WO2018129700A1

WO2018129700A1 - Power allocation for data channel and reference signals

Info

Publication number: WO2018129700A1
Application number: PCT/CN2017/071061
Authority: WO
Inventors: Bo Chen; Chao Wei; Yu Zhang; Xiaohui Liu
Original assignee: Qualcomm Incorporated
Priority date: 2017-01-13
Filing date: 2017-01-13
Publication date: 2018-07-19

Abstract

Certain aspects of the present disclosure relate to methods and apparatus for power allocation for data channel and User Equipment (UE) specific reference signal.

Description

POWER ALLOCATION FOR DATA CHANNEL AND REFERENCE SIGNALS

INTRODUCTION

Aspects of the present disclosure relate to wireless communications systems and, more particularly, to techniques for power allocation for data channel and User Equipment (UE) specific reference signal.

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power) . Examples of such multiple-access technologies include Long Term Evolution (LTE) systems, code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

A wireless communication network may include a number of Node Bs that can support communication for a number of user equipments (UEs) . A UE may communicate with a Node B via the downlink and uplink. The downlink (or forward link) refers to the communication link from the Node B to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the Node B.

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of an emerging telecommunication standard is new radio (NR, e.g., 5G radio access (RA) ) . NR is a set of enhancements to the LTE mobile standard promulgated by Third Generation Partnership Project (3GPP) . It is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards using OFDMA with a cyclic prefix (CP) on the downlink (DL) and on the uplink (UL) as well as support beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in NR technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

SUMMARY

The systems, methods, and devices of the disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of this disclosure as expressed by the claims which follow, some features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description” one will understand how the features of this disclosure provide advantages that include improved communications between access points and stations in a wireless network.

Certain aspects of the present disclosure provide a method for wireless communications by a Base Station (BS) . The method generally includes determining a ratio between Energy Per Resource Element (EPRE) corresponding to Demodulation Reference Signal (DMRS) and EPRE corresponding to Physical Downlink Shared Channel (PDSCH) for a UE, determining, for the UE, a transmission power corresponding to each DMRS port in a plurality of resources across a system bandwidth based at least on the corresponding determined ratio, and transmitting on each DMRS port based on the corresponding determined transmission power.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects.

FIG. 1 is a block diagram conceptually illustrating an example telecommunications system, according to aspects of the present disclosure.

FIG. 2 is a block diagram conceptually illustrating an example downlink frame structure in a telecommunications system, according to aspects of the present disclosure.

FIG. 2A shows another exemplary transmission timeline 200a that may be used in a TDD system in which one or more aspects of the present disclosure may be practiced.

FIG. 3 is a diagram illustrating an example uplink frame structure in a telecommunications system, according to aspects of the present disclosure.

FIG. 4 is a block diagram conceptually illustrating a design of an example Node B and user equipment (UE) , according to aspects of the present disclosure.

FIG. 5 illustrates a typical DMRS structure across two different PRBs, in accordance with certain aspects of the present disclosure.

FIG. 6 illustrates a 1-symbol DMRS structure using comb 4, in accordance with certain aspects of the present disclosure.

FIG. 7 illustrates a NR MU-MIMO DMRS structure across multiple PRBs, in accordance with certain aspects of the present disclosure.

FIG. 8 illustrates example operations that may be performed by a Base Station (BS) for maintaining a consistent ratio between DMRS and PDSCH EPREs for a UE, in accordance with certain aspects of the present disclosure.

FIG. 9 illustrates an example DMRS structure across multiple PRBs where muted DMRS ports are not used for data transmission and the power corresponding to the muted DMRS ports is used for the remaining scheduled DMRS ports, in accordance with certain aspects of the present disclosure.

FIG. 10 illustrates an example DMRS structure across multiple PRBs where unused DMRS ports reused for data transmission, in accordance with certain aspects of the present disclosure.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized on other aspects without specific recitation.

DETAILED DESCRIPTION

For Multi-User (MU) MIMO transmissions in Transmission Mode (TM) 9 or TM 10, multiple data streams are transmitted from different UEs simultaneously from multiple transmit antennas with different precoders. Generally, all these data streams share the Node B’s transmission power. Further, multiple orthogonal UE-specific reference signal ports (e.g., DMRS ports) are multiplexed by Code Division Multiplexing (CDM) (e.g., Orthogonal Cover Code (OCC) -2 and OCC-4) . Each DMRS port is generally associated with one data stream and all DMRS ports share the NodeB’s transmission power. A Node B generally transmits DMRS with the same Power Spectral Density (PSD) on DMRS Resource Elements (REs) in different subbands/Physical Resource Blocks (PRBs) . Each UE may generally assume that a ratio between Energy Per Resource Element (EPRE) corresponding to PDSCH and EPRE corresponding to DMRS is constant (e.g., 0 dB) across the system bandwidth, since the number of DMRS ports and the number of multiplexed data streams is always identical in MU-MIMO transmissions.

In certain aspects, for MU-MIMO transmission in NR MIMO, different multi-user pairing hypotheses may be scheduled in different PRBs/subbands and the ratio between PDSCH and DMRS EPREs may be different across PRBs/subbands for a particular UE. In this case, the Node B may need to indicate to the UE, the PDSCH EPRE to DMRS EPRE ratios for each PRB/subband to maintain acceptable demodulation performance, which will require prohibitive signaling overhead.

Certain aspects of the present disclosure discuss techniques for maintaining the ratio between PDSCH and DMRS EPREs consistent (e.g., substantially constant) in NR MIMO for each UE with little or no additional overhead.

For example, a Base Station (BS) determines a ratio between EPRE corresponding to DMRS and EPRE corresponding to PDSCH for a UE. The BS then determines, for the UE, a transmission power corresponding to each DMRS port in a plurality of resources across a system bandwidth based at least on the corresponding determined ratio and transmits on each DMRS port based on the corresponding determined transmission power.

Various aspects of the disclosure are described more fully hereinafter with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

The word “exemplary” is used herein to mean “serving as an example, instance, or illustration. ” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects.

Although particular aspects are described herein, many variations and permutations of these aspects fall within the scope of the disclosure. Although some benefits and advantages of the preferred aspects are mentioned, the scope of the disclosure is not intended to be limited to particular benefits, uses, or objectives. Rather, aspects of the disclosure are intended to be broadly applicable to different wireless technologies, system configurations, networks, and transmission protocols, some of which are illustrated by way of example in the figures and in the following description of the preferred aspects. The detailed description and drawings are merely illustrative of the disclosure rather than limiting and the scope of the disclosure is being defined by the appended claims and equivalents thereof.

The techniques described herein may be used for various wireless communication networks such as LTE, CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other networks. The terms “network” and “system” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA) , cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM) . An OFDMA network may implement a radio technology such as NR (e.g. 5G RA) , Evolved UTRA (E-UTRA) , Ultra Mobile Broadband (UMB) , IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS) . NR is an emerging wireless communications technology under development in conjunction with the 5G Technology Forum (5GTF) . 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-Aand GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP) . cdma2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2) . The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies.

For clarity, while aspects may be described herein using terminology commonly associated with 3G and/or 4G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as 5G and later, including NR technologies.

New radio (NR) may refer to radios configured to operate according to a new air interface (e.g., other than Orthogonal Frequency Divisional Multiple Access (OFDMA) - based air interfaces) or fixed transport layer (e.g., other than Internet Protocol (IP)) . NR may include Enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g., 80 MHz beyond) , millimeter wave (mmW) targeting high carrier frequency (e.g., 60 GHz) , massive MTC (mMTC) targeting non-backward compatible MTC techniques, and mission critical targeting ultra reliable low latency communications (URLLC) . For these general topics, different techniques are considered, such as coding, low-density parity check (LDPC) , and polar codes. NR cell may refer to a cell operating according to the new air interface or fixed transport layer. A NR Node B (e.g., 5G Node B) may correspond to one or multiple transmission reception points (TRPs) .

NR cells can be configured as access cell (ACells) or data only cells (DCells) . For example, the RAN (e.g., a central unit or distributed unit) can configure the cells. DCells may be cells used for carrier aggregation or dual connectivity, but not used for initial access, cell selection/reselection, or handover. In some cases, DCells may not transmit synchronization signals—in some cases DCells may transmit SS. TRPs may transmit downlink signals to UEs indicating the cell type. Based on the cell type indication, the UE may communicate with the TRP. For example, the UE may determine TRPs to consider for cell selection, access, handover, and/or measurement based on the indicated cell type.

In some cases, the UE can receive measurement configuration from the RAN. The measurement configuration information may indicate ACells or DCells for the UE to measure. The UE may monitor/detect measurement reference signals from the cells based on measurement configuration information. In some cases, the UE may blindly detect MRS. In some cases the UE may detect MRS based on MRS-IDs indicated from the RAN. The UE may report the measurement results.

EXAMPLE WIRELESS COMMUNICATIONS SYSTEM

FIG. 1 illustrates an example wireless network 100 in which aspects of the present disclosure may be performed. For example, the wireless network may be new radio (NR) or 5G network. In certain aspects, a Base Station (BS) (e.g., Node B 110) may determine a ratio between EPRE corresponding to DMRS and EPRE corresponding to PDSCH for a UE. The BS may then determine, for the UE, a transmission power corresponding to each DMRS port in a plurality of resources across a system bandwidth based at least on the corresponding determined ratio, and may transmit on each DMRS port based on the corresponding determined transmission power.

Each of the Node Bs 110 may be configured to perform the operations 800 of FIG. 8. Furthermore, the Node Bs 110 and the UEs 120 may be configured to perform other aspects described for power allocation of data channel and UE specific reference signal.

The system illustrated in FIG. 1 may be, for example, a long term evolution (LTE) network. The wireless network 100 may include a number of Node Bs (e.g., eNodeBs, eNBs, 5G Node B, etc) 110 and other network entities. A Node B may be a station that communicates with the UEs and may also be referred to as a base station, an access point, or a 5G Node B.

Each Node B 110 may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of an Node B and/or an Node B subsystem serving this coverage area, depending on the context in which the term is used.

A Node B may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cell. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG) , UEs for users in the home, etc. ) . A Node B for a macro cell may be referred to as a macro Node B. A Node B for a pico cell may be referred to as a pico Node B. A Node B for a femto cell may be referred to as a femto Node B or a home Node B. In the example shown in FIG. 1, the

Node Bs

110a, 110b and 110c may be macro Node Bs for the

macro cells

102a, 102b and 102c, respectively. The Node B 110x may be a pico Node B for a pico cell 102x. The Node Bs 110y and 110z may be femto Node Bs for the

femto cells

102y and 102z, respectively. A Node B may support one or multiple (e.g., three) cells.

The wireless network 100 may also include relay stations. A relay station is a station that receives a transmission of data and/or other information from an upstream station (e.g., a Node B or a UE) and sends a transmission of the data and/or other information to a downstream station (e.g., a UE or a Node B) . A relay station may also be a UE that relays transmissions for other UEs. In the example shown in FIG. 1, a relay station 110r may communicate with the Node B 110a and a UE 120r in order to facilitate communication between the Node B 110a and the UE 120r. A relay station may also be referred to as a relay Node B, a relay, etc.

The wireless network 100 may be a heterogeneous network that includes Node Bs of different types, e.g., macro Node Bs, pico Node Bs, femto Node Bs, relays, transmission reception points (TRPs) , etc. These different types of Node Bs may have different transmit power levels, different coverage areas, and different impact on interference in the wireless network 100. For example, macro Node Bs may have a high transmit power level (e.g., 20 Watts) whereas pico Node Bs, femto Node Bs and relays may have a lower transmit power level (e.g., 1 Watt) .

The wireless network 100 may support synchronous or asynchronous operation. For synchronous operation, the Node Bs may have similar frame timing, and transmissions from different Node Bs may be approximately aligned in time. For asynchronous operation, the Node Bs may have different frame timing, and transmissions from different Node Bs may not be aligned in time. The techniques described herein may be used for both synchronous and asynchronous operation.

A network controller 130 may couple to a set of Node Bs and provide coordination and control for these Node Bs. The network controller 130 may communicate with the Node Bs 110 via a backhaul. The Node Bs 110 may also communicate with one another, e.g., directly or indirectly via wireless or wireline backhaul.

The UEs 120 (e.g., 120x, 120y, etc. ) may be dispersed throughout the wireless network 100, and each UE may be stationary or mobile. A UE may also be referred to as a terminal, a mobile station, a subscriber unit, a station, etc. A UE may be a cellular phone, a smart phone, a personal digital assistant (PDA) , a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a netbook, a smart book, a drone, a robot/robotic device, a wearable device (e.g., smart glasses, smart watch, smart wristband, smart clothing, smart ring, smart jewelry) , a monitor, a meter, a camera, a navigation/positioning device, a healthcare/medical device, etc. A UE may be able to communicate with macro Node Bs, pico Node Bs, femto Node Bs, relays, etc. In FIG. 1, a solid line with double arrows indicates desired transmissions between a UE and a serving Node B, which is a Node B designated to serve the UE on the downlink and/or uplink. A dashed line with double arrows indicates interfering transmissions between a UE and a Node B.

LTE utilizes orthogonal frequency division multiplexing (OFDM) on the downlink and single-carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM partition the system bandwidth into multiple (K) orthogonal subcarriers, which are also commonly referred to as tones, bins, etc. Each subcarrier may be modulated with data. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may be dependent on the system bandwidth. For example, the spacing of the subcarriers may be 15 kHz and the minimum resource allocation (called a ‘resource block’ ) may be 12 subcarriers (or 180 kHz) . Consequently, the nominal FFT size may be equal to 128, 256, 512, 1024 or 2048 for system bandwidth of 1.25, 2.5, 5, 10 or 20 megahertz (MHz) , respectively. The system bandwidth may also be partitioned into subbands. For example, a subband may cover 1.08 MHz (i.e., 6 resource blocks) , and there may be 1, 2, 4, 8 or 16 subbands for system bandwidth of 1.25, 2.5, 5, 10 or 20 MHz, respectively. New radio (NR) may use a different air interface, other than OFDM-based. NR networks may include entities such central units or distributed units.

While aspects of the examples described herein may be associated with LTE technologies, aspects of the present disclosure may be applicable with other wireless communications systems, such as NR. NR may utilize OFDM with a CP on the uplink and downlink and include support for half-duplex operation using TDD. A single component carrier bandwidth of 100 MHZ may be supported. NR resource blocks may span 12 sub-carriers with a sub-carrier bandwidth of 75 kHz over a 0.1 ms duration. Each radio frame may consist of 50 subframes with a length of 10 ms. Consequently, each subframe may have a length of 0.2 ms. Each subframe may indicate a link direction (i.e., DL or UL) for data transmission and the link direction for each subframe may be dynamically switched. Each subframe may include DL/UL data as well as DL/UL control data. Beamforming may be supported and beam direction may be dynamically configured. MIMO transmissions with precoding may also be supported. MIMO configurations in the DL may support up to 8 transmit antennas with multi-layer DL transmissions up to 8 streams and up to 2 streams per UE. Multi-layer transmissions with up to 2 streams per UE may be supported. Aggregation of multiple cells may be supported with up to 8 serving cells. Alternatively, NR may support a different air interface, other than an OFDM-based. NR networks may include entities such central units or distributed units.

FIG. 2 shows a down link (DL) frame structure used in a telecommunication systems (e.g., LTE) . The transmission timeline for the downlink may be partitioned into units of radio frames. Each radio frame may have a predetermined duration (e.g., 10 milliseconds (ms) ) and may be partitioned into 10 sub-frames with indices of 0 through 9. Each sub-frame may include two slots. Each radio frame may thus include 20 slots with indices of 0 through 19. Each slot may include L symbol periods, e.g., 7 symbol periods for a normal cyclic prefix (as shown in FIG. 2) or 14 symbol periods for an extended cyclic prefix. The 2L symbol periods in each sub-frame may be assigned indices of 0 through 2L–1. The available time frequency resources may be partitioned into resource blocks. Each resource block may cover N subcarriers (e.g., 12 subcarriers) in one slot.

In LTE, a Node B may send a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) for each cell in the Node B. The primary and secondary synchronization signals may be sent in

symbol periods

6 and 5, respectively, in each of

sub-frames

0 and 5 of each radio frame with the normal cyclic prefix, as shown in FIG. 2. The synchronization signals may be used by UEs for cell detection and acquisition. The Node B may send a Physical Broadcast Channel (PBCH) in symbol periods 0 to 3 in slot 1 of sub-frame 0. The PBCH may carry certain system information.

The Node B may send a Physical Control Format Indicator Channel (PCFICH) in only a portion of the first symbol period of each sub-frame, although depicted in the entire first symbol period in FIG. 2. The PCFICH may convey the number of symbol periods (M) used for control channels, where M may be equal to 1, 2 or 3 and may change from sub-frame to sub-frame. M may also be equal to 4 for a small system bandwidth, e.g., with less than 10 resource blocks. In the example shown in FIG. 2, M＝3. The Node B may send a Physical HARQ Indicator Channel (PHICH) and a Physical Downlink Control Channel (PDCCH) in the first M symbol periods of each sub-frame (M＝3 in FIG. 2) . The PHICH may carry information to support hybrid automatic retransmission (HARQ) . The PDCCH may carry information on uplink and downlink resource allocation for UEs and power control information for uplink channels. Although not shown in the first symbol period in FIG. 2, it is understood that the PDCCH and PHICH are also included in the first symbol period. Similarly, the PHICH and PDCCH are also both in the second and third symbol periods, although not shown that way in FIG. 2. The Node B may send a Physical Downlink Shared Channel (PDSCH) in the remaining symbol periods of each sub-frame. The PDSCH may carry data for UEs scheduled for data transmission on the downlink. The various signals and channels in LTE are described in 3GPP TS 36.211, entitled “Evolved Universal Terrestrial Radio Access (E-UTRA) ； Physical Channels and Modulation, ” which is publicly available.

The Node B may send the PSS, SSS and PBCH in the center 1.08 MHz of the system bandwidth used by the Node B. The Node B may send the PCFICH and PHICH across the entire system bandwidth in each symbol period in which these channels are sent. The Node B may send the PDCCH to groups of UEs in certain portions of the system bandwidth. The Node B may send the PDSCH to specific UEs in specific portions of the system bandwidth. The Node B may send the PSS, SSS, PBCH, PCFICH and PHICH in a broadcast manner to all UEs, may send the PDCCH in a unicast manner to specific UEs, and may also send the PDSCH in a unicast manner to specific UEs.

A number of resource elements may be available in each symbol period. Each resource element may cover one subcarrier in one symbol period and may be used to send one modulation symbol, which may be a real or complex value. Resource elements not used for a reference signal in each symbol period may be arranged into resource element groups (REGs) . Each REG may include four resource elements in one symbol period. The PCFICH may occupy four REGs, which may be spaced approximately equally across frequency, in symbol period 0. The PHICH may occupy three REGs, which may be spread across frequency, in one or more configurable symbol periods. For example, the three REGs for the PHICH may all belong in symbol period 0 or may be spread in

symbol periods

0, 1 and 2. The PDCCH may occupy 9, 18, 32 or 64 REGs, which may be selected from the available REGs, in the first M symbol periods. Only certain combinations of REGs may be allowed for the PDCCH.

A UE may know the specific REGs used for the PHICH and the PCFICH. The UE may search different combinations of REGs for the PDCCH. The number of combinations to search is typically less than the number of allowed combinations for the PDCCH. A Node B may send the PDCCH to the UE in any of the combinations that the UE will search.

A UE may be within the coverage of multiple Node Bs. One of these Node Bs may be selected to serve the UE. The serving Node B may be selected based on various criteria such as received power, path loss, signal-to-noise ratio (SNR) , etc.

In some networks (e.g., NR or 5G networks) , devices may communicate by transmitting signals in different locations of a slot, e.g., such as in DL centric slot and/or UL centric slot. A DL centric slot may be used for transmitting DL data from the base station to one or more UEs, and a UL centric slot may be used for transmitting UL data from one or more UEs to a base station. A UL-centric slot is a slot with a majority of the OFDM symbols used for UL transmission. It typically has few DL symbols at the beginning (e.g. 2 symbols) , then a guard duration, then UL symbols. A DL-centric slot is a slot with a majority of OFDM symbols used for DL transmission. It typically has most of the first symbols on DL (e.g. 12 symbols) , then a guard interval, then a few UL symbols (1-2 symbols) . FIG. 2A shows another exemplary transmission timeline 200a that may be used in a TDD system in which one or more aspects of the present disclosure may be practiced. The timeline includes a plurality DL-centric slots 202 (e.g., subframes) that have most symbols 204 dedicated to DL transmissions (e.g., from a BS to a UE) and a common UL burst 206 at the end with very limited resources dedicated to UL transmissions (e.g., from a UE to a BS) . The timeline also includes a plurality of UL-centric slots 210 (e.g., subframes) that each have a DL symbol 212 at the beginning of the slot, but the remaining symbols 214 of the slot are dedicated to UL transmissions. As seen in the UL slot 210b, the UL symbols 214 may be allocated to various users (e.g., UEs) for a variety of UL transmissions (e.g., OFDM PUSCH, SC-FDM PUSCH, SC-FDM PUCCH, OFDM PUCCH) . Similarly, while not shown, the DL symbols 204 of a DL slot 202 may be allocated for a variety of DL transmissions (e.g., PDCCH, PDSCH) to one or more UEs.

FIG. 3 is a diagram 300 illustrating an example of an uplink (UL) frame structure in a telecommunications system (e.g., LTE) . The available resource blocks for the UL may be partitioned into a data section and a control section. The control section may be formed at the two edges of the system bandwidth and may have a configurable size. The resource blocks in the control section may be assigned to UEs for transmission of control information. The data section may include all resource blocks not included in the control section. The UL frame structure results in the data section including contiguous subcarriers, which may allow a single UE to be assigned all of the contiguous subcarriers in the data section.

A UE may be assigned

resource blocks

310a, 310b in the control section to transmit control information to a Node B. The UE may also be assigned

resource blocks

320a, 320b in the data section to transmit data to the Node B. The UE may transmit control information in a physical UL control channel (PUCCH) on the assigned resource blocks in the control section. The UE may transmit only data or both data and control information in a physical UL shared channel (PUSCH) on the assigned resource blocks in the data section. A UL transmission may span both slots of a subframe and may hop across frequency.

A set of resource blocks may be used to perform initial system access and achieve UL synchronization in a physical random access channel (PRACH) 330. The PRACH 330 carries a random sequence and cannot carry any UL data/signaling. Each random access preamble occupies a bandwidth corresponding to six consecutive resource blocks. The starting frequency is specified by the network. That is, the transmission of the random access preamble is restricted to certain time and frequency resources. There is no frequency hopping for the PRACH. The PRACH attempt is carried in a single subframe (1 ms) or in a sequence of few contiguous subframes and a UE can make only a single PRACH attempt per frame (10 ms) .

FIG. 4 illustrates example components of the base station 110 and UE 120 illustrated in FIG. 1, which may be used to implement aspects of the present disclosure. One or more components of the BS 110 and UE 120 may be used to practice aspects of the present disclosure. For example, antennas 452, Tx/Rx 222,

processors

466, 458, 464, and/or controller/processor 480 of the UE 120 and/or antennas 434,

processors

460, 420, 438, and/or controller/processor 440 of the BS 110 may be used to perform the operations described herein and illustrated with reference to FIGs. 5-10. The BS 110 may comprise a TRP.

FIG. 4 shows a block diagram of a design of a base station/Node B/TRP 110 and a UE 120, which may be one of the base stations/Node Bs/TRPs and one of the UEs in FIG. 1. For a restricted association scenario, the base station 110 may be the macro Node B 110c in FIG. 1, and the UE 120 may be the UE 120y. The base station 110 may also be a base station of some other type. The base station 110 may be equipped with antennas 434a through 434t, and the UE 120 may be equipped with antennas 452a through 452r.

At the base station 110, a transmit processor 420 may receive data from a data source 412 and control information from a controller/processor 440. The control information may be for the PBCH, PCFICH, PHICH, PDCCH, etc. The data may be for the PDSCH, etc. The processor 420 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The processor 420 may also generate reference symbols, e.g., for the PSS, SSS, and cell-specific reference signal. A transmit (TX) multiple-input multiple-output (MIMO) processor 430 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 432a through 432t. Each modulator 432 may process a respective output symbol stream (e.g., for OFDM, etc. ) to obtain an output sample stream. Each modulator 432 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators 432a through 432t may be transmitted via the antennas 434a through 434t, respectively.

At the UE 120, the antennas 452a through 452r may receive the downlink signals from the base station 110 and may provide received signals to the demodulators (DEMODs) 454a through 454r, respectively. Each demodulator 454 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator 454 may further process the input samples (e.g., for OFDM, etc. ) to obtain received symbols. A MIMO detector 456 may obtain received symbols from all the demodulators 454a through 454r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 458 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 120 to a data sink 460, and provide decoded control information to a controller/processor 480.

On the uplink, at the UE 120, a transmit processor 464 may receive and process data (e.g., for the PUSCH) from a data source 462 and control information (e.g., for the PUCCH) from the controller/processor 480. The transmit processor 464 may also generate reference symbols for a reference signal. The symbols from the transmit processor 464 may be precoded by a TX MIMO processor 466 if applicable, further processed by the demodulators 454a through 454r (e.g., for SC-FDM, etc. ) , and transmitted to the base station 110. At the base station 110, the uplink signals from the UE 120 may be received by the antennas 434, processed by the modulators 432, detected by a MIMO detector 436 if applicable, and further processed by a receive processor 438 to obtain decoded data and control information sent by the UE 120. The receive processor 438 may provide the decoded data to a data sink 439 and the decoded control information to the controller/processor 440.

The controllers/

processors

440 and 480 may direct the operation at the base station 110 and the UE 120, respectively. The processor 440 and/or other processors and modules at the base station 110 may perform or direct, e.g., the execution of various processes for the techniques described herein and those illustrated in the appended drawings. The processor 480 and/or other processors and modules at the UE 120 may also perform or direct, e.g., the execution of various processes for the techniques described herein and those illustrated in the appended drawings. A scheduler 444 may schedule UEs for data transmission on the downlink and/or uplink.

EXAMPLE NEW RADIO CELL MEASUREMENT

New radio (NR) may refer to radios configured to operate according to a wireless standard, such as 5G (e.g. wireless network 100) . NR may include Enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g. 80 MHz beyond) , millimeter wave (mmW) targeting high carrier frequency (e.g. 60 GHz) , massive MTC (mMTC) targeting non-backward compatible MTC techniques, and mission critical targeting ultra reliable low latency communications (URLLC) .

NR cell may refer to a cell operating according in the NR network. A NR Node B (e.g., Node B 110) may correspond to one or multiple transmission reception points (TRPs) . As used herein, a cell may refer to a combination of downlink (and potentially also uplink) resources. The linking between the carrier frequency of the downlink resources and the carrier frequency of the uplink resources is indicated in the system information (SI) transmitted on the downlink resources. For example, system information can be transmitted in a physical broadcast channel (PBCH) carrying a master information block (MIB) .

NR RAN architecture may include a central unit (CU) (e.g., network controller 130) . The CU may be an Access node controller (ANC) . The CU terminates backhaul interface to RAN-CN, terminates backhaul interface to neighbor RAN node. The RAN may include a distributed unit that may be one or more TRPs that may be connected to one or more ANCs (not shown) . TRPs may advertise System Information (e.g., Global TRP ID) , may include PDCP/RLC/MAC functions, may comprise one or more antenna ports, may be configured to individually (dynamic selection) or jointly (joint transmission) , and may serve traffic to the UE.

EXAMPLE TECHNIQUES FOR POWER ALLOCATION FOR DATA CHANNEL AND UE-SPECIFIC REFERENCE SIGNAL

FIG. 5 illustrates a typical DMRS structure 500 across two different physical resource blocks (PRBs) , in accordance with certain aspects of the present disclosure. As shown, PRB 500a includes two configured DMRS ports P7 and P8, each configured DMRS port corresponding to one data stream. For example, the DMRS port P7 corresponds to UE1 data stream and DMRS port P8 corresponds to UE2 data stream. PRB 500B includes four configured DMRS ports P7, P8, P11, and P13, each configured DMRS port corresponding to one data stream. For example, DMRS ports P7, P8, P11, and P13 correspond to UE1-UE4 data streams respectively. As discussed above, a Node B transmits DMRS with the same PSD on DMRS REs in both the

PRBs

500a and 500b. Since, the number of configured DMRS ports is same as the number of configured data streams, Node B power is equally divided between the DMRS ports and the data streams. Thus, as shown, the ratio between EPREs of PDSCH and DMRS for each UE (e.g., UE1) is constant at 0 dB.

Current DMRS design for NR MIMO uses 1-symbol DMRS structure to achieve low latency requests. The NR MIMO DMRS design uses a comb structure (e.g., FDM) with cyclic shifts (CDM) as a basic port-multiplexing approach to achieve more orthogonal ports. Generally speaking, for MU-MIMO case, DMRS ports for different UEs may be multiplexed using FDM. Further, for each UE, DMRS ports for different layers may be multiplexed by CDM.

FIG. 6 illustrates a 1-symbol DMRS structure 600 using comb 4, in accordance with certain aspects of the present disclosure. As shown, DMRS ports P0, P1, P2, and P3 are FDM across REs and each of P0/P4, P1/P5, P2/P6, and P3/P7 are CDM within each RE. In certain aspects, each DMRS ports P0/P4, P1/P5, P2/P6, and P3/P7 may be configured for different UEs. Thus, DMRS ports for different UEs are FDM across REs, and DMRS ports assigned to a particular UE may be CDM within an RE.

In certain aspects, for MU-MIMO transmission in NR MIMO, different multi-user pairing hypotheses may be scheduled in different PRBs/subbands.

FIG. 7 illustrates a NR MU-MIMO DMRS structure 700 across multiple PRBs, in accordance with certain aspects of the present disclosure. As shown PRB0 uses 4 UEs pairing with each DMRS port corresponding to data streams of 4 different UEs (e.g., UEs 0-3 as shown in FIG. 7) , one stream per UE. Thus, the total power for each RE is divided among four streams corresponding to UEs 0-3. Thus, as shown, for PRB0, assuming total power per RE is 1, the DMRS EPRE is 1 and the PDSCH EPRE is 1/4, and the ratio between PDSCH EPRE and DMRS EPRE is -6dB.

On the other hand, PRB 1 uses 2 UEs pairing with each DMRS port corresponding to data streams of 2 different UEs (e.g., UEs 0-1 as shown in FIG. 7) , one stream per UE. Thus, the total power for each RE is divided among two stream corresponding to UEs 0-1. Thus, as shown, for PRB1, assuming total power per RE is 1, the DMRS EPRE is 1 and the PDSCH EPRE is 1/2, and the ration between PDSCH EPRE and DMRS EPRE is -3dB.

Thus, as illustrated in FIG. 7 and discussed above, based on the different multi-user pairing hypotheses in different PRBs/subbands, the ratio between PDSCH and DMRS EPREs may be different across PRBs/subbands for a particular UE. In this case, the Node B may need to indicate to the UE, the PDSCH EPRE to DMRS EPRE ratios for each PRB/subband to maintain acceptable demodulation performance, but which may require prohibitive signaling overhead.

FIG. 8 illustrates example operations 800 that may be performed by a Base Station (BS) for maintaining a consistent ratio between DMRS and PDSCH EPREs for a UE, in accordance with certain aspects of the present disclosure. Operations 800 may begin, at 802, by determining a ratio between EPRE corresponding to DMRS and EPRE corresponding to PDSCH for a UE. At 804, the BS determines, for the UE, a transmission power corresponding to each DMRS port in a plurality of resources across a system bandwidth based at least on the corresponding determined ratio. At 806, the BS transmits on each DMRS port based on the corresponding determined transmission power.

In certain aspects, the ratio of DMRS EPRE to PDSCH EPRE for a UE may be determined by a Node B according to one or more parameters indicating real time PDSCH scheduling information including but not limited to a maximum number of configured DMRS ports across a system bandwidth, a minimum number of configured MU layers across the system bandwidth, a number of DMRS ports configured for the UE, and whether unused DMRS ports are reused for data transmission.

Once the Node B has determined the EPRE ratio for a UE, the Node B may transmit DMRS with different PSD on DMRS REs in different PRBs/subbands, as opposed to with the same PSD in LTE, to maintain the determined ratio consistent (e.g., substantially constant) across the system bandwidth.

In certain aspects, the transmission power on each DMRS port for each PRB/subband for the UE may be determined by the Node B according one or more parameters indicating real time PDSCH scheduling information including but not limited to a total power used for a DMRS RE, a number of MU layers configured for a given subband or PRM, and the determined ratio of DMRS EPRE to PDSCH EPRE that is to be maintained at the determined value.

In an aspect, the Node B may indicate the determined ratio to the UE either semi-statically via higher layer signaling or dynamically via L1 signaling.

In certain aspects, unused subframes are muted not for data transmission (e.g. not used for data transmission) and the power corresponding to the muted DMRS ports is used for the remaining scheduled DMRS ports. In this case the ratio,

between the EPRE corresponding to DMRS and the EPRE corresponding to PDSCH for a UE_j in an l^th subband or PRB is determined as,

where

is the transmission power corresponding to DMRS port i for UE_j ,

is the transmission power on the PDSCH layer i which corresponds to DMRS port i, P is the total power for a DMRS Resource Element (RE) , m_l is a number of scheduled MU-MIMO layers in the l^th subband or PRB, n_j is the number of DMRS ports (e.g., multiplexed by cyclic shifts CDM) per RE for UE_j, and M is the maximum number of configured DMRS ports across a system bandwidth.

In this case, the eNB may indicate the ratio of DMRS EPRE to PDSCH EPRE, i.e., 10log

(dB) to UE_j either via higher layer signaling or L1 signaling.

The transmission power corresponding to DMRS port i for UE_j in the l^th subband or PRB is given by,

The transmission power on the PDSCH layer i which corresponds to DMRS port i in the l^th subband or PRB is given by,

FIG. 9 illustrates an example DMRS structure 900 across multiple PRBs where muted DMRS ports are not used for data transmission and the power corresponding to the muted DMRS ports is used for the remaining scheduled DMRS ports, in accordance with certain aspects of the present disclosure.

As shown, PRB_0 uses 4 UEs pairing with 4 UEs 0-3 scheduled in PRB_0. As shown, PRB_0 implements 4 UEs pairing in {2+1+1+1) configuration, meaning UE 0 has 2 layers (e.g., one DMRS port per layer) and each of UEs 1-3 has one layer each. DMRS ports P0 and P4 correspond to UE0, DMRS port P1 corresponds to UE1, DMRS port P2 corresponds to UE3 and DMRS port P3 corresponds to UE3. The DMRS ports for the UEs 0-3 are FDM, i.e., the DMRS port (s) corresponding to each UE is scheduled in a different RE in frequency. The DMRS ports P0 and P4 corresponding to UE0 are CDM in one RE.

Thus, the maximum number of configured DMRS ports M ＝ 5 including ports P0-P4. The number of scheduled MIMO layers for PRB, 0 m0 ＝ 5 as a total of 5 layers are scheduled, one layer per DMRS port. For UE0, the total number of DMRS per RE, n₀ ＝ 2, since two ports P0 and P4 are scheduled for UE0. For UE 1, the total number of DMRS per RE, n₁ ＝ 1, since only one port P1 is scheduled for UE1. Following the equations for determining the ratio of DMRS EPRE to PDSCH EPRE discussed above, the ratio for UE0,

and the ratio for UE1,

As shown in FIG. 9, the transmission powers for DMRS ports P0 and P1 for PRB_0 may be determined based on the corresponding determined ratios in accordance with the equations discussed above.

As shown, PRB_1 uses 2 UEs pairing with 2

UEs

0 and 1 scheduled in PRB_1. As shown, PRB_1 implements 2 UEs pairing in {2+1} configuration, meaning UE 0 has 2 layers (e.g., one DMRS port per layer) and UE 1 has one layer. DMRS ports P0 and P4 correspond to UE0 and DMRS port P1 corresponds to UE1. The DMRS ports for the UE0 and UE1 are FDM over different REs in frequency, and the ports P0 and P4 corresponding to UE0 are CDM in one RE.

The maximum number of configured DMRS ports is still M ＝ 5 including ports P0-P4, but ports P2 and P3 are muted not for data transmission (e.g., no data transmission on these ports) and the power of these muted ports is used to boost power of the remaining scheduled ports. The number of scheduled MIMO layers for PRB 1, m1 ＝ 3 as a total of 3 layers are scheduled, one layer per DMRS port. For UE0, the total number of DMRS per RE, n₀ ＝ 2, since two ports P0 and P4 are scheduled for UE0. For UE 1, the total number of DMRS per RE, n₁ ＝ 1, since only one port P1 is scheduled for UE1. Following the equations for determining the ratio of DMRS EPRE to PDSCH EPRE discussed above, the ratio for UE0,

and the ratio for UE1,

As shown in FIG. 9 the transmission powers for DMRS ports P0 and P1 for PRB_1 may be determined based on the corresponding determined ratios in accordance with the equations discussed above.

As shown, PRB_L uses 3 UEs pairing with 3

UEs

0, 1 and 3 scheduled in PRB_L. As shown, PRB_L implements 3 UEs pairing in {2+1+1} configuration, meaning UE0 has two layers (e.g., one DMRS port per layer) and each of

UEs

1 and 3 has one layer each. DMRS ports P0 and P4 correspond to UE0, DMRS port P1 corresponds to UE1 and DMRS port P3 corresponds to UE 3. The DMRS ports for

UEs

0, 1, and 3 are FDM over different REs in frequency, and the ports P0 and P4 corresponding to UE 0 are CDM in one RE.

The maximum number of configured DMRS ports is still M ＝ 5 including ports P0-P4, but port P2 is muted not for data transmission (e.g., no data transmission on this port) and the power of the muted port is used to boost power of the remaining scheduled ports. The number of scheduled MIMO layers for PRB_L mL, ＝ 4 as a total of 4 layers are scheduled, one layer per DMRS port. For UE0, the total number of DMRS per RE, n₀ ＝ 2, since two ports P0 and P4 are scheduled for UE0. For UE 1, the total number of DMRS per RE, n₁ ＝ 1, since only one port P1 is scheduled for UE0. Following the equations for determining the ratio of DMRS EPRE to PDSCH EPRE discussed above, the ratio for UE0,

and the ratio for UE1,

As shown in FIG. 9 the transmission powers for DMRS ports P0 and P1 for PRB_L may be determined based on the corresponding determined ratios in accordance with the equations discussed above.

Thus, based on the techniques discussed above the ratio of DMRS EPRE to PDSCH EPRE across the

PRBs

0, 1 and L remains constant for each UE. For example, for UE0, the ratio

for each of the PRBs. Similarly, for UE1, the ratio

for each of the PRBs. The ratios may be similarly determined for other UEs across a plurality of PRBs.

In certain aspects, unused subframes are not muted but are used for data transmission. In this case the ratio,

where

is the transmission power corresponding to DMRS port i for UE_j ,

is the transmission power on the PDSCH layer i which corresponds to DMRS port i, P is the total power for a DMRS Resource Element (RE) , m_l is a number of scheduled MU-MIMO layers in the l^th subband or PRB, n_j is the number of DMRS ports (e.g., multiplexed by cyclic shifts CDM) per RE for UE_j, and N is the minimum number of MU layers across a system bandwidth.

(dB) to UE_j either via L1 signaling.

FIG. 10 illustrates an example DMRS structure 1000 across multiple PRBs where unused DMRS ports reused for data transmission, in accordance with certain aspects of the present disclosure.

Thus, the minimum number of configured MU layers N ＝ 3. The number of scheduled MIMO layers for PRB 0, m0 ＝ 5 as a total of 5 layers are scheduled, one layer per DMRS port. For UE0, the total number of DMRS per RE, n₀ ＝ 2, since two ports P0 and P4 are scheduled for UE0. For UE 1, the total number of DMRS per RE, n₁ ＝ 1, since only one port P1 is scheduled for UE1. Following the equations for determining the ratio of DMRS EPRE to PDSCH EPRE discussed above, the ratio for UE0,

and the ratio for UE1,

As shown in FIG. 10, the transmission powers for DMRS ports P0 and P1 for PRB_0 may be determined based on the corresponding determined ratios in accordance with the equations discussed above.

As shown, PRB_1 uses 2 UEs pairing with 2

UEs

0 and 1 scheduled in PRB_1. As shown, PRB_1 implements 2 UEs pairing in {2+1} configuration, meaning UE 0 has 2 layers (e.g., one DMRS port per layer) and UE 1 has one layer. DMRS ports P0 and P4 correspond to UE0 and DMRS port P1 corresponds to UE1. The DMRS ports for the UE0 and UE1 are FDM over different REs in frequency, and the ports P0 and P4 corresponding to UE0 are CDM in one RE. As shown, the unused DMRS ports P2 and P3 are used for PDSCH.

The minimum number of configured MU layers N ＝ 3. The number of scheduled MIMO layers for PRB 1, m1 ＝ 3 as a total of 3 layers are scheduled, one layer per DMRS port. For UE0, the total number of DMRS per RE, n₀ ＝ 2, since two ports P0 and P4 are scheduled for UE0. For UE 1, the total number of DMRS per RE, n₁ ＝ 1, since only one port P1 is scheduled for UE0. Following the equations for determining the ratio of DMRS EPRE to PDSCH EPRE discussed above, the ratio for UE0,

and the ratio for UE1,

As shown in FIG. 10 the transmission powers for DMRS ports P0 and P1 for PRB_1 may be determined based on the corresponding determined ratios in accordance with the equations discussed above.

As shown, PRB_L uses 3 UEs pairing with 3

UEs

0, 1, and 3 are FDM over different REs in frequency, and the ports P0 and P4 corresponding to UE 0 are CDM in one RE. As shown, the unused DMRS port P2 is used for PDSCH.

The minimum number of configured MU layers N ＝ 3. The number of scheduled MIMO layers for PRB_L, mL ＝ 4 as a total of 4 layers are scheduled, one layer per PRB. For UE0, the total number of DMRS per RE, n₀ ＝ 2, since two ports P0 and P4 are scheduled for UE0. For UE 1, the total number of DMRS per RE, n₁ ＝ 1, since only one port P1 is scheduled for UE1. Following the equations for determining the ratio of DMRS EPRE to PDSCH EPRE discussed above, the ratio for UE0,

and the ratio for UE1,

As shown in FIG. 10, the transmission powers for DMRS ports P0 and P1 for PRB_L may be determined based on the corresponding determined ratios in accordance with the equations discussed above.

PRBs

0, 1 and L remains constant for each UE. For example, for UE0, the ratio

for each of the PRBs. Similarly, for UE1, the ratio

The methods disclosed herein comprise one or more steps or actions for achieving the described method. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.

As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c) .

As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure) , ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information) , accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” Unless specifically stated otherwise, the term “some” refers to one or more. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for. ”

The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component (s) and/or module (s) , including, but not limited to a circuit, an application specific integrated circuit (ASIC) , or processor. Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus-function components with similar numbering.

The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) or other programmable logic device (PLD) , discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

If implemented in hardware, an example hardware configuration may comprise a processing system in a wireless node. The processing system may be implemented with a bus architecture. The bus may include any number of interconnecting buses and bridges depending on the specific application of the processing system and the overall design constraints. The bus may link together various circuits including a processor, machine-readable media, and a bus interface. The bus interface may be used to connect a network adapter, among other things, to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the PHY layer. In the case of a user terminal 120 (see FIG. 1) , a user interface (e.g., keypad, display, mouse, joystick, etc. ) may also be connected to the bus. The bus may also link various other circuits such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further. The processor may be implemented with one or more general-purpose and/or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuitry that can execute software. Those skilled in the art will recognize how best to implement the described functionality for the processing system depending on the particular application and the overall design constraints imposed on the overall system.

If implemented in software, the functions may be stored or transmitted over as one or more instructions or code on a computer-readable medium. Software shall be construed broadly to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media include both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. The processor may be responsible for managing the bus and general processing, including the execution of software modules stored on the machine-readable storage media. A computer-readable storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. By way of example, the machine-readable media may include a transmission line, a carrier wave modulated by data, and/or a computer readable storage medium with instructions stored thereon separate from the wireless node, all of which may be accessed by the processor through the bus interface. Alternatively, or in addition, the machine-readable media, or any portion thereof, may be integrated into the processor, such as the case may be with cache and/or general register files. Examples of machine-readable storage media may include, by way of example, RAM (Random Access Memory) , flash memory, ROM (Read Only Memory) , PROM (Programmable Read-Only Memory) , EPROM (Erasable Programmable Read-Only Memory) , EEPROM (Electrically Erasable Programmable Read-Only Memory) , registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof. The machine-readable media may be embodied in a computer-program product.

A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. The computer-readable media may comprise a number of software modules. The software modules include instructions that, when executed by an apparatus such as a processor, cause the processing system to perform various functions. The software modules may include a transmission module and a receiving module. Each software module may reside in a single storage device or be distributed across multiple storage devices. By way of example, a software module may be loaded into RAM from a hard drive when a triggering event occurs. During execution of the software module, the processor may load some of the instructions into cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When referring to the functionality of a software module below, it will be understood that such functionality is implemented by the processor when executing instructions from that software module.

Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) , or wireless technologies such as infrared (IR) , radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include compact disc (CD) , laser disc, optical disc, digital versatile disc (DVD) , floppy disk, and

disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Thus, in some aspects computer-readable media may comprise non-transitory computer-readable media (e.g., tangible media) . In addition, for other aspects computer-readable media may comprise transitory computer-readable media (e.g., a signal) . Combinations of the above should also be included within the scope of computer-readable media.

Thus, certain aspects may comprise a computer program product/computer readable medium for performing the operations presented herein. For example, such a computer program product may comprise a computer-readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein.

Further, it should be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station as applicable. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, various methods described herein can be provided via storage means (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc. ) , such that a user terminal and/or base station can obtain the various methods upon coupling or providing the storage means to the device. Moreover, any other suitable technique for providing the methods and techniques described herein to a device can be utilized.

It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

WHAT IS CLAIMED IS:

Claims

The method of wireless communication by a Base Station (BS) , comprising:

determining a ratio between Energy Per Resource Element (EPRE) corresponding to Demodulation Reference Signal (DMRS) and EPRE corresponding to Physical Downlink Shared Channel (PDSCH) for a UE；

determining, for the UE, a transmission power corresponding to each DMRS port in a plurality of resources across a system bandwidth based at least on the corresponding determined ratio； and

transmitting on each DMRS port based on the corresponding determined transmission power.
The method of claim 1, wherein the ratio between the EPRE corresponding to DMRS and the EPRE corresponding to PDSCH for the UE is determined based on one or more parameters including, a number of maximum configured DMRS ports across a system bandwidth, a number of DMRS ports configured for the UE, the minimum number of Multi-User (MU) layers configured across the system bandwidth, or whether unused DMRS ports are used for data transmission.
The method of claim 1, wherein the ratio,
between the EPRE corresponding to DMRS and the EPRE corresponding to PDSCH for the UE_j, is determined as,

wherein,

M is the number of maximum configured DMRS ports across a system bandwidth, and n_j is a number of DMRS ports per RE for UE_j.
The method of claim 3, wherein unused DMRS ports are muted not for data transmission and power corresponding to the muted DMRS ports is used for scheduled DMRS ports.
The method of claim 3, further comprising transmitting the ratio,
between the EPRE corresponding to DMRS and the EPRE corresponding to PDSCH for the UE_j either semi-statically via higher layer signaling or dynamically via L1 signaling.
The method of claim 1, wherein the ratio,
between the EPRE corresponding to DMRS and the EPRE corresponding to PDSCH for the UE_j, is determined as,

wherein,

N is the minimum number of Multi-User (MU) layers configured across the system bandwidth, and

n_j is a number of DMRS ports per RE for UE_j.
The method of claim 6, wherein unused DMRS ports are reused for data transmission.
The method of claim 6, further comprising transmitting the ratio,
between the EPRE corresponding to DMRS and the EPRE corresponding to PDSCH for the UE_j dynamically via L1 signaling. .
The method of claim 1, wherein the transmission power corresponding to each DMRS port is determined based on one or more parameters including, a total power used for a DMRS Resource element (RE) , a number of multi-user (MU) layers configured for a given subband or Physical Resource Block (PRB) or the ratio between the EPRE corresponding to DMRS and the EPRE corresponding to PDSCH.
The method of claim 1, wherein the transmission power, corresponding to a DMRS port i for the UE_j, in an l^th subband or PRB is determined as,

wherein,

P is the total power for a DMRS Resource Element (RE) ,

m_l is a number of scheduled MU-MIMO layers in the l^th subband or PRB, and

is the ratio between the EPRE corresponding to DMRS and the EPRE corresponding to PDSCH for the UE_j.
The method of claim 1, wherein all DMRS ports are included in one or more symbols of one or more PRBs.
The method of claim 1, wherein DMRS ports assigned to different UEs are frequency division multiplexed across Resource Elements (REs) and DMRS ports assigned to a single UE within a RE are code division multiplexed.
The method of claim 1, wherein the plurality of resources include Physical Resource Blocks (PRBs) or subbands.
The method of claim 1, wherein determining the transmission power corresponding to each DMRS port is based on maintaining the ratio between the EPRE corresponding to DMRS and the EPRE corresponding to PDSCH for the UE consistent across the plurality of the resources.
The method of claim 14, wherein maintaining the ratio consistent includes maintaining the ratio constant across the plurality of the resources.
A method, apparatus, system, computer program product, computer-readable medium, and processing system as substantially described herein with reference to and as illustrated by the accompanying drawings.