transmissions during the common transmission time interval satisfies a maximum constraint.

The computer program code, when executed by the at least one processor, may cause the apparatus to adapt the at least one of the MCS and the number of resource blocks in response to determining that a sum of transmission powers indicated by plural uplink transmission allocation messages exceeds the maximum constraint, each of the plural uplink transmission allocation messages relating to a different cell. The computer program code, when executed by the at least one processor, may cause the apparatus to, in response to determining that the sum of the transmission powers indicated by the plural uplink transmission allocation messages does not exceed the maximum constraint, utilise MCSs and numbers of resource blocks specified in the uplink allocation messages when performing the plural uplink transmissions.

The computer program code, when executed by the at least one processor, may cause the apparatus to adapt the at least one of the MCS and the number of resource blocks for each of plural uplink transmissions allocated to the user equipment.

The computer program code, when executed by the at least one processor, may cause the apparatus to indicate to an access point whether the MCS or number of resource blocks for an uplink transmission allocated by the access point has been adapted. The computer program code, when executed by the at least one processor, may cause the apparatus to indicate to the access point the adapted MCS or the adapted number of resource blocks. The computer program code, when executed by the at least one processor, may cause the apparatus to indicate to the access point identities of the adapted number of resource blocks which are being utilised for the uplink transmission.

The computer program code, when executed by the at least one processor, may cause the apparatus to determine by the user equipment a split of the user equipment's transmission power between the uplink transmissions, and to adapt the at least one of the MCS and the number of resource blocks based on the determined split of the transmission power.

The computer program code, when executed by the at least one processor, may cause the apparatus to, for at least one of the plural uplink transmissions, utilise the number of resource blocks specified in a received uplink allocation message and to adapt the MCS from that specified in the uplink allocation message. The computer program code, when executed by the at least one processor, may cause the apparatus to adapt the MCS thereby to achieve a larger transport block size. The computer program code, when executed by the at least one processor, may cause the apparatus to adapt the MCS to an MCS within a range of possible MCSs that is bounded by the MCS indicated in the uplink allocation message and a lowest available MCS. The split of the transmission power may be determined in accordance with:

where: Pj is the transmission power for the uplink transmission to aj ^th cell,

Wj is the assigned bandwidth allocated for the j ^th cell,

l/dj is the SINR per unit transmit power per Hz for hej ^th cell, and

λ is a variable that is calculated such that a sum of the transmission powers Pj over all cells is equal to the maximum constraint of the transmission power of the user equipment.

The computer program code, when executed by the at least one processor, may cause the apparatus to, for at least one of the plural uplink transmissions, utilise the MCS specified in an uplink allocation message and to adapt the number of resource blocks from that specified in the uplink allocation message. The computer program code, when executed by the at least one processor, may cause the apparatus to determine the split of the transmission power of the user equipment based on a rate of transmission per unit power for each of the uplink transmissions. The computer program code, when executed by the at least one processor, may cause the apparatus to allocate a portion of the uplink transmission power to the uplink transmissions in descending order based on the transmission rate per unit power of the respective uplink transmissions. The computer program code, when executed by the at least one processor, may cause the apparatus to allocate the portion of the uplink transmission power to the uplink transmissions in descending order based on the transmission rate per unit power of the respective uplink transmissions until the maximum constraint on the transmission power has been reached.

The computer program code, when executed by the at least one processor, may cause the apparatus to adapt the MCS and the number of resource blocks from the MCS and the number of resource blocks specified in the uplink allocation message. The MCS and number of resource blocks may be adapted in accordance with a solution to the following optimization problem:

M

max Wj log [ 1 H ^, — )

pJ ^w J i \ ^w i ^d i)

such that: ∑ _{= 1} Pj≤P,

0 < wj≤ Wj Vj, and

Pj≥ O. V _j ,

where: Pj is the transmission power for the uplink transmission to aj ^th cell,

Wj is the assigned bandwidth allocated for the j ^th cell,

Wj is the bandwidth decided by the UE for the j ^th cell, and

i/dj is the SINR per unit transmit power per Hz for thej ^w cell, P is the maximum UE transmit power, and

M is the number of cells that have allocated uplinks to the UE.

In a fifth aspect, this specification describes a computer-readable medium having computer-readable code stored thereon, the computer-readable code, when executed by at least one processor, cause performance of at least adapting at least one of a modulation and coding scheme, MCS, and a number of resource blocks for at least one of plural uplink transmissions allocated to a user equipment for a common transmission time interval such that a total transmission power utilised by the user equipment when performing the plural uplink transmissions during the common transmission time interval satisfies a maximum constraint. The computer-readable code stored on the medium of the fifth aspect may further cause performance of any of the operations described with reference to the method of the first aspect.

In a sixth aspect, this specification describes apparatus comprising means for adapting at least one of a modulation and coding scheme, MCS, and a number of resource blocks for at least one of plural uplink transmissions allocated to a user equipment for a common transmission time interval such that a total transmission power utilised by the user equipment when performing the plural uplink transmissions during the common transmission time interval satisfies a maximum constraint. The apparatus of the sixth aspect may further comprise means for causing performance of any of the operations described with reference to the method of the first aspect.

Brief Description of the Figures For better understanding of the present application, reference will now be made by way of example to the accompanying drawings in which:

Figure l is an example of a mobile telecommunications radio access network including plural access points and one or more user equipments (UEs);

Figure 2 is a flow chart illustrating various operations which may be performed by UEs operating within the network of Figure l;

Figure 3 is a flow chart illustrating various operations which may be performed by access points operating within the network of Figure l;

Figure 4 is a flow chart illustrating various operations which may be performed by UEs operating within the network of Figure 1;

Figure 5 is a schematic illustration of an example configuration of a UE which may be configured to perform various operations such as some of those described with reference to Figures 1 and 2 and 4;

Figure 6 is a schematic illustration of an example configuration of an access point which may be configured to perform various operations such some of as those described with reference to Figures 1 and 3;

Figure 7 is an illustration of a computer-readable medium upon which computer readable code may be stored;

Figure 8 is a bar chart showing a comparison between a simulated performance of a method in which a UE adapts a number of resource block used in an uplink transmission and a simulated performance of a corresponding baseline scheme;

Figure 9 is a bar chart showing a comparison between a simulated performance of a method in which the UE adapts a modulation and coding scheme used in an uplink transmission and a simulated performance of a corresponding baseline scheme; and Figures 10 and 11 show simulation results illustrating benefits of methods described herein.

Detailed Description

In the description and drawings, like reference numerals refer to like elements

throughout.

Various methods and apparatuses are described in detail below, by way of example only, in the context of a mobile telecommunications radio access network 1, such as that illustrated in Figure 1. The network 1 comprises one or more access points or base stations (eNodeBs, eNBs) 6-1 to 6-n (generally referred to by numeral 6). Only a small number of eNBs 6 are shown in FIG. 1, but a radio access network may typically comprise thousands of eNBs 6. Together, the eNBs 6 may provide radio coverage to one or more user equipment (UE) 5-1 to 5-n (generally referred to by numeral 5) over a wide geographical area.

Each eNB 6 operates one or more cells, which are denoted in Figure 1, for illustrative purposes only, by the dashed circles 7-1 to 7-nA and 7n-B or sectors thereof (generally referred to using numeral 7). Although most of the coverage areas of the cells are shown illustratively as circles in Figure 1, in reality, the coverage area of each cell depends on the transmission power and the directionality of the antenna (or antennas) by which the cell is operated. The coverage area of each cell may also depend on obstacles (such as buildings) which are in the vicinity of the eNB 6, carrier frequency and channel propagation characteristics etc.

The configuration of the coverage area of the cells 7 may be selected so as to serve UEs 5 in a particular area while not providing coverage to other areas. For instance, the configuration of a coverage area of a cell may be selected so as to provide coverage for an area in which users are commonly present while not providing coverage for areas in which users are seldom present. For instance, in Figure 1, the first cell 7-1 operated by the first eNB 6-1 is depicted as only a sector of a circle. In one extreme example, an eNB 6 may be configured to provide coverage (via a cell) up and down a road but not either side of the road.

As mentioned above, a single eNB 6 may, in some examples, provide two or more cells. For instance, a first cell 7 may be provided in a first direction from the eNB 6 while a second cell 7 may be provided in a different direction. In Figure 1, this is illustrated by the second eNB 6-2 which is shown as operating two different cells 7-2A and 7-2B.

The eNBs 6 may be configured to utilise different radio access technologies from one another (e.g. 4G and 5G). In addition or alternatively, the eNBs 6 may utilise different radio interfaces, for instance any of wide area, centimetre-wave (cmW) and millimetre- wave (mmW) bands. For instance, in Figure 1, the first, second and fourth eNBs 6-1, 6-2, 4-6 may utilise a wide area interface, the third eNB 6-3 may utilise a cmW interface, which has a smaller range of coverage, and the nth eNB 6-n may utilise a mmW interface which has a coverage area that is smaller still. In some examples, a single eNB 6 may operate multiple cells each having a different carrier frequency. This can be seen in Figure 1 in respect of the n ^th eNB 6-n which is operating a first cell 7n-A having, for instance, a cmW carrier frequency and a second cell 7-nB having, for instance, an mmW carrier frequency. The mobile telecommunications radio access network l may be, but is certainly not limited to, an Evolved Universal Terrestrial Radio Access (E-UTRA) network, which may sometimes be referred to as LTE Advanced network. The eNBs 6 and UEs 5 in the network 1 may be configured to communicate with one another using an OFDM-based access scheme, such as orthogonal frequency division multiple access (OFDMA) and/or single carrier frequency division multiple access (SC-FDMA). For instance, in some non- limiting examples OFDMA may be used for downlink communications whereas SC-FDMA may be used for uplink communications. One or more of the UEs 5 may be configured for bi-directional communication with one or more of the eNBs 6. In such examples, the transmission of data from the eNB 6 to the UE 5 may be referred to as "downlink". Transmission of data from the UE 5 to the eNB 6 may be referred to as "uplink". The eNBs 6, or some other entity within the network 1, may be operable to schedule uplink timeslots (transmission time intervals) for the UEs 5 within a particular cell 7 operated by the eNBs 6. Scheduling information including a modulation and coding scheme (MCS) and a number of physical resource blocks (N _PR B) allocated for a particular uplink transmission by the UE 5 is then communicated to the UE 5, for instance by the eNB 6 operating the cell 7. The scheduling information may further include the scheduled time slot/transmission time interval (TTI) for the uplink transmission. The scheduling information may be transmitted as a message which may be referred to as an uplink scheduling grant or an uplink allocation message.

As can be seen in Figure 5, the UE 5 comprises control apparatus 50 which is configured to control operation of other components forming part of the UE 5 thereby to enable transmission of data, via uplink, to the eNBs 6 as well as receipt of data from the eNBs 6, via downlink. The control apparatus 50 may additionally be configured to cause performance of any other operations described herein with reference to the UEs 5, for instance with reference to Figures 2 and 4. Example configurations of the control apparatus 50 and the UE 5 as a whole, as illustrated in Figure 5, are discussed in more detail later.

Similarly, as illustrated in Figure 6, the eNBs 6 may comprise control apparatus 60 for enabling bi-directional communication with one or more UEs 5, including transmission of scheduling information. The control apparatus 60 may additionally be configured to cause performance of any other operations described herein with reference to the eNBs 6, for instance in relation to Figure 3. Example configurations of the control apparatus 60 and the eNB 6 as a whole, as illustrated in Figure 6, are discussed in more detail later. The network l may be configured such that a single UE 5 may receive multiple uplink allocation grants (or messages) each relating to a scheduled uplink transmission within a different one of plural cells 7. As illustrated in Figure 1, each of the different cells from which the multiple uplink allocation grants are received operates using a different carrier frequency. For instance, in the example of Figure 1, the first UE 5-1 may receive plural uplink allocation messages each being in respect of a different one of the cell operated by the first eNB 6-4 (which is a wide area cell) and the first and second cells 7-nA, 7-nB operated by the n ^th eNB 6-n (which are cmW and mmW cells respectively).

In the example of Figure 1, two of the cells are operated by the same eNB 7-n and so plural uplink allocation messages are received from a single eNB 7-n. However, in other examples, each of the cells 7 from which the uplink allocation messages are received may be operated by a different eNB 6 and so each uplink allocation message may be received from a different eNB 6. As will be appreciated, at least some of the cells in respect of which the multiple uplink allocation messages are received may be co-located.

As discussed above, the uplink allocation messages may include scheduling information specifying a modulation and coding scheme (MCS) for use in the allocated uplink transmission and a number of physical resource blocks to be used by the UE 5 when performing the allocated uplink transmission. The uplink allocation messages may also specify the scheduled time slot or transmission time interval (TTI) for the allocated uplink transmission. The UEs 5 are configured to operate in uplink multi-connectivity mode, in which the UE 5 is operable to perform uplink transmissions within plural different cells simultaneously (i.e. within a particular TTI). This may serve to reduce latency of transmission of data from the UE 5 to the eNBs 6. However, in the absence of coordinated uplink scheduling by the eNBs 6 or a strict partitioning of the maximum UE uplink transmission power, the sum power required by the UE 5 to honour the simultaneous allocated uplinks (in accordance with the parameters, e.g. MCS and N _P R _B , specified in the uplink allocation messages) may exceed the UE's maximum permitted or available transmission power. Coordinated uplink scheduling by the eNBs 6 would introduce additional co-ordination delay as well as signalling overhead on, for instance, the X2-like backhaul between the eNBs 6. Strict partitioning of the maximum UE uplink transmission power on the other hand may result in sub-optimal UL grants that do not optimally use the available power at the UE and so may result in sub-optimal data rates. In view of the above, the UEs 5 (or, more specifically, their control apparatuses) are configured to autonomously adapt at least one of the MCS and the number of resource blocks NPRB for at least one of plural uplink transmissions that is allocated to the UE 5 for a common transmission time interval (TTI). The adaptation of the MCS or NPRB is performed such that a sum transmission power utilised by the UE 5 when performing the plural uplink transmissions during the common TTI satisfies a maximum constraint. In this way, the UE 5 may be able to maximise data throughput without exceeding the UE's maximum transmission power.

The adaptation of the at least one of the MCS and N _PRB may be performed in response to determining that a sum of transmission powers indicated by plural uplink transmission allocation messages for the common TTI, each of which relates to a different cell, exceeds the maximum constraint. However, if it is instead determined that the sum of the transmission powers indicated by the plural uplink transmission allocation messages does not exceed the maximum constraint, the UE 5 may be configured to utilise MCSs and numbers of resource blocks, as specified in each of the received uplink allocation messages, when performing the plural simultaneous uplink transmissions. As will be discussed in more detail below, the UE 5 may be configured to adapt at least one of the MCS and the NPRB for each of the plural uplink transmissions that are allocated within the common TTI. However, whether or not the UE 5 adapts the MCS and N _PRB for one or more than one of its uplink allocations, the UE 5 may in some examples be configured so as to leave some of its allocated uplink transmissions unused, if such is required to satisfy the maximum power constraint.

The UE 5 may be configured to utilise the number of resource blocks specified in a received uplink allocation message for at least one of the plural uplink transmissions and to adapt only the MCS from that specified in the uplink allocation message. Alternatively, the UE 5 may be configured to utilise the MCS specified in the uplink allocation message but to adapt the N _PR B from that specified in the uplink allocation message. In yet other examples, the UE 5 may be configured to adapt both the MCS and the N _PR B from those specified in a particular uplink allocation message. Regardless of whether the UE 5 is adapting the MCS and/or the N _PR B, the UE 5 may be configured to determine a split of its maximum allowed or available transmission power between the plural uplink transmissions, and to adapt the MCS and/or N _PR B based on the determined split of the maximum transmission power. As will be discussed in more detail below, the split of the maximum transmission power may be determined based on factors including, for instance, the maximum transmission power of the UE 5 and signal-to- interference-plus-noise ratio (SINR) constraints for each cell.

Figure 2 is a flow chart illustrating various operations which may be performed by a UE 5 (or more specifically its control apparatus 50) operating in multi-connectivity mode within the network of Figure 1. In operation S2.1, the UE 5 receives one or more uplink allocation messages. Each of the uplink transmission allocation messages relates to a different cell and, in some instances, may be received from a different eNB 6. Each of the uplink allocation messages may specify a TTI for an allocated uplink transmission as well as an MCS and number of resource blocks N _PR B to be used for the uplink transmission of data to a base station which operates the cell to which the uplink allocation relates.

In operation S2.2, the UE 5 determines whether plural uplink transmission allocation messages relating to plural cells have been received for the same transmission time interval (which may also be referred to as a common timeslot).

In response to determining that plural uplink transmission allocation messages relating to plural cells have not been received for the same transmission time interval (i.e. a negative determination), the UE 5 proceeds to operation S2.3. In operation S2.3, the UE 5 prepares a transport block for transmission during the allocated TTI using the MCS and NPRB specified in the received uplink transmission allocation message for the TTI. After this, the UE proceeds to operation S2.9, which is discussed later. In response to determining in operation S2.2 that plural uplink transmission allocation messages relating to plural cells have been received for the same transmission time interval (i.e. a positive determination), the UE 5 proceeds to operation S2.4.

In operation S2.4, the UE 5 determines whether the sum of the power required to honour each of the allocated uplink transmissions for the TTI satisfies the maximum power constraint for the UE 5. Put another way, the UE 5 determines whether the sum of the power required to honour each of the allocated uplink transmissions for the TTI is less than or equal to the maximum transmission power of the UE.

In response to determining that the sum of the power required to honour each of the allocated uplink transmissions for the TTI does satisfies the maximum power constraint for the UE 5 (i.e. a positive determination), the UE 5 proceeds to operation S2.5.

In operation S2.5, the UE 5 prepares transport blocks for transmission during the allocated TTI to the eNB(s) 6 operating each cell for which an allocation was received. Each of the transport blocks is prepared using the MCS and N _PR B specified in the received uplink transmission allocation message for the respective cell. After this, the UE 5 proceeds to operation S2.9.

If, however, a negative determination is reached in operation S2.4 (i.e. it is determined that the sum of the transmission power required to honour each of the allocated uplink transmissions for the TTI does not satisfy (or exceeds) the maximum power constraint), the UE 5 proceeds to operation S2.6.

In operation S2.6, the UE 5 determines the division of UE transmission power between the simultaneous uplink transmissions in respect of the plural different cells. The way in which this is performed may depend on whether the UE 5 is configured to adapt the MCS, the NPRB or both jointly and is discussed in more detail below.

In operation S2.7, the UE 5 adapts the MCS and/or N _PR B for at least one of the allocated uplink transmissions based on the determined division of transmission power between the uplink allocations. As will be appreciated, the MCS and/or N _PR B may be adapted for plural allocated uplink transmissions if the determined division of power for each of the uplink transmissions necessitates this. In some instances, the specified MCS and N _PR B may be honoured for one or more of the allocations but may be adapted for at least one other. The relationship between MCS and/or N _PRB and transmission power is well known to the person skilled in the art and so it is not explained in detail in this specification.

Next, in operation S2.8, the UE 5 prepares one or more transport block(s) for

transmission during the allocated TTI using the modified MCSs and/or numbers of resource blocks. In addition to this, the UE 5 may also prepare one or more transport block for transmission during the TTI in accordance with the MCS and NPRB specified in one of the uplink allocation messages. In operation 2.9, having prepared the transport block(s) in any of operations S2.3, S2.5 and S2.8, the UE 5 adds a respective header and cyclic redundancy check (CRC) information to each transport block thereby to form a packet for transmission.

In some examples, the header may include signalling information indicating which MCS has been used and/or the number (and, in some cases, also the identities) of resource blocks that have been used. In other examples, the signalling information may be provided by the UE 5 to the eNB 6 in a way other than by via the header. The signalling information may be independently-decodable relative to the transport block such that the eNB receiving the packet can determine the MCS and NPRB prior to attempting to decode the transport block. The independently decodable signalling information may be transmitted with a pre-determined MCS and using a pre-determined resource block, both of which are known by the recipient eNB.

In some examples, the UE 5 may be configured to provide the independently-decodable signalling information (via the header or otherwise) only in the event that the UE has adapted the MCS and/or NPRB from that specified in the respective uplink transmission allocation message. As such, the signalling information may be omitted when preparing a packet based on a transport block that was formed in accordance with a received uplink transmission allocation message. This may reduce the signalling overhead of the network as a whole. In other examples, however, the independently-decodable signalling information (via the header or otherwise) may be provided regardless as to whether or not the MCS and/or N _PR B has been adapted from that specified in the uplink allocation.

In some examples, the signalling information may include an indicator (e.g. in the form of a flag) indicating whether the MCS and/or NPRB has been adapted. In some examples, the indicator may be configured to indicate which parameter has been adapted (i.e. whether it is only the MCS, only the NPRB or both of them). The indicator can be decoded initially and may allow the eNB 6 to determine if it needs to decode the remainder of the signalling information (including e.g. the information specifying the MCS and/or N _PRB that has been used).

In some implementations, the UE 5 may not be configured to provide the independently- decodable signalling information. Instead, the eNBs 6 may be configured to blindly detect the MCS and/or the number and identities of the resource blocks that have been used. In yet other examples, the UE 5 may be configured to provide in the independently- decodable signalling information only the indicator indicating whether and/or which of the parameters (the MCS and/or N _PR B) has been adapted. As such, the UE 5 may not include the information identifying the MCS and/or number of resource blocks that have been used. Based on this, the eNB 6 may be configured to perform blind detection or not, as required. For instance, if the indicator indicates that an adaptation of the uplink parameters has occurred, the UE 5 may perform blind detection but may not if the indicator indicates that adaptation has not occurred. Subsequently, in operation S2.10, the UE 5 causes uplink transmission of the one or more packets during the allocated TTI to the eNB(s) operating the one or more cells 7.

Although not shown in Figure 2, after transmission of the data packet, the UE 5 may return to operation S2.1. Figure 3 is a flow chart illustrating various operations which may be performed by an eNB 6 (or more specifically the eNB control apparatus 60) operating within the network of Figure 1. In particular, the flow chart illustrates various operations which may be performed by the eNB 6 in relation to allocating and receiving uplink transmissions from the UE5.

In operation S3.1, the eNB 6 may determine whether the UE 5 is operating in multi- connectivity mode. This may be determined in any suitable way, for instance as part of hand-shaking procedures performed when the UE 5 enters the coverage area of the cell 7 being operated by the eNB 6.

In response to determining that the UE 5 is operating in multi-connectivity mode, the eNB 6 proceeds to operation S3.2 in which the eNB 6 determines a transmission time interval for the UE 5. In addition, the eNB 6 determines the MCS and number of resource blocks that are to be used by the UE 5 for the uplink.

The determination regarding the MCS and N _PR B may be based on an assumption that the UE's maximum transmit power (i.e. a transmission power defined by the maximum constraint) is available for the uplink transmission in each cell. In this way, the UE 5 may be able to achieve a relatively high data rate even in the event that it only receives an uplink transmission message for a single cell. In other examples, the eNB 6 may be configured to adaptively determine the MCS and number of resource blocks based on observed load conditions. In particular, in response to observing a lower/lighter load (e.g. a load below a threshold), the eNB 6 may determine the MCS and number of resource blocks under the assumption that the UE's maximum transmit power (e.g. a transmission power defined by the maximum constraint) is available for the uplink transmission in the cell. In response to determining a

higher/heavier loads (e.g. a load above a threshold), the eNB 6 may determine the MCS and number of resource blocks under the assumption that only a fraction of the UE's maximum transmission power is available. For instance, the fraction of the transmission power may be determined such that the sum of fractions of powers assumed by all the connected cells for a given UE is equal to l.

The MCS and number of physical resource blocks allocated to a UE 5 may be determined based on one or more of a message received from the UE 5 indicating an amount or data in a transmit buffer of the UE 5 (which may be referred to as a buffer status report), an amount of data that is scheduled to be transmitted by the UE 5 and an estimated SINR for the UE 5 (which may be determined based on, for instance, "ACKS" and "NACKS" passed between the UE 5 and the eNB 6). Next, in operation S3.3, the eNB 6 causes transmission to the UE 5 of the uplink transmission allocation message relating to a cell 7 operated by the eNB 6.

Subsequent to operation S3.3, the eNB 6, in operation S3.4, may receive an uplink transmission of data from the UE 5 to which the scheduling information was sent. As will be appreciated, the receipt of the uplink transmission of data may be dependent on the decision of the UE 5 to perform an uplink transmission within that cell. For instance, if the UE 5 does not allocate any transmission power for the cell operated by the eNB 6, the eNB may not receive an uplink transmission of data from the UE 5. Assuming that an uplink transmission is received, the eNB 6, in operation S3.5, may perform blind detection in respect of the received packet, thereby to enable the eNB 6 to determine the MCS and/or the number (and, optionally, also the identities) of the resource blocks that have been utilised by the UE 5. Alternatively, the eNB 6 may decode, separately from the transport block of the data packet, signalling information which may indicate, among other things, the MCS and/ or the number (and, optionally, also the identities) of the resource blocks that have been utilised. As discussed previously, the signalling data may be included in the header of the received data packet. In yet other examples, the eNB 6 may initially decode the indicator indicating whether and/or which of the MCS and N _PR B have been adapted and may perform blind detection or decoding of further signalling data in dependence on the indicator.

Blind detection to determine the adapted MCS and/or the adapted number of resource blocks may be performed in respect of the relevant uplink channel, e.g. the physical shared uplink channel (PUSCH), during the transmission time interval allocated for the uplink transmission from the UE 5. An example of a form of blind detection that may be suitable, particularly for determining the number of resource blocks that have been used by the UE 5, is energy detection. Blind detection may be similar to discontinuous transmission (DTX) detection.

The performance of blind detection on the uplink channel during the transmission time interval may enable the eNB 6 to determine the number and/ or an identity of the resource blocks utilised by the UE 5. Put another way, it may enable the determination as to how many and/or which of the allocated resource blocks are used/unused by the UE.

Subsequent to operation S3.5, the eNB 6 may determine in operation S3.6, based on the blind detection/ signalling information, whether the MCS and/ or the number of resource blocks have been adapted. If it is determined that the MCS and/or the number of resource blocks have been adapted, the eNB 6 may proceed to operation S3.7.

In operation S3.7, the eNB may decode the transport block based on information obtained in operation S3.5 regarding which MCS has been used and/or the number of resource blocks of the allocated number of resource blocks that have been used.

If, however, it is determined that the no adaptation of either the MCS or the number of resource blocks has been performed, the eNB 6 may proceed to operation S3.11. In operation S3.11, the eNB 6 may decode the transport block based on the MCS and number of resource blocks originally allocated to the UE 5 in operation S3.2.

Returning now to operation S3.1, if it is determined the UE 5 is not operating in multi- connectivity mode, the eNB may proceed to operation S3.8 in which the allocation of the MCS and number of resource blocks for the UE 5 for a particular TTI are determined. The determination of operation S3.8 may be performed in substantially the same way as described with reference to the determination of operation S3.2. Next, in operation S3.9, the eNB 6 causes transmission to the UE 5 of the uplink transmission allocation message relating to a cell operated by the eNB 6. Subsequent to operation S3.9, the eNB 6, in operation S3.10, may receive an uplink transmission of data from the UE 5 to which the scheduling information was sent. After this, because the eNB 6 knows that the UE 5 is not operating in multi-connectivity mode, the eNB 6 proceed directly to operation S3.11 (i.e. without decoding any separately decodable signalling data and/or performing blind detection). As discussed above, in operation S3.11, the eNB 6 may decode the transport block based on the MCS and number of resource blocks originally allocated to the UE 5 in operation S3.2.

As discussed with reference to each of Figures 1 to 3, the UE 5 may be configured to adapt at least one of the modulation and coding scheme and the number of resources blocks utilised for an uplink transmission within a particular cell. Put another way, in some instances, the UE may be configured to adapt only the MCS, in other instances it may be configured to adapt only the number of resource blocks that are used and in yet others it may be configured to adapt jointly both the MCS and the number of resource blocks used. Example implementation details of each of these alternatives will now be discussed.

Adaptation of MCS

When the UE 5 is configured to adapt only the MCS, it may be configured to do so in such a way as to achieve a larger transport block size (or, put another way, a higher data throughput). Additionally or alternatively, the UE 5 may be configured to adapt the MCS to an MCS that is within a range of possible MCSs that is bounded by the MCS indicated in the uplink allocation message and the lowest available MCS (MCS ₀ ).

The problem of determining how to split the uplink transmission power between parallel uplinks in respect of two or more different cells (e.g. in operation S2.6) can be modelled as a variant of the classical water-filling problem. For example, the problem may be modelled as:

Equation 1

such that: ∑ _{= 1} P _j ≤P, and In the above expressions, Pj is the transmission power for the uplink transmission to aj ^th cell, Wj is the assigned number of resource blocks allocated for thej ^w cell, i/dj is the SINR per unit transmit power per Hz (or the ratio of the channel gain to the total interference plus noise per PRB) for the j ^th cell, M is the number of cells that have allocated uplinks to the UE 5 in a particular TTI, and P is the maximum UE transmit power.

The problem set out with respect to Equation l is convex with linear constraints and, as such, global maxima can be obtained. More specifically, the Karush-Kuhn-Tucker (KKT) conditions can be applied to determine optimal powers to be allocated for the uplink transmissions in each of the cells.

The solution to the above problem may be as follows:

Equation 2 where λ is a variable that is calculated such that a sum of the transmission powers Pj over all cells is equal to the maximum constraint of the transmission power of the UE 6. The "+" operator ensures that the sum of the transmission powers Pj is either a positive value or is set to zero (or put another way Pj ⁺ = max(Pj,o)).

The UE 6 may be configured to identify an optimal value of λ which maximises the weighted sum of the data throughput of all cells. The optimal value of λ may be determined in an iterative manner as follows:

Equation 3 where Δ is the step size of the iteration process and λ _η is the n ^th step iteration value.

In some examples, the upper and lower bounds with respect to the power for each uplink may be applied to problem set out in relation to Equation l. In such examples, the lower bound may correspond to the transmit power needed to operate at the lowest possible MCS (e.g. MCSo). The upper bound may, for instance, correspond to a maximum transmit power as determined by the eNB in the uplink allocation grant.

Adaptation of NPRB

When the UE 5 is adapting only the number of resource blocks used for a particular uplink transmission, it may be able to do so by allocating power to each of the uplink

transmissions in a decreasing order of the effective rate (the rate per unit transmit power), without changing the allocated MCS. Put another way, the UE 5 may be configured to determine the split of its maximum transmission power based on a rate of transmission per unit power for each of the uplink transmissions.

Determining the split of the transmission power of the UE (e.g. in operation S2.6 of Figure 2) may be performed such that the uplink transmission having the highest transmission rate per unit power is allocated with transmission power first. The UE may then allocate transmission power to other cells in decreasing order of rate per unit transmission power, until the maximum power constraint is reached.

Figure 4 illustrates various operations which may be employed by the UE 5 in order to determine the division of power between the various cells 7 in respect of which the UE 5 has received an uplink allocation. The operations depicted in Figure 4 may, in some examples, constitute operation S2.6 of Figure 2, in which the UE determines the split of its transmission power between the cells.

Firstly, in operation S2.6-1, the UE 5 may determine which of the allocated uplink transmissions has the largest rate per unit power (effective rate) from a list of M uplink allocations in respect of which an uplink allocation message was received. The rate per unit power may be determined based on the allocated MCS in the uplink allocation grant and the estimated pathloss at the UE to be used in the uplink power control equation. The uplink power control equation can then be used to determine the aggregate transmit power for a given choice of P ₀ and alpha values as defined in the LTE specifications for uplink power control.

Subsequently, in operation S2.6-2, the UE 5 allocates power for the uplink transmission identified in operation S2.6-1. More particularly, the UE 5 may allocate power sufficient to make use of as many of the allocated resource blocks for identified uplink as possible. Next, in operation S2.6-3, the UE 5 may determine if there is any remaining transmission power for allocation to other uplink transmissions. In response to a negative

determination (i.e. a determination that there is no power remaining), the UE 5 proceeds to operation S2.7 of Figure 2. In response to a positive determination (i.e. a determination that there is power remaining for allocation), however, the UE 5 proceeds to operation S2.6-4.

In operation, S2.6-4, the UE 5 removes the uplink transmission for which power has been allocated from the list of available uplinks and proceeds to operation S2.6-5.

In operation S2.6-5, the UE 5 determines whether there are any more allocated uplink transmissions remaining on the list of available uplinks (from which the uplink(s) for which power has already been allocated have been removed). If there are no remaining uplinks to which to allocate power, the UE 5 proceeds to operation S2.7. If, however, there are remaining uplinks, the UE 5 returns to operation S2.6-1.

As discussed above, in operation S2.6-1, the UE 5 determines which of the allocated uplink transmissions from the list of available uplinks for which power has not yet been allocated has the largest rate per unit power (effective rate). Put another way, in the second iteration of operation S2.6-1, the UE 5 could be said to determine the allocated uplink that has the second highest rate per unit power. Subsequently, the UE 5 proceeds to operation S2.6-2 in which the UE 5 allocates as much power as is possible (based on the number of allocated resource blocks and the maximum constraint on the transmission power) to that uplink transmission.

Subsequently, the UE 5 proceeds to operation S2.6-3 to determine if there is more transmission power available for allocation. If not, the UE 5 proceeds to operation S2.7 and, if so, the UE 5 returns to operation S2.6-4. This process is repeated until a negative determination is reached in either of operations S2.6-3 (i.e. it is determined that the transmission power according the maximum constraint has been allocated) and S2.6-5 (i.e. it is determined that power has been allocated to all available uplinks).

As will of course be appreciated, for some uplinks/cells, the UE 5 may not make use of all the resource blocks that it has been allocated because there is not a sufficient amount of the maximum transmission power remaining unallocated. In such a situation, the remaining resource blocks are left unused. Resource blocks being "left unused" may, in this context, be understood to mean that no signal is transmitted by the UE 5 for the frequencies corresponding to the "unused" resource blocks. Leaving the resource blocks unused may contrast with padding the resource blocks, for instance with zeros or a padding buffer status report (a padding BSR), and then transmitting them to the eNB 5. By leaving allocated resource blocks unused when they are not required, the amount of inter-cell interference due to transmission of padding data may be reduced. Inter-cell interference may degrade performance in neighbouring cells, and so by reducing it, performance of the overall network 1 may be improved.

When some resource blocks of an allocation are to be unused, the UE may make use of the resource blocks in a particular order (for instance, lowest-to-highest numbered resource block or vice versa) which may be specified by the eNB 6 as part of the uplink allocation message or may be pre-programmed into the UE 5.

Joint Adaptation of MCS and NPRB

In some examples, the UE 5 may be configured to jointly adapt the MCS and the number of resource blocks as required. In doing so, the UE 5 may allocate transmission power to the various available uplinks based on optimisation of the problem set out in association with Equation 4 below. As will be appreciated, optimisation of this problem may maximise throughput of data by the UE 5.

Equation 4

such that: ∑ _{= 1} Pj≤P,

0 < w _j ≤ W _j , V;, and

In the above expressions, Pj is the transmission power for the uplink transmission to aj ^th cell, wj is the assigned number of resource blocks allocated for hej ^th cell, i/dj is the SINR per unit transmit power per Hz (or the ratio of the channel gain to the total interference plus noise per PRB) for the j ^th cell, u>j is the bandwidth decided by the UE for the j ^th cell, M is the number of cells that have allocated uplinks to the UE 5 in a particular TTI, and P is the maximum UE transmit power. As discussed above in relation to the problem set out with respect to Equation l, the problem with respect to Equation 4 is convex with linear constraints and, as such, global maxima can be obtained. More specifically, the KKT conditions can be applied to determine optimal powers to be allocated for the uplink transmissions in each of the cells.

Simulations

Results of simulations performed in respect of both the MCS adaptation and the N _PR B adaptation have shown significant performance results over corresponding baselines schemes.

Baseline Schemes

The following baseline schemes were used to benchmark the performance of the adaptation schemes described herein.

In both baseline schemes (i.e. the scheme for comparing with MCS adaptation and the scheme for comparing with N _PR B adaptation) it was assumed that the UE 5 receives uplink grants {(η _1; MCSi), (n ₂ ,MCS ₂ )} from two cells where / is the number of PRBs allocated by cell j and MCSj is the MCS allocated by cell j.

In both baselines schemes, the UE 5 was simulated to compute the transmission powers Pi, P2 allocated to each cell as follows: Pl_max Pl nax/

Equation 5 where: Pi_ _max and P ₂ _max are derived by the UE using the PRB allocation received from the cell, the estimated path loss to each cell and the FPC equation as standardized in LTE. The FPC equation can be found in section 5.1.1.1 of 3GPP TS 36.213 which is available from www.3gpp.0rg.

In the baseline scheme for NPRB adaptation, the numbers of PRBs ¾ and n ₂ used on the two links were then computed as follows using the powers Pi, P ₂ computed above.

Pi

n _t = max I 0,

Equation 6

Equation 7 where: PLj is the path loss from the UE to the eNB operating thej ^th cell,

Po is a configurable value, similar to the one defined in LTE standards,

In the baseline scheme for MCS adaptation, the throughput values Si and S ₂ achieved cells 1 and 2 respectively were computed as follows:

Equation 8

Equation 9 where: PLj is the path loss from the UE to the eNB operating thej ^th cell,

Ii and I ₂ are the inter-cell interference values per Hz in cell 1 and 2, respectively (note: an average value of 10 dB is assumed in the simulations),

wj is the total bandwidth allocated from the j ^th cell, where the bandwidth of one PRB on the j ^th cell is τ _; (put another way, the number of PRBs allocated by the j ^th cell is

iVis the thermal noise per Hz.

Results of Simulations

The simulations for both the MCS adaptation and the N _PR B adaptation were performed based on an assumption that a single UE 5 is connected to two cells operating at different carrier frequencies. In addition, a maximum uplink transmit power of 23 dBm was assumed. The path loss values for the cells were generated from a uniform distribution from unif(b,b+70), where b can take values from the set {60,70,...,100}. Figure 8 shows a comparison between the simulated performance of the scheme described herein in which the number of transmitted PRBs (NPRB) is adapted and the simulated performance of the corresponding baseline scheme. Figure 9 shows a comparison of the simulated performance between the scheme described herein in which the MCS is adapted and the simulated performance of the corresponding baseline scheme.

From the simulation results of Figures 8 and 9, it can be seen that the proposed schemes for adapting the number of PRBs and MCS show significant performance improvement over the corresponding baseline schemes. As can be seen, with increase in the upper bound on the path loss range, the sum of the powers on the two links exceeds the maximum UE transmit power more often, which results in better performance of the schemes described herein. The trends are similar for both the schemes.

To illustrate the source of the gains, let us consider a scenario where a UE 5 is connected to two 20 MHz cells to which it has path losses of 90 dB and 100 dB, respectively. Let us assume that P ₀ for the uplink channel (PUSCH) is equal to -8odBm, and alpha is equal to 1.

In one prior art method (for instance as described in Section II A of the paper "An

Enhanced Power Control Scheme for Dual Connectivity" by Jin Liu, Jianguo Liu and Huan Sun (2014 IEEE 80th Vehicular Technology Conference, VTC2014-Fall)), the sum power of 23 dBm (the assumed maximum uplink transmit power) may be split such that each cell keeps its allocations within 20 dBm so that the sum power required at the UE 5 may never exceed 23 dBm.

Clearly, in this case, if only one cell is scheduling the UE 5 but the other is not, the throughput would be lower than it otherwise could have been. For example, if the first cell is scheduling the UE in a particular TTI but the second cell is not, then the first cell would only be able to allocate a number of PRBs corresponding to 10 dBm assuming the UE has a pathloss of 90 dB, i.e., 10 PRBs. This is calculated by subtracting the sum of P ₀ (=-80 dBm) and the path loss for the UE (=90 dB) from the power limit for each UE as imposed by the cell (=20 dBm).

However, if the first cell assumed that the second cell was not scheduling the UE, and if it turns out to be correct, it could have allocated it 20 PRBs, effectively doubling the throughput. Thus, the methods described herein may double the throughput in those situations where only one of the cells 7 is scheduling the UE 5.

In the case where both cells 7 assume the full transmit power is available for itself, the two cells 7 would each allocate the UE 5 twenty physical resource blocks. However, the UE 5 would exceed the maximum transmit power if it used all these PRBs. As such, as per our proposed method of RB adaptation, the UE only uses the 20 PRBs it got from cell 1, but none of the PRBs it got from cell 2. A method that uses a nominal share of 50% of the power for the two cells will also perform poorly. Assuming the same received SINR at the two cells of, say, 5 dB, if the full transmit power was used for each of the cells, by using a 50% power share, the received SINR would drop to 2dB. Thus, the UE 5 would be able to achieve a rate of Si plus S ₂ equals

30.ibps/Hz. This is determined based on equations 8 and 9 above where Si =

20xlog ₂ (i+i.585) and S ₂ = 2xlog ₂ (i+i.585). However, with the method of varying the number physical resource blocks as described above, the UE 5 would be able to achieve a transport block size corresponding to 20 PRBs at an SINR of sdB (i.e. 20xlog ₂ (i+3.i6) = 4i.i3bps/Hz). This equates to a gain of about 36% in the throughput of the UE. Figures 10 and 11 show further simulation results illustrating the benefits of the methods described herein.

In particular, Figures 10 and 11 illustrate the percentage gain in UE geomean throughput against different values of P ₀ _PUSCH (configurable value, similar to the one defined in LTE standards) and a (the path loss compensation factor) for each of the MCS and RB adaptation methods described herein.

For both Figures, the throughput is computed using the Shannon capacity equation (see, for instance, Shannon, C.E., "Collected Papers", Edited by Sloane & Wyner, IEEE press 1993), and path loss values based on 3GPP UMa Case 1 scenario (for Figure 10) and 3GPP UMa Case 3 scenario (for Figure 11). Descriptions for UMa Cases 1 and 3 can be found in Table A.2.1.1-1 of 3GPP TS 36.814 which is available from www.3gpp.0rg. For generation of both sets of results P _max was assumed to be 23 dBm. From Figures 10 and 11 it can be seen that both methods provide throughput gains over the baseline scheme and that MCS adaptation provides better gains than RB adaptation method (the MCS adaptation results are denoted by the upper line in each figure). In addition, it can be seen that better gains are achieved for the 3GPP UMa Case 3 scenario. This may be because, with the increase in the upper bound on path loss range (as per case 3), the sum of the powers on the two uplinks exceeds the maximum UE transmit power more frequently and so the methods described herein become particularly beneficial.

For both Figures, the percentage gains are determined based on the following baseline scheme assumptions:

Without power split, assuming aggressive grants, the two transmit powers Pi, P ₂ are computed as per the fractional power control equation;

- Pi(dB) = Po_PUSCH + aPLi;

P2(dB) = Po_PUSCH + a PL2;

The maximum number of PRBs that can be supported ( , n ₂ ) are

?¾= floor(db2pow(P _max )/db2pow(Pi));

n ₂ = floor(db2pow(Pmax)/db2pow(P ₂ ));

The function db2pow converts a dB value to a linear value.

Given that resources on each cell are shared across multiple UEs, each cell allocates PRBs Ni alloc _? N ₂ _aiioc as below:

Ni aiioc= uniform random value in (o, ?¾);

uniform random value in (o, n ₂ );

The above PRB allocations are assumed the upper limit for both the baseline scheme as well as our proposed RB adaptation scheme.

For the baseline scheme, assuming static equal power split between the 2 BSs PRBs are allocated as follows;

Baseline Ji =floor( db2pow(P _max -3)/db2pow(Pi));

- Base line _n ₂ =ftoor( db2pow(P _max -3)/db2pow(P ₂ ));

n ₂ =min(N ₂ alloc, Baseline_n ₂ ).

Example Configurations of UEs and eNBs

Figure 5 is a schematic illustration of an example configuration of one or more of the UEs 5 depicted in Figure 1, which may be used for communicating with the eNBs 6 via a wireless interface. The UE 5 may be any device capable of at least sending or receiving radio signals to or from the eNBs 6 and of performing operations as described above, in particular with reference to Figures 1, 2, 4, 8 and 9. The UE 5 may communicate via an appropriate radio interface arrangement 505 of the UE 5. The interface arrangement 505 may be provided for example by means of a radio part 505-2 (e.g. a transceiver) and an associated antenna arrangement 505-1. The antenna arrangement 505-1 may be arranged internally or externally to the UE 5.

As discussed above, the UE 5 comprises control apparatus 50 which is operable to control the other components of the UE 5 in addition to performing any suitable combinations of the operations described in connection with UE 5 with reference to Figures 1, 2, 4, 8 and 9 (where applicable). The control apparatus 50 may comprise processing apparatus 501 and memory 502. Computer-readable code 502-2A may be stored on the memory, which when executed by the processing apparatus 501, causes the control apparatus 50 to perform any of the operations described herein in relation to the UE 5. Also, the memory may include a transmission buffer 502-1B. Example configurations of the memory 502 and processing apparatus 501 will be discussed in more detail below

The UE 5 may be, for example, a device that does not need human interaction, such as an entity that is involved in Machine Type Communications (MTC). Alternatively, the UE 5 may be a device designed for tasks involving human interaction such as making and receiving phone calls between users, and streaming multimedia or providing other digital content to a user. Non-limiting examples include a smart phone, and a laptop

computer/notebook computer/tablet computer/e-reader device provided with a wireless interface facility.

Where the UE 5 is a device designed for human interaction, the user may control the operation of the UE 5 by means of a suitable user input interface UII 504 such as key pad, voice commands, touch sensitive screen or pad, combinations thereof or the like. A display 503, a speaker and a microphone may also be provided. Furthermore, the UE 5 may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto.

Figure 6 is a schematic illustration of an example configuration of one or more the eNBs 6 depicted in Figure 1, which may be used for communicating with the UEs 5 via a wireless interface. The eNB 6, which may be referred to a base station or access point (AP), comprises a radio frequency antenna array 601 configured to receive and transmit radio frequency signals. Although the eNB 6 in Figure 6 is shown as having an array 601 of four antennas, this is illustrative only. The number of antennas may vary, for instance, from one to many hundreds.

The eNB 6 further comprises radio frequency interface circuitry 603 configured to interface the radio frequency signals received and transmitted by the antenna 601 and the control apparatus 60. The radio frequency interface circuitry 603 may also be known as a transceiver. The apparatus 60 may also comprise an interface 609 via which, for example, it can communicate (e.g. via X2 messages) with other network elements such as the other eNBs 6.

The eNB control apparatus 60 may be configured to process signals from the radio frequency interface circuitry 603, control the radio frequency interface circuitry 603 to generate suitable RF signals to communicate information to the UEs 5 via the wireless communications link, and also to exchange information with other network elements 6 via the interface 609. .

The control apparatus 60 may comprise processing apparatus 602 and memory 604. Computer-readable code 604-2A may be stored on the memory 604, which when executed by the processing apparatus 602, causes the control apparatus 60 to perform any of the operations assigned to the eNBs 6 described above, in particular with reference to Figures 1 and 3.

As should of course be appreciated, the apparatuses 5, 6 shown in each of FIGS. 5 and 6 described above may comprise further elements which are not directly involved with processes and operations in respect which this application is focussed.

Some further details of components and features of the above-described

apparatus/entities/apparatuses 5, 6, 50, 60 and alternatives for them will now be described.

The control apparatuses 50, 60 may comprise processing apparatus 501, 602

communicatively coupled with memory 502, 604. The memory 502, 604 has computer readable instructions 502-2A, 604-2A stored thereon, which when executed by the processing apparatus 501, 602 causes the control apparatus 50, 60 to cause performance of various ones of the operations described herein. The control apparatus 50, 60 may in some instance be referred to, in general terms, as "apparatus". The processing apparatus 501, 602 may be of any suitable composition and may include one or more processors 501A, 602A of any suitable type or suitable combination of types. For example, the processing apparatus 501, 602 may be a programmable processor that interprets computer program instructions 502-2A, 604-2A and processes data. The processing apparatus 501, 602 may include plural programmable processors.

Alternatively, the processing apparatus 501, 602 may be, for example, programmable hardware with embedded firmware. The processing apparatus 501, 602 may be termed processing means. The processing apparatus 501, 602 may alternatively or additionally include one or more Application Specific Integrated Circuits (ASICs). In some instances, processing apparatus 501, 602 may be referred to as computing apparatus.

The processing apparatus 501, 602 is coupled to the memory (which may be referred to as one or more storage devices) 502, 604 and is operable to read/write data to/from the memory 502, 604. The memory 502, 604 may comprise a single memory unit or a plurality of memory units, upon which the computer readable instructions (or code) 502- 2A, 604-2A is stored. For example, the memory 502, 604 may comprise both volatile memory 502-1 and non-volatile memory 502-2. For example, the computer readable instructions/program code 502-2A, 604-2A may be stored in the non-volatile memory 502-2, 604-2 and may be executed by the processing apparatus 501, 602 using the volatile memory 502-1, 604-1 for temporary storage of data or data and instructions. In some examples, a transmission buffer 502-1B of the UE 5 may be constituted by volatile memory 502-1 of the UE control apparatus 50. Examples of volatile memory include RAM, DRAM, and SDRAM etc. Examples of non-volatile memory include ROM, PROM, EEPROM, flash memory, optical storage, magnetic storage, etc. The memories in general may be referred to as non-transitory computer readable memory media.

The term 'memory', in addition to covering memory comprising both non-volatile memory and volatile memory, may also cover one or more volatile memories only, one or more non-volatile memories only, or one or more volatile memories and one or more non- volatile memories.

The computer readable instructions/program code 502-2A, 604-2A may be preprogrammed into the control apparatus 20. Alternatively, the computer readable instructions 502-2A, 604-2A may arrive at the control apparatus 50, 60 via an

electromagnetic carrier signal or may be copied from a physical entity 70 such as a computer program product, a memory device or a record medium such as a CD-ROM or DVD an example of which is illustrated in Figure 7. The computer readable instructions 502-2A, 604-2A may provide the logic and routines that enables the entities

devices/apparatuses 5, 6, 50, 60 to perform the functionality described above. The combination of computer-readable instructions stored on memory (of any of the types described above) may be referred to as a computer program product.

Embodiments of the present invention may be implemented in software, hardware, application logic or a combination of software, hardware and application logic. The software, application logic and/or hardware may reside on memory, or any computer media. In an example embodiment, the application logic, software or an instruction set is maintained on any one of various conventional computer-readable media. In the context of this document, a "memory" or "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.

Reference to, where relevant, "computer-readable storage medium", "computer program product", "tangibly embodied computer program" etc., or a "processor" or "processing apparatus" etc. should be understood to encompass not only computers having differing architectures such as single/multi-processor architectures and sequencers/parallel architectures, but also specialised circuits such as field programmable gate arrays FPGA, application specify circuits ASIC, signal processing devices and other devices. References to computer program, instructions, code etc. should be understood to express software for a programmable processor firmware such as the programmable content of a hardware device as instructions for a processor or configured or configuration settings for a fixed function device, gate array, programmable logic device, etc.

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. Similarly, it will also be appreciated that flow diagrams of Figures 2, 3 and 4 are examples only and that various operations depicted therein may be omitted, reordered and or combined.

Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims. It is also noted herein that while the above describes various examples, 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 as defined in the appended claims.