WO2017196398A1

WO2017196398A1 - Qcl (quasi co-location) for dm-rs (demodulation reference signal) antenna ports for comp (coordinated multi-point)

Info

Publication number: WO2017196398A1
Application number: PCT/US2016/067994
Authority: WO
Inventors: Alexei Davydov
Original assignee: Intel Corporation
Priority date: 2016-05-13
Filing date: 2016-12-21
Publication date: 2017-11-16
Also published as: DE112016006854T5

Abstract

Techniques for determining whether DM-RS (Demodulation Reference Signal) APs (Antenna Ports) are QCL-ed (Quasi Co-Located) with co-scheduled DM-RS APs are discussed. One example embodiment can comprise an apparatus that can be employed at a UE (User Equipment), that can comprise a memory; and one or more processors configured to: process higher layer signaling that indicates, in connection with a MU (Multi User)-MIMO (Multiple Input Multiple Output) transmission, a QCL (Quasi Co-Location) type for one or more DM-RS (Demodulation Reference Signal) APs (Antenna Ports) associated with the UE; and determine, based on the indicated QCL type, whether the one or more DM-RS APs are QCL-ed (Quasi Co-Located) with one or more co-scheduled DM-RS APs associated with a distinct UE.

Description

QCL (QUASI CO-LOCATION) FOR DM-RS (DEMODULATION REFERENCE SIGNAL) ANTENNA PORTS FOR COMP (COORDINATED MULTI-POINT)

REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No.

62/336,380 filed May 13, 2016, entitled "QCL FOR DM-RS ANTENNA PORTS FOR CS/CB FECOMP", the contents of which are herein incorporated by reference in their entirety.

FIELD

[0002] The present disclosure relates to wireless technology, and more specifically to techniques for facilitating quasi co-location (QCL) assumptions and signaling in connection with DM-RS (Demodulation Reference Signal) antenna ports.

BACKGROUND

[0003] In conventional LTE (Long Term Evolution) systems, downlink (DL) coordinated multipoint (CoMP) can improve throughput for cell edge users. Because PDSCH (Physical Downlink Shared Channel) might not originate from the same location as a serving cell, quasi co-location (QCL) signaling can be employed for PDSCH which can indicate which set of reference signals correspond to the same transmission point as the PDSCH.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] FIG. 1 is a block diagram illustrating an example user equipment (UE) useable in connection with various aspects described herein.

[0005] FIG. 2 is a diagram illustrating UE-specific RSs in transmission modes 9 and 10 in connection with various aspects discussed herein.

[0006] FIG. 3 is a diagram illustrating an example of a DPS CoMP scheme that can be employed in connection with various aspects discussed herein.

[0007] FIG. 4A is a diagram illustrating an example scenario of MU-MIMO

transmission wherein DM-RS antenna ports designated to different UEs originate from the same transmission point, according to various aspects described herein.

[0008] FIG. 4B is a diagram illustrating an example scenario of MU-MIMO

transmission wherein DM-RS antenna ports designated to different UEs originate from different transmission points, according to various aspects described herein. [0009] FIG. 5 is a block diagram illustrating a system that facilitates channel estimation at a UE (user equipment) of DM-RS (demodulation reference signal) APs (antenna ports) co-scheduled with DM-RS APs associated with that UE, according to various aspects described herein.

[0010] FIG. 6 is a block diagram illustrating a system that facilitates generation of higher layer signaling that indicates whether DM-RS AP(s) associated with a UE are QCL-ed with co-scheduled DM-RS AP(s), according to various aspects described herein.

[0011] FIG. 7 is a flow diagram illustrating a method that facilitates determination by a UE of whether DM-RS AP(s) of that UE are QCL-ed with co-scheduled DM-RS AP(s), according to various aspects described herein.

[0012] FIG. 8 is a flow diagram illustrating a method that facilitates generation of higher layer signaling by a base station that indicates whether DM-RS AP(s) of a UE are QCL-ed with co-scheduled DM-RS AP(s), according to various aspects described herein.

DETAILED DESCRIPTION

[0013] The present disclosure will now be described with reference to the attached drawing figures, wherein like reference numerals are used to refer to like elements throughout, and wherein the illustrated structures and devices are not necessarily drawn to scale. As utilized herein, terms "component," "system," "interface," and the like are intended to refer to a computer-related entity, hardware, software (e.g., in execution), and/or firmware. For example, a component can be a processor (e.g., a microprocessor, a controller, or other processing device), a process running on a processor, a controller, an object, an executable, a program, a storage device, a computer, a tablet PC and/or a user equipment (e.g., mobile phone, etc.) with a processing device. By way of illustration, an application running on a server and the server can also be a component. One or more components can reside within a process, and a component can be localized on one computer and/or distributed between two or more computers. A set of elements or a set of other components can be described herein, in which the term "set" can be interpreted as "one or more."

[0014] Further, these components can execute from various computer readable storage media having various data structures stored thereon such as with a module, for example. The components can communicate via local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from one component interacting with another component in a local system, distributed system, and/or across a network, such as, the Internet, a local area network, a wide area network, or similar network with other systems via the signal).

[0015] As another example, a component can be an apparatus with specific functionality provided by mechanical parts operated by electric or electronic circuitry, in which the electric or electronic circuitry can be operated by a software application or a firmware application executed by one or more processors. The one or more processors can be internal or external to the apparatus and can execute at least a part of the software or firmware application. As yet another example, a component can be an apparatus that provides specific functionality through electronic components without mechanical parts; the electronic components can include one or more processors therein to execute software and/or firmware that confer(s), at least in part, the functionality of the electronic components.

[0016] Use of the word exemplary is intended to present concepts in a concrete fashion. As used in this application, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless specified otherwise, or clear from context, "X employs A or B" is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then "X employs A or B" is satisfied under any of the foregoing instances. In addition, the articles "a" and "an" as used in this application and the appended claims should generally be construed to mean "one or more" unless specified otherwise or clear from context to be directed to a singular form. Furthermore, to the extent that the terms "including", "includes", "having", "has", "with", or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term

"comprising."

[0017] As used herein, the term "circuitry" may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some embodiments, the circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. In some embodiments, circuitry may include logic, at least partially operable in hardware.

[0018] Embodiments described herein may be implemented into a system using any suitably configured hardware and/or software. FIG. 1 illustrates, for one embodiment, example components of a User Equipment (UE) device 100. In some embodiments, the UE device 100 may include application circuitry 102, baseband circuitry 104, Radio Frequency (RF) circuitry 106, front-end module (FEM) circuitry 108 and one or more antennas 1 10, coupled together at least as shown.

[0019] The application circuitry 102 may include one or more application processors. For example, the application circuitry 102 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor(s) may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors may be coupled with and/or may include memory/storage and may be configured to execute instructions stored in the memory/storage to enable various applications and/or operating systems to run on the system.

[0020] The baseband circuitry 104 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 104 may include one or more baseband processors and/or control logic to process baseband signals received from a receive signal path of the RF circuitry 106 and to generate baseband signals for a transmit signal path of the RF circuitry 106. Baseband processing circuity 104 may interface with the application circuitry 102 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 106. For example, in some embodiments, the baseband circuitry 104 may include a second generation (2G) baseband processor 104a, third generation (3G) baseband processor 104b, fourth generation (4G) baseband processor 104c, and/or other baseband processor(s) 104d for other existing generations, generations in development or to be developed in the future (e.g., fifth generation (5G), 6G, etc.). The baseband circuitry 104 (e.g., one or more of baseband processors 104a-d) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 106. The radio control functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, etc. In some embodiments, modulation/demodulation circuitry of the baseband circuitry 104 may include Fast-Fourier Transform (FFT), precoding, and/or constellation

mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry 104 may include convolution, tail-biting convolution, turbo, Viterbi, and/or Low Density Parity Check (LDPC) encoder/decoder functionality.

Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments.

[0021] In some embodiments, the baseband circuitry 104 may include elements of a protocol stack such as, for example, elements of an evolved universal terrestrial radio access network (EUTRAN) protocol including, for example, physical (PHY), media access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), and/or radio resource control (RRC) elements. A central processing unit (CPU) 104e of the baseband circuitry 104 may be configured to run elements of the protocol stack for signaling of the PHY, MAC, RLC, PDCP and/or RRC layers. In some embodiments, the baseband circuitry may include one or more audio digital signal processor(s) (DSP) 104f. The audio DSP(s) 104f may be include elements for compression/decompression and echo cancellation and may include other suitable processing elements in other embodiments. Components of the baseband circuitry may be suitably combined in a single chip, a single chipset, or disposed on a same circuit board in some embodiments. In some embodiments, some or all of the constituent components of the baseband circuitry 104 and the application circuitry 102 may be implemented together such as, for example, on a system on a chip (SOC).

[0022] In some embodiments, the baseband circuitry 104 may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 104 may support communication with an evolved universal terrestrial radio access network (EUTRAN) and/or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN). Embodiments in which the baseband circuitry 104 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

[0023] RF circuitry 106 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 106 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 106 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 108 and provide baseband signals to the baseband circuitry 104. RF circuitry 106 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 1 04 and provide RF output signals to the FEM circuitry 108 for transmission. [0024] In some embodiments, the RF circuitry 106 may include a receive signal path and a transmit signal path. The receive signal path of the RF circuitry 106 may include mixer circuitry 1 06a, amplifier circuitry 106b and filter circuitry 106c. The transmit signal path of the RF circuitry 106 may include filter circuitry 106c and mixer circuitry 106a. RF circuitry 106 may also include synthesizer circuitry 106d for synthesizing a frequency for use by the mixer circuitry 106a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 106a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry 108 based on the synthesized frequency provided by synthesizer circuitry 106d. The amplifier circuitry 106b may be configured to amplify the down-converted signals and the filter circuitry 106c may be a low-pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitry 104 for further processing. In some embodiments, the output baseband signals may be zero- frequency baseband signals, although this is not a requirement. In some embodiments, mixer circuitry 1 06a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect.

[0025] In some embodiments, the mixer circuitry 106a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 106d to generate RF output signals for the FEM circuitry 108. The baseband signals may be provided by the baseband circuitry 104 and may be filtered by filter circuitry 1 06c. The filter circuitry 1 06c may include a low-pass filter (LPF), although the scope of the embodiments is not limited in this respect.

[0026] In some embodiments, the mixer circuitry 106a of the receive signal path and the mixer circuitry 106a of the transmit signal path may include two or more mixers and may be arranged for quadrature downconversion and/or upconversion respectively. In some embodiments, the mixer circuitry 106a of the receive signal path and the mixer circuitry 106a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry 1 06a of the receive signal path and the mixer circuitry 106a may be arranged for direct downconversion and/or direct upconversion, respectively. In some embodiments, the mixer circuitry 106a of the receive signal path and the mixer circuitry 106a of the transmit signal path may be configured for super-heterodyne operation. [0027] In some embodiments, the output baseband signals and the input baseband signals may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternate embodiments, the output baseband signals and the input baseband signals may be digital baseband signals. In these alternate embodiments, the RF circuitry 106 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry 104 may include a digital baseband interface to communicate with the RF circuitry 106.

[0028] In some dual-mode embodiments, a separate radio IC circuitry may be provided for processing signals for each spectrum, although the scope of the

embodiments is not limited in this respect.

[0029] In some embodiments, the synthesizer circuitry 106d may be a fractional-N synthesizer or a fractional N/N+1 synthesizer, although the scope of the embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry 106d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.

[0030] The synthesizer circuitry 106d may be configured to synthesize an output frequency for use by the mixer circuitry 106a of the RF circuitry 1 06 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 106d may be a fractional N/N+1 synthesizer.

[0031] In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO), although that is not a requirement. Divider control input may be provided by either the baseband circuitry 104 or the applications processor 102 depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a look-up table based on a channel indicated by the applications processor 1 02.

[0032] Synthesizer circuitry 1 06d of the RF circuitry 106 may include a divider, a delay-locked loop (DLL), a multiplexer and a phase accumulator. In some embodiments, the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide the input signal by either N or N+1 (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip- flop. In these embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

[0033] In some embodiments, synthesizer circuitry 1 06d may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a LO frequency (fLO). In some embodiments, the RF circuitry 106 may include an IQ/polar converter.

[0034] FEM circuitry 108 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more antennas 1 10, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 106 for further processing. FEM circuitry 108 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 106 for transmission by one or more of the one or more antennas 1 1 0.

[0035] In some embodiments, the FEM circuitry 108 may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry may include a low-noise amplifier (LNA) to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 106). The transmit signal path of the FEM circuitry 108 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 106), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 1 1 0.

[0036] In some embodiments, the UE device 100 may include additional elements such as, for example, memory/storage, display, camera, sensor, and/or input/output (I/O) interface.

[0037] Additionally, although the above example discussion of device 100 is in the context of a UE device, in various aspects, a similar device can be employed in connection with a base station (BS) such as an Evolved NodeB (eNB), etc.

[0038] In LTE (Long Term Evolution) Rel-9 (Release 9), dual layer beamforming based transmission mode 8 (TM8) is introduced. In TM8, PDSCH (physical downlink shared channel) demodulation is based on UE (User Equipment)-specific RS (Reference Signal). One UE-specific RS (e.g., DM-RS (demodulation reference signal)) port is precoded using the same precoder as its associated PDSCH layer. For MU (Multi User)-MIMO (Multiple Input Multiple Output), transparent MU-MIMO is supported because UE-specific RS overhead does not change with the increase of MU-MIMO transmission rank. In Rel-9, a maximum of four rank one users can be served in one MU-MIMO transmission. In order to support four rank one users with only two UE- specific RS port 7/8, one additional scrambling code with SCID (Scrambling ldentity)=1 is introduced. Thus four rank one users can use a {UE-specific RS, SCID} pair which belongs to {7/8, 0/1 } to generate UE-specific RS sequences. Because DMRS

(Demodulation Reference Signals) with different SCID are not orthogonal, the eNB (Evolved NodeB) has to rely on spatial precoding to mitigate the inter-user interference.

[0039] In LTE Rel-1 0, TM9 extends the UE-specific RS structure of TM8 to support up to rank eight SU-MIMO transmission. But when it comes to MU-MIMO, TM9 simply keeps the same MU-MIMO transmission order as TM8. Two UE-specific RS ports {1 1 , 13} are added to the same 12 REs of UE-specific RS ports {7, 8} using length four orthogonal cover code. The second group of 12 REs are reserved for the other four UE- specific RS ports {9, 10, 12, 14}. When the transmission rank is greater than 2, both UE- specific RS groups are used. Referring to FIG. 2, illustrated is a diagram showing UE- specific RSs in transmission mode 9 in connection with various aspects discussed herein. The DM-RS structure of FIG. 2 is also applicable to transmission mode 10.

[0040] In Rel-1 3 support of larger number of orthogonal DM-RS (e.g., UE-specific RS) antenna ports was introduced to support high dimensional MU-MIMO. More specifically, up to four UE may be scheduled with orthogonal DM-RS antenna ports 7, 8, 1 1 , and 1 3 with a single MIMO layer.

[0041] Table 1 , below, shows antenna ports, scrambling identities, and numbers of layers for DM-RS for one and two codewords.

Table 1 : Antenna port(s), scrambling identity and number of layers indication

(OCC=2)

2 1 layer, port 8, n_Scio=0 2 2 layer, port 7-8, A?_SC/D=0 (OCC=4)

(OCC=2)

3 1 layer, port 8, A?_SC/D=1 3 2 layer, port 7-8, A?_SC/D=1 (OCC=4)

(OCC=2)

4 1 layer, port 7, A?_SC/D=0 4 2 layer, port 11 ,1 3, A?SC/D=0

(OCC=4) (OCC=4)

5 1 layer, port 7, A?_SC/D=1 5 2 layer, port 11 , 13, A?SC/D=1

(OCC=4) (OCC=4)

6 1 layer, port 8, n_Scio=0 6 3 layer, port 7-9

(OCC=4)

7 1 layer, port 8, A?_SC/D=1 7 4 layer, port 7-10

(OCC=4)

8 1 layer, port 11 , n_Scio=0 8 5 layer, port 7-11

(OCC=4)

9 1 layer, port 11 , A?_SC/D=1 9 6 layer, port 7-12

(OCC=4)

10 1 layer, port 13, n_SCiD=0 10 7 layers, ports 7-13

(OCC=4)

11 1 layer, port 13, A?_SC/D=1 11 8 layers, ports 7-14

(OCC=4)

12 2 layers, ports 7-8 12 Reserved

13 3 layers, ports 7-9 13 Reserved

14 4 layers, ports 7-10 14 Reserved

15 Reserved 15 Reserved

[0042] If the UE is not configured with higher layer parameter dmrs-tableAlt, and, for example, an antenna port ^{p e {7}'^8} is used, then the UE cannot assume that the other antenna port in the set ^{7'^8} is not associated with transmission of PDSCH to another UE.

[0043] If the UE is configured with higher layer parameter dmrs-tableAlt, and, for example, a single layer transmission scheme on antenna port ^{p G} i⁷'⁸'¹¹'¹³)

corresponding to any of one codeword values 4-1 1 in Table 1 is used, then the UE cannot assume that the other antenna ports in the set i⁷'⁸'¹¹'¹³) is not associated with transmission of PDSCH to another UE. [0044] In Rel-1 1 , downlink (DL) coordinated multi-point (DL CoMP) was introduced to address the issue of throughput performance for cell edge users. The throughput improvement in DL CoMP is achieved by coordination of the neighboring cells, for example, by using dynamic point selection (DPS). Referring to FIG. 3, illustrated is a diagram showing an example of a DPS CoMP scheme that can be employed in connection with various aspects discussed herein.

[0045] In DPS CoMP, the transmission point can be dynamically selected for the UE based on one or more of the instantaneous channel and/or interference conditions and/or cell load.

[0046] As the PDSCH transmission in DL CoMP might be not co-located with the serving cell, a quasi co-location (QCL) signaling has been introduced to indicate the set of reference signals (e.g., and corresponding antenna ports) which experience the same propagation (those that belong to the same transmission point (TP)).

[0047] In Rel-1 1 of the 3GPP (Third Generation Partnership Project) TS (technical specification) 36.21 1 , quasi co-location is defined as follows: "Two antenna ports are said to be quasi co-located if the large-scale properties of the channel over which a symbol on one antenna port is conveyed can be inferred from the channel over which a symbol on the other antenna port is conveyed. The large-scale properties include one or more of delay spread, Doppler spread, Doppler shift, average gain, and average delay."

[0048] The relationship between reference signals and antenna ports can be defined as follows: (a) CRS are transmitted using antenna ports 0,1 ,2,3; (b) CSI-RS are transmitted using antenna ports 15,16,1 7,18,19,20,21 ,22; (c) PDSCH UE-specific RS are transmitted using antenna ports 7,8; and (d) ePDCCH UE-specific RS are transmitted using antenna ports 107,1 08, 109, 1 10.

[0049] Two quasi co-location (QCL) behaviors Type A and Type B are defined in Rel-1 1 in technical specification (TS) 36.213 version 1 1 .1 .0:

[0050] "7.1 .10 Antenna ports quasi co-location for PDSCH

[0051] "A UE configured in transmission mode 1 -10 may assume the antenna ports 0

- 3 of a serving cell are quasi co-located (as defined in TS 36.21 1 v.1 1 .1 .0) with respect to delay spread, Doppler spread, Doppler shift, average gain, and average delay.

[0052] "A UE configured in transmission mode 8-10 may assume the antenna ports 7

- 14 of a serving cell are quasi co-located (as defined in TS 36.21 1 v.1 1 .1 .0) for a given subframe with respect to delay spread, Doppler spread, Doppler shift, average gain, and average delay. [0053] "A UE configured in transmission mode 1 -9 may assume the antenna ports 0 - 3, 5, 7 - 22 of a serving cell are quasi co-located (as defined in Rel-1 1 TS 36.21 1 v.1 1 .1 .0) with respect to Doppler shift, Doppler spread, average delay, and delay spread.

[0054] "A UE configured in transmission mode 10 is configured with one of two quasi co-location types by higher layer signaling to decode PDSCH according to transmission scheme associated with antenna ports 7-14:

[0055] " - Type A: The UE may assume the antenna ports 0 - 3, 7 - 22 of a serving cell are quasi co-located (as defined in TS 36.21 1 v.1 1 .1 .0) with respect to delay spread, Doppler spread, Doppler shift, and average delay

[0056] " - Type B: The UE may assume the antenna ports 15 - 22 corresponding to the CSI-RS resource configuration identified by 'CSI-RS resource configuration identity for PDSCH RE mapping' in Section 7.1 .9 (of 36.21 3) and the antenna ports 7 - 14 associated with the PDSCH are quasi co-located (as defined in defined in TS 36.21 1 v.1 1 .1 .0) with respect to Doppler shift, Doppler spread, average delay, and delay spread."

[0057] In QCL behaviour type A, CRS, CSI-RS and UE-specific RS can be quasi-co- located with respect to delay spread, Doppler spread, Doppler shift, and average delay.

[0058] In QCL behaviour type B, DCI based signaling can be used to indicate quasi- co-location between antenna ports of one CSI-RS (among four configured) and UE- specific RS antenna ports of the same serving cell with respect to delay spread, Doppler spread, Doppler shift, and average delay.

[0059] Parameters for determining PDSCH RE (Resource Element) mapping and PDSCH antenna port quasi co-location can be configured via higher layer signaling. Table 2, below (corresponding to Table 7.1 .9-1 of 3GPP TS 36.213 version 1 1 .1 .0), shows values for an indicator field that can be used to indicate different parameter sets.

Table 2: PDSCH RE Mapping and Quasi-Co-Location Indicator field in DCI format

2D

[0060] The parameters for determining PDSCH antenna port quasi co-location that can be configured via higher layer signaling for each parameter set can include: (a) CSI- RS resource configuration identity for quasi co-location and (b) Physical Cell ID for quasi co-location.

[0061] In various aspects, techniques disclosed herein can employ a QCL (quasi co- location) assumption for DM-RS (Demodulation Reference Signal) antenna ports for MU-MIMO (multi-user multiple input multiple output). Two types of QCL can be addressed via various techniques discussed herein: (a) QCL type A, when the serving DM-RS ports and co-scheduled DM-RS ports are QCL-ed (quasi co-located), and (b) QCL type B, when the serving DM-RS ports and co-scheduled DM-RS ports are not QCL-ed. In aspects, QCL signaling discussed herein can be employed for non-QCL-ed DM-RS antenna ports.

[0062] In various aspects, embodiments discussed herein can be employed in two distinct MU-MIMO transmission scenarios, as shown in FIGS. 4A and 4B.

[0063] Referring to FIG. 4A, illustrated is a diagram showing an example scenario of MU-MIMO transmission wherein DM-RS antenna ports designated to different UEs originate from the same transmission point, according to various aspects described herein. In the scenario illustrated in FIG. 4A, all the DM-RS antenna ports transmitted by the transmission point have the same time and frequency offsets, and are therefore quasi co-located. In this case, a common compensation can be applied by a UE for demodulation of the received DM-RS antenna ports.

[0064] Referring to FIG. 4B, illustrated is a diagram showing an example scenario of MU-MIMO transmission wherein DM-RS antenna ports designated to different UEs originate from different transmission points, according to various aspects described herein. In this case, DM-RS antenna ports transmitted by different transmission points can have different the time and frequency offsets and are therefore non quasi co- located. In this case, different compensations can be applied by the UE(s) for demodulation of the received DM-RS antenna ports.

[0065] In various embodiments, higher layer signaling can be used to indicate the QCL assumptions for co-scheduled DM-RS antenna ports.

[0066] In a first set of embodiments, when QCL type A is configured for a UE, that UE can assume that DM-RS antenna ports that can be co-scheduled with the serving DM-RS antenna ports are QCL-ed with respect to time and frequency offsets. The DM- RS antenna ports can be QCL-ed with the serving cell CRS. For example, if a UE is receiving data associated with DM-RS antenna ports 7 and 8, to perform channel estimation for DM-RS antenna ports 1 1 and 13, the assumption of QCL can significantly simplify the calculations involved in channel estimation, as the time and frequency offsets are already known.

[0067] In a second set of embodiments, when QCL type B is configured for a UE, that UE can assume that DM-RS antenna ports that can be co-scheduled with the serving DM-RS antenna ports for the UE are not QCL-ed with respect to time and frequency offsets (e.g., if the UE is served via DM-RS ports 1 1 and 13, then the UE can assume that DM-RS antenna ports 7 and 8 are not QCL-ed, e.g., are from a distinct transmission point (TP)). In some such scenarios, the UE can directly estimate time and frequency offsets associated with the co-scheduled DM-RS ports. In other such scenarios, to improve the time and frequency offset tracking for possibly co-scheduled DM-RS antenna ports, higher layer QCL signaling can be provided to the UE, which can indicate the parameters of the reference signals from the neighboring transmission point that can be used for time and frequency tracking and compensation for the co- scheduled DM-RS antenna ports. The reference signals can also include the reference signals transmitted by the serving transmission point. The higher layer QCL signaling can indicate parameters associated with reference signals that can comprise DM-RS, channel state information reference signals (CSI-RS), and/or cell specific reference signal (CRS). The higher layer signaling can indicate parameters of CSI-RS such as scrambling identity, sub frame configuration, resource of CSI-RS and number of CSI-RS ports, physical cell ID. The higher layer signaling can indicate parameters of CRS such as physical cell ID.

[0068] Referring to FIG. 5, illustrated is a block diagram of a system 500 that facilitates channel estimation at a UE (user equipment) of DM-RS (demodulation reference signal) APs (antenna ports) co-scheduled with DM-RS APs associated with that UE, according to various aspects described herein. System 500 can include one or more processors 510 (e.g., one or more baseband processors such as one or more of the baseband processors discussed in connection with FIG. 1 ), transceiver circuitry 520 (e.g., comprising one or more of transmitter circuitry or receiver circuitry, which can employ common circuit elements, distinct circuit elements, or a combination thereof), and a memory 530 (which can comprise any of a variety of storage mediums and can store instructions and/or data associated with one or more of processor(s) 510 or transceiver circuitry 520). In various aspects, system 500 can be included within a user equipment (UE). As described in greater detail below, system 500 can determine, based on higher layer signaling, whether DM-RS APs co-scheduled with DM-RS APs of a UE are QCL-ed (quasi co-located) with one another.

[0069] Transceiver circuitry 520 can receive, and processor(s) 510 can process, higher layer signaling (e.g., QCL signaling) from a serving (BS) base station. Depending on the type of received signal or message, processing (e.g., by processor(s) 510, processor(s) 610, etc.) can comprise one or more of: identifying physical resources associated with the signal/message, detecting the signal/message, resource element group deinterleaving, demodulation, descrambling, and/or decoding.

[0070] Based on the received higher layer QCL signaling, processor(s) 510 can determine a QCL type for one or more DM-RS APs that are associated with a UE employing system 500. In various aspects, processor(s) 510 can determine the QCL type to be QCL type A as discussed herein (e.g., wherein the DM-RS AP(s) are QCL-ed with co-scheduled DM-RS AP(s)), or QCL type B as discussed herein (e.g., wherein the DM-RS AP(s) are non-QCL-ed with co-scheduled DM-RS AP(s)).

[0071] In a first set of scenarios, processor(s) 510 determine, based on the higher layer signaling, that QCL type A is the QCL type for the DM-RS AP(s) associated with the UE employing system 500 (e.g., with QCL-ed co-scheduled DM-RS AP(s)). In such scenarios, processor(s) 510 can determine the time and frequency offsets for the co- scheduled DM-RS AP(s) to be the same as for the DM-RS AP(s) associated with the UE. On that basis, processor(s) 51 0 can perform channel estimation for the co- scheduled DM-RS AP(s) that can be substantially simplified compared to conventional techniques.

[0072] In a second set of scenarios, processor(s) 510 determine, based on the higher layer signaling, that QCL type B is the QCL type for the DM-RS AP(s) associated with the UE employing system 500 (e.g., with non-QCL-ed co-scheduled DM-RS AP(s)). In such scenarios, processor(s) 51 0 can determine the time and frequency offsets for the co-scheduled DM-RS AP(s) based on estimation of the time and frequency offsets. [0073] In some aspects, processor(s) 51 0 can directly estimate time and frequency offsets of the co-scheduled DM-RS APs. In other aspects, the higher layer QCL signaling can comprise assistive signaling that can facilitate time and/or frequency offset estimation. For example, the higher layer signaling can indicate CSI-RS AP(s) and/or CRS AP(s) that are QCL-ed with the co-scheduled DM-RS AP(s), and processor(s) 510 can perform estimation based on the indicated CSI-RS AP(s) and/or CRS AP(s). In some such aspects, the higher layer signaling can indicate one or more parameters associated with the indicated CSI-RS AP(s) and/or CRS AP(s), which can facilitate estimation of time and frequency offsets by processor(s) 510. The parameter(s) can comprise one or more of: a physical cell identity for the indicated CSI-RS AP(s) and/or CRS AP(s), a scrambling identity for the indicated CSI-RS AP(s), a subframe

configuration for the indicated CSI-RS AP(s), or a CSI-RS resource and number of CSI- RS APs for the indicated CSI-RS AP(s).

[0074] Referring to FIG. 6, illustrated is a block diagram of a system 600 at a base station that facilitates generation of higher layer signaling that indicates whether DM-RS AP(s) associated with a UE are QCL-ed with co-scheduled DM-RS AP(s), according to various aspects described herein. System 600 can include one or more processors 610 (e.g., one or more baseband processors such as one or more of the baseband processors discussed in connection with FIG. 1 ), transceiver circuitry 620 (e.g., which can comprise one or more of transmitter circuitry (e.g., associated with one or more transmit chains) or receiver circuitry (e.g., associated with one or more receive chains), wherein the transmitter circuitry and receiver circuitry can employ common circuit elements, distinct circuit elements, or a combination thereof), and memory 630 (which can comprise any of a variety of storage mediums and can store instructions and/or data associated with one or more of processor(s) 610 or transceiver circuitry 620). In various aspects, system 600 can be included within an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B (Evolved Node B, eNodeB, or eNB) or other base station in a wireless communications network. In some aspects, the processor(s) 61 0, transceiver circuitry 620, and the memory 630 can be included in a single device, while in other aspects, they can be included in different devices, such as part of a distributed architecture. As described in greater detail below, system 600 can facilitate higher layer signaling that can assist a UE in estimation of time and frequency offsets of DM-RS AP(s) co-scheduled with DM-RS AP(s) of that UE.

[0075] Processor(s) 610 can determine, for a UE, whether or not DM-RS AP(s) associated with that UE are QCL-ed with co-scheduled DM-RS AP(s). Processor(s) 610 can generate higher layer signaling that indicates a QCL type that indicates whether or not the DM-RS AP(s) associated with that UE are QCL-ed with the co-scheduled DM- RS AP(s) (e.g., the higher layer signaling can indicate QCL type A when they are QCL- ed, and QCL type B when non-QCL-ed), and can output the higher layer signaling to transceiver circuitry 620 for transmission. Depending on the type of signal or message generated, outputting for transmission (e.g., by processor(s) 510, processor(s) 610, etc.) can comprise one or more of the following: generating a set of associated bits that indicate the content of the signal or message, coding (e.g., which can include adding a cyclic redundancy check (CRC) and/or coding via one or more of turbo code, low density parity-check (LDPC) code, tailbiting convolution code (TBCC), etc.), scrambling (e.g., based on a scrambling seed), modulating (e.g., via one of binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), or some form of quadrature amplitude modulation (QAM), etc.), and/or resource mapping (e.g., to a scheduled set of resources, to a set of time and frequency resources granted for uplink transmission, etc.).

[0076] In various aspects, when the DM-RS AP(s) associated with that UE are non- QCL-ed with co-scheduled DM-RS AP(s), processor(s) 61 0 can provide additional information via the higher layer QCL signaling that can assist the UE in estimating time and frequency offsets associated with the co-scheduled DM-RS AP(s). For example, processor(s) 610 can indicate one or more additional RS AP(s) (e.g., CSI-RS AP(s) and/or CRS AP(s)) that are QCL-ed with the co-scheduled DM-RS AP(s). As another example, processor(s) 61 0 can indicate one or more parameters associated with the co- scheduled DM-RS AP(s) or with the one or more additional RS AP(s), which can facilitate estimation of time and frequency offsets of the co-scheduled DM-RS AP(s) by the UE. For example, the parameters can include one or more of: a physical cell ID, a scrambling identity for the indicated CSI-RS AP(s), a subframe configuration for the indicated CSI-RS AP(s), or a CSI-RS resource and number of CSI-RS APs for the indicated CSI-RS AP(s).

[0077] Referring to FIG. 7, illustrated is a flow diagram of a method 700 that facilitates determination by a UE of whether DM-RS AP(s) of that UE are QCL-ed with co-scheduled DM-RS AP(s), according to various aspects described herein. In some aspects, method 700 can be performed at a UE. In other aspects, a machine readable medium can store instructions associated with method 700 that, when executed, can cause a UE to perform the acts of method 700. [0078] At 710, higher layer QCL signaling can be received that can indicate a QCL type for a set of DM-RS AP(s) associated with the UE employing method 700. In various aspects, the higher layer QCL signaling can indicate one or more additional RS AP(s) and optionally parameters associated with the one or more additional RS AP(s).

[0079] At 720, a determination can be made whether the set of DM-RS AP(s) are QCL-ed with a set of co-scheduled DM-RS AP(s) based on the higher layer QCL signaling.

[0080] At 730, in response to a determination that the set of DM-RS AP(s) are QCL- ed with the set of co-scheduled DM-RS AP(s), time and frequency offsets of the DM-RS AP(s) can be employed for the co-scheduled DM-RS AP(s) for channel estimation.

[0081] At 740, in response to a determination that the set of DM-RS AP(s) are non- QCL-ed with the set of co-scheduled DM-RS AP(s), time and frequency offsets of the DM-RS AP(s) can be estimated, either directly or based on the indicated one or more additional RS AP(s) and/or the optionally indicated parameters associated with the one or more additional RS AP(s).

[0082] Additionally or alternatively, method 700 can include one or more other acts described above in connection with system 500.

[0083] Referring to FIG. 8, illustrated is a flow diagram of a method 800 that facilitates generation of higher layer signaling by a base station that indicates whether DM-RS AP(s) of a UE are QCL-ed with co-scheduled DM-RS AP(s), according to various aspects described herein. In some aspects, method 800 can be performed at an eNB. In other aspects, a machine readable medium can store instructions associated with method 800 that, when executed, can cause an eNB to perform the acts of method 800.

[0084] At 810, a determination can be made whether or not DM-RS AP(s) associated with a UE are QCL-ed with co-scheduled DM-RS AP(s).

[0085] At 820, higher layer signaling can be generated comprising a QCL type that indicates whether or not DM-RS AP(s) associated with a UE are QCL-ed with co- scheduled DM-RS AP(s).

[0086] At 830, optionally, the higher layer signaling can additionally indicate one or more additional RS AP(s) and/or parameters associated with the one or more additional RS AP(s).

[0087] Additionally or alternatively, method 800 can include one or more other acts described above in connection with system 600. [0088] Examples herein can include subject matter such as a method, means for performing acts or blocks of the method, at least one machine-readable medium including executable instructions that, when performed by a machine (e.g., a processor with memory, an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or the like) cause the machine to perform acts of the method or of an apparatus or system for concurrent communication using multiple communication technologies according to embodiments and examples described.

[0089] Example 1 is an apparatus configured to be employed within a User

Equipment (UE), comprising: a memory; and one or more processors configured to: process higher layer signaling that indicates, in connection with a MU (Multi User)- MIMO (Multiple Input Multiple Output) transmission, a QCL (Quasi Co-Location) type for one or more DM-RS (Demodulation Reference Signal) APs (Antenna Ports) associated with the UE; and determine, based at least in part on the indicated QCL type, whether the one or more DM-RS APs are QCL-ed (Quasi Co-Located) with one or more co- scheduled DM-RS APs associated with a distinct UE.

[0090] Example 2 comprises the subject matter of any variation of any of example(s) 1 , wherein the one or more processors are further configured to determine time and frequency offsets associated with the one or more co-scheduled DM-RS APs based at least in part on the indicated QCL type.

[0091] Example 3 comprises the subject matter of any variation of any of example(s) 1 -2, wherein the one or more processors are further configured to determine that the one or more DM-RS APs are QCL-ed with the one or more co-scheduled DM-RS based at least in part on the indicated QCL type.

[0092] Example 4 comprises the subject matter of any variation of any of example(s) 1 -2, wherein the one or more processors are further configured to determine that the one or more DM-RS APs are non-QCL-ed with the one or more co-scheduled DM-RS based at least in part on the indicated QCL type.

[0093] Example 5 comprises the subject matter of any variation of any of example(s)

4, wherein the higher layer signaling further indicates one or more parameters associated with one or more additional reference signal (RS) APs that are QCL-ed with the one or more co-scheduled DM-RS APs.

[0094] Example 6 comprises the subject matter of any variation of any of example(s)

5, wherein the one or more parameters comprise a physical cell ID (identity). [0095] Example 7 comprises the subject matter of any variation of any of example(s) 5, wherein the one or more additional RS APs comprise one or more CRS (Cell Specific RS) APs.

[0096] Example 8 comprises the subject matter of any variation of any of example(s) 5, wherein the one or more additional RS APs comprise one or more CSI-RS (Channel State Information RS) APs.

[0097] Example 9 comprises the subject matter of any variation of any of example(s) 8, wherein the one or more parameters comprise a scrambling identity.

[0098] Example 10 comprises the subject matter of any variation of any of example(s) 8, wherein the one or more parameters comprise a subframe configuration.

[0099] Example 1 1 comprises the subject matter of any variation of any of example(s) 8, wherein the one or more parameters comprise a CSI-RS resource and a number of CSI-RS APs.

[00100] Example 12 comprises the subject matter of any variation of any of example(s) 5-6, wherein the one or more additional RS APs comprise one or more CRS (Cell Specific RS) APs.

[00101 ] Example 13 comprises the subject matter of any variation of any of example(s) 5-6, wherein the one or more additional RS APs comprise one or more CSI- RS (Channel State Information RS) APs.

[00102] Example 14 comprises the subject matter of any variation of any of example(s) 8-9, wherein the one or more parameters comprise a subframe

configuration.

[00103] Example 15 comprises the subject matter of any variation of any of example(s) 8-10, wherein the one or more parameters comprise a CSI-RS resource and a number of CSI-RS APs.

[00104] Example 16 is an apparatus configured to be employed within an Evolved NodeB (eNB), comprising: a memory; and one or more processors configured to:

determine, for a MU (Multi User)-MIMO (Multiple Input Multiple Output) transmission, whether one or more DM-RS (Demodulation Reference Signal) APs (Antenna Ports) associated with a first User Equipment (UE) are QCL-ed (Quasi Co-Located) with one or more co-scheduled DM-RS APs associated with a second UE; and generate higher layer signaling that indicates whether the one or more co-scheduled DM-RS APs are QCL-ed with the one or more DM-RS APs associated with the first UE. [00105] Example 17 comprises the subject matter of any variation of any of example(s) 16, wherein the one or more co-scheduled DM-RS APs are QCL-ed with the one or more DM-RS APs associated with the first UE.

[00106] Example 18 comprises the subject matter of any variation of any of example(s) 16, wherein the one or more co-scheduled DM-RS APs are non-QCL-ed with the one or more DM-RS APs associated with the first UE.

[00107] Example 19 comprises the subject matter of any variation of any of example(s) 18, wherein the higher layer signaling indicates one or more parameters associated with at least one RS (Reference Signal) AP that is QCL-ed with the co- scheduled DM-RS APs, wherein the at least one RS AP comprises at least one CSI-RS (Channel State Information Reference Signal) AP or at least one CRS (Cell Specific Reference Signal) AP.

[00108] Example 20 comprises the subject matter of any variation of any of example(s) 19, wherein the one or more parameters comprise a physical cell identity associated with the at least one CSI-RS AP or with the at least one CRS AP.

[00109] Example 21 comprises the subject matter of any variation of any of example(s) 19-20, wherein the at least one RS AP comprises the at least one CSI-RS AP, and wherein the one or more parameters comprise a scrambling identity.

[00110] Example 22 comprises the subject matter of any variation of any of example(s) 19-20, wherein the at least one RS AP comprises the at least one CSI-RS AP, and wherein the one or more parameters comprise a subframe configuration.

[00111 ] Example 23 comprises the subject matter of any variation of any of example(s) 19-20, wherein the at least one RS AP comprises the at least one CSI-RS AP, and wherein the one or more parameters comprise a CSI-RS resource and a number of CSI-RS APs.

[00112] Example 24 is a machine readable medium comprising instructions that, when executed, cause a User Equipment (UE) to: receive higher layer QCL (Quasi Co- Location) signaling that indicates a QCL type associated with a MU (Multi User)-MIMO (Multiple Input Multiple Output) transmission for a set of DM-RS (Demodulation

Reference Signal) APs (Antenna Ports) associated with the UE; determine, based at least in part on the QCL type, whether the set of DM-RS APs associated with the UE are QCL-ed (Quasi Co-Located) with a set of co-scheduled DM-RS APs associated with a second UE; in response to a determination that the set of DM-RS APs associated with the UE are QCL-ed with the set of co-scheduled DM-RS APs, employ time and frequency offsets of the set of DM-RS APs for the set of co-scheduled DM-RS APs; and in response to a determination that the set of DM-RS APs associated with the UE are non-QCL-ed with the set of co-scheduled DM-RS APs, determine time and frequency offsets for the for the set of co-scheduled DM-RS APs based at least in part on the higher layer QCL signaling.

[00113] Example 25 comprises the subject matter of any variation of any of example(s) 24, wherein the higher layer QCL signaling indicates that the set of DM-RS APs associated with the UE are non-QCL-ed with the set of co-scheduled DM-RS APs, wherein the higher layer QCL signaling further indicates an additional set of RS

(Reference Signal) APs that are QCL-ed with the set of co-scheduled DM-RS APs, and wherein the instructions, when executed, further cause the UE to determine the time and frequency offsets based at least in part on the additional set of RS APs.

[00114] Example 26 comprises the subject matter of any variation of any of example(s) 25, wherein the higher layer QCL signaling further indicates one or more parameters associated with the additional set of RS APs, and wherein the instructions, when executed, further cause the UE to determine the time and frequency offsets based at least in part on the one or more parameters.

[00115] Example 27 comprises the subject matter of any variation of any of example(s) 24-26, wherein the instructions, when executed, further cause the UE to perform channel estimation associated with the set of co-scheduled DM-RS APs based at least in part on the determined time and frequency offsets.

[00116] Example 28 is an apparatus configured to be employed within a User

Equipment (UE), comprising: means for receiving higher layer QCL (Quasi Co-Location) signaling that indicates a QCL type associated with a MU (Multi User)-MIMO (Multiple Input Multiple Output) transmission for a set of DM-RS (Demodulation Reference Signal) APs (Antenna Ports) associated with the UE; means for determining, based at least in part on the QCL type, whether the set of DM-RS APs associated with the UE are QCL-ed with a set of co-scheduled DM-RS APs associated with a second UE;

means for employing time and frequency offsets of the set of DM-RS APs for the set of co-scheduled DM-RS APs, in response to a determination that the set of DM-RS APs associated with the UE are QCL-ed with the set of co-scheduled DM-RS APs; and means for determining time and frequency offsets for the for the set of co-scheduled DM-RS APs based at least in part on the higher layer QCL signaling, in response to a determination that the set of DM-RS APs associated with the UE are non-QCL-ed with the set of co-scheduled DM-RS APs. [00117] Example 29 comprises the subject matter of any variation of any of example(s) 28, wherein the higher layer QCL signaling indicates that the set of DM-RS APs associated with the UE are non-QCL-ed with the set of co-scheduled DM-RS APs, wherein the higher layer QCL signaling further indicates an additional set of RS

(Reference Signal) APs that are QCL-ed with the set of co-scheduled DM-RS APs, and wherein the means for determining the time and frequency offsets are configured to determine the time and frequency offsets based at least in part on the additional set of RS APs.

[00118] Example 30 comprises the subject matter of any variation of any of example(s) 29, wherein the higher layer QCL signaling further indicates one or more parameters associated with the additional set of RS APs, and wherein the means for determining the time and frequency offsets are configured to determine the time and frequency offsets based at least in part on the one or more parameters.

[00119] Example 31 comprises the subject matter of any variation of any of example(s) 28-30, further comprising means for performing channel estimation associated with the set of co-scheduled DM-RS APs based at least in part on the determined time and frequency offsets.

[00120] The above description of illustrated embodiments of the subject disclosure, including what is described in the Abstract, is not intended to be exhaustive or to limit the disclosed embodiments to the precise forms disclosed. While specific embodiments and examples are described herein for illustrative purposes, various modifications are possible that are considered within the scope of such embodiments and examples, as those skilled in the relevant art can recognize.

[00121 ] In this regard, while the disclosed subject matter has been described in connection with various embodiments and corresponding Figures, where applicable, it is to be understood that other similar embodiments can be used or modifications and additions can be made to the described embodiments for performing the same, similar, alternative, or substitute function of the disclosed subject matter without deviating therefrom. Therefore, the disclosed subject matter should not be limited to any single embodiment described herein, but rather should be construed in breadth and scope in accordance with the appended claims below.

[00122] In particular regard to the various functions performed by the above described components or structures (assemblies, devices, circuits, systems, etc.), the terms (including a reference to a "means") used to describe such components are intended to correspond, unless otherwise indicated, to any component or structure which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary implementations. In addition, while a particular feature may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application.

Claims

CLAIMS What is claimed is:

1 . An apparatus configured to be employed within a User Equipment (UE), comprising:

a memory; and

one or more processors configured to:

process higher layer signaling that indicates, in connection with a MU (Multi User)-MIMO (Multiple Input Multiple Output) transmission, a QCL (Quasi Co-Location) type for one or more DM-RS (Demodulation Reference Signal) APs (Antenna Ports) associated with the UE; and

determine, based on the indicated QCL type, whether the one or more DM-RS APs are QCL-ed (Quasi Co-Located) with one or more co-scheduled DM-RS APs associated with a distinct UE.

2. The apparatus of claim 1 , wherein the one or more processors are further configured to determine time and frequency offsets associated with the one or more co- scheduled DM-RS APs based at least in part on the indicated QCL type.

3. The apparatus of any of claims 1 -2, wherein the one or more processors are further configured to determine that the one or more DM-RS APs are QCL-ed with the one or more co-scheduled DM-RS APs based on the indicated QCL type.

4. The apparatus of any of claims 1 -2, wherein the one or more processors are further configured to determine that the one or more DM-RS APs are non-QCL-ed with the one or more co-scheduled DM-RS APs based on the indicated QCL type.

5. The apparatus of claim 4, wherein the higher layer signaling further indicates one or more parameters associated with one or more additional reference signal (RS) APs that are QCL-ed with the one or more co-scheduled DM-RS APs.

6. The apparatus of claim 5, wherein the one or more parameters comprise a physical cell ID (identity).

7. The apparatus of claim 5, wherein the one or more additional RS APs comprise one or more CRS (Cell Specific RS) APs.

8. The apparatus of claim 5, wherein the one or more additional RS APs comprise one or more CSI-RS (Channel State Information RS) APs.

9. The apparatus of claim 8, wherein the one or more parameters comprise a scrambling identity.

10. The apparatus of claim 8, wherein the one or more parameters comprise a subframe configuration.

1 1 . The apparatus of claim 8, wherein the one or more parameters comprise a CSI- RS resource and a number of CSI-RS APs.

12. An apparatus configured to be employed within an Evolved NodeB (eNB), comprising:

a memory; and

one or more processors configured to:

determine, for a MU (Multi User)-MIMO (Multiple Input Multiple Output) transmission, whether one or more DM-RS (Demodulation Reference Signal) APs (Antenna Ports) associated with a first User Equipment (UE) are QCL-ed (Quasi Co-Located) with one or more co-scheduled DM-RS APs associated with a second UE; and

generate higher layer signaling that indicates whether the one or more co- scheduled DM-RS APs are QCL-ed with the one or more DM-RS APs associated with the first UE.

13 The apparatus of claim 12, wherein the one or more co-scheduled DM-RS APs are QCL-ed with the one or more DM-RS APs associated with the first UE.

14. The apparatus of claim 12, wherein the one or more co-scheduled DM-RS APs are non-QCL-ed with the one or more DM-RS APs associated with the first UE.

15. The apparatus of claim 14, wherein the higher layer signaling indicates one or more parameters associated with at least one RS (Reference Signal) AP that is QCL-ed with the co-scheduled DM-RS APs, wherein the at least one RS AP comprises at least one CSI-RS (Channel State Information Reference Signal) AP or at least one CRS (Cell Specific Reference Signal) AP.

16. The apparatus of claim 15, wherein the one or more parameters comprise a physical cell identity associated with the at least one CSI-RS AP or with the at least one CRS AP.

17. The apparatus of any of claims 15-16, wherein the at least one RS AP comprises the at least one CSI-RS AP, and wherein the one or more parameters comprise a scrambling identity.

18. The apparatus of any of claims 15-16, wherein the at least one RS AP comprises the at least one CSI-RS AP, and wherein the one or more parameters comprise a subframe configuration.

19. The apparatus of any of claims 15-16, wherein the at least one RS AP comprises the at least one CSI-RS AP, and wherein the one or more parameters comprise a CSI- RS resource and a number of CSI-RS APs.

20. A machine readable medium comprising instructions that, when executed, cause a User Equipment (UE) to:

receive higher layer QCL (Quasi Co-Location) signaling that indicates a QCL type associated with a MU (Multi User) -Ml MO (Multiple Input Multiple Output) transmission for a set of DM-RS (Demodulation Reference Signal) APs (Antenna Ports) associated with the UE;

determine, based on the QCL type, whether the set of DM-RS APs associated with the UE are QCL-ed (Quasi Co-Located) with a set of co-scheduled DM-RS APs associated with a second UE;

in response to a determination that the set of DM-RS APs associated with the UE are QCL-ed with the set of co-scheduled DM-RS APs, employ time and frequency offsets of the set of DM-RS APs for the set of co-scheduled DM-RS APs; and in response to a determination that the set of DM-RS APs associated with the UE are non-QCL-ed with the set of co-scheduled DM-RS APs, determine time and frequency offsets for the for the set of co-scheduled DM-RS APs based on the higher layer QCL signaling.

21 . The machine readable medium of claim 20, wherein the higher layer QCL signaling indicates that the set of DM-RS APs associated with the UE are non-QCL-ed with the set of co-scheduled DM-RS APs, wherein the higher layer QCL signaling further indicates an additional set of RS (Reference Signal) APs that are QCL-ed with the set of co-scheduled DM-RS APs, and wherein the instructions, when executed, further cause the UE to determine the time and frequency offsets based on the additional set of RS APs.

22. The machine readable medium of claim 21 , wherein the higher layer QCL signaling further indicates one or more parameters associated with the additional set of RS APs, and wherein the instructions, when executed, further cause the UE to determine the time and frequency offsets based on the one or more parameters.

23. The machine readable medium of any of claims 20-22, wherein the instructions, when executed, further cause the UE to perform channel estimation associated with the set of co-scheduled DM-RS APs based on the determined time and frequency offsets.