Patent Description:
Spectrum sharing is a technology that enables wireless technology entities to exploit existing Long Term Evolution (LTE), also referred to as <NUM>th Generation (<NUM>), spectrum bands to transition to <NUM>th Generation (<NUM>) New Radio (NR) applications without the extra expenses of acquiring new <NUM> NR spectrum or <NUM> radio and baseband hardware. Spectrum sharing allows LTE and NR to concurrently coexist and share the spectrum in a single band with minimal impact on LTE performance.

There are several possible spectrum sharing techniques between NR and LTE radio access technologies (RATs) that can be adopted on a static frequency division multiplexing (FDM) or time division multiplexing (TDM) basis, as well as dynamic or instantaneous sharing on a TDM basis.

The spectrum sharing between LTE and NR transmissions is managed by avoiding the collision with LTE dedicated signals including Cell-specific reference signals (CRS), and sync block signals e.g., primary synchronization signals (PSS)/secondary synchronization signals (SSS). Spectrum sharing can be performed on a resource element (RE) level or on a symbol-resource block level.

RE level spectrum sharing may be used for rate matching around the always-transmitted CRS LTE signals. Meanwhile, symbol-resource block level may be used to block certain resource blocks, RBs, from colliding with dedicated LTE signals such as LTE PSS/SSS. These block-based patterns may be expressed by two bit maps; namely, a frequency domain bit map with granularity of one RB and a time domain bit map with granularity of one OFDM symbol.

Further, in LTE, there is the possibility of boosting the CRS power. A problem with power boosting is the danger of power over allocation of a radio unit (RU) at a node. There are two incidents/levels where the RU can be over-allocated in power, and the RF output power exceeds, for example, 40W (40W RU), on the symbol level (<NUM>) and in mean power over several subframes ≥ <NUM> level. At the symbol level, clipping of power peaks may occur in the RU, and the error vector magnitude (EVM) increases. In case of over-allocating mean power, the RU gets overheated, and the power amplifier saturates at a lower level, which negatively affects communication.

However, it may also be beneficial to utilize as much power as possible of the total RF power, for example, 40W, for transmission of physical channels since, theoretically, the capacity of a radio channel increases directly when the power per symbol is increased (Shannon's theorem). Therefore, the capacity of the channels could be increased if full power could be utilized.

When the power of the CRS is varying, there is a possibility to increase or decrease the power in the REs in the same symbol where the CRS is located. This corresponds to the PDSCH type B REs. The power of PDSCH type B REs can be varied according to the Third Generation Partnership Project (3GPP) parameter PB that specifies a power relation (pdschTypeBGain or PB /PA ) between PDSCH type A and PDSCH type B resources elements. The power is set relatively to the power level of the resource elements of PDSCH type A. The values may only be in the range crsGain= [<NUM>, <NUM><NUM>, <NUM>,<NUM>,-<NUM>,-<NUM>,-<NUM>] [dB]. For example, crsGain=<NUM> means that the CRS power is 3dB higher than the power of a resource element for PDSCH type A. PDSCH type A corresponds to REs within a symbol (<NUM>) that does not contain CRSs in the air interface.

A network node, such as an eNB, has to transmit the 3GPP parameters to the wireless device where the 3GPP parameters include the following:.

• <MAT>
• PB = (<NUM>-<NUM>) from table <NUM> below.

PB is a common cell parameter that is broadcasted in SIB2. PA = - crsGain is a dedicated wireless device parameter and is sent the first time in a RRCConnectionSetup message, and later in a.

RRCConnectionReconfiguration message. Also in the
RRCConnectionReestablishment message.

Normally PB is specified first by SIB2 and PA is determined by Table <NUM>, and may be specified later in a RRC message (e.g., RRC Connection Setup, RRC Connection Reconfiguration).

For the wireless device, the issues of over-allocation are not present, and P A only defines a power relation between CRS and PDSCH for demodulation purposes.

However, in LTE, one general guideline has been that all RE's for all types of physical channels have the same power = Pref = PA (reference level). In general, in order to boost or allow REs to deviate from the reference level, there must be empty REs with zero power such that other non-zero REs can get increased power without over-allocation on symbol level, i.e., the non-zero power REs can take the power that would have been used in the REs with zero power, i.e., empty REs. Empty REs occur when the number of TX antennas is ≥ <NUM>, when CRS is transmitted from neighboring antennas.

When the power of the CRS is varying, there is a possibility to increase or decrease the power in the REs in the same symbol where the CRS is located. This corresponds to the PDSCH type B REs. The power of these can be varied according to the 3GPP parameter PB that specifies a power relation (pdschTypeBGain) between PDSCH type A and PDSCH type B resources elements.

Decreasing the RE power of PDSCH type B, can be used to decrease over-allocation on symbol power or mean power for high CRS boost levels. Increasing the RE power of PDSCH type B can be used to improve power utilization for low boost levels.

With less than or equal <NUM> dB CRS power boost, the power is taken from the position where the CRS is blanked where the other antenna port is sending it. Thus, its moving it from one blank CRS position to another. With +<NUM> or +<NUM> dB power boost, there could be an issue as PDSCH PA or PB (as described in 3GPP Technical Specification <NUM> PDSCH-Config field descriptions) may have to be set lower. <FIG> is a diagram of serveral examples of various CRS gains for LTE CRS power boosting where over-allocation may occur.

In dynamic spectrum sharing (DSS), since the CRS is spread for the entire bandwidth, but LTE PDSCH type B is narrower such that spectrum is shared, LTE can no longer be counted on to balance the power budget. When a LTE assigns a low bandwidth (BW), but NR is assigned the rest of PDSCH, the LTE network node currently does not know about this NR borrowing of power such that power over-allocation may occur.

Another issue occurs when the CRS is boosted where over-allocation may occur on symbols where there are REs that do not belong to PDSCH type B, which are not scalable. This may occur in DSS in the region where NR PDSCH/PDCCH is scheduled instead of LTE PDSCH.

In one more case, when the NR PDSCH is boosted (e.g., uses full power over quarter BW in non-CRS symbols), there is much less power in CRS symbols where there should not be a NR PDSCH power reduction in non-CRS symbols.

Therefore, over-allocation in spectrum shared between two radio access technologies (RATs) is an issue that has not been addressed by existing systems owing to the lackof communications between RATs (e.g., between LTE and NR) regarding power modification. As a result, over-allocation may occur.

Patent application <CIT>proposes a method for improving interference co-ordination between different types of RAN nodes in a radio access network.

Some embodiments advantageously provide a method and system for power handling in spectrum sharing configurations between a first RAT and second RAT, according to the independent claims.

In legacy LTE, the CRS power boosting is managed according to the 3GPP parameter PB that specifies a power relation (pdschTypeBGain) between PDSCH type A and PDSCH type B resources elements. In a spectrum sharing solution between LTE and NR, LTE can no longer be counted on to balance the power budget and avoid power over-allocation in the radio, etc.. The present disclosure, in some embodiments, advantageously blanks a few PDSCH resource blocks (RBs) or even less than a RB in the shared NR region or applies a power back-off to allow scaling of the power of symbols that have CRS within them. The present disclosure, in some embodiments, advantageously allows scaling of the symbols that have CRS rate matching.

One or more of the following advantages may be provided by one or more of the embodiments described herein:.

The present disclosure provides, in some embodiments, a rule/formula/signaling that may reduce NR PDSCH power such as in CRS symbols in order to stay within a power budget.

Before describing in detail example embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to power handling in spectrum sharing configurations between a first RAT and second RAT. Accordingly, components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

The term "network node" used herein can be any kind of network node comprised in a radio network which may further comprise any of base station (BS), radio base station, base transceiver station (BTS), base station controller (BSC), radio network controller (RNC), g Node B (gNB), evolved Node B (eNB or eNodeB), Node B, multi-standard radio (MSR) radio node such as MSR BS, multi-cell/multicast coordination entity (MCE), integrated access and backhaul (IAB) node, relay node, donor node controlling relay, radio access point (AP), transmission points, transmission nodes, Remote Radio Unit (RRU) Remote Radio Head (RRH), a core network node (e.g., mobile management entity (MME), self-organizing network (SON) node, a coordinating node, positioning node, MDT node, etc.), an external node (e.g., 3rd party node, a node external to the current network), nodes in distributed antenna system (DAS), a spectrum access system (SAS) node, an element management system (EMS), etc. The network node may also comprise test equipment. The term "radio node" used herein may be used to also denote a wireless device (WD) such as a wireless device (WD) or a radio network node.

The WD may also be a radio communication device, target device, device to device (D2D) WD, machine type WD or WD capable of machine to machine communication (M2M), low-cost and/or low-complexity WD, a sensor equipped with WD, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer Premises Equipment (CPE), an Internet of Things (IoT) device, or a Narrowband IoT (NB-IOT) device, first RAT (e.g., <NUM> or NR) enabled wireless device, second RAT (e.g., LTE) enabled wireless device, dual connectivity wireless device (i.e., wireless device enabled with both the first RAT and second RAT), etc..

References herein to an NR wireless device refer to a wireless device engaging in or configured to engage in communication with a network node using the 3GPP NR wireless communication standard. References herein to an LTE wireless device refer to a wireless device engaging in or configured to engage in communication with a network node using the 3GPP LTE wireless communication standard. References herein to a first RAT network node refer to a network node engaging in or configured to engage in communication with another network element using a first RAR. References herein to a second RAT network node refer to a network node engaging in or configured to engage in communication with another network element using a second RAT. The second RAT may be different from the first RAT.

Some embodiments provide power handling in spectrum sharing configurations between a first RAT and second RAT.

Referring again to the drawing figures, in which like elements are referred to by like reference numerals, there is shown in <FIG> a schematic diagram of a communication system <NUM>, according to an embodiment, such as a 3GPP-type cellular network that supports standards such NR (<NUM>, a first RAT) and LTE (i.e., a second RAT) such as for spectrum sharing among the two RATs, which comprises an access network <NUM>, such as a radio access network, and a core network <NUM>. The access network <NUM> comprises a plurality of network nodes 16a, 16b, 16c (referred to collectively as network nodes <NUM>), such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 18a, 18b, 18c (referred to collectively as coverage areas <NUM>). In some embodiments, network node 16a is a first RAT network node <NUM> and network node 16b is a second RAT network node 16b. Each network node 16a, 16b, 16c is connectable to the core network <NUM> over a wired or wireless connection <NUM>. A first wireless device (WD) 22a located in coverage area 18a is configured to wirelessly connect to, or be paged by, the corresponding network node 16a. A second WD 22b in coverage area 18b is wirelessly connectable to the corresponding network node 16b. While a plurality of WDs 22a, 22b (collectively referred to as wireless devices <NUM>) are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole WD is in the coverage area or where a sole WD is connecting to the corresponding network node <NUM>. Note that although only two WDs <NUM> and three network nodes <NUM> are shown for convenience, the communication system may include many more WDs <NUM> and network nodes <NUM>.

As an example, WD <NUM> can be in communication with an eNB, i.e., a second RAT network node <NUM>, for LTE/E-UTRAN and a gNB, i.e., a first RAT network node, for NR/NG-RAN.

Connections between various entities in system <NUM> may extend via an optional intermediate network <NUM>.

A network node 16a, for example, is configured to include a power handling unit <NUM> which is configured to perform one or more network node <NUM> functions as described herein such as with respect to power handling in spectrum sharing configurations between a first RAT and second RAT. A network node 16b, for example, is configured to include a reference signal unit <NUM> which is configured to perform one or more network node <NUM> functions as described herein such as with respect to power handling in spectrum sharing configurations between a first RAT and second RAT.

Example implementations, in accordance with an embodiment, of the WD <NUM> and network node <NUM> discussed in the preceding paragraphs will now be described with reference to <FIG>. The communication system <NUM> includes a network node 16a provided in a communication system <NUM> and including hardware <NUM> enabling it to communicate with WD <NUM> and other network nodes <NUM>. In some embodiments, network node 16a is an NR network node <NUM>, i.e., a network node <NUM> that operates or is configured to operate using the 3GPP communication standard The hardware <NUM> may include a communication interface <NUM> for setting up and maintaining a wired or wireless connection with an interface of a different communication entities of the communication system <NUM>, as well as a radio interface <NUM> for setting up and maintaining at least a wireless connection with a WD <NUM> located in a coverage area <NUM> served by the network node 16a. The communication interface <NUM> may be configured to facilitate a connection one or more entities in system <NUM> such as another network node <NUM> via a backhaul link. The connection may be direct or it may pass through a core network <NUM> of the communication system <NUM> and/or through one or more intermediate networks <NUM> outside the communication system <NUM>.

In the embodiment shown, the hardware <NUM> of the network node 16a further includes processing circuitry <NUM>.

Thus, the network node 16a further has software <NUM> stored internally in, for example, memory <NUM>, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the network node 16a via an external connection. The processing circuitry <NUM> may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by network node 16a. Processor <NUM> corresponds to one or more processors <NUM> for performing network node 16a functions described herein. The memory <NUM> is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software <NUM> may include instructions that, when executed by the processor <NUM> and/or processing circuitry <NUM>, causes the processor <NUM> and/or processing circuitry <NUM> to perform the processes described herein with respect to network node 16a. For example, processing circuitry <NUM> of the network node 16a may include power handling unit <NUM> that is configured to perform one or more network node 16a functions as described herein. In one or more embodiments, network node 16a is a NR network node <NUM>.

The communication system <NUM> includes a network node 16b provided in a communication system <NUM> and including hardware and software as described with respect to network node 16a. However, in one or more embodiments, processing circuitry <NUM> of the network node 16b may include reference signal unit <NUM> that is configured to perform one or more network node 16b functions as described herein. In one or more embodiments, network node 16b is a LTE network node <NUM>, i.e., a network node <NUM> that operates or is configured to operate using the 3GPP communication standard.

The WD <NUM> may have hardware <NUM> that may include a radio interface <NUM> configured to set up and maintain a wireless connection with a network node <NUM> serving a coverage area <NUM> in which the WD <NUM> is currently located.

The processing circuitry <NUM> may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by WD <NUM>. The processor <NUM> corresponds to one or more processors <NUM> for performing WD <NUM> functions described herein. The WD <NUM> includes memory <NUM> that is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software <NUM> may include instructions that, when executed by the processor <NUM> and/or processing circuitry <NUM>, causes the processor <NUM> and/or processing circuitry <NUM> to perform the processes described herein with respect to WD <NUM>.

In some embodiments, the inner workings of the network node <NUM> and WD <NUM> may be as shown in <FIG> and independently, the surrounding network topology may be that of <FIG>.

Although <FIG> and <FIG> show various "units" such as power handling unit <NUM> and reference signal unit <NUM> as being within a respective processor, it is contemplated that these units may be implemented such that a portion of the unit is stored in a corresponding memory within the processing circuitry. In other words, the units may be implemented in hardware or in a combination of hardware and software within the processing circuitry. In one or more embodiments, the functionality of first RAT network node 16a and second RAT network node 16b may be performed by a single network node <NUM> configured to provide communications in both RAT types.

<FIG> is a flowchart of an example process in a network node 16a for power handling in spectrum sharing configurations between a first RAT and second RAT. One or more blocks described herein may be performed by one or more elements of network node 16a such as by one or more of processing circuitry <NUM>, processor <NUM>, radio interface <NUM>, power handling unit <NUM> and/or communication interface <NUM>. Network node <NUM> such as via processing circuitry <NUM> and/or processor <NUM> and/or radio interface <NUM> and/or power handling unit <NUM> and/or communication interface <NUM> is configured to determine (Block S100) whether an estimated power for first RAT transmission on at least one resource element, RE, in a spectrum shared by the first RAT network node 16a and second RAT network node 16b allows for an estimated mean power for the shared spectrum to meet a predefined criterion, as described herein. Network node <NUM> such as via processing circuitry <NUM> and/or processor <NUM> and/or radio interface <NUM> and/or power handling unit <NUM> and/or communication interface <NUM> is configured to perform (Block S102) at least one action based at least in part on the determination whether the estimated mean power for the shared spectrum meets the predefined criterion, as described herein.

According to one or more embodiments, the at least one action corresponds to indicating at least one power value associated with the estimated mean power for the shared spectrum where the indication of the at least one power value is based at least on the predefined criterion being met, as described herein. According to one or more embodiments, the at least one action includes modifying an estimated power for first RAT transmission on at least one resource element, RE, in a spectrum shared by the first RAT network node 16a and second RAT network node 16b where the modified estimated power for first RAT transmission allows the estimated mean power for the spectrum shared by the first RAT network node 16a and the second RAT network node 16b to meet the predefined criterion. The at least one action further includes causing first RAT transmission according to the modified estimated power.

According to one or more embodiments, the at least one action includes modifying the estimated power of at least a subset of symbols for first RAT transmission. According to one or more embodiments, the modifying of the estimated power for first RAT transmission includes one of decreasing resource element, RE, power for first RAT transmission to compensate for a cell-specific reference signals, CRS, gain level, and increasing RE power for first RAT transmission by using unused power in at least one RE in the shared spectrum. According to one or more embodiments, the at least one action includes modifying the estimated power includes lowering the estimated power for first RAT transmission.

According to one or more embodiments, the at least one action includes rate matching a physical downlink shared channel, PDSCH, associated with the first RAT network node 16a with REs associated with the second RAT network node 16b. According to one or more embodiments, the at least one action includes blanking at least one resource block, RB, symbol, RBS, in a RB in the spectrum shared by the first RAT network node 16a and the second RAT network node 16b. According to one or more embodiments, the processing circuitry <NUM> is further configured to prevent scheduling data transmission on the at least one RBS in the RB to perform the blanking. According to one or more embodiments, the at least one action includes reducing a power per resource element, RE, over a first plurality of REs associated with the first RAT network node 16a. A power per RE over a second plurality of REs associated with the second RAT network node 16b is reduced.

According to one or more embodiments, an amount of overall power reduced by the reduction of the power per RE over the first and second plurality of REs is at least one of less than and equal to <NUM> dB. According to one or more embodiments, the at least one action is configured to allow for a cell-specific reference signals, CRS, gain for a RE carrying CRS to be above a threshold. According to one or more embodiments, a power level for second RAT transmission in the spectrum shared by the first RAT network node 16a and second RAT network node 16b is fixed at a reference power level.

According to one or more embodiments, the spectrum shared by the first RAT network node 16a and second RAT network node 16b includes dedicated signaling for the second RAT network node 16b. According to one or more embodiments, the dedicated signaling corresponds to cell-specific reference signals, CRS. According to one or more embodiments, the processing circuitry <NUM> is further configured to receive a plurality of second RAT parameters associated with the estimated mean power for the spectrum shared by the first RAT network node 16a and second RAT network node 16b. The at least one action includes modifying the estimated power based on the plurality of second RAT parameters.

According to one or more embodiments, the plurality of second RAT parameters includes: a first parameter that specifies a power relation between a first type of physical downlink shared channel, PDSCH, resources and a second type of PDSCH resources, and a second parameter that specifies a reference power level for the second type of PDSCH resources. According to one or more embodiments, the first RAT transmission corresponds to physical downlink shared channel, PDSCH, transmission on a first type of PDSCH resources where the second RAT transmission corresponds to PDSCH transmission on a second type of PDSCH resources. According to one or more embodiments, the predefined criterion includes a maximum mean power limit where the predefined criterion is met based on a mean power being less than or equal to the maximum mean power limit.

<FIG> is a flowchart of an example process in a network node 16b related to power handling in spectrum sharing configurations between a first RAT and second RAT. One or more blocks described herein may be performed by one or more elements of network node 16a such as by one or more of processing circuitry <NUM>, processor <NUM>, radio interface <NUM>, reference signal unit <NUM> and/or communication interface <NUM>. Network node <NUM> such as via processing circuitry <NUM> and/or reference signal unit <NUM> and/or processor <NUM> and/or radio interface <NUM> and/or communication interface <NUM> is configured to optionally cause transmission (Block S104) of values for a plurality of parameters associated related to power handling in a shared spectrum, as described herein. For example, the second RAT network node 16b may communicate parameters such as PB and/or PA to the first RAT network node 16a in order for the first RAT network node 16a to determine whether and/or how to modify power and/or to communicate these parameters to the first RAT wireless device <NUM>. Network node <NUM> such as via processing circuitry <NUM> and/or reference signal unit <NUM> and/or processor <NUM> and/or radio interface <NUM> and/or communication interface <NUM> is configured to optionally reduce (Block S106) at least one value for at least one of the plurality of parameters to avoid power over-allocation, as described herein.

In one or more embodiments, the plurality of parameters includes PA and PB, and/or the plurality of parameters may be transmitted to the first RAT network node 16a.

Having generally described arrangements for power handling in spectrum sharing configurations between a first RAT and second RAT, details for these arrangements, functions and processes are provided as follows, and which may be implemented by network nodes <NUM>, e.g., network node 16a and network node 16b. In particular, one or more embodiments described herein provides coordination between a first RAT network node 16a (e.g., NR gNB) and a second RAT network node 16b (e.g., LTE eNb) where the second RAT network node 16b may communicate a plurality of second RAT parameters or power related parameters such as PB and PA to the first RAT network node 16a. In one or more embodiments, one or more of the parameters may indicate CRS power boost such that the first RAT network node 16a may perform power modification based on the indicated CRS power boost. The first RAT network node 16a may use these value for dynamic power modification and/or may communicate these values to a NR wireless device <NUM>, for example.

Several methods are described herein and relate to:.

The various methods may be performed by first RAT network node 16a and/or second RAT network node 16b.

This is currently no definitive method in the 3GPP NR standard to manage the power allocation in a similar manner as is performed in networks operated using the 3GPP LTE standard. In particular, in one or more embodiments, the power values (also referred to as power parameters, RAT parameters, parameters and/or values) are communicated to the first RAT network node 16a, which may then be communicated to the NR wireless devices <NUM> (which may be a feature that may be added to the 3GPP standard), which can be performed through coordination between a first RAT network node (e.g., gNB) and second RAT network node 16b (e.g., eNB).

When assigning NR PDSCH in the region of LTE CRS, the first RAT (e.g., first RAT network node 16a) may skip the CRS resource elements and assign NR PDSCH around them to avoid collisions of NR PDSCH and LTE CRS. RE-Level rate matching pattern may be used based on 3GPP TS <NUM>. <NUM> of <NUM> v15.

In one or more embodiments, DSS may benefit from this coordination between the first RAT network node 16a and second RAT network node 16b, as described herein. When NR wireless device <NUM> is configured with CRS pattern, i.e., WD <NUM> is configured in RRCReconfiguration with LTE CRS rate matching that make NR wireless devices <NUM> aware of LTE CRS for the purpose of NR PDSCH rate matching (instead of puncturing), the first RAT network node 16a such as by one or more of processing circuitry <NUM>, processor <NUM>, radio interface <NUM> and/or power handling unit <NUM> and/or communication interface <NUM> can also get the values of PA, PB that LTE wireless devices <NUM> are configured with and adapt the NR REs power values accordingly in the NR part of the spectrum where CRSs coexist, i.e., the first RAT network node 16a is able to perform power modification for the first RAT wireless device <NUM> using values communicated to it by the second RAT network node 16b. In one or more embodiments, the second RAT network node 16b (i.e., LTE eNB) can to lower the values of PA, PB to levels that avoid the power over-allocation per symbol/and or mean power, where, for example, these lowered/reduced values may be communicated to the first RAT network node 16a.

In one or more embodiments, it is sufficient to look at the following to determine whether power over-allocation exist or may occur:.

In case LTE is operating or is configured to operate without power overallocation with, for example, crsGain=<NUM> dB within the overlapping BW between LTE and NR, the power values may still need to be communicated to the NR wireless devices <NUM> such as by one or more of processing circuitry <NUM>, processor <NUM>, radio interface <NUM> and/or power handling unit <NUM> and/or communication interface <NUM> to avoid any power over-allocation.

In this case, the energy in all empty REs caused by RS transmitted on other antennas is used. The empty REs in SSS/PSS symbols and the second symbol in PBCH corresponds to the power PREF*(<NUM> subframes*<NUM> [Pref]+<NUM>[RB]*<NUM> Pref)/<NUM>= <NUM> [W], and added to PMEAN result in a total mean power of <NUM>+<NUM>=<NUM>[W]. Example <NUM> is illustrated in <FIG>.

In case of crsGain=<NUM>, <NUM>, <NUM> dB, there will be power overallocation in some cases of pdschTypeBGain e.g., <NUM>/<NUM> etc. Below some examples:.

In particular, in <FIG>, if the PB, PA values are coordinated with the first RAT, and the level of power of NR PDSCH REs can be reduced to avoid the over-allocation while still using the crs power boost of pdschTypeBGain =<NUM>/<NUM>. In another example, this pdschTypeBGain is lowered to for instance pdschTypeBGain = <NUM>/<NUM>.

In another example, crsGain=<NUM>. 0dB with pdschTypeBGain=<NUM>/<NUM>. This will cause over allocation in all PDSCH type B symbols and PMEAN= <NUM> W. Coordination of the second RAT network node 16b with the first RAT network node 16a may help avoid this coordination by reducing PDSCH type B to one such as to lead to full allocation in PDSCH type B symbols.

In another example, to fully utilize the power, if crsGain=0dB, -1dB, -2dB, - 3dB, pdschTypeBGain=<NUM>/<NUM> can be used to get maximum utilization and there will still be a gap to boost the NR PDSCH REs both within the symbols that have CRS as well as symbols without CRS.

In other words, since the coordination between the first RAT and the second RAT exists in 3GPP for CRS rate matching, the disclosure advantageously adds new functionality to this coordination to communicate parameters such as LTE parameters PB, PA and also helps avoid power over-allocation in DSS such as based on the communicated parameters, which may indicate CRS power boost, if any.

In case of non-capable wireless devices <NUM>, i.e., early wireless devices may not be equipment with one or more of the functions described herein, some PRBs may be blanked to reduce overall power allocation, which leads us to the second method, i.e., Method <NUM>.

The power is equally distributed among REs and is dependent on the BW of the channel. The number of RBs in NR is larger than number of RBs in LTE for same channel bandwidth, e.g., in <NUM> BW, number of RBs in LTE is <NUM> while in NR the number of RBs is <NUM>. Then there are extra two RBs in NR that do not have CRS in them. This may also need to be accounted for when balancing the power per symbol in DSS.

In order to help avoid increasing signaling and help reduce the complexity of exchanging info between the first RAT and second RAT, PRB blanking may be used such as by the first RAT network node 16a, i.e., one or more RBs are kept blank to balance the power and avoid overallocation with the need to account for LTE in order to know the exact CRS power boost or PDSCH REs powers. There is a tradeoff between NR spectral efficiency and reducing signaling and protecting LTE as a higher priority.

PDSCH resource mapping with RB symbol level granularity may be used and may be based on 3GPP TS <NUM><NUM>. In particular, certain RBS are blanked to avoid power overflow. The RRC message is described in 3GPP TS <NUM><NUM>. In this case, the whole RB may not need to be blanked such that a small part or subset or portion of the RB may be blanked based on amount of the overflow of the power. This can be calculated based on the channel BW used in the DSS cell.

In one or more embodiments, the RB blanking is performed through the NR scheduler at the first RAT network node 16a by not scheduling any data in certain RB based on the available BW especially is there is coordination between LTE and NR schedulers in DSS.

As described in some of the previous examples, when there is a small delta between the second RAT (i.e., LTE) and the first RAT (i.e., NR) overall power allocation, one method may be to reduce the overall power by decreasing the power per resource element (REs) slightly over all REs in both the first RAT and second RAT. The amount of power reduce should be small or minimal amounts as indicated in the previous examples of about <NUM>-<NUM> dB from the overall total power. In one or more embodiments, the amount is equal to the (number of LTE RBs/number of NR RBs). Further, in one or more embodiments, the downlink allocation of PRBs may be split <NUM>-<NUM>% in <NUM> bandwidth in a non-MBSFN subframe as illustrated in <FIG>.

Therefore, in one or more embodiments, spectrum sharing between a first RAT (i.e., LTE) and a second RAT (i.e., NR) is provided where the power budget is kept within the limit in order to help prevent over-allocation of mean power and per symbol power that may cause radio overheating and EVM. One or more embodiments may be performed through one or more of NR RB blanking, power back-off, and signaling between LTE and NR for coordination between the two RATs such as via the signaling of parameters, for example.

Claim 1:
A method implemented by a first radio access technology, RAT, network node (16a), for spectrum sharing with a second RAT network node (16b), the method comprising:
determining whether an estimated power for first RAT transmission on at least one resource element, RE, in a spectrum shared by the first RAT network node (16a) and second RAT network node (16b) allows for an estimated mean power for the shared spectrum to meet a predefined criterion; and
performing at least one action based at least in part on the determination whether the estimated mean power for the shared spectrum meets the predefined criterion,
wherein:
- the at least one action is configured to allow for a cell-specific reference signals, CRS, gain for a RE carrying CRS to be above a threshold; and
- the at least one action includes reducing a power per resource element, RE, over a first plurality of REs associated with the first RAT network node (16a); and a power per RE over a second plurality of REs associated with the second RAT network node (16b) being reduced.