A Network Node And Method Of Determining Amounts Of Downlink Transmission Power For Downlink Shared Channels In A Wireless Communications Network

TECHNICAL FIELD

Embodiments herein relate to transmission powers of downlink shared channels in a wireless telecommunications network. In particular, embodiments herein relate to a network node and a method for determining amounts of downlink transmission power for downlink shared channels in a wireless telecommunications network.

BACKGROUND

In a typical cellular network, also referred to as a wireless communication system, User equipment, UEs, communicate via a Radio Access Network, RAN, to one or more core networks, CNs.

A user equipment is a mobile terminal by which a subscriber may access services offered by an operator's core network and services outside operator's network to which the operator's RAN and CN provide access. The user equipment may be for example communication devices such as mobile telephones, cellular telephones, smart phones, tablet computers or laptops with wireless capability. The user equipment may be portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile devices, enabled to communicate voice and/or data, via the radio access network, with another entity, such as another mobile station or a server. user equipments are enabled to communicate wirelessly in the cellular network. The communication may be performed e.g. between two user equipments, between a user equipment and a regular telephone and/or between the user equipment and a server via the RAN and possibly one or more CNs, comprised within the cellular network.

The RAN covers a geographical area which is divided into cell areas, with each cell area being served by a base station, e.g. a Radio Base Station (RBS), which in some RANs is also called eNodeB (eNB), NodeB, B node or network node. A cell area is a geographical area where radio coverage is provided by the radio base station at a base station site. Each cell area is identified by an identity within the local radio area, which is broadcast in the cell area. The base stations communicate over the air interface operating on radio frequencies with the user equipment within range of the base stations. It should be noted that a base station may serve one or more cells, also referred to as cell carriers, within its cell area.

According to one example, a RAN may be based on a Wideband Code Division Multiple Access/High Speed Packet Access, WCDMA/HSPA, technology. In such a RAN, there are different ways to send data in downlink transmissions to a user equipment when the user equipments is operating in an active state, e.g. a CELL_DCH state. Note that this active state may be considered as opposite to an idle state, e.g. a CELL_FACH state. In the idle state, the user equipment only communicate using common channels, while in the active state, the user equipment may communicate using both common and dedicated channels.

In the active state, a Dedicated Physical CHannel, DPCH, also sometimes referred to as a DCH channel, or a High-Speed Downlink Shared CHannel, HS-DSCH, may be used in addition to the common channels. Using the HS-DSCH channel is usually referred to as HSDPA operation, and unlike the DPCH, the HS-DSCH channel is shared amongst multiple user equipments. The HS-DSCH channels may thus be referred to as a shared channel as oppose to a dedicated channel, such as, DPCH.

In practice, the DPCH and HS-DSCH channels may co-exist, i.e. be used simultaneously by the network node, for downlink transmissions. This means that at a given time instant, a network node may transmit both DPCH and HS-DSCH transmissions to user equipments within the same cell.

However, this also means that the available resources of the network node, such as, channelization codes, downlink transmission, DL TX, power, etc., needs to be shared between the DPCH and HS-DSCH transmissions. Also, since the resources of the network node that are allocated to the HS-DSCH transmissions are shared, they are therefore used as a common resource. This means that for each Transmission Time Interval, TTI, the common resource may be dynamically shared between the user equipments in the same cell. This enables a large part, e.g. some or all, of the common resources of the network node to be allocated to one or more specific user equipments in a given TTI. On the contrary, the resources of the network node that are allocated to the DPCH transmissions are used as a dedicated resource.

For the HS-DSCH downlink transmissions, the possibility to dynamically share and allocate the resources of the network node as a common resource in a cell is particularly beneficial for packet data. This is because packet data generally have bursty characteristics resulting in a highly varying resource need for the user equipments in the cell, and because dynamically deciding to which user equipment in the cell the resources of the network node is to be allocated allows for more resources to be given to those user equipments in the cell having data in their data priority queues at the network node that needs to be transmitted. This will thus increase the overall efficiency of the downlink data transmissions in the cell.

This also means that the more resources of the network node, i.e. channelization codes, DL TX power, etc., that are available for transmissions in the cell, the more payload data, i.e. information bits, may be sent on the HS-DSCH channel in the cell. While the number of channelization codes available for HS-PDSCH downlink transmissions are limited to 15 SF16 HS-PDSCH codes, the available DL TX power is only dependent of the capabilities of the power amplifier that is used for physically transmitting the data in the cell.

In a cell, the total DL TX power, i.e. the total cell power, needs to be shared between all physical channels. This comprises the physical channels associated with the DPCH channels, such as, e.g. F-DPCH, DPDCH and DPCCH. It also comprises the physical channels associated with the HS-DSCH channels, such as, e.g. HS-PDSCH, HS-SCCH. In order to maximize the HSDPA performance, i.e. the use of the physical channels associated with the HS-DSCH channels, while at the same time maintaining the quality of the dedicated channels, i.e. the quality of the physical channels associated with the DPCH channels, a common approach is to allow HS-DSCH transmissions in a cell to use the remaining DL TX power once DL TX power has been allocated for the common and dedicated cannels in the cell. One example of this common approach is illustrated in FIG. 1. Here, the common channels are allocated a constant amount of the total DL TX power, while the amount of the total DL TX power to the dedicated channels is power controlled. Thus, the remaining DL TX power available for the HS-DSCH channel will vary.

Given the amount of DL TX power in a cell and the number of channelization codes available for the HS-DSCH downlink transmission in a cell, the network node may determine, for each TTI, to which user equipment in the cell data shall be transmitted to on the downlink on the HS-DSCH channel, and how much data which should be transmitted in the TTI. The amount of data that may be sent, or the Transport Block Size, TBS, that is used, in a single TTI is commonly based on the available number of channelization codes in the cell and the DL TX power available to the HS-DSCH transmission in the cell.

For every TTI, or scheduling opportunity, the network node may determine how much DL TX power that may be used for the HS-DSCH transmission, i.e. P_HS, in the TTI for a cell based on the following formula (Eq. 1):

P
_HS
=P
_{total cell power}
−P
_{dedicated channels}
−P
_{common channels} (Eq. 1)

Here, the P_{total cell power}is the total DL TX power that is allocated to the cell, the P_{dedicated channels}is the DL TX power that is allocated to the dedicated channels in the cell, and the P_{common channels}is the DL TX power that is allocated to the common channels in the cell. The common channels may comprise e.g. CPICH, E-AGCH, E-HICH, HS-SCCH. Once the available P_HSand the available number of channelization codes are known for the cell, it is straightforward for the network node to determine how much data that may be sent in the TTI for the cell based on a specific Quality of Service, QoS. The specific QoS may be measured in terms of e.g. a target BLock Error Rate, BLER.

However, this means that, for example, when there is not enough data in the user equipment's priority queues at the network node for the cell, e.g. data may be transmitted with the desired QoS-level utilizing less power than P_HS, the result may be that not all of the available P_HSwill be used for HS-DSCH downlink transmission in the cell for the TTI.

SUMMARY

It is an object of embodiments herein to increase power resource utilization in a wireless telecommunications network.

According to a first aspect of embodiments herein, the object is achieved by a method performed by a network node for determining amounts of downlink transmission power for a downlink shared channel to be used in a Transmission Time Interval, TTI, by cells served by the network node in a wireless telecommunications network. The network node determines downlink transmission power available to the cells for physical channels associated with the downlink shared channel based on the downlink transmission power allocated in the cells to physical channels associated with other downlink channels. Further, the network node determines an additional amount of downlink transmission power available to at least one first cell based on the difference between the determined downlink transmission power available to at least one second cell and a downlink transmission power that is required for the amount of data that is to be transmitted in the at least one second cell.

According to a second aspect of embodiments herein, the object is achieved by a network node for determining amounts of downlink transmission power for a downlink shared channel to be used in a TTI by cells served by the network node in a wireless telecommunications network. The network node comprising processing circuitry configured to determine downlink transmission power available to the cells for physical channels associated with the downlink shared channel based on the downlink transmission power allocated in the cells to physical channels associated with other downlink channels. Further, the processing circuitry is also configured to determine an additional amount of downlink transmission power available to at least one first cell based on the difference between the determined downlink transmission power available to at least one second cell and a downlink transmission power that is required for the amount of data that is to be transmitted in the at least one second cell.

By first determining the DL TX power available to the cells for the shared downlink channel, e.g. HS-DSCH, based on the DL TX power allocated in the cells to other downlink channels, and then determine an additional amount of DL TX power available to a first cell as the difference between the determined DL TX power available to at least one second cell and a DL TX power that is required for the amount of data that is to be transmitted in the at least one second cell, the network node is enabled to identify in which TTIs there are opportunities for a cell to share DL TX power with respect to the DL TX power that the cell has been allocated, and opportunities for another cell to use additional DL TX power with respect to the DL TX power that the another cell has been allocated.

Thus, unused amounts of DL TX power available for the shared downlink channel in a cell may be utilized by another cell sharing the same power amplifier for its downlink shared channel, while the sum of the DL TX power used by all cells that are sharing a power amplifier do not exceed the capabilities of the power amplifier. This provides for a dynamic inter-cell power sharing that instantaneous reallocates DL TX power to the cells in which further DL TX power resources are needed, and thus reduces the possibility that a DL TX power resource is left unused in the power amplifier for a TTI.

Hence, the power resource utilization in the wireless telecommunications network is increased.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the embodiments will become readily apparent to those skilled in the art by the following detailed description of exemplary embodiments thereof with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic diagram illustrating dynamic HSDPA power allocation of the total DL TX power in a cell,

FIG. 2 is a schematic block diagram illustrating embodiments of a network node in a wireless communications network,

FIG. 3 is a flowchart depicting embodiments of a method in a network node,

FIG. 4 is a schematic diagram illustrating downlink transmission power allocation to common, dedicated and shared channels according to some embodiments,

FIG. 5 is a further schematic diagram illustrating downlink transmission power allocation to shared channels according to some embodiments,

FIG. 6 is a further schematic diagram illustrating downlink transmission power allocation to shared channels according to some embodiments,

FIG. 7 is a flowchart depicting embodiments of a method in a network node,

FIG. 8 is a flowchart depicting embodiments of a method in a network node,

FIG. 9 is a block diagram depicting embodiments of a network node,

FIG. 10 is a block diagram depicting embodiments of a network node, and

FIG. 11 is a block diagram depicting embodiments of a network node.

DETAILED DESCRIPTION

The figures are schematic and simplified for clarity, and they merely show details which are essential to the understanding of the embodiments presented herein, while other details have been left out. Throughout, the same reference numerals are used for identical or corresponding parts or steps.

FIG. 2 shows a schematic block diagram illustrating embodiments of a network node 110 in a wireless communications network 100.

The network node 110 may comprise several power amplifiers and antennas providing radio coverage to user equipments 121 in a cell area 115. In this example, the cells 201, 202 which provide radio coverage in the same sector 111 of the cell area 115 may share a radio unit in the network node 110, and thus may also share the power amplifier(s) of said radio unit. The same applies, in this example, to the cells 203, 204 which provide radio coverage in the same sector 112, and to the cells 205, 206 which provide radio coverage in the same sector 113.

It should be noted that some of the cells may transmit on the same cell carrier but in different sectors and thus in this case be referred to as one single cell. An example illustrating this principle is, for example, to have the cells 201, 203 and 205 transmit on the same cell carrier but in different sectors 111, 112, and 113, respectively, and may thus in this case be referred to as a one single cell. Here, the cells 202, 204 and 206 transmit on the same cell carrier but in different sectors 111, 112, and 113, respectively, and thus in this case also may be referred to as a one single cell.

It should also be noted that in a wireless telecommunications network 100 as described above, it is important that the sum of the DL TX power used by all cells that are sharing a power amplifier in the network node 100, e.g. cells 201 and 202, cells 203 and 204, cells 205 and 206, respectively, do not exceed the capabilities of the power amplifier(s) of their radio unit in the network node 110.

As part of understanding the embodiments described herein, a problem will first be identified and discussed in more detail. As described in with reference to FIG. 1 above, the total DL TX power of a cell is provided in the network node by one or more radio units comprising one or more power amplifiers. Each power amplifier is used to transmit downlink data associated with one or more cells or cell carriers.

It is common that the total DL TX power associated with a power amplifier is divided in a semi-static manner amongst the cell or cell carriers handled by the power amplifier. For example, in case of having two cells sharing an 80 W power amplifier, the two cells is each allocated 40 W. This means the DL TX power allocated to one cell, i.e. 40 W, is then a dedicated shared resource that only may be used for downlink transmissions in that specific cell. To ensure that the transmissions in each cell do not exceed its allocated 40 W, the network node may reduce amounts of DL TX power in each cell that may be used by the HS-DSCH transmission.

However, this semi-static division of the total power of the power amplifier between the cells will cause inefficiency in the wireless telecommunications network, since not all cells will be able to use all its allocated amount of DL TX power available for HS-DSCH downlink transmissions. For example, in situations where one of the cells serves a user equipment that have a lot of data in its data priority queues at the network node, e.g. is wirelessly downloading a large data file, while another one of the cells does not serve any user equipment that has data in its data priority queues at the network node, the latter cell may not utilize all of its dedicated shared resource, i.e. its amount of DL TX power available for HS-DSCH downlink transmissions.

According to another aspect that must be considered, the total DL TX power that may be provided to all of its cells by a power amplifier is limited in that the sum of the instantaneous DL TX power associated with all physical channels of the cells utilizing the power amplifier should not exceed the capabilities of the power amplifier in terms of its maximum power capability. This is due to the fact that, when the total DL TX power level exceeds the maximum power level for which the power amplifier has been designed, there will be a non-linear distortion of the output signal. Therefore, this limitation is also important in order to protect the power amplifier, and to ensure that the transmitted downlink transmission signal has good signal properties.

In the following, according to embodiments herein which relate to determining amounts of DL TX power for downlink shared channels in a wireless telecommunications network 100, there will be disclosed a dynamic inter-cell power sharing of the power resources of a power amplifier in a network node which increased the power resource utilization in the wireless telecommunications network 100.

Example of embodiments of a method performed by a network node 110 for determining amounts of downlink transmission power for a downlink shared channel to be used in a Transmission Time Interval, TTI, by cells 201-206 served by the network node 110 in a wireless telecommunications network 100, will now be described with reference to the flowchart depicted in FIG. 3. FIG. 3 is an illustrated example of actions or operations which may be taken by a network node 110. The method may comprise the following actions.

Action 301

In this action, the network node 110 determine DL TX power available to cells for downlink shared channels based on the DL TX power allocated in the cells to other downlink channels. This means that the network node 110 determines the downlink transmission power available to the cells, e.g. cell 201 and 202 in FIG. 2, for physical channels associated with the downlink shared channel based on the downlink transmission power allocated in the cells, e.g. cell 201 and 202, to physical channels associated with other downlink channels, respectively.

This is illustrated in the schematic diagram of FIG. 4, which depicts an example of a DL TX power allocation in a TTI to common, dedicated and shared channels according to some embodiments.

In the example of FIG. 4, the total DL TX power for all physical channels associated with downlink channels for each of the cells, e.g. cell 201 and 202, for a TTI is denoted P_{total cell DL TX}power and which level is marked with a dashed line in FIG. 4.

It may also be seen in FIG. 4 that a portion of the total DL TX power for all physical channels associated with downlink channels in the TTI for each of the cells 201 and 202 has been allocated to dedicated channels and common channels, i.e. P_{common channels+dedicated channels}. This is shown by the horizontally lined portions of the DL TX power for the cells 201 and 202.

Furthermore, a portion of the total DL TX power for all physical channels associated with downlink channels in the TTI for each of the cells 201 and 202 has also been allocated to physical channels associated with the Enhance Uplink, EUL, shown as dotted portions in FIG. 4 and denoted P_{EUL channels}. Although shown separately, for the sake of simplicity, this portion is described in the following as comprised in the portion allocated to the dedicated channels and common channels, P_{common channels+dedicated channels}, described above.

Hence, for the TTI, or scheduling opportunity, the network node 110 may determine how much of the total DL TX power for all physical channels associated with downlink channels in each cell 201, 202 that may be used for the downlink transmission on the downlink shared channel, i.e. P_{shared channels}, in each cell 201, 202 in accordance with the following equation, Eq. 2:

P
_{shared channels}
=P
_{total cell DL TX power}
−P
_{dedicated channels+common channels} (Eq. 2)

This means that the remaining parts or remainders of the total DL TX power for all physical channels associated with downlink channels for each of the cells 201, 202, after deducting the portions allocated to dedicated channels and common channels in each cell 201, 202, may be used for downlink shared channel transmissions, e.g. HS-DSCH downlink transmissions. That is, the portions illustrated in FIG. 4 in between the dashed line and the upper edge of the dotted portion of the DL TX power for the cells 201 and 202.

Thus, the DL TX power available to each of the cells 201, 202 for physical channels associated with their downlink shared channel for a TTI, i.e. P_{shared channels}, are determined.

Action 302

After determining the DL TX power available to the cells for physical channels associated with the downlink shared channel, respectively, the network node 110 determines an additional amount of DL TX power available to at least one first cell, e.g. cell 201, based on the difference between the determined DL TX power available to at least one second cell, e.g. cell 202, and a DL TX power that is required for the amount of data that is to be transmitted in the at least one second cell.

In more detail, this means that the network node 110 may determine an additional amount of DL TX power available to at least one first cell, e.g. cell 201, for the downlink shared channel as the difference between the determined DL TX power available to at least one second cell, e.g. cell 202, for the downlink shared channel and a DL TX power that is required for the amount of downlink shared channel data that is to be transmitted in the at least one second cell, e.g. cell 202.

This is also illustrated in the schematic diagram of FIG. 4.

In the example of FIG. 4, the DL TX power that is required for the amount of data that is to be transmitted on the downlink shared channel in the cell 202 does not use all of the DL TX power available to the cell 202 for the downlink shared channel in the TTI, i.e. P_{shared channels}, determined by the network node 110 in Action 301. This is shown by the fact that there is still DL TX power available to the cell 202 after portions of the determined DL TX power available to the cell 202 for the downlink shared channel in the TTI have been allocated according to the amount of data that is to be transmitted on the downlink shared channel in the cell 202. The DL TX power that is required for the amount of data that is to be transmitted on the downlink shared channel in the cell 202, i.e. P_HS-DSCHand P_HS-SCCH, is shown in FIG. 4 by the diagonally lined and tiled portions on the right.

It should be noted that there may be several reasons why the DL TX power that is required for the amount of downlink shared channel data that is to be transmitted in the cell 202 does not use all of the DL TX power available to the cell 202 for the downlink shared channel in the TTI, i.e. P_{shared channels}.

For example, the network node 110 may not have any downlink shared channel data, e.g. HS-DSCH data, in the data Priority Queue, PQ, of the at least one second cell 202 ready to be transmitted in the TTI. In another example, the network node 110 may not have enough downlink shared channel data in the data Priority Queue, PQ, of the at least one second cell 202 for consuming or using all of its available DL TX power for the downlink shared channel in the TTI. This may occur e.g. when a determined Block Error Rate, BLER, quality may be achieved by using only a portion or part of the available DL TX power for the downlink shared channel in the TTI for the cell. According to a further example, the network node 110 may determine that the number of channelization codes available for downlink shared channel transmissions, e.g. HS-PDSCH downlink transmissions, does not allow for all of the available DL TX power for the downlink shared channel in the TTI for the cell to be used. This may occur e.g. when there is a limitation due to the maximum supported Transport Block Size, TBS.

In the example of FIG. 4, the DL TX power that is required for the amount of data that is to be transmitted on the downlink shared channel in the cell 201 may be higher than the DL TX power available to the cell 201 for the downlink shared channel in the TTI as determined by the network node 110 in Action 301. Thus, there is a need in cell 201 to use more DL TX power for transmitting the downlink shared channel data in its data Priority Queue, PQ, in the network node 110. Thus, the network node 110 may share the DL TX power available to the cell 202 for the downlink shared channel in the TTI, i.e. P_{shared channels}, which will not be used in the cell 202 with the cell 201. This is shown by the wavy lined portion diagonally on the left in FIG. 4. This result in that the total available DL TX power available to the cell 201 for the downlink shared channel in the TTI will be larger than the DL TX power available to the cell 201 for the downlink shared channel in the TTI as determined by the network node 110 in Action 301.

This is further illustrated in the schematic diagrams of FIGS. 5-6, which depicts an example of a DL TX power allocation in a TTI for downlink shared channels in cells of the network node 110 according to some embodiments.

In FIG. 5, the DL TX power available to a first cell, P_HS,1, for the downlink shared channel in the TTI as determined by the network node 110 in Action 301 is shown to left. In the centre of FIG. 5, the DL TX power available to a second cell, P_HS,2, for the downlink shared channel in the TTI as determined by the network node 110 in Action 301 is shown. To the right in FIG. 5, the DL TX power available to a third cell, P_HS,3, for the downlink shared channel in the TTI as determined by the network node 110 in Action 301 is shown.

As illustrated by the dotted and wavy portions in FIG. 5, the transmission of downlink shared channel data in the first cell and second cell use all of its available DL TX power, i.e. P_HS,1and P_HS,2. However, as illustrated by the diagonally lined portion in FIG. 5, the transmission of downlink shared channel data in the third cell does not use all of its available DL TX power, i.e. P_HS,3. This means that network node 110 may share a part or all of the difference between the DL TX power available to the third cell for the downlink shared channel in the TTI, i.e. P_HS,3, and the DL TX power that is required for the amount of data that is to be transmitted on the downlink shared channel in the TTI in the third cell, i.e. P_{HS,3, used}, with the other first and second cells. The difference between the DL TX power available to a cell for the downlink shared channel in a TTI and the DL TX power that is required for the amount of data that is to be transmitted on the downlink shared channel in the TTI in the cell is hereinafter referred to as unused DL TX power of the cell.

FIG. 6 shows an example of how the unused DL TX power of the third cell shown in FIG. 5 may be re-allocated by the network node 110 to the first and second cell. In this example, the first and second cell is each provided with an equal part of the unused DL TX power of the third cell shown in FIG. 5.

It should be noted that other partitions of the unused DL TX power than e.g. the equal partition of the unused DL TX power of the third cell shown in FIG. 5 between the first and second cells, may also be performed as will be described in more detail below.

To partition or divide the unused DL TX power from a cell, e.g. the third cell in FIG. 5, amongst one or more other cells, e.g. the first and second cell in FIG. 5, that have downlink shared channel data in the priority queues for its user equipments at the network node 110 awaiting transmission, the network node 110 may perform one or more, or a combination, of the following actions:

A1) divide the unused DL TX power from the third cell equally to the first and second cells;

A2) divide the unused DL TX power from the third cell taking into account the amount of the downlink shared channel data in the priority queues at the network node 110 for each of the first and second cell. For example, if the first cell only has a small amount of downlink shared channel data that may be transmitted in the TTI, the first cell may be excluded and all of the unused DL TX power from the third cell may be allocated to the second cell;

A3) divide the unused DL TX power from the third cell based on the available channelization codes that the first and second cell will have available in the TTI. This may be performed since a cell with more channelization codes available will, in general, be able to use more of the unused DL TX power from the third cell. This is because of the limited set of TBS sizes that are supported for a given number of available channelization codes;

A4) divide the unused DL TX power from the third cell based on the DL TX power allocated in the first and second cell to physical channels associated with other downlink channels. This may be performed since a cell with high DL TX power associated with other downlink channels will benefit relatively more from getting additional DL TX power for its downlink shared channels;

A5) divide the unused DL TX power from the third cell taking into account the actual radio conditions, such as, e.g. the Channel Quality Indicator, CQI, of the user equipments having downlink shared channel data in its priority queues at the network node 110 awaiting transmission;

A6) divide the unused DL TX power from the third cell taking into account the priority of the transmissions of the user equipments associated with the each cell. For example, if the first cell serves one or more user equipments that have been assigned a high priority in the TTI, the first cell will be allocated more of the unused DL TX power from the third cell than the second cell which e.g. may only serve one or more user equipments that have been assigned a low priority.

A7) divide the unused DL TX power from the third cell taking into account whether any of the first or second cell would benefit from transmitting additional downlink shared channel data, i.e. have enough downlink shared channel data in the priority queues at the network node 110, and for which additional downlink shared channel data there is an initial transmission. For example, no or less of the unused DL TX power from the third cell will be given to cells for which there will be retransmissions of the downlink shared channel data.

In some embodiments, the network node 110 identifies TTIs in which at least one cell of a number of cells that are sharing a power amplifier in a network node 110 may share its allocated DL TX power for downlink shared channels in the TTI, as determined by the network node 110 in Action 301, with another cell of the number of cells that are sharing a power amplifier in a network node 110. To determine if a cell may share its allocated DL TX power, i.e. does not use all of its allocated DL TX power, the network node 110 may first schedule the amount of downlink shared channel data that is to be transmitted in the cell for its determined DL TX power. After this scheduling, the network node 110 may re-allocate the unused DL TX power to other cells that are sharing the same power amplifier in the network node 110 which may benefit from and use the additional amount of DL TX power to transmit more downlink shared channel data in the TTI. These embodiments are described more in detail in reference to FIG. 7 below.

In some embodiments, all of the DL TX powers for downlink shared channels in the TTI, as determined by the network node 110 in Action 301, available to all cells sharing a power amplifier in a network node 110 may be added or summed into a common power pool in the network node 110. These embodiments are described more in detail in reference to FIG. 8 below.

Action 303

In this optional action, after determining the additional amount of DL TX power available to at least one first cell, the network node 110 transmits a downlink transmission of data in the at least one first cell, e.g. cell 201, on the downlink shared channel using the determined DL TX power available to the at least one first cell and the determined additional amount of DL TX power. In more detail, this means that the network node 110 may transmit a downlink transmission of data in the TTI in the at least one first cell 201 on physical channels associated with the downlink shared channel, e.g. HS-DSCH, using the determined DL TX power available to the at least one first cell 201 plus the additional amount of DL TX power available to the at least one first cell 201 determined in Action 302.

Example of embodiments of a method performed by a network node 110 for determining amounts of downlink transmission power for a downlink shared channel to be used in a Transmission Time Interval, TTI, by cells 201-206 served by the network node 110 in a wireless telecommunications network 100, will now be described with reference to the flowchart depicted in FIG. 7. FIG. 7 is an illustrated example of actions or operations which may be taken by a network node 110. The method may comprise the following actions.

Action 701

In this optional action, the network node 110 determine the cells that may be able to share DL TX power with each other, i.e. the number of cells that are sharing the same power amplifier in the network node 110, e.g. cells 203, 204 in FIG. 2. This may also be previously determined or set in the network node 110.

Action 702

In this action, the network node 110 determines the DL TX power available to the cells, e.g. cells 203, 204 in FIG. 2, for their downlink shared channels in the TTI. This is based on the DL TX power allocated in the cells to other downlink channels.

Action 703

In this action, the network node 110 schedules the amount of data that is to be transmitted in the cells, e.g. cells 203, 204 in FIG. 2, based on the downlink transmission power available to the cells as determined in Action 702. This may also comprise performing Transport Format Resource Combination, TFRC, selection for the scheduled amount of data.

Action 704

In this optional action, the network node 110 may determine if there are any more cells that may be able to share DL TX power with the cells, i.e. the number of cells that are sharing the same power amplifier in the network node 110, e.g. cells 203, 204 in FIG. 2.

Action 705

In this action, the network node 110 identifies if there are any cells that does not use all of its DL TX power. This means that the network node 110 identifies, or determines, an additional amount of DL TX power available to at least one first cell, e.g. cell 203, based on the difference between the determined DL TX power available to the at least one second cell, e.g. cell 204, and the DL TX power required for transmitting the scheduled amount of data, i.e. the amount of data scheduled in Action 703 within the at least one second cell, e.g. cell 204.

The identification may, for example, be based on that there is no data that is to be transmitted in the at least one second cell, e.g. cell 204. Alternatively, the identification may be based on that the data that is to be transmitted in downlink transmission in the second cell, e.g. cell 204, is able to be transmitted with a determined level of Quality of Service, QoS, using less than the DL TX power available to the at least one second cell, e.g. cell 204. Further, the identification may also be based on that the number of channelization codes available for the physical channels associated with the downlink shared channel do not allow all of the DL TX power available to the at least one second cell, e.g. cell 204, to be used by the at least one second cell, e.g. cell 204.

Action 706

In this action, the network node 110 divides, or re-allocates, the unused DL TX power. This means that the network node 110 determines how much of the identified additional amount of DL TX power available to the at least one first cell, e.g. cell 203, in Action 705 that is available to each of the at least one first cell, e.g. cell 203. In other words, the network node 110 divides the additional amount of DL TX power from the at least one second cell, e.g. cell 204, to the at least one first cell, e.g. cell 203.

Here, the network node 110 may also determine which cells that would benefit from and could use additional amount of DL TX power to transmit more downlink shared channel data in the TTI, and therefore should be comprised in the at least one first cell, e.g. cell 203. That is, the network node 110 may further determine the at least one first cell, e.g. cell 203, in which a downlink transmission of data in the TTI is able to favorably use more than the determined amount of DL TX power available to the at least one first cell, e.g. cell 203. The determination may, for example, be based on that the downlink transmission of data in the TTI for the at least one first cell, e.g. cell 203, is able to transmit more data with a determined level of QoS when using more than the determined amount of downlink transmission power available to the at least one first cell, e.g. cell 203. Alternatively, the determination may be based on that the downlink transmission of data in the TTI for the at least one first cell, e.g. cell 203, is able to transmit data with an higher level of Quality of Service, QoS, than a predetermined level of QoS when using more than the determined amount of downlink transmission power available the at least one first cell, e.g. cell 203. Also, the level of QoS may be determined as a target Block Error Rate, BLER, value.

In some embodiments, how much of the identified additional amount of DL TX power available to the at least one first cell, e.g. cell 203, that is available to each of the at least one first cell, e.g. cell 304, is determined by a weight parameter, β, or a set limit.

As described above, the cells that do not use all of its DL TX power, e.g. cell 204, will allow that part of its available DL TX power is shared with other cells that share the same power amplifier in the same network node 110, e.g. cell 203. The amount of DL TX power that may be available to and shared with the other cells, e.g. cell 203, may be determined by a weight parameter or variable β. The weight parameter or variable β may have a value between 0 and 1. Thus, the network node 110 may by, e.g. setting a suitable value of β, adjust how much of the DL TX power allocated to the cells that do not use all of its DL TX power, e.g. cell 204, that may be made available to and shared with the other cells, e.g. cell 203.

For example, if the network node 110 sets the weight parameter or variable to β=1, then all of the unused DL TX power allocated to the cells that do not use all of its DL TX power, e.g. cell 204, may be shared with the other cells, e.g. cell 203. According to another example, if the network node 110 sets the weight parameter or variable to β=0.5, then only half of the unused DL TX power allocated to the cells that do not use all of its DL TX power, e.g. cell 204, may be shared with the other cells, e.g. cell 203.

Here, it may be noted that there are reasons for not allowing all of the unused DL TX power that is allocated to the cells that do not use all of its DL TX power, e.g. cell 204, to be shared with the other cells, e.g. cell 203. For example, different cells, e.g. cells 203 and 204, may have different cell timings. This implies that one TTI of one cell, e.g. cell 203, will overlap with two TTIs of the other cell, e.g. cell 204. Thus, by only allowing that part of the unused DL TX power allocated to the cells that do not use all of its DL TX power, e.g. cell 204, may be shared with the other cells, e.g. cell 203, in a TTI, the network node 110 may guarantee that the cells, e.g. cell 204, that do not use all of its DL TX power (i.e. that shared its DL TX power with the other cells e.g. cell 203) will have a minimum guaranteed amount DL TX power available for its downlink shared channel transmissions.

Alternatively, the network node 110 may allow the cells that do not use all of its DL TX power, e.g. cell 204, to share a min(βP_HS,P_HS−P_HS,reserved) of its DL TX power. In this embodiment, a DL TX power value P_HS,reservedmay be reserved in the power sharing cells. Thus, for example, if the weight parameter or variable β is set to β=0.7, i.e. 70% of the unused DL TX power may be shared with other cells, and an absolute DL TX power value P_HS,reserved=4 W has been set as the minimum reserved DL TX power value in the sharing cells, then the minimum of these two DL TX powers values may indicate the DL TX power that is to be kept for the cell, while the rest of the unused DL TX power may be shared to other cells. This ensures that each of the cells that do not use all of its DL TX power, e.g. cell 204, will always have a power level, P_HS,reserved, available for their downlink shared channel transmissions.

Action 707

In this optional action, the network node 110 determines the at least one first cell, e.g. cell 203, that has been allocated a portion or share of the identified additional amount of DL TX power available to the at least one first cell, e.g. cell 203, as determined in Action 706.

Action 708

In this action, the network node 110 calculates, or determines, new DL TX powers available to the at least one first cell, e.g. cell 203, for their downlink shared channels in the TTI, i.e. the determined DL TX power available to the at least one first cell, e.g. cell 203, plus the identified additional amount of DL TX power available to the at least one first cell, e.g. cell 203, as determined in Action 706.

Action 709

In this action, the network node 110 schedules amounts of data that is to be transmitted in each of the at least one first cell, e.g. cell 203, according to the new DL TX powers available to the at least one first cell, e.g. cell 203. This means that the network node 110 schedules amounts of data that is to be transmitted in each of the at least one first cell, e.g. cell 203, for the determined DL TX power available to each of the at least one first cell, e.g. cell 203, and for the identified additional amount of downlink transmission power available to each of the at least one first cell, e.g. cell 203, respectively, as determined in Action 706. The network node 110 may perform Transport Format Resource Combination, TFRC, selection for the scheduled amount of data in each of the at least one first cell, e.g. cell 203, respectively.

Action 710

In this optional action, the network node 110 determines if there are any more cells than the at least one first cell, e.g. cell 203, that may benefit from and could use additional amount of DL TX power to transmit more downlink shared channel data in the TTI.

Further example of embodiments of a method performed by a network node 110 for determining amounts of downlink transmission power for a downlink shared channel to be used in a Transmission Time Interval, TTI, by cells 201-206 served by the network node 110 in a wireless telecommunications network 100, will now be described with reference to the flowchart depicted in FIG. 8. FIG. 8 is an illustrated example of actions or operations which may be taken by a network node 110. The method may comprise the following actions.

Action 801

In this optional action, the network node 110 determine the cells that may be able to share DL TX power with each other, i.e. the number of cells that are sharing the same power amplifier in the network node 110, e.g. cells 205, 206 in FIG. 2. This may also be previously determined or set in the network node 110.

Action 802

In this action, the network node 110 determines the DL TX power available to the cells, e.g. cells 205 and 206 in FIG. 2, for their downlink shared channels in the TTI. This is based on the DL TX power allocated in the cells to other downlink channels.

Action 803

Action 804

In this action, the network node 110 sums up all of the DL TX power available to the cells, e.g. cells 205 and 206, for their downlink shared channels in the TTI as determined in Action 802. This means that all of the DL TX powers for downlink shared channels in the TTI available to all cells sharing a power amplifier in a network node 110 may be added or summed into a common power pool in the network node 110.

Action 805

In this action, the network node 110 chooses or selects a user equipment in any of the cells sharing the power amplifier to schedule. This means that the network node 110 may, by using e.g. a downlink shared channel scheduler, determine the amounts of the DL TX powers in the common power pool that are allocated to the cells based on the user equipments therein. This may be performed based on e.g. a priority order of the downlink shared channel transmissions of user equipments in each of the cells, e.g. cells 205 and 206, according to which the user equipments are to be scheduled. This means that all of the DL TX powers in the common power pool may be allocated to one or more of the cells sharing the power amplifier in the network node 110 based on downlink shared channel transmissions of the specific user equipments.

An advantage with these embodiments is that the total DL TX power of the power amplifier in the network node 110 are allocated to the cells with the user equipments having the highest priority downlink shared channel transmissions. Also, in these embodiments, there is no need for the network node 110 to identify cells that do not use all its available DL TX power for its downlink shared channel transmissions as described with reference to the embodiments depicted in FIG. 7.

Thus, in these embodiments, the network node 110 may first determine DL TX power available to the cells, e.g. cells 205 and 206, for physical channels associated with the downlink shared channel based on the DL TX power allocated in the cells, e.g. cells 205 and 206, to physical channels associated with other downlink channels (as described in Action 802), and then determine, in this Action 804, an additional amount of DL TX power available to at least one first cell, e.g. cell 205, based on the determined DL TX power available to at least one second cell, e.g. cell 206. This is because the additional amount of DL TX power available to at least one first cell, e.g. cell 205, when based on the common power pool will be shared by the determined DL TX power available to at least one second cell, e.g. cell 206.

In these embodiments, the network node 110 also jointly schedules the user equipments in the at least one first cell, e.g. cell 205, and the at least one second cell, e.g. cell 206. In some embodiments, how much of the additional amount of DL TX power that is available to each of the at least one first cell, e.g. cell 205, is determined by a weight parameter or variable, γ, or a set limit.

Action 806

In this action, the network node 110 performs TFRC selection for the amount of data to be scheduled for the user equipment in the cells, e.g. cells 205, 206, that was selected in Action 805.

Action 807

In this action, the network node 110 checks, or determines, whether there is any DL TX power for downlink shared channel transmissions left in the common power pool in the network node 110. If yes, then the network node 110 will proceed to Action 808. If no, then the network node 110 has no more DL TX power for downlink shared channel transmissions to share.

Action 808

In this action, the network node 110 chooses or selects the next user equipment to schedule. This may comprise e.g. checking, or determining, whether there is any user equipment that is served by the network node 110 in the cells, e.g. cells 205 and 206, that has downlink shared channel data in its priority queues in the network node 110 and wherein the cells, e.g. cells 205 and 206, have channelization codes still available for the physical channels associated with the downlink shared channel.

To perform the method actions in the network node 110 for determining amounts of downlink transmission, DL TX, power for a downlink shared channel to be used in a TTI by cells, e.g. cells 201-206 in FIG. 2, served by the network node 110 in a wireless telecommunications network 100, the network node 110 may comprise the following arrangement depicted in FIG. 9. FIG. 9 shows a schematic block diagram of embodiments of a network node 110.

The network node 110 comprises a one or more downlink shared channel schedulers 931-936, which may also be referred to as schedulers, HS-DSCH or HS schedulers. The one or more downlink shared channel schedulers 931-936 may be comprised in one or more baseband units 930.

The one or more downlink shared channel schedulers 931-936 may be configured to first determine downlink transmission power available to the cells, e.g. cells 201-206 in FIG. 2, for physical channels associated with the downlink shared channel based on the DL TX power allocated in the cells to physical channels associated with other downlink channels, and then determine an additional amount of DL TX power available to at least one first cell, e.g. cell 201, based on the difference between the determined DL TX power available to at least one second cell, e.g. cell 202, and a DL TX power that is required for the amount of data that is to be transmitted in the at least one second cell, e.g. cell 202.

In some embodiments, the network node 110 may be configured, by using e.g. radio circuitry 950, to transmit a downlink transmission of data in the TTI in the at least one first cell, e.g. cell 201, on its physical channels associated with the downlink shared channel using the determined DL TX power available to the at least one first cell, e.g. cell 201, and the additional amount of DL TX power available to the at least one first cell, e.g. cell 201. In some embodiments, the one or more downlink shared channel schedulers 931-936 are configured to schedule the amount of data that is to be transmitted in the at least one second cell, e.g. cell 202, for the determined DL TX power available to a second cell, e.g. cell 202, and identify the additional amount of DL TX power available to the at least one first cell, e.g. cell 201, based on the difference between the determined DL TX power available to the at least one second cell, e.g. cell 202, and the DL TX power required for transmitting the scheduled amount of data.

In some embodiments, the one or more downlink shared channel schedulers 931-936 are configured to determine how much of the identified additional amount of DL TX power available to the at least one first cell, e.g. cell 201, that is available to each of the at least one first cell and to schedule amounts of data that is to be transmitted in each of the at least one first cell, e.g. cell 201, based on the determined DL TX power available to each of the at least one first cell and the determined identified additional amount of DL TX power available to each of the at least one first cell, e.g. cell 201, respectively.ln some embodiments, the one or more downlink shared channel schedulers 931-936 are configured to determine the at least one first cell, e.g. cell 201, in which a downlink transmission of data in the TTI is able to favorably use more than the determined amount of downlink transmission power available to the at least one first cell, e.g. cell 201.In some embodiments, the one or more downlink shared channel schedulers 931-936 are configured to determine how much of the identified additional amount of DL TX power available to the at least one first cell, e.g. cell 201, that is available to each of the at least one first cell by using a weight parameter β or a set limit.

In some embodiments, the one or more downlink shared channel schedulers 931-936 may be configured to sums up all of the DL TX power available to the cells, e.g. cells 205 and 206, for their downlink shared channels in the TTI. In this case, the one or more downlink shared channel schedulers 931-936 may also determine the amounts of the DL TX powers in the common power pool that are allocated to the cells based on the user equipments therein. This may be performed based on e.g. a priority order of the downlink shared channel transmissions of user equipments in each of the cells, e.g. cells 205 and 206, according to which the user equipments are to be scheduled.

The network node 110 may comprise a processing circuitry 910, which may also be referred to as a processor or a processing unit. The processing circuitry 910 may comprise the baseband unit 930 and the downlink shared channel schedulers 931-936.

The embodiments determining amounts of DL TX power for a downlink shared channel to be used in a TTI by cells, e.g. the cells 201-206 in FIG. 2, served by the network node 110 in a wireless telecommunications network 100, may be implemented through one or more processors, such as the processing circuitry 910 in the network node 110 depicted in FIG. 9, together with computer program code for performing the functions and actions of the embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code or code means for performing the embodiments herein when being loaded into the processing circuitry 910 in the network node 110. The computer program code may e.g. be provided as pure program code in the network node 110 or on a server and downloaded to the network node 110.

The network node 110 may further comprise a memory 920 comprising one or more memory units. The memory 920 may be arranged to be used to store data, such as, e.g. the DL TX power available to the cells for their downlink shared channels in the TTI and weight parameters, e.g. β and γ, or set limits, to perform the methods herein when being executed in the network node 110.

Those skilled in the art will also appreciate that the processing circuitry 910 and the memory 920 described above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in a memory, that when executed by the one or more processors such as the processing circuitry 910 perform as described above. One or more of these processors, as well as the other digital hardware, may be included in a single application-specific integrated circuit (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system-on-a-chip (SoC).

Furthermore, the network node 110 may also comprise one or more radio units 951, 952, 953, wherein each radio unit 951, 952, 953 comprises at least one power amplifier and one or more antennas. The one or more antennas may be used by the radio units 951, 952, 953 for transmitting downlink shared channel data to the served user equipments in the cells for which each of the radio units 951, 952, 953 are providing radio coverage, such as, e.g. the cells 201-202, 203-204, 205-206, in sector 111, 112, 113 in FIG. 2, respectively. The network node 110 may also comprise a radio circuitry 950, which may also be referred to as a radio or radio equipment. The radio circuitry 950 may comprise the radio units 951, 952, 953.

It should also be noted that although the embodiments herein are described such that all the cells that serve user equipments in the same cell area sector are handled by the same one or more downlink shared channel schedulers 931-936 in the same base band unit 930 and the same radio unit 951, 952, 953, i.e. same power amplifier, as depicted in FIG. 9, the embodiments are also applicable to other configuration or setups as well.

According to one example, as depicted in FIG. 10, the cells that serve user equipments in the same cell area sector may be handled by the same one or more downlink shared channel schedulers 1031-1036 in the same base band unit 1030, but different physical radio units 1051-1056 may be used by at least two of the cells, e.g. cells 201-202. In some embodiments, Virtual Antenna Mapper, VAM, precoders 1041-1046 may here be used in the network node 110 to provide a common “virtual” power amplifier that may comprise several transmission branches. The processing circuitry 1010, the memory 1020, the baseband unit 1030, and the radio circuitry 1050 in the network node 110 may be configured or adapted to handle this configuration or setup as well.

According to another example, as depicted in FIG. 11, the cells that serve user equipments in the same cell area sector may be handled by the different downlink shared channel schedulers 1131-1133 and 1141-1143, which may be located in different baseband units 1130 and 1140. The cells of the downlink shared channel, HS-DSCH, schedulers 1131-1133 and 1141-1143 may be interconnected via e.g. a Common Public Radio Interface, CPRI, and may be handled by the same radio unit 951, 952, 953, i.e. same power amplifier, respectively. The processing circuitry 1110, the memory 1120, the baseband units 1130 and 1140, and the radio circuitry 1150 in the network node 110 may be configured or adapted to handle this configuration or setup as well.

Further examples of different configurations or setups may also be considered, such as, e.g. various combinations of the examples above, and therefore these examples should not be construed as limiting to the embodiments described herein.

Furthermore, it should be noted that the downlink shared channel schedulers that identify the opportunities for the dynamic power sharing between cells as described in the embodiments above are implemented in the processing circuitry, e.g. processing circuitry 910, 1010, 1110, which means that there is no involvement of the radio units, e.g. the radio units 951-953, 1051-1056, 1151-1153, and that the decisions on whether or not to share power between cells may be taken by the downlink shared channel schedulers in the processing circuitry in the network node 110 as frequently as for every scheduling opportunity, i.e. for each TTI.

It should also be noted that while the embodiments above are described in the context of WCDMA/HSPA technology, the embodiments may also be adapted and applicable to other Radio Access Technologies, RATs, such as, e.g. Long Term Evolution—LTE, in which several cells or cell carriers share one or more power amplifiers, PAs.

As used herein, the term “and/or” comprises any and all combinations of one or more of the associated listed items. Further, as used herein, the common abbreviation “e.g.”, which derives from the Latin phrase “exempli gratia,” may be used to introduce or specify a general example or examples of a previously mentioned item, and is not intended to be limiting of such item. If used herein, the common abbreviation “i.e.”, which derives from the Latin phrase “id est,” may be used to specify a particular item from a more general recitation. The common abbreviation “etc.”, which derives from the Latin expression “et cetera” meaning “and other things” or “and so on” may have been used herein to indicate that further features, similar to the ones that have just been enumerated, exist. As used herein, the singular forms “a”, “an” and “the” are intended to comprise also the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes,” “comprises,” “including” and/or “comprising,” when used in this specification, specify the presence of stated features, actions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, actions, integers, steps, operations, elements, components, and/or groups thereof. Unless otherwise defined, all terms comprising technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the described embodiments belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The embodiments herein are not limited to the above described preferred embodiments. Various alternatives, modifications and equivalents may be used. Therefore, the above embodiments should not be construed as limiting.

A Network Node And Method Of Determining Amounts Of Downlink Transmission Power For Downlink Shared Channels In A Wireless Communications Network

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