WO2019047162A1

WO2019047162A1 - Techniques for mapping transmissions to different layers in wireless communications

Info

Publication number: WO2019047162A1
Application number: PCT/CN2017/101048
Authority: WO
Inventors: Xiaohui Liu; Yu Zhang; Liangming WU; Wanshi Chen; Hao Xu
Original assignee: Qualcomm Incorporated
Priority date: 2017-09-08
Filing date: 2017-09-08
Publication date: 2019-03-14

Abstract

Aspects described herein relate to mapping transmissions to multiple layers in wireless communications. Multiple bits of data can be encoded to multiple modulation symbols for transmission over multiple layers in wireless communications, such that a repeated bit is encoded for transmission over a different layer of the multiple layers than an original bit corresponding to the repeated bit. The multiple modulation symbols can be transmitted over the multiple layers.

Description

TECHNIQUES FOR MAPPING TRANSMISSIONS TO DIFFERENT LAYERS IN WIRELESS COMMUNICATIONS

BACKGROUND

Aspects described herein relate generally to wireless communication systems, and more particularly, to mapping symbols to resources for transmission in wireless communication systems.

Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power) . Examples of such multiple-access systems include code-division multiple access (CDMA) systems, time-division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, and orthogonal frequency-division multiple access (OFDMA) systems, and single-carrier frequency division multiple access (SC-FDMA) systems.

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. For example, a fifth generation (5G) wireless communications technology (which can be referred to as 5G new radio (5G NR) ) is envisaged to expand and support diverse usage scenarios and applications with respect to current mobile network generations. In an aspect, 5G communications technology can include: enhanced mobile broadband addressing human-centric use cases for access to multimedia content, services and data； ultra-reliable-low latency communications (URLLC) with certain specifications for latency and reliability； and massive machine type communications, which can allow a very large number of connected devices and transmission of a relatively low volume of non-delay-sensitive information. As the demand for mobile broadband access continues to increase, however, further improvements in 5G communications technology and beyond may be desired.

Currently, in multiple-input multiple-output (MIMO) communications, it is possible that different MIMO layers have different performance constraints. For example, one MIMO layer may have a different transmission power or signal-to- interference-and-noise ratio (SINR) than another MIMO layer. This may result in transmission loss in communicating over one or more of the multiple MIMO layers.

SUMMARY

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

According to an example, a method for mapping transmissions to multiple multiple-input multiple-output (MIMO) layers in wireless communications is provided. The method includes encoding multiple bits of data to multiple modulation symbols for transmission over multiple MIMO layers in wireless communications, such that a repeated bit is encoded for transmission over a different layer of the multiple MIMO layers than an original bit corresponding to the repeated bit, and transmitting the multiple modulation symbols over the multiple MIMO layers.

In another example, an apparatus for mapping transmissions to multiple MIMO layers in wireless communications is provided. The apparatus includes a transceiver for communicating one or more wireless signals via one or more antennas, a memory configured to store instructions, and one or more processors communicatively coupled with the transceiver and the memory. The one or more processors are configured to encode multiple bits of data to multiple modulation symbols for transmission over multiple MIMO layers in wireless communications, such that a repeated bit is encoded for transmission over a different layer of the multiple MIMO layers than an original bit corresponding to the repeated bit, and transmit the multiple modulation symbols over the multiple MIMO layers.

In another example, an apparatus for mapping transmissions to multiple MIMO layers in wireless communications is provided. The apparatus includes means for encoding multiple bits of data to multiple modulation symbols for transmission over multiple MIMO layers in wireless communications, such that a repeated bit is encoded for transmission over a different layer of the multiple MIMO layers than an original bit corresponding to the repeated bit, and means for transmitting the multiple modulation symbols over the multiple MIMO layers.

According to an example, a method for balancing transmission power across multiple MIMO layers is provided. The method includes observing a channel based on a sounding report or a channel state information (CSI) report, computing a transmission power for each of multiple MIMO layers after beamforming each of the multiple MIMO layers for transmitting over the channel based on the sounding report or the CSI report, determining a power allocation as a function of the transmission power for the multiple MIMO layers, and allocating power to each of the multiple MIMO layers based on the power allocation.

In another example, an apparatus for balancing transmission power across multiple MIMO layers is provided. The apparatus includes a transceiver for communicating one or more wireless signals via one or more antennas, a memory configured to store instructions, and one or more processors communicatively coupled with the transceiver and the memory. The one or more processors are configured to observe a channel based on a sounding report or a CSI report, compute a transmission power for each of multiple MIMO layers after beamforming each of the multiple MIMO layers for transmitting over the channel based on the sounding report or the CSI report determine a power allocation as a function of the transmission power for the multiple MIMO layers, and allocate power to each of the multiple MIMO layers based on the power allocation.

In yet another example, an apparatus for balancing transmission power across multiple MIMO layers is provided. The apparatus includes means for observing a channel based on a sounding report or a CSI report, means for computing a transmission power for each of multiple MIMO layers after beamforming each of the multiple MIMO layers for transmitting over the channel based on the sounding report or the CSI report, means for determining a power allocation as a function of the transmission power for the multiple MIMO layers, and means for allocating power to each of the multiple MIMO layers based on the power allocation.

According to an example, a method for balancing transmission power across multiple MIMO layers is provided. The method includes receiving, from one or more user equipment, a measured power compensation value for each of multiple MIMO layers, and allocating power to each of the multiple MIMO layers based at least in part on, for each of the multiple MIMO layers, adding the measured power compensation value to a previous transmission power.

In another example, an apparatus for balancing transmission power across multiple MIMO layers is provided. The apparatus includes a transceiver for communicating one or more wireless signals via one or more antennas, a memory configured to store instructions, and one or more processors communicatively coupled with the transceiver and the memory. The one or more processors are configured to receive, from one or more user equipment, a measured power compensation value for each of multiple MIMO layers, and allocate power to each of the multiple MIMO layers based at least in part on, for each of the multiple MIMO layers, adding the measured power compensation value to a previous transmission power.

In yet another example, an apparatus for balancing transmission power across multiple MIMO layers is provided. The apparatus includes means for receiving, from one or more user equipment, a measured power compensation value for each of multiple MIMO layers, and means for allocating power to each of the multiple MIMO layers based at least in part on, for each of the multiple MIMO layers, adding the measured power compensation value to a previous 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

The disclosed aspects will hereinafter be described in conjunction with the appended drawings, provided to illustrate and not to limit the disclosed aspects, wherein like designations denote like elements, and in which:

FIG. 1 illustrates an example of a wireless communication system, in accordance with aspects described herein；

FIG. 2 is a block diagram illustrating an example of a base station, in accordance with aspects described herein；

FIG. 3 is a flow chart illustrating an example of a method for encoding bits for transmission over multiple layers, in accordance with aspects described herein；

FIG. 4 is a flow chart illustrating an example of a method for balancing transmission power of multiple layers by observing a channel, in accordance with aspects described herein；

FIG. 5 is a flow chart illustrating an example of a method for balancing transmission power of multiple layers, in accordance with aspects described herein；

FIG. 6 is a graphical representation of examples of encodings of bits, in accordance with aspects described herein； and

FIG. 7 is a block diagram illustrating an example of a MIMO communication system including a base station and a UE, in accordance with aspects described herein.

DETAILED DESCRIPTION

Various aspects are now described with reference to the drawings. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects. It may be evident, however, that such aspect (s) may be practiced without these specific details.

The described features generally relate to transmitting repeated transmissions (e.g., repeated bits, symbols, etc. ) over multiple layers in multiple-input multiple-output (MIMO) communications to improve reliability of the transmissions or otherwise suppress loss due to different constraints of the multiple layers. For example, using a single modulation and coding scheme (MCS) across multiple MIMO layers may be suboptimal in certain scenarios, such as for a correlated or power imbalanced transmission channel, which may result in decoding performance degradation due to bimodal (or multimodal) SNR distribution over the multiple layers. In current systems, a single MCS (and/or redundancy version (RV) , new data indicator (NDI) , etc. ) in downlink control information is assumed for up to four MIMO layers, and two codewords can be supported with more than four MIMO layers. Aspects described herein relate to suppressing loss from bimodal (or multimodal) SNR by using physical (PHY) layer optimizations.

For example, transmissions can be mapped into multiple MIMO layers to improve reliability thereof (e.g., where one layer has a higher transmit power than another layer) . In this example, bits and/or symbols (e.g., quadrature amplitude modulation (QAM) symbols) generated from the bits, which are transmitted multiple times, can be mapped to different layers for two or more of the transmissions. In addition, for example, one layer can use a different MCS or coding rate than another layer. In one specific example, transmitting the bits or symbols on a different layer can be accomplished by modifying a rate-matching buffer length to cause repeated bits/symbols to be encoded and/or transmitted on the different layer. In addition, in an example, transmission power can be balanced across the multiple layers from a single or multiple transmission point, as described herein.

The described features will be presented in more detail below with reference to FIGS. 1-5.

As used in this application, the terms “component, ” “module, ” “system” and the like are intended to include a computer-related entity, such as but not limited to hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a computing device and the computing device can be a component. One or more components can reside within a process and/or thread of execution and a component can be localized on one computer and/or distributed between two or more computers. In addition, these components can execute from various computer readable media having various data structures stored thereon. The components can communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets, such as data from one component interacting with another component in a local system, distributed system, and/or across a network such as the Internet with other systems by way of the signal.

Techniques described herein may be used for various wireless communication systems such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and other systems. The terms “system” and “network” may often be used interchangeably. A CDMA system may implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA) , etc. CDMA2000 covers IS-2000, IS-95, and IS-856 standards. IS-2000 Releases 0 and A are commonly referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD) , etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. A TDMA system may implement a radio technology such as Global System for Mobile Communications (GSM) . An OFDMA system may implement a radio technology such as Ultra Mobile Broadband (UMB) , Evolved UTRA (E-UTRA) , IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDM^TM, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS) . 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are new releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and 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 systems and radio technologies mentioned above as well as other systems and radio technologies, including cellular (e.g., LTE) communications over a shared radio frequency spectrum band. The description below, however, describes an LTE/LTE-A system for purposes of example, and LTE terminology is used in much of the description below, although the techniques are applicable beyond LTE/LTE-A applications (e.g., to 5G networks or other next generation communication systems) .

The following description provides examples, and is not limiting of the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in other examples.

Various aspects or features will be presented in terms of systems that can include a number of devices, components, modules, and the like. It is to be understood and appreciated that the various systems can include additional devices, components, modules, etc. and/or may not include all of the devices, components, modules etc. discussed in connection with the figures. A combination of these approaches can also be used.

FIG. 1 illustrates an example of a wireless communication system 100 in accordance with various aspects described herein. The wireless communication system 100 may include one or more base stations 105, one or more UEs 115, and a core network 130. The core network 130 may provide user authentication, access authorization, tracking, internet protocol (IP) connectivity, and other access, routing, or mobility functions. The base stations 105 may interface with the core network 130 through backhaul links 132 (e.g., S1, etc. ) . The base stations 105 may perform radio configuration and scheduling for communication with the UEs 115, or may operate under the control of a base station controller (not shown) . In various examples, the base stations 105 may communicate, either directly or indirectly (e.g., through core network 130) , with one another over backhaul links 134 (e.g., X2, etc. ) , which may be wired or wireless communication links.

The base stations 105 may wirelessly communicate with the UEs 115 via one or more base station antennas. Each of the base stations 105 may provide communication coverage for a respective geographic coverage area 110. In some examples, base stations 105 may be referred to as a network entity, a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, eNodeB (eNB) , Home NodeB, a Home eNodeB, or some other suitable terminology. The geographic coverage area 110 for a base station 105 may be divided into sectors making up only a portion of the coverage area (not shown) . The wireless communication system 100 may include base stations 105 of different types (e.g., macro or small cell base stations) . There may be overlapping geographic coverage areas 110 for different technologies.

In some examples, the wireless communication system 100 may be or include a Long Term Evolution (LTE) or LTE-Advanced (LTE-A) network. The wireless communication system 100 may also be a next generation network, such as a 5G wireless communication network. In LTE/LTE-A networks, the term evolved node B (eNB) , gNB, etc. may be generally used to describe the base stations 105, while the term UE may be generally used to describe the UEs 115. The wireless communication system 100 may be a heterogeneous LTE/LTE-A network in which different types of eNBs provide coverage for various geographical regions. For example, each eNB or base station 105 may provide communication coverage for a macro cell, a small cell, or other types of cell. The term “cell” is a 3GPP term that can be used to describe a base station, a carrier or component carrier associated with a base station, or a coverage area (e.g., sector, etc. ) of a carrier or base station, depending on context.

A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs 115 with service subscriptions with the network provider.

A small cell may include a lower-powered base station, as compared with a macro cell, that may operate in the same or different (e.g., licensed, unlicensed, etc. ) frequency bands as macro cells. Small cells may include pico cells, femto cells, and micro cells according to various examples. A pico cell, for example, may cover a small geographic area and may allow unrestricted access by UEs 115 with service subscriptions with the network provider. A femto cell may also cover a small geographic area (e.g., a home) and may provide restricted access by UEs 115 having an association with the femto cell (e.g., UEs 115 in a closed subscriber group (CSG) , UEs 115 for users in the home, and the like) . An eNB for a macro cell may be referred to as a macro eNB, gNB, etc. An eNB for a small cell may be referred to as a small cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB may support one or multiple (e.g., two, three, four, and the like) cells (e.g., component carriers) .

The communication networks that may accommodate some of the various disclosed examples may be packet-based networks that operate according to a layered protocol stack and data in the user plane may be based on the IP. A packet data convergence protocol (PDCP) layer can provide header compression, ciphering, integrity protection, etc. of IP packets. A radio link control (RLC) layer may perform packet segmentation and reassembly to communicate over logical channels. A media access control (MAC) layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use HARQ to provide retransmission at the MAC layer to improve link efficiency. In the control plane, the radio resource control (RRC) protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE 115 and the base stations 105. The RRC protocol layer may also be used for core network 130 support of radio bearers for the user plane data. At the physical (PHY) layer, the transport channels may be mapped to physical channels.

The UEs 115 may be dispersed throughout the wireless communication system 100, and each UE 115 may be stationary or mobile. A UE 115 may also include or be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology. A UE 115 may be a cellular phone, a personal digital assistant (PDA) , a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, an entertainment device, a vehicular component, or the like. A UE may be able to communicate with various types of base stations and network equipment including macro eNBs, small cell eNBs, relay base stations, and the like.

The communication links 125 shown in wireless communication system 100 may carry UL transmissions from a UE 115 to a base station 105, or downlink (DL) transmissions, from a base station 105 to a UE 115. The downlink transmissions may also be called forward link transmissions while the uplink transmissions may also be called reverse link transmissions. Each communication link 125 may include one or more carriers, where each carrier may be a signal made up of multiple sub-carriers (e.g., waveform signals of different frequencies) modulated according to the various radio technologies described above. Each modulated signal may be sent on a different sub-carrier and may carry control information (e.g., reference signals, control channels, etc. ) , overhead information, user data, etc. The communication links 125 may transmit bidirectional communications using frequency division duplex (FDD) (e.g., using paired spectrum resources) or time division duplex (TDD) operation (e.g., using unpaired spectrum resources) . Frame structures may be defined for FDD (e.g., frame structure type 1) and TDD (e.g., frame structure type 2) .

In aspects of the wireless communication system 100, base stations 105 or UEs 115 may include multiple antennas for employing antenna diversity schemes to improve communication quality and reliability between base stations 105 and UEs 115. Additionally or alternatively, base stations 105 or UEs 115 may employ multiple input multiple output (MIMO) techniques that may take advantage of multi-path environments to transmit multiple spatial layers carrying the same or different coded data.

Wireless communication system 100 may support operation on multiple cells or carriers, a feature which may be referred to as carrier aggregation (CA) or multi-carrier operation. A carrier may also be referred to as a component carrier (CC) , a layer, a channel, etc. The terms “carrier, ” “component carrier, ” “cell, ” and “channel” may be used interchangeably herein. A UE 115 may be configured with multiple downlink CCs and one or more uplink CCs for carrier aggregation. Carrier aggregation may be used with both FDD and TDD component carriers.

In aspects of the wireless communication system 100, one or more of the base stations 105 and/or UEs 115 may include a bit encoding component 240 for encoding bits of a codeword for transmission in the wireless network such that repeated bits can be transmitted over a different layer than corresponding original bits. This can improve reliability of communications by transmitting the repeated portions of the codeword over layers that may use different MCS, that may have different signal-to-interference-and-noise ratios (SINRs) , etc. It should be understood that in certain implementations, a bit encoding component 240 provisioned within a base station 105 may be the same or may be different in some manner, e.g., in design or function, than a bit encoding component 240 provisioned within a UE 115.

Turning now to FIGS. 2-6, aspects are depicted with reference to one or more components and one or more methods that may perform the actions or operations described herein, where aspects in dashed line may be optional. Although the operations described below in FIG. 3 are presented in a particular order and/or as being performed by an example component, it should be understood that the ordering of the actions and the components performing the actions may be varied, depending on the implementation. Moreover, it should be understood that the following actions, functions, and/or described components may be performed by a specially-programmed processor, a processor executing specially-programmed software or computer-readable media, or by any other combination of a hardware component and/or a software component capable of performing the described actions or functions.

Referring to FIG. 2, a block diagram 200 is shown that includes a portion of a wireless communications system having multiple UEs 115 in communication with a base station 105 via communication links 125, where the base station 105 is also connected to a network 210. The UEs 115 may be examples of the UEs described herein that are configured to encode communications such that repeated bits are encoded over different layers for transmission. Moreover the base station 105 may be an example of the base stations described herein (e.g., eNB, gNB, etc. providing one or more macrocells, small cells, etc. ) that are configured to encode communications such that repeated bits are encoded over different layers for transmission. Thus, in an example, though the bit encoding component 240 and various other components are shown as part of the base station 105, one or more UEs 115 can include the same or similar components to achieve the functionality described herein.

In an aspect, the base station in FIG. 2 may include one or more processors 205 and/or memory 202 that may operate in combination with a bit encoding component 240 to perform the functions or methods (e.g., method 300 of FIG. 3) presented herein. In accordance described aspects, the bit encoding component 240 may include an encoding component 242 for storing and/or providing multiple bits of one or more codewords for transmission, a rate-matching component 244 for storing a portion of the bits in a rate-matching buffer (or other buffer) for encoding the bits in multiple symbols, a resource mapping component 246 for mapping the bits in the rate-matching buffer to the multiple symbols, and/or an optional buffer length computing component 248 for determining a buffer length for the rate-matching buffer such to cause repeated bits in a codeword to be transmitted over different layers. Bit encoding component 240 may also optionally include a power balancing component 250 for balancing transmission power over the multiple layers.

The one or more processors 205 may include a modem 220 that uses one or more modem processors. The various functions related to the bit encoding component 240, and/or its sub-components, may be included in modem 220 and/or processor 205 and, in an aspect, can be executed by a single processor, while in other aspects, different ones of the functions may be executed by a combination of two or more different processors. For example, in an aspect, the one or more processors 205 may include any one or any combination of a modem processor, or a baseband processor, or a digital signal processor, or a transmit processor, or a transceiver processor associated with transceiver 270, or a system-on-chip (SoC) . In particular, the one or more processors 205 may execute functions and components included in the bit encoding component 240.

In some examples, the bit encoding component 240 and each of the sub-components may comprise hardware, firmware, and/or software and may be configured to execute code or perform instructions stored in a memory (e.g., a computer-readable storage medium, such as memory 202 discussed below) . Moreover, in an aspect, the base station 105 in FIG. 2 may include a radio frequency (RF) front end 290 and transceiver 270 for receiving and transmitting radio transmissions to, for example, UEs 115. The transceiver 270 may coordinate with the modem 220 to receive signals for, or transmit signals or modulation symbols generated by, the bit encoding component 240 to the UEs. RF front end 290 may be connected to one or more antennas 273 and can include one or more switches 292, one or more amplifiers (e.g., power amplifiers (PAs) 294 and/or low-noise amplifiers 291) , and one or more filters 293 for transmitting and receiving RF signals on uplink channels and downlink channels, transmitting and receiving signals, etc. In an aspect, the components of the RF front end 290 can connect with transceiver 270. The transceiver 270 may connect to one or more of modem 220 and processors 205.

The transceiver 270 may be configured to transmit (e.g., via transmitter (TX) radio 275) and receive (e.g., via receiver (RX) radio 280) wireless signals through antennas 273 via the RF front end 290. In an aspect, the transceiver 270 may be tuned to operate at specified frequencies such that the base station 105 can communicate with, for example, UEs 115. In an aspect, for example, the modem 220 can configure the transceiver 270 to operate at a specified frequency and power level based on the configuration of the base station 105 and communication protocol used by the modem 220.

The base station 105 in FIG. 2 may further include a memory 202, such as for storing data used herein and/or local versions of applications or bit encoding component 240 and/or one or more of its sub-components being executed by processor 205. Memory 202 can include any type of computer-readable medium usable by a computer or processor 205, such as random access memory (RAM) , read only memory (ROM) , tapes, magnetic discs, optical discs, volatile memory, non-volatile memory, and any combination thereof. In an aspect, for example, memory 202 may be a computer-readable storage medium that stores one or more computer-executable codes defining bit encoding component 240 and/or one or more of its sub-components. Additionally or alternatively, the base station 105 may include a bus 211 for coupling one or more of the RF front end 290, the transceiver 274, the memory 202, or the processor 205, and to exchange signaling information between each of the components and/or sub-components of the base station 105.

In an aspect, the processor (s) 205 may correspond to one or more of the processors described in connection with the base station in FIG. 5. Similarly, the memory 202 may correspond to the memory described in connection with the base station in FIG. 5.

FIG. 3 illustrates a flow chart of an example of a method 300 for encoding (e.g., by a base station, UE, or other wireless device) bits for transmitting over multiple layers in wireless communications.

At Block 302, multiple bits of data can be encoded to multiple modulation symbols for transmission over multiple layers in wireless communications, such that a repeated bit is encoded for transmission over a different layer of the multiple layers than an original bit corresponding to the repeated bit. In an aspect, bit encoding component 240, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, etc., can encode the multiple bits of data to the multiple modulation symbols for transmission over multiple layers in wireless communications, such that the repeated bit is encoded for transmission over the different layer of the multiple layers than the original bit corresponding to the repeated bit. In an example, the repeated bits may correspond to repetition of bit transmissions in case of low coding rate in a single transmission, HARQ retransmission in low and/or high coding rate, etc. For example, in a first transmission with a coding rate lower than a mother-code (e.g., default code rate at the base station 105) may have some bits/symbols transmitted more than once time. Thus, these bits/symbols can be encoded for transmission over a different layer than the original bits.

For example, bit encoding component 240 can encode the multiple bits of a codeword to multiple symbols using quadrature amplitude modulation (QAM) or other encoding schemes. In addition, bit encoding component 240 can map the symbols to one or more of multiple layers. For example, each layer may correspond to a MIMO layer over which symbols can be transmitted using different MCS, based on a different SINR, etc. In an example, each MIMO layer can correspond to one or more of multiple antenna ports that can be used for transmitting wireless communications.

Accordingly, in an example, bit encoding component 240 can map the symbols to different layers such to ensure a repeated symbol, that include repeated bits of a codeword, is mapped to a different layer than an original symbol corresponding to the original bits of the codeword that are repeated. For example, bit encoding component 240 may manage the mapping of symbols via resource mapping component 246 in this regard to determine whether a symbol includes repeated bits, determine a layer where a prior symbol including the original bits is mapped, and determine a different layer for mapping the symbol that includes the repeated bits. In this example, the encoding component 240 can provide the bits to be mapped, the rate-matching component 244 can populate a rate-matching buffer with the bits, and the resource mapping component 246 can map the bits in the rate-matching buffer to symbols (e.g., QAM symbols) such that repeated bits are mapped to symbols that are to be transmitted over different layers. In one example, the bits at encoding component 242 may be stored in a circular buffer, and when the encoding component 242 reaches the end of the buffer and moves to the beginning to obtain additional bits for transmission, it may know these are repeated bits. Accordingly, rate-matching component 244 can begin storing the repeated bits in the rate-matching buffer at a position that is mapped to a symbol associated with a different layer than the original bits.

In another example, encoding the multiple bits of data may optionally include, at Block 304, generating an encoding buffer for encoding the multiple bits to be of a buffer length such to cause the repeated bit to be encoded over the different layer than the original bit. In an aspect, bit encoding component 240, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, etc., can generate the encoding buffer for encoding the multiple bits to be of the buffer length such to cause the repeated bit to be encoded over the different layer than the original bit. In an example, the bit encoding component 240 can generate the encoding buffer based on this buffer length for first transmissions and/or retransmissions, and may do so for substantially any case where a single codeword is mapped to multiple layers, as described above and further herein. Moreover, for example, the bit encoding component 240 can generate the encoding buffer based on this buffer length for downlink communications at the base station 105, uplink communications at the UE 115, etc., and/or for control and/or data communications.

For example, bit encoding component 242 can indicate a number of bits in a codeword to be mapped to symbols and transmitted in wireless communications to the rate-matching component 244 and/or to the buffer length computing component 248. In this example, buffer length computing component 248 can compute the buffer length for the encoding buffer, which can be a rate-matching buffer described above, based on the number of bits in the codeword and other parameters, such as a number of bits per symbol used in the QAM scheme, a number of layers available for transmitting wireless communications, etc. The buffer length computing component 248 can compute the buffer length for the encoding buffer (e.g., the rate-matching buffer used by rate-matching component 244 as described above) based on these parameters to ensure repeated bits are mapped to symbols that are transmitted over different layers. In this example, rate-matching component 244 can store the bits from encoding component 242 in the rate-matching buffer based on the computed buffer length for generating the symbols for mapping to different layers via resource mapping component 246.

In a specific example, given a number of bits for each QAM symbol, denoted Q, a number of bits for a codeword, denoted N, and a number of layers, denoted K, buffer length computing component 248 can compute the buffer length for the rate-matching buffer, denoted R, such that (M/Q) ％K＝R, (R∈ [1, K-1] ) . In an example, M may be greater (or less) than N, with abs (M-N) bits of Nrandomly being repeated (or deleted) by the rate-matching component 244 in filling the rate-matching buffer, accordingly to the computed buffer length, with bits of the codeword from encoding component 242.

A specific example is shown in FIG. 6, which illustrates examples of block representations of

encodings

600, 620 of multiple bits to multiple symbols corresponding to multiple layers.

Encodings

600, 620 are depicted with reference to multiple bit indices of a rate-matching buffer that are mapped (e.g., by a resource mapping component 246) to multiple symbol indices, and each symbol index is associated with a layer index. In encoding 600, each symbol index is associated with two bit indices and a single layer. In this example, bits 1-4 are mapped to symbols 1-2, where symbol 1 is transmitted over a first layer (layer 1) and symbol 2 is transmitted over a second layer (layer 2) . In encoding 600, the buffer length of the rate-matching buffer is not set to cause repeated bits to be transmitted over different layers. Thus, in this example, as shown at 602, bits 1-4 are mapped to symbols 1-2 where

symbols

1 and 2 are respectively transmitted over

layers

1 and 2. Then, as shown at 604, the repeated bits 1-4 are also mapped to symbols 1-2 where

symbols

1 and 2 are respectively transmitted over

layers

1 and 2. In this example, double transmission of bits 1-4 may be due to repetition in case of low coding rate in a single transmission, HARQ retransmission in low and/or high coding rate, etc.

In encoding 620, however, buffer length computing component 248 can compute a different buffer length for the rate-matching buffer to avoid this mapping of bits to symbols that correspond to the same layer for repeated bits. For example, buffer length computing component 248 can compute the buffer length using the formula above to be 14, as (14/2) ％2＝R (R∈ [1, 2-1] ) is satisfied for R. In this example, as shown at 622, bits 1-4 are mapped to symbols 1-2 where

symbols

1 and 2 are respectively transmitted over

layers

1 and 2. Then, due to the rate-matching buffer being 14 bits, as shown at 624, the repeated bits 1-2 are mapped to symbol 1, which is now transmitted over

layer

1 and 2. Thus, the repeated bits naturally occupy a different layer than the corresponding original bits based on selecting the rate-matching buffer length in this regard.

At Block 306, the multiple modulation symbols can be transmitted over the multiple layers. In an aspect, transceiver 270, e.g., in conjunction with processor (s) 205, memory 202, etc., can transmit the multiple modulation symbols over the multiple layers. Thus, for example, repeated portions of the codeword can be transmitted over different layers to mitigate undesirable effects of bimodal (or multimodal) SINR and/or to allow for using different MCS to transmit the repeated portions of the codeword. A receiving device can accordingly receive and decode the encoded transmission. In addition, transceiver 270 can transmit the modulation symbols over the multiple layers along with one or more transmission points (e.g., one or more other base stations, cells, etc. ) .

Optionally, at Block 308, transmission power can be balanced across the multiple layers for transmitting the multiple modulation symbols over the multiple layers. In an aspect, power balancing component 250, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, etc., can balance the transmission power across the multiple layers for transmitting the multiple modulation symbols over the multiple layers. For example, power balancing component 250 can modify power used to transmit over each of the multiple layers such to achieve a substantially balanced power over each of the multiple layers and/or over each of multiple transmission points. In an example, power balancing component 250 can assume a same power for demodulation reference signal (DMRS) and corresponding data such that the power balancing component 250 may not need to indicate, to a receiving device, an absolute power allocation.

In an example, balancing the transmission power at Block 308 may optionally include, at Block 310, observing a channel related to the multiple layers. For example, power balancing component 250, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, etc., can observe the channel related to the multiple layers. In an example, power balancing component 250 can observe the full channel via a sounding or channel state information (CSI) report (e.g., a report received at the base station 105 from the UE 115) , and power balancing component 250 can balance the transmission power across the multiple layers based on the observed channel. In one example, the observed channel may allow the power balancing component 250 to estimate power used by other transmission points. In addition, for example, power balancing component 250 can compute the transmission power for each layer after beamforming one or more modulated symbols for transmission over the given layer. In one example, power balancing component 250 can determine a transmission power to allocate to each of the multiple layers based on computing an average power, minimum power, median power, or similar metrics, etc. across the layers, as indicated in the sounding or CSI report.

In another example, balancing the transmission power at Block 308 may optionally include, at Block 312, receiving, from a receiving device, a report of measured power compensation for each of the multiple layers. For example, power balancing component 250, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, etc., can receive, from the receiving device (e.g., a UE 115 where the bit encoding component 240, power balancing component 250, etc. are part of a base station 105 or vice versa) , a report of measured power compensation for each of the multiple layers (e.g., based on one or multiple transmission points) . For example, the receiving device may report measured power compensation value for each layer, which may correspond to a power compensation used by one or more transmitting devices in transmitting over the layer. For example, the power compensation value can be denoted ΔP (i) , where i is the layer index. Power balancing component 250, for example, can allocate transmission power for each layer based on applying the power compensation value such that P' (i) ＝P (i) +ΔP (i) where P (i) and P' (i) are original and new power for each layer.

FIG. 4 illustrates a flow chart of an example of a method 400 for balancing transmission power (e.g., by a base station, UE, or other wireless device) for transmitting over multiple layers in wireless communications.

At Block 402, a channel can be observed based on a sounding report or CSI a report. In an aspect, power balancing component 250, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, etc., can observe the channel based on the sounding report or the CSI report. For example, the sounding report or the CSI report can provide information regarding energy detected on the channel (e.g., where the channel relates to the multiple layers) . Optionally, this may include, at Block 404, receiving the sounding report or the CSI report from one or more UEs or a network listening module (NLM) on a base station 105.

At Block 404, a transmission power for each of multiple layers can be computed after beamforming each of the multiple layers for transmitting over the channel based on the sounding report or the CSI report. In an aspect, power balancing component 250, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, etc., can compute the transmission power for each of multiple layers after beamforming each of the multiple layers for transmitting over the channel based on the sounding report or the CSI report. For example, power balancing component 250 can determine the transmission power determined for each layer based on a beamforming matrix specified for the layer.

At Block 406, a power allocation can be determined as a function of the transmission power for the multiple layers. In an aspect, power balancing component 250, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, etc., can determine the power allocation as a function of the transmission power for the multiple layers. For example, power balancing component 250 can determine the power allocation for a given layer based on a function of the transmission power for the multiple layers, where the function may include an average of the transmission power for the multiple layers, a minimum of the transmission power for the multiple layers, etc.

At Block 408, a power can be allocated to each of the multiple layers based on the power allocation. In an aspect, power balancing component 250, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, etc., can allocate power to each of the multiple layers based on the power allocation determined for the given layer.

FIG. 5 illustrates a flow chart of an example of a method 500 for balancing transmission power (e.g., by a base station, UE, or other wireless device) for transmitting over multiple layers in wireless communications.

At Block 502, a measured power compensation can be received from one or more UEs for each of multiple layers. In an aspect, power balancing component 250, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, etc., can receive, from the one or more UEs, a measured power compensation value for each of the multiple layers. For example, the one or more UEs (e.g., UE 115) may report the measured power compensation value measured for transmitting devices, as described above, which may be included in measurement report or other report requested by the base station 105.

At Block 504, power can be allocated to each of the multiple layers based at least in part on, for each of the multiple layers, adding the measured power compensation value to a previous transmission power. In an aspect, power balancing component 250, e.g., in conjunction with processor (s) 205, memory 202, transceiver 270, etc., can allocate power to each of the multiple layers based at least in part on, for each of the multiple layers, adding the measured power compensation value to a previous transmission power. As described, for example, power balancing component 250 can allocate transmission power for each layer based on applying the power compensation value such that P' (i) ＝P (i) +ΔP (i) where P (i) and P' (i) are original and new power for each layer.

FIG. 7 is a block diagram of a MIMO communication system 700 including a base station 105 and a UE 115. The MIMO communication system 700 may illustrate aspects of the wireless communication system 100 described with reference to FIG. 1. The base station 105 may be an example of aspects of the base station 105 described with reference to FIGS. 1-2. The base station 105 may be equipped with

antennas

734 and 735, and the UE 115 may be equipped with

antennas

752 and 753. In the MIMO communication system 700, the base station 105 may be able to send data over multiple communication links at the same time. Each communication link may be called a “layer” and the “rank” of the communication link may indicate the number of layers used for communication. For example, in a 2x2 MIMO communication system where base station 105 transmits two “layers, ” the rank of the communication link between the base station 105 and the UE 115 is two.

At the base station 105, a transmit (Tx) processor 720 may receive data from a data source. The transmit processor 720 may process the data. The transmit processor 720 may also generate control symbols or reference symbols. A transmit MIMO processor 730 may perform spatial processing (e.g., precoding) on data symbols, control symbols, or reference symbols, if applicable, and may provide output symbol streams to the transmit modulator/

demodulators

732 and 733. Each modulator/demodulator 732 through 733 may process a respective output symbol stream (e.g., for OFDM, etc. ) to obtain an output sample stream. Each modulator/demodulator 732 through 733 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a DL signal. In one example, DL signals from modulator/

demodulators

732 and 733 may be transmitted via the

antennas

734 and 735, respectively.

The UE 115 may be an example of aspects of the UEs 115 described with reference to FIGS. 1-2. At the UE 115, the

UE antennas

752 and 753 may receive the DL signals from the base station 105 and may provide the received signals to the modulator/

demodulators

754 and 755, respectively. Each modulator/demodulator 754 through 755 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each modulator/demodulator 754 through 755 may further process the input samples (e.g., for OFDM, etc. ) to obtain received symbols. A MIMO detector 756 may obtain received symbols from the modulator/

demodulators

754 and 755, perform MIMO detection on the received symbols, if applicable, and provide detected symbols. A receive (Rx) processor 758 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, providing decoded data for the UE 115 to a data output, and provide decoded control information to a processor 780, or memory 782.

The processor 780 may in some cases execute stored instructions to instantiate a bit encoding component 240 (see e.g., FIGS. 1 and 2) .

On the uplink (UL) , at the UE 115, a transmit processor 764 may receive and process data from a data source. The transmit processor 764 may also generate reference symbols for a reference signal. The symbols from the transmit processor 764 may be precoded by a transmit MIMO processor 766 if applicable, further processed by the modulator/demodulators 754 and 755 (e.g., for SC-FDMA, etc. ) , and be transmitted to the base station 105 in accordance with the communication parameters received from the base station 105. At the base station 105, the UL signals from the UE 115 may be received by the

antennas

734 and 735, processed by the modulator/

demodulators

732 and 733, detected by a MIMO detector 736 if applicable, and further processed by a receive processor 738. The receive processor 738 may provide decoded data to a data output and to the processor 740 or memory 742.

The processor 740 may in some cases execute stored instructions to instantiate a bit encoding component 240 (see e.g., FIGS. 1 and 2) .

The components of the UE 115 may, individually or collectively, be implemented with one or more ASICs adapted to perform some or all of the applicable functions in hardware. Each of the noted modules may be a means for performing one or more functions related to operation of the MIMO communication system 700. Similarly, the components of the base station 105 may, individually or collectively, be implemented with one or more ASICs adapted to perform some or all of the applicable functions in hardware. Each of the noted components may be a means for performing one or more functions related to operation of the MIMO communication system 700.

The above detailed description set forth above in connection with the appended drawings describes examples and does not represent the only examples that may be implemented or that are within the scope of the claims. The term “example, ” when used in this description, means “serving as an example, instance, or illustration, ” and not “preferred” or “advantageous over other examples. ” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, well-known structures and apparatuses are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

Information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, computer-executable code or instructions stored on a computer-readable medium, or any combination thereof.

The various illustrative blocks and components described in connection with the aspects described herein may be implemented or performed with a specially-programmed device, such as but not limited to a processor, a digital signal processor (DSP) , an ASIC, a FPGA or other programmable logic device, a discrete gate or transistor logic, a discrete hardware component, or any combination thereof designed to perform the functions described herein. A specially-programmed processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A specially-programmed processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a non-transitory computer-readable medium. Other examples and implementations are within the scope and spirit of the disclosure and appended claims. For example, due to the nature of software, functions described above can be implemented using software executed by a specially programmed processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. Also, as used herein, including in the claims, “or” as used in a list of items prefaced by “at least one of” indicates a disjunctive list such that, for example, a list of “at least one of A, B, or C” means A or B or C or AB or AC or BC or ABC (i.e., A and B and C) .

Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage medium may be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. 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, 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 Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

The previous description is provided to enable a person skilled in the art to make or use the aspects described herein. Various modifications described aspects will be readily apparent to those skilled in the art, and the common principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Furthermore, although elements of the described aspects and/or embodiments may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. Additionally, all or a portion of any aspect and/or embodiment may be utilized with all or a portion of any other aspect and/or embodiment, unless stated otherwise. Thus, the disclosure is not to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

A method for mapping transmissions to multiple multiple-input multiple-output (MIMO) layers in wireless communications, comprising:

encoding multiple bits of data to multiple modulation symbols for transmission over multiple MIMO layers in wireless communications, such that a repeated bit is encoded for transmission over a different layer of the multiple MIMO layers than an original bit corresponding to the repeated bit； and

transmitting the multiple modulation symbols over the multiple MIMO layers.
The method of claim 1, wherein the encoding the multiple bits comprises:

generating an encoding buffer for encoding the multiple bits to be of a buffer length such to cause the repeated bit to be encoded over the different layer than the original bit； and

storing the multiple bits in the encoding buffer based on the buffer length.
The method of claim 2, wherein generating the encoding buffer comprises generating the encoding buffer such that a value of the buffer length divided by a number of bits per modulation symbol and modulo a number of layers is equal to a value inclusively between one and the number of layers minus one.
The method of claim 1, wherein at least two layers of the multiple MIMO layers are associated with different modulation and coding schemes.
The method of claim 1, wherein the original bit and the repeated bit correspond to a single codeword encoded for transmission over the multiple MIMO layers.
The method of claim 1, further comprising balancing transmission power across the multiple MIMO layers for transmitting the multiple modulation symbols over the multiple MIMO layers.
The method of claim 6, further comprising observing a channel related to the multiple MIMO layers, wherein balancing the transmission power across the multiple MIMO layers is based on computing an average power for the channel across the multiple MIMO layers.
The method of claim 7, wherein balancing the transmission power for a given layer is performed after beamforming for the given layer.
The method of claim 6, further comprising receiving a report of measured power compensation from a device for each of the multiple MIMO layers, wherein balancing the transmission power across the multiple MIMO layers is based on applying power compensation values for each of the multiple MIMO layers based on the report.
An apparatus for mapping transmissions to multiple multiple-input multiple-output (MIMO) layers in wireless communications, comprising:

a transceiver for communicating one or more wireless signals via one or more antennas；

a memory configured to store instructions； and

one or more processors communicatively coupled with the transceiver and the memory, wherein the one or more processors are configured to:

encode multiple bits of data to multiple modulation symbols for transmission over multiple MIMO layers in wireless communications, such that a repeated bit is encoded for transmission over a different layer of the multiple MIMO layers than an original bit corresponding to the repeated bit； and

transmit the multiple modulation symbols over the multiple MIMO layers.
The apparatus of claim 10, wherein the one or more processors are configured to encode the multiple bits at least in part by:

generating an encoding buffer for encoding the multiple bits to be of a buffer length such to cause the repeated bit to be encoded over the different layer than the original bit； and

storing the multiple bits in the encoding buffer based on the buffer length.
The apparatus of claim 11, wherein the one or more processors are configured to generate the encoding buffer such that a value of the buffer length divided by a number of bits per modulation symbol and modulo a number of layers is equal to a value inclusively between one and the number of layers minus one.
The apparatus of claim 10, wherein at least two layers of the multiple MIMO layers are associated with different modulation and coding schemes.
The apparatus of claim 10, wherein the original bit and the repeated bit correspond to a single codeword encoded for transmission over the multiple MIMO layers.
The apparatus of claim 10, wherein the one or more processors are further configured to balance transmission power across the multiple MIMO layers for transmitting the multiple modulation symbols over the multiple MIMO layers.
An apparatus for mapping transmissions to multiple multiple-input multiple-output (MIMO) layers in wireless communications, comprising:

means for encoding multiple bits of data to multiple modulation symbols for transmission over multiple MIMO layers in wireless communications, such that a repeated bit is encoded for transmission over a different layer of the multiple MIMO layers than an original bit corresponding to the repeated bit； and

means for transmitting the multiple modulation symbols over the multiple MIMO layers.
The apparatus of claim 16, wherein the means for encoding encodes the multiple bits at least in part by:

generating an encoding buffer for encoding the multiple bits to be of a buffer length such to cause the repeated bit to be encoded over the different layer than the original bit； and

storing the multiple bits in the encoding buffer based on the buffer length.
The apparatus of claim 17, wherein the means for encoding generates the encoding buffer such that a value of the buffer length divided by a number of bits per modulation symbol and modulo a number of layers is equal to a value inclusively between one and the number of layers minus one.
The apparatus of claim 16, wherein at least two layers of the multiple MIMO layers are associated with different modulation and coding schemes.
The apparatus of claim 16, further comprising means for balancing transmission power across the multiple MIMO layers for transmitting the multiple modulation symbols over the multiple MIMO layers.
A method for balancing transmission power across multiple multiple-input multiple-output (MIMO) layers, comprising:

observing a channel based on a sounding report or a channel state information (CSI) report；

computing a transmission power for each of multiple MIMO layers after beamforming each of the multiple MIMO layers for transmitting over the channel based on the sounding report or the CSI report；

determining a power allocation as a function of the transmission power for the multiple MIMO layers； and

allocating power to each of the multiple MIMO layers based on the power allocation.
The method of claim 21, wherein determining the power allocation comprises determining at least one of a median or mean average of the transmission powers computed for each of the multiple MIMO layers, or a minimum of the transmission powers computed for each of the multiple MIMO layers.
The method of claim 21, wherein observing the channel comprises receiving the sounding report or the CSI report from at least one of one or more user equipment or a network listening module.
An apparatus for balancing transmission power across multiple multiple-input multiple-output (MIMO) layers, comprising:

a transceiver for communicating one or more wireless signals via one or more antennas；

a memory configured to store instructions； and

one or more processors communicatively coupled with the transceiver and the memory, wherein the one or more processors are configured to:

observe a channel based on a sounding report or a channel state information (CSI) report；

compute a transmission power for each of multiple MIMO layers after beamforming each of the multiple MIMO layers for transmitting over the channel based on the sounding report or the CSI report；

determine a power allocation as a function of the transmission power for the multiple MIMO layers； and

allocate power to each of the multiple MIMO layers based on the power allocation.
An apparatus for balancing transmission power across multiple multiple-input multiple-output (MIMO) layers, comprising:

means for observing a channel based on a sounding report or a channel state information (CSI) report；

means for computing a transmission power for each of multiple MIMO layers after beamforming each of the multiple MIMO layers for transmitting over the channel based on the sounding report or the CSI report；

means for determining a power allocation as a function of the transmission power for the multiple MIMO layers； and

means for allocating power to each of the multiple MIMO layers based on the power allocation.
A method for balancing transmission power across multiple multiple-input multiple-output (MIMO) layers, comprising:

receiving, from one or more user equipment, a measured power compensation value for each of multiple MIMO layers； and

allocating power to each of the multiple MIMO layers based at least in part on, for each of the multiple MIMO layers, adding the measured power compensation value to a previous transmission power.
An apparatus for balancing transmission power across multiple multiple-input multiple-output (MIMO) layers, comprising:

a transceiver for communicating one or more wireless signals via one or more antennas；

a memory configured to store instructions； and

one or more processors communicatively coupled with the transceiver and the memory, wherein the one or more processors are configured to:

receive, from one or more user equipment, a measured power compensation value for each of multiple MIMO layers； and

allocate power to each of the multiple MIMO layers based at least in part on, for each of the multiple MIMO layers, adding the measured power compensation value to a previous transmission power.
An apparatus for balancing transmission power across multiple multiple-input multiple-output (MIMO) layers, comprising:

means for receiving, from one or more user equipment, a measured power compensation value for each of multiple MIMO layers； and

means for allocating power to each of the multiple MIMO layers based at least in part on, for each of the multiple MIMO layers, adding the measured power compensation value to a previous transmission power.