CN109314872B

CN109314872B - Apparatus and computer readable storage medium in wireless communication network

Info

Publication number: CN109314872B
Application number: CN201680083733.3A
Authority: CN
Inventors: 张羽书; 朱源; 牛华宁; 熊岗; 李庆华
Original assignee: Apple Inc
Current assignee: Apple Inc
Priority date: 2016-03-28
Filing date: 2016-03-28
Publication date: 2021-03-23
Anticipated expiration: 2036-03-28
Also published as: CN109314872A; WO2017166024A1

Abstract

Methods and apparatus are provided for controlling signaling of channel state information reference signals in a wireless communication system, including an apparatus for an eNB in a wireless communication network, the apparatus comprising: a control circuit to generate a first channel state information reference signal (CSI-RS) and map the generated CSI-RS to symbols of a self-contained subframe structure; and transmit circuitry, coupled to the control circuitry, to transmit the mapped CSI-RS symbols.

Description

Apparatus and computer readable storage medium in wireless communication network

Technical Field

Embodiments described herein relate generally to the field of wireless communications, and more particularly, to a method and apparatus for signaling of reference signals.

Background

It is becoming increasingly important to be able to provide telecommunication services to fixed and mobile users as efficiently and inexpensively as possible. In addition, the increased use of mobile applications has led to increased interest in developing wireless systems capable of transmitting large amounts of data at high speeds.

It has been proposed to use a wide range of frequency bands (including millimeter wave frequencies) to achieve wider bandwidths and to promote increased user throughput. In addition, future networks are expected to handle a wider range of traffic types, including device-to-device, trunking, etc., as well as traditional voice and data services. Thus, it may be expected that traffic is varying and bursty in nature, and current implementations may not efficiently support the proposed frequency and traffic profile (profile).

Drawings

Aspects, features and advantages of embodiments of the present invention will become apparent from the following description of the invention with reference to the accompanying drawings, in which like numerals represent like elements, and in which:

fig. 1 is a diagram of an example wireless network in accordance with various embodiments;

FIG. 2a shows a type 1 self-contained subframe structure;

FIG. 2b illustrates a type 2 self-contained subframe structure;

fig. 3a and 3b illustrate a type 1 self-contained subframe structure according to an embodiment;

fig. 4a and 4b illustrate a type 2 self-contained subframe structure according to an embodiment;

fig. 5 illustrates a method performed by an eNB according to an embodiment;

fig. 6 illustrates a method performed by a User Equipment (UE), in accordance with some embodiments;

FIG. 7 is a block diagram of an example system operable to implement some embodiments; and

fig. 8 is a block diagram of an example user equipment device operable to implement some embodiments.

Detailed Description

Various aspects of the illustrative embodiments will be described using terms commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. It will be apparent, however, to one skilled in the art that some alternative embodiments may be practiced using portions of the described aspects. For purposes of explanation, specific numbers, materials, and configurations are set forth in order to provide a thorough understanding of the illustrative embodiments. It will be apparent, however, to one skilled in the art that alternative embodiments may be practiced without the specific details. In other instances, well-known features are omitted or simplified in order not to obscure the illustrative embodiments.

Further, various operations will be described as multiple discrete operations, in turn, in a manner that is most helpful in understanding the illustrative embodiments; however, the order of description should not be construed as to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation.

The phrase "in one embodiment" is used repeatedly. The phrase generally does not refer to the same embodiment, however, it may. Unless the context dictates otherwise, the words "comprising," "having," and "including" are synonymous. The phrase "A/B" means "A or B". The phrase "A and/or B" means "(A), (B) or (A and B)". The phrase "at least one of A, B and C" means "(A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C)". The phrase "(A) B" means "(B) or (A B)", i.e., A is optional.

Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the embodiments of the present invention. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that embodiments of the present disclosure be limited only by the claims and the equivalents thereof.

As used herein, the term "module" may refer to, be a 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 instructions and/or programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality.

The following inventive embodiments may be used in a variety of applications including transmitters and receivers of a radio system, although the invention is not limited in this respect. Radio systems specifically included within the scope of the present invention include, but are not limited to, Network Interface Cards (NICs), network adapters, fixed or mobile client devices, repeaters, base stations, femtocells, gateways, bridges, hubs, routers, access points, or other network devices. Moreover, radio systems within the scope of the present invention may be implemented in cellular radiotelephone systems, satellite systems, two-way radio systems, and computing devices including such radio systems, including Personal Computers (PCs), tablets and related peripherals, Personal Digital Assistants (PDAs), personal computing accessories, handheld communication devices, and all systems which may be related in nature and to which the principles of the embodiments of the present invention may be suitably applied.

Fig. 1 schematically illustrates a wireless communication network 100 in accordance with various embodiments. The wireless communication network 100 (hereinafter "network 100") may be an access network of a third generation partnership project (3GPP) Long Term Evolution (LTE), a long term evolution-advanced (LTE-a) network such as an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN), or a 5G network.

Network 100 may include a base station, e.g., an evolved node base station (eNB)102, configured to wirelessly communicate with one or more mobile devices or terminals, e.g., User Equipment (UE) 104. In some embodiments, the eNB 102 may be a fixed station (e.g., a fixed node) or a mobile station/node.

The eNB 104 may include receiver circuitry 120 with which to receive signals from the UE 104 via one or more antennas 130. The eNB 104 may include transmitter circuitry 124 with which to transmit signals to the UE 104 via one or more antennas 130. The eNB 104 may also include controller circuitry 128 in communication with the receiver module 120 and the transmitter module 124 and configured to encode and decode the information conveyed by the signals. The controller module 128 also includes CSI-RS configuration circuitry 126 to facilitate generating and mapping CSI-RS messages in the network 100.

In various embodiments, the control circuit 128 may be included in a device separate from the receiver circuit 120 and/or the transmitter circuit 124. For example, the eNB 104 may be implemented as part of a cloud RAN (C-RAN).

In various embodiments, the UE 104 and/or eNB 102 may include

multiple antennas

156, 130 to implement a multiple-input multiple-output (MIMO) transmission system, which may operate in various MIMO modes, including single-user MIMO (SU-MIMO), multi-user MIMO (MU-MIMO), closed-loop MIMO, open-loop MIMO, or variations of smart antenna processing.

In various embodiments, the UE 104 includes transmitter circuitry 148 for transmitting signals to the eNB 102 and receiver circuitry 144 for receiving signals from the eNB 102. The UE 104 also includes controller circuitry 152 coupled between the receiver circuitry 144 and the transmitter circuitry 148 and including communication circuitry 154 for encoding and decoding the signaled information. The controller circuitry 152 may also include CSI reporting circuitry 158 to facilitate the UE 104 in measuring and reporting channel state information.

Example embodiments provide systems, apparatuses, and methods for controlling signaling of CSI-RS in millimeter wave (mmW) systems.

It has been proposed to use millimeter wave (mmW) frequencies for 5G networks to achieve wider available bandwidth so that user data throughput can be increased. To facilitate efficient operation at mmW frequencies and to better match the expected traffic profile of a 5G network, a new subframe structure, such as the self-contained subframe structure shown in fig. 1, may be used for such broadband systems. When such a new subframe structure is introduced, backward compatibility with current wireless standards may be broken. However, this provides an opportunity for new physical layer signal design.

To improve spectral efficiency in wireless networks, 5G networks may use multiple-input multiple-output (MIMO) techniques to achieve spatial multiplexing. In particular, full-dimensional MIMO (FD-MIMO) or massive MIMO has been proposed.

To support new physical layer signal design, a new channel state information reference signal (CSI-RS) may need to be designed to support downlink transmission (Tx) beam measurement and selection in this new frame structure, thereby enabling large-scale MIMO to be applied.

Fig. 2 a/2 b show self-contained subframe structures that may be used. In particular, fig. 2a shows a type 1 subframe 210 that includes a Physical Downlink Control Channel (PDCCH)212 and a Physical Downlink Shared Channel (PDSCH)214 from the eNB 102 to the UE 104 and an Acknowledgement (ACK)218 of data transmitted in the PDSCH 214 from the UE to the eNB. A guard gap 216 is provided between the PDSCH 214 and the ACK region 218 to avoid interference.

Fig. 2b shows a type 2 subframe 220 that includes a Physical Downlink Control Channel (PDCCH)212 from the eNB 102 to the UE 104, a Physical Uplink Shared Channel (PUSCH)224 from the UE to the eNB, and an Acknowledgement (ACK)218 of data sent in the PUSCH 224 from the eNB 102 to the UE 104. In the type 2 subframe 220,

guard gaps

222, 216 are provided between the PDCCH 212 and the PUSCH 224 and between the PUSCH 224 and the ACK region 218 to avoid interference.

Further, omni-directional antennas may be used in both eNodeB 102 and UE 104. Thus, Tx beamforming and receive (Rx) beamforming may be used in the downlink. The CSI-RS may be used to measure one or more Tx beams and search for the best receive (Rx) beam. However, it has not been defined how this control signaling of CSI-RS supports Tx and Rx beamforming to be supported in the

new frame structures

210, 220 of fig. 2 a/2 b.

CSI-RS signal generation

A base sequence for the CSI-RS may be generated based on a cell ID and a Quadrature Phase Shift Keying (QPSK) waveform or a number of subframes in a Zadoff-Chu sequence to enable symmetric design of the CSI-RS and a Sounding Reference Signal (SRS).

To support analog beamforming, the CSI-RS may be mapped to more than one symbol within different Tx beams. Furthermore, each Tx beam may be applied to more than one Antenna Port (AP). To facilitate measuring a greater number of Tx beams in one subframe, more symbols and APs may be used for CSI-RS.

For both the type 1 and type 2

subframe structures

210, 220 shown in fig. 2a and 2b (which may show examples for self-contained subframe structures), CSI-RS may be mapped to different symbols.

In an embodiment, as shown in fig. 3a, for a type 1 subframe structure 310, CSI-RS may be mapped to a first location 312 between PDCCH 212 and PDSCH 214 regions, such that in the event that the Rx beam for PDSCH depends on information in the downlink assignment transmitted in the PDCCH, the CSI-RS may be used as a gap for PDCCH decoding processing.

Alternatively, as shown in fig. 3b, in the type 1 subframe 320, the CSI-RS may be mapped to a second location 322 after the PDSCH.

For the type 2 structure, the CSI-RS may be mapped to symbols after the PDCCH and before the ACK. Fig. 4a and 4b illustrate type 2

subframe structures

410, 420 including CSI-RS. According to the arrangement shown in fig. 4a, CSI-RS may be mapped to a first location 412, i.e. to symbols between the gap region 222 before the PDCCH 212 and PUSCH 224 in subframe 410. Alternatively, as shown in fig. 4b, the CSI-RS may be mapped to a second location 422, i.e., to a symbol between the gap region 216 and the ACK region 218 after the PUSCH 224 of the type 2 subframe 420.

In an embodiment, the CSI-RS may be mapped to any of the shown positions in the type 1 or type 2 subframe. In some embodiments, two locations may be used simultaneously.

In an embodiment, as shown in fig. 4a, for a type 2 subframe 410, CSI-RS may be mapped to a first location 412 between PDCCH 212 and a first GAP region 222, while SRS may be mapped to symbols in a second location 422 between a GAP region 216 and an ACK region 218 after PUSCH 224 of a type 2 subframe.

Control signaling for CSI-RS

Since there may be only one opportunity for downlink transmission in the self-contained subframe, the CSI-RS may be transmitted periodically. The periodicity and subframe offset of each CSI-RS process may be configured via RRC signaling. Therefore, in each subframe, symbols allocated for CSI-RS transmission may not be needed for this purpose.

In an embodiment, for subframes that do not include CSI-RS transmission, the symbols reserved for CSI-RS may be treated as gaps and no data is mapped to these symbols.

In an embodiment, the first positions for CSI-RS in type 1 and type 2 subframes may be used for periodic CSI reporting by the UE 104. The number of APs and symbols for the CSI-RS allocation may be fixed in the system or configured via a Master Information Block (MIB), a System Information Block (SIB), or RRC signaling.

In the case where the capacity of the PDCCH (i.e., the number of symbols allocated to the PDCCH) is variable in the system, the UE 104 may first need to determine the number of symbols for the PDCCH to identify the starting symbol index of the CSI-RS allocation to be used for CSI reporting.

In an embodiment, CSI reporting may be in an aperiodic mode. For example, the second location of the CSI-RS in type 1 and type 2 subframes may be used for aperiodic CSI reporting.

In an embodiment, aperiodic CSI reporting may be triggered in response to downlink control information (e.g., a downlink assignment, which may include CSI-RS triggering information). A 2-bit field may be used in the downlink assignment to trigger CSI measurements, and an indication of this triggering may be listed in table 1 as an example. Alternatively, the information in table 1 may be configured for each CSI process, and the downlink assignment may contain a CSI process indicator, where a value of 0 may indicate that no CSI-RS is present, and a value of x (where x is not equal to 0) may indicate that the configuration associated with CSI process x-1 is to be used for aperiodic CSI reporting.

Table 1: CSI-RS trigger indication

In an embodiment, the aperiodic CSI transmission may be triggered using a semi-persistent scheduling (SPS) mechanism using downlink control signaling. The SPS configuration may be predefined in RRC signaling and may contain the following information, for example: a number of OFDM symbols per subframe for CSI-RS; CSI-RS OFDM location (first location after PDCCH, or second location after PDSCH/PUSCH); a CSI-RS transmission period and offset; whether interference averaging is allowed between IMRs of the same OFDM symbol on all subframes or a subset thereof scheduled by one SPS schedule. The scheduled aperiodic CSI transmission may be stopped by a corresponding SPS release.

In an embodiment, for a UE 104 with no PDSCH transmission in a particular subframe, aperiodic CSI reporting may be triggered by providing a downlink assignment for CSI measurement on PDCCH only, which may include CSI process index only or the following information:

group index of Tx Beam in CSI-RS symbol 0

Group index of Tx Beam in CSI-RS symbol 1

·......

Group index of Tx Beam in CSI-RS symbol N-1

The Tx beams may be divided into several groups according to their correlation, which may be configured by RRC signaling. N indicates the maximum number of aperiodic CSI-RS, which may be configured by RRC signaling or fixed in the system. The group index 0 may indicate that the CSI-RS is not applied in the symbol. The UE may then measure the Tx beam group with the corresponding Rx beam. A special case may be defined as a group containing only one Tx beam. The UE may use the Tx beam index to derive a corresponding Rx beam searched from the Tx beams including the reference signal.

In an embodiment, for another type of subframe structure, cross-subframe scheduling may be used to trigger aperiodic CSI. For example, for subframe k containing CSI-RS, aperiodic CSI may be scheduled in subframe k-g, where g may be fixed in the system or configured via RRC signaling or downlink assignment for CSI reporting.

Fig. 5 illustrates a method 500 performed by the eNB 102, in accordance with some embodiments. According to the illustrated method, the eNB 102 first configures (502) CSI-RS transmission using Downlink Control Information (DCI) or RRC signaling according to the techniques described above. The eNB 102 then generates (504) CSI-RS and maps the generated CSI-RS to symbols of a self-contained subframe structure based on the configuration of the CSI-RS. The eNB 102 then transmits (506) the subframe including the CSI-RS symbols to one or more UEs 104.

Fig. 6 illustrates a method 600 performed by the UE 104, in accordance with some embodiments. According to the illustrated method, the UE 104 receives (602) CSI-RS configuration information in the form of DCI or RRC signaling. Based on the received CSI-RS configuration, the UE 104 can then receive and measure CSI-RS symbols in the subframe that the UE 104 receives from the eNB 102. Then, the UE 104 reports (606) channel state information corresponding to the measured CSI-RS according to the received configuration information according to the above-described technique.

Embodiments of the technology herein may be described as relating to third generation partnership project (3GPP) Long Term Evolution (LTE) or LTE-advanced (LTE-a) standards. For example, terms or entities such as enodeb (enb), Mobility Management Entity (MME), User Equipment (UE), etc. may be used, which may be considered LTE related terms or entities. However, in other embodiments, the techniques may be used with or in connection with other wireless technologies, such as Institute of Electrical and Electronics Engineers (IEEE)802.16 wireless technology (WiMax), IEEE 802.11 wireless technology (WiFi), various other wireless technologies such as global system for mobile communications (GSM), enhanced data rates for GSM evolution (EDGE), GSM EDGE Radio Access Network (GERAN), Universal Mobile Telecommunications System (UMTS), UMTS Terrestrial Radio Access Network (UTRAN), or other 2G, 3G, 4G, 5G, etc. developed or to be developed technologies. In those embodiments where LTE-related terms such as eNB, MME, UE, etc. are used, one or more entities or components may be used which may be considered equivalent or approximately equivalent to one or more terms or entities based on LTE.

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, one or more software or firmware modules. In some embodiments, the circuitry may comprise logic that operates, at least in part, in hardware.

The embodiments described herein may be implemented into a system using suitably configured hardware and/or software. Fig. 7 illustrates, for one embodiment, exemplary components of an electronic device 700. In embodiments, electronic device 700 may be, may be implemented as, may be incorporated into or be part of a User Equipment (UE), an evolved node b (enb), or any other suitable electronic device. In some embodiments, electronic device 700 may include application circuitry 702, baseband circuitry 704, Radio Frequency (RF) circuitry 706, front-end module (FEM) circuitry 708, and one or more antennas 710 coupled together at least as shown.

The application circuitry 702 may include one or more application processors. For example, the application circuitry 702 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor may include any combination of general-purpose processors and special-purpose processors (e.g., graphics processors, application processors, etc.). The processor may be coupled to and/or may include memory/storage and may be configured to: the instructions stored in the memory/storage are executed to enable various applications and/or operating systems to run on the system.

The baseband circuitry 704 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. Baseband circuitry 704 may include one or more baseband processors and/or control logic to process baseband signals received from a receive signal path of RF circuitry 706 and to generate baseband signals for a transmit signal path of RF circuitry 706. Baseband circuitry 704 may interface with application circuitry 702 for generating and processing baseband signals and controlling operation of RF circuitry 706. For example, in some embodiments, the baseband circuitry 704 may include a second generation (2G) baseband processor 704a, a third generation (3G) baseband processor 704b, a fourth generation (4G) baseband processor 704c, and/or other baseband processors 704d for other existing generations, generations in development or to be developed in the future (e.g., fifth generation (5G), 6G, etc.). The baseband circuitry 704 (e.g., one or more of the baseband processors 704 a-d) may process various radio control functions that enable communication with one or more radio networks via the RF circuitry 706. The radio control functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, and the like. In some embodiments, the modulation/demodulation circuitry of baseband circuitry 704 may include Fast Fourier Transform (FFT), precoding, and/or constellation mapping/demapping functionality. In some embodiments, the encoding/decoding circuitry of baseband circuitry 704 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 functions are not limited to these examples, and other suitable functions may be included in other embodiments.

In some embodiments, baseband circuitry 704 may include elements of a protocol stack, such as elements of an Evolved Universal Terrestrial Radio Access Network (EUTRAN) protocol, including, for example, Physical (PHY) elements, Medium Access Control (MAC) elements, Radio Link Control (RLC) elements, Packet Data Convergence Protocol (PDCP) elements, and/or Radio Resource Control (RRC) elements. The Central Processing Unit (CPU)704e of the baseband circuitry 704 may be configured to: elements of the protocol stack are run for signaling at the PHY, MAC, RLC, PDCP, and/or RRC layers. In some embodiments, the baseband circuitry may include one or more audio Digital Signal Processors (DSPs) 704 f. The audio DSP 704f may include elements for compression/decompression and echo cancellation, and may include other suitable processing elements in other embodiments.

The baseband circuitry 704 may also include memory/storage 704 g. The memory/storage 704g may be used to load and store data and/or instructions for operations performed by the processor of the baseband circuitry 704. Memory/storage for one embodiment may include any combination of suitable volatile memory and/or non-volatile memory. Memory/storage 704g may include any combination of various levels of memory/storage, including but not limited to Read Only Memory (ROM) with embedded software instructions (e.g., firmware), random access memory (e.g., Dynamic Random Access Memory (DRAM)), cache, buffers, and the like. The memory/storage 704g may be shared among the various processors or may be dedicated to a particular processor.

In some embodiments, components of the baseband circuitry may be combined as appropriate in a single chip, a single chipset, or disposed on the same circuit board. In some embodiments, some or all of the constituent components of baseband circuitry 704 and application circuitry 702 may be implemented together, for example, on a system on a chip (SOC).

In some embodiments, the baseband circuitry 704 may provide communications compatible with one or more radio technologies. For example, in some embodiments, baseband circuitry 704 may support communication with an evolved universal terrestrial radio access network (E-UTRAN) and/or other Wireless Metropolitan Area Networks (WMANs), Wireless Local Area Networks (WLANs), Wireless Personal Area Networks (WPANs). Embodiments in which the baseband circuitry 704 is configured to support wireless communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

The RF circuitry 706 may enable communication with a wireless network using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 706 may include switches, filters, amplifiers, and the like to facilitate communication with the wireless network. RF circuitry 706 may include a receive signal path that may include circuitry to down-convert RF signals received from FEM circuitry 708 and provide baseband signals to baseband circuitry 704. RF circuitry 706 may also include a transmit signal path, which may include circuitry to up-convert baseband signals provided by baseband circuitry 704 and provide an RF output signal to FEM circuitry 708 for transmission.

In some embodiments, RF circuitry 706 may include a receive signal path and a transmit signal path. The receive signal path of RF circuit 706 may include a mixer circuit 706a, an amplifier circuit 706b, and a filter circuit 706 c. The transmit signal path of RF circuitry 706 may include filter circuitry 706c and mixer circuitry 706 a. RF circuitry 706 may further include synthesizer circuitry 706d for synthesizing the frequencies used by mixer circuitry 706a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuit 706a of the receive signal path may be configured to: the RF signal received from the FEM circuit 708 is downconverted based on the synthesized frequency provided by the synthesizer circuit 706 d. The amplifier circuit 706b may be configured to: the downconverted signal is amplified, and the filter circuit 706c may be a Low Pass Filter (LPF) or a Band Pass Filter (BPF) configured to: unwanted signals are removed from the down-converted signal to generate an output baseband signal. The output baseband signal may be provided to baseband circuitry 704 for further processing. In some embodiments, the output baseband signal may be a zero frequency baseband signal, but this is not required. In some embodiments, mixer circuit 706a of the receive signal path may comprise a passive mixer, although the scope of the embodiments is not limited in this respect.

In some embodiments, the mixer circuit 706a of the transmit signal path may be configured to: the input baseband signal is upconverted based on the synthesized frequency provided by synthesizer circuit 706d to generate an RF output signal for FEM circuit 708. The baseband signal may be provided by baseband circuitry 704 and may be filtered by filter circuitry 706 c. Filter circuit 706c may include a Low Pass Filter (LPF), although the scope of the embodiments is not limited in this respect.

In some embodiments, mixer circuit 706a of the receive signal path and mixer circuit 706a of the transmit signal path may include two or more mixers and may be arranged for quadrature down-conversion and/or up-conversion, respectively. In some embodiments, mixer circuit 706a of the receive signal path and mixer circuit 706a 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, mixer circuit 706a of the receive signal path and mixer circuit 706a of the transmit signal path may be arranged for direct down-conversion and/or direct up-conversion, respectively. In some embodiments, mixer circuit 706a of the receive signal path and mixer circuit 706a of the transmit signal path may be configured for superheterodyne operation.

In some embodiments, the output baseband signal and the input baseband signal may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternative embodiments, the output baseband signal and the input baseband signal may be digital baseband signals. In these alternative embodiments, RF circuitry 706 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry, and baseband circuitry 704 may include a digital baseband interface to communicate with RF circuitry 706.

In some dual-mode embodiments, 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.

In some embodiments, synthesizer circuit 706d may be a fractional-N synthesizer or a fractional-N/N +1 synthesizer, although the scope of embodiments is not so limited as other types of frequency synthesizers may be suitable. For example, the synthesizer circuit 706d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer including a phase locked loop with a frequency divider.

The synthesizer circuit 706d may be configured to: the output frequency used by mixer circuit 706a of RF circuit 706 is synthesized based on the frequency input and the divider control input. In some embodiments, the synthesizer circuit 706d can be a fractional N/N +1 synthesizer.

In some embodiments, the frequency input may be provided by a Voltage Controlled Oscillator (VCO), but this is not required. The divider control input may be provided by the baseband circuitry 704 or the application processor 702, depending on the desired output frequency. In some embodiments, the divider control input (e.g., N) may be determined from a look-up table based on the channel indicated by the application processor 702.

Synthesizer circuit 706d of RF circuit 706 may include a divider, a Delay Locked Loop (DLL), a multiplexer, and a phase accumulator. In some embodiments, the divider may be a dual-mode divider (DMD) and the phase accumulator may be a Digital Phase Accumulator (DPA). In some embodiments, the DMD may be configured to: the input signal is divided by N or N +1 (e.g., based on a carry) 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 decompose the VCO period into Nd equal phase groups, 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.

In some embodiments, the synthesizer circuit 706d may be configured to: a carrier frequency is generated 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 a quadrature generator and divider circuit to generate a plurality of signals at the carrier frequency having a plurality of different phases relative to each other. In some embodiments, the output frequency may be the LO frequency (fLO). In some embodiments, the RF circuitry 706 may include an IQ/polar converter.

FEM circuitry 708 may include a receive signal path, which may include circuitry configured to operate on RF signals received from one or more antennas 710, amplify the received signals, and provide amplified versions of the received signals to RF circuitry 706 for further processing. FEM circuitry 708 may further include a transmit signal path, which may include circuitry configured to amplify signals provided by RF circuitry 706 for transmission by one or more of the one or more antennas 710.

In some embodiments, FEM circuitry 708 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 the received RF signal and provide the amplified received RF signal as an output (e.g., to RF circuitry 706). The transmit signal path of the FEM circuitry 708 may include: a Power Amplifier (PA) to amplify an input RF signal (e.g., provided by RF circuitry 706); and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 610).

In some embodiments, electronic device 700 may include additional elements, such as memory/storage, a display, a camera, sensors, and/or input/output (I/O) interfaces.

In some embodiments, electronic device 700 of fig. 7 may be configured to implement one or more processes, techniques, and/or methods, or portions thereof, as described herein. These processes may include one or more of the following examples.

Fig. 8 illustrates an embodiment in which the electronic device 700 implements the UE 104 in the specific form of a mobile device 800.

In various embodiments, the user interface may include, but is not limited to, a display 840 (e.g., a liquid crystal display, a touch screen display, etc.), a speaker 830, a microphone 890, one or more cameras 880 (e.g., still and/or video cameras), a flashlight (e.g., a light emitting diode flash), and a keyboard 870.

In various embodiments, the peripheral component interfaces may include, but are not limited to, a non-volatile memory port, an audio jack, and a power interface.

In various embodiments, the sensors may include, but are not limited to, a gyroscope sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may also be part of or interact with a network interface to communicate with components of a positioning network, such as Global Positioning System (GPS) satellites.

In various embodiments, the electronic device 700 may be a mobile computing device, such as, but not limited to, a laptop computing device, a tablet computing device, a netbook, a mobile phone, and so forth. In various embodiments, system 800 may have more or fewer components and/or different architectures.

In an embodiment, the wireless network implemented may be a Long Term Evolution (LTE) advanced wireless communication standard of the third generation partnership project, which may include, but is not limited to, releases 8, 9, 10, 11, 12, 13, and 14 or later of the LTE-a or 5G standards of 3 GPP.

Although certain embodiments have been illustrated and described herein for purposes of description, various alternative and/or equivalent embodiments or implementations calculated to achieve the same purposes may be substituted for the embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that the embodiments described herein be limited only by the claims and the equivalents thereof.

Examples of the invention

Example 1 may include a system that configures channel state information reference signal (CSI-RS) transmissions on an eNodeB side and in a self-contained subframe structure that may contain two types of subframes: a type 1 subframe for downlink data transmission and a type 2 subframe for uplink data transmission.

Example 2 may include the system of example 1, for the type 1 subframe, the CSI-RS may be mapped to a symbol following a Physical Downlink Control Channel (PDCCH) or a Physical Downlink Shared Channel (PDSCH).

Example 3 may include the system of example 1, and for a type 2 subframe, the CSI-RS may be mapped to a symbol after the PDCCH or before an Acknowledgement (ACK).

Example 4 may include the system of example 1, the CSI-RS in the symbol after the PDCCH may be for periodic CSI reporting, and the CSI-RS before the ACK or after the PDSCH may be for aperiodic CSI reporting.

Example 5 may include the system of example 4, the number of symbols of the periodic CSI-RS may be configured by RRC signaling or fixed in the system.

Example 6 may include the system of example 4, the region may be considered a gap if the UE is not configured to measure CSI-RS in one subframe.

Example 7 may include the system of example 4, the aperiodic CSI reporting may be triggered by Downlink Control Information (DCI).

Example 8 may include the system of example 7, the 2-bit CSI trigger may be added to the DCI, and a value thereof may indicate a beam pattern of the CSI-RS, and a value of 3 may indicate that the aperiodic CSI-RS is not present in the subframe.

Example 9 may include the system of example 7, wherein the transmission beam group for each CSI-RS symbol may be configured in DCI for periodic CSI reporting.

Example 10 may include the system of example 4, wherein semi-persistent scheduling (SPS) may be used for periodic CSI reporting, and wherein the interference average may be configured by Intel persistent DCI.

Example 11 may include the system of example 4, the aperiodic CSI reporting may be pre-scheduled in other types of subframe structures, and a subframe offset between the control signaling and the CSI-RS subframe may be fixed in the system or configured by RRC signaling or indicated by DCI.

Example 12 may include an apparatus for an eNB in a wireless communication network, the apparatus comprising: a control circuit to: generating a first channel state information reference signal (CSI-RS), and mapping the generated CSI-RS to symbols of a self-contained subframe structure; and transmit circuitry, coupled to the control circuitry, to transmit the mapped CSI-RS symbols.

Example 13 may include the apparatus of example 12, the control circuitry further to: the first CSI-RS is mapped to symbols between a Physical Downlink Control Channel (PDCCH) and a Physical Downlink Shared Channel (PDSCH) in a type 1 self-contained subframe structure.

Example 14 may include the apparatus of example 12, the control circuitry further to: the first CSI-RS is mapped to symbols between Physical Downlink Shared Channel (PDSCH) and Acknowledgement (ACK) symbols in a type 1 self-contained subframe structure.

Example 15 may include the apparatus of example 12, the control circuitry to further: mapping the first CSI-RS to at least one of: a symbol between a Physical Downlink Control Channel (PDCCH) and a gap region before a Physical Uplink Shared Channel (PUSCH) in a type 2 self-contained subframe structure; and a symbol between a gap region after PUSCH in a type 2 self-contained subframe structure and an Acknowledgement (ACK) symbol.

Example 16 may include the apparatus of example 13, the control circuitry further to: and when no CSI-RS is sent, allocating symbols of a subframe reserved for the CSI-RS to be used for CSI reporting.

Example 17 may include the apparatus of example 13, the control circuitry further to: generating and mapping second CSI-RSs to symbols between a Physical Downlink Shared Channel (PDSCH) and Acknowledgement (ACK) symbols in a type 1 self-contained subframe structure.

Example 18 may include the apparatus of example 16, wherein the symbols reserved for the first CSI-RS in the subframe will provide periodic CSI reporting and the symbols reserved for the second CSI-RS will provide aperiodic CSI reporting when no CSI-RS is to be transmitted.

Example 19 may include the apparatus of any one of examples 11 to 18, wherein the generated CSI-RS is mapped to a first number of symbols of a self-contained subframe structure, the first number of symbols including one of: a predetermined number of symbols; and a plurality of symbols configured using Radio Resource Control (RRC) signaling.

Example 20 may include the apparatus of example 17, the control circuitry to further: generating Downlink Control Information (DCI) including an indication to initiate aperiodic CSI reporting.

Example 21 may include the apparatus of example 20, wherein the DCI includes a CSI trigger value indicating a beam pattern of the CSI-RS.

Example 22 may include the apparatus of example 21, wherein the CSI trigger value comprises a plurality of bits.

Example 23 may include the apparatus of example 21 or example 22, wherein the CSI trigger value comprises a predetermined value to indicate that no aperiodic CSI-RS exists in the current subframe.

Example 24 may include the apparatus of example 18, the control circuitry to: generating downlink control information including an indication of a transmission beam set associated with each CSI-RS symbol to be used for periodic CSI reporting in a current subframe.

Example 25 may include the apparatus of example 18, the control circuitry to: generating downlink control information including an indication of a semi-persistent scheduling grant to be used for periodic CSI reporting.

Example 26 may include the apparatus of example 25, wherein the DCI further includes an indication to apply interference averaging to the CSI-RS symbols.

Example 27 may include the apparatus of example 18, the control circuitry to further: generating Downlink Control Information (DCI) including an indication of at least one resource block to be used for aperiodic CSI reporting in a second subframe later than a first subframe used to transmit the DCI.

Example 28 may include the apparatus of example 27, wherein the subframe offset comprising the number of subframes between the first subframe and the second subframe comprises one of: a predetermined value; a value indicated by radio resource control signaling; and the value indicated in the DCI.

Example 29 may include an apparatus for a User Equipment (UE) in a wireless communication network, the apparatus comprising: a receive circuit to: receiving an indication of a channel state information reference signal (CSI-RS) configuration, and receiving a first CSI-RS based on the received indication, wherein the first CSI-RS is mapped to symbols of a self-contained subframe structure; and a control circuit for: channel state information is determined based on the received CSI-RS symbols.

Example 30 may include the apparatus of example 29, wherein the indication of the CSI-RS configuration comprises one of: downlink Control Information (DCI); and Radio Resource Control (RRC) signaling.

Example 31 may include the apparatus of example 29 or example 30, wherein the first CSI-RS is mapped to at least one of: symbols between a Physical Downlink Control Channel (PDCCH) and a Physical Downlink Shared Channel (PDSCH) in a type 1 self-contained subframe structure; and symbols between a Physical Downlink Shared Channel (PDSCH) and Acknowledgement (ACK) symbols in a type 1 self-contained subframe structure.

Example 32 may include the apparatus of example 29 or example 30, wherein the first CSI-RS is mapped to at least one of: a symbol between a Physical Downlink Control Channel (PDCCH) and a gap region before a Physical Uplink Shared Channel (PUSCH) in a type 2 self-contained subframe structure; and a symbol between a gap region after PUSCH in a type 2 self-contained subframe structure and an Acknowledgement (ACK) symbol.

Example 33 may include the apparatus of example 29 or example 30, wherein the received CSI-RS configuration includes an indication that no CSI-RS is present in the allocated symbols of the subframe, and the control circuitry is to treat the allocated symbols as gap regions in response to the indication that no CSI-RS is present.

Example 34 may include the apparatus of example 29 or example 30, wherein the received CSI-RS configuration includes an indication that symbols of a subframe reserved for CSI-RS are allocated for CSI reporting when there is no CSI-RS to transmit, the apparatus further comprising transmit circuitry to: the CSI report is sent in the allocated symbols of the subframe.

Example 35 may include the apparatus of example 29, wherein the received CSI-RS configuration includes an indication of: the first CSI-RS is mapped to symbols between a Physical Downlink Control Channel (PDCCH) and a Physical Downlink Shared Channel (PDSCH) in a type 1 self-contained subframe structure and the second CSI-RS is mapped to symbols between a Physical Downlink Shared Channel (PDSCH) and an Acknowledgement (ACK) symbol in the type 1 self-contained subframe structure.

Example 36 may include the apparatus of example 35, wherein the received CSI-RS configuration includes an indication of: when no CSI-RS is to be transmitted, the symbols reserved for the first CSI-RS in the subframe will provide periodic CSI reporting, and the symbols reserved for the second CSI-RS will provide aperiodic CSI reporting.

Example 37 may include the apparatus of example 29 or example 30, wherein the CSI-RS is mapped to a first number of symbols of the self-contained subframe structure, the first number of symbols including one of: a predetermined number of symbols; and a plurality of symbols configured using Radio Resource Control (RRC) signaling.

Example 38 may include the apparatus of example 36, the receive circuitry to: receiving Downlink Control Information (DCI) including an indication to initiate aperiodic CSI reporting.

Example 39 may include the apparatus of example 38, wherein the DCI includes a CSI trigger value indicating a beam pattern of the CSI-RS.

Example 40 may include the apparatus of example 39, wherein the CSI trigger value comprises a plurality of bits.

Example 41 may include the apparatus of example 39 or example 40, wherein the CSI trigger value comprises a predetermined value to indicate that no aperiodic CSI-RS exists in the current subframe.

Example 42 may include the apparatus of example 36, the receive circuitry to: receiving Downlink Control Information (DCI) including an indication of a transmission beam set associated with each CSI-RS symbol to be used for periodic CSI reporting in a current subframe.

Example 43 may include the apparatus of example 36, the receive circuitry to: receiving Downlink Control Information (DCI) including an indication of a semi-persistent scheduling grant to be used for periodic CSI reporting.

Example 44 may include the apparatus of example 43, wherein the DCI further includes an indication to apply interference averaging to the CSI-RS symbols.

Example 45 may include the apparatus of example 36, the receive circuitry to: receiving Downlink Control Information (DCI) including an indication of at least one resource block to be used for aperiodic CSI reporting in a second subframe later than a first subframe used to transmit the DCI.

Example 46 may include the apparatus of example 45, wherein the subframe offset comprising the number of subframes between the first subframe and the second subframe comprises one of: a predetermined value; a value indicated by radio resource control signaling; and the value indicated in the DCI.

Example 47 may include a computer program product comprising computer program code that, when executed, performs the steps of: generating a first channel state information reference signal (CSI-RS); mapping the generated CSI-RS to symbols of a self-contained subframe structure; and transmitting the mapped CSI-RS symbols.

Example 48 may include a computer program product comprising computer program code that, when executed, performs the steps of: receiving an indication of a channel state information reference signal (CSI-RS) configuration; receiving a first CSI-RS based on the received indication, wherein the first CSI-RS is mapped to symbols of a self-contained subframe structure; and determining channel state information based on the received CSI-RS symbols.

Example 49 may include a User Equipment (UE) comprising the apparatus of any of examples 19 to 46, the UE further comprising at least one of a display, a keyboard, and a touchscreen.

Example 50 may include an apparatus for an eNB in a wireless communication network, the apparatus comprising: a control circuit to: the method includes generating a first channel state information reference signal (CSI-RS), mapping the generated CSI-RS to symbols of a self-contained subframe structure, and causing the mapped CSI-RS symbols to be transmitted.

Example 51 may include an apparatus for a User Equipment (UE) in a wireless communication network, the apparatus comprising control circuitry to: obtaining an indication of a channel state information reference signal (CSI-RS) configuration; obtaining a first CSI-RS based on the obtained indication, wherein the first CSI-RS is mapped to symbols of a self-contained subframe structure; and determining channel state information based on the obtained CSI-RS symbols.

Claims

1. An apparatus for a base station in a wireless communication network, the apparatus comprising:

a control circuit configured to:

generating a first channel state information reference signal (CSI-RS); and

mapping the generated first CSI-RS to symbols of a self-contained subframe structure; and

transmit circuitry coupled to the control circuitry, the transmit circuitry configured to transmit the mapped first CSI-RS symbol,

wherein the self-contained subframe structure comprises a type 1 self-contained subframe structure, and wherein the type 1 self-contained subframe structure comprises a physical downlink control channel, PDCCH, and a physical downlink shared channel, PDSCH, from the base station to a user equipment, UE, and an acknowledgement, ACK, of data transmitted in the PDSCH, from the UE to the base station, and wherein a gapped area is provided between the PDSCH and the ACK in the type 1 self-contained subframe structure; alternatively, the first and second electrodes may be,

the self-contained subframe structure comprises a type 2 self-contained subframe structure, and wherein the type 2 self-contained subframe structure comprises a physical downlink control channel, PDCCH, from the base station to a user equipment, UE, a physical uplink shared channel, PUSCH, from the UE to the base station, and an acknowledgement, ACK, from the base station to the UE of data sent in the PUSCH, and wherein a gap region is provided between the PDCCH and the PUSCH and between the PUSCH and the ACK in the type 2 self-contained subframe structure.

2. The apparatus of claim 1, wherein the self-contained subframe structure comprises the type 1 self-contained subframe structure, and wherein the control circuitry is further configured to:

mapping the first CSI-RS to symbols between the PDCCH and the PDSCH in the type 1 self-contained subframe structure.

3. The apparatus of claim 1, wherein the self-contained subframe structure comprises the type 1 self-contained subframe structure, and wherein the control circuitry is further configured to:

mapping the first CSI-RS to symbols between a gap region after the PDSCH in the type 1 self-contained subframe structure and the ACK.

4. The apparatus of claim 1, wherein the self-contained subframe structure comprises the type 2 self-contained subframe structure, and wherein the control circuitry is further configured to:

mapping the first CSI-RS to at least one of:

a symbol between the PDCCH and a gap region preceding the PUSCH in the type 2 self-contained subframe structure; and

a symbol between a gap region after the PUSCH in the type 2 self-contained subframe structure and the ACK.

5. The apparatus of claim 2, wherein the control circuitry is further configured to:

and when no CSI-RS is sent, allocating symbols of a subframe reserved for the CSI-RS including the first CSI-RS to be used for CSI reporting.

6. The apparatus of claim 2, wherein the control circuitry is further configured to:

generating a second CSI-RS and mapping the second CSI-RS to symbols between a gap region after the PDSCH and the ACK in the type 1 self-contained subframe structure.

7. The apparatus of claim 5, wherein the control circuitry is further configured to:

generating a second CSI-RS and mapping the second CSI-RS to symbols between a gap region after the PDSCH and the ACK in the type 1 self-contained subframe structure, wherein periodic CSI reporting is provided for symbols reserved for the first CSI-RS and aperiodic CSI reporting is provided for symbols reserved for the second CSI-RS in the subframe when no CSI-RS is to be transmitted.

8. The apparatus of any of claims 1-7, wherein the first CSI-RS is mapped to a first number of symbols of the self-contained subframe structure, the first number of symbols comprising one of: a predetermined number of symbols; or a plurality of symbols configured using radio resource control, RRC, signaling.

9. The apparatus of claim 7, wherein the control circuitry is further configured to:

generating downlink control information, DCI, including an indication to initiate aperiodic CSI reporting.

10. The apparatus of claim 9, wherein the DCI includes a CSI trigger value indicating a beam pattern of the CSI-RS including the first CSI-RS.

11. The apparatus of claim 7, wherein the control circuitry is further configured to:

generating downlink control information including an indication of a transmission beam set associated with each CSI-RS symbol to be used for periodic CSI reporting in a current subframe.

12. The apparatus of claim 7, wherein the control circuitry is further configured to:

generating downlink control information including an indication of a semi-persistent scheduling grant to be used for periodic CSI reporting.

13. The apparatus of claim 7, wherein the control circuitry is further configured to:

generating downlink control information, DCI, comprising an indication of at least one resource block to be used for aperiodic CSI reporting in a second subframe later than a first subframe used for transmitting the DCI.

14. An apparatus for a user equipment, UE, in a wireless communication network, the apparatus comprising:

a receive circuit configured to:

receiving an indication of a configuration of channel state information reference signals, CSI-RSs, wherein the CSI-RSs comprise a first CSI-RS; and

receiving the first CSI-RS based on the received indication, wherein the first CSI-RS is mapped to symbols of a self-contained subframe structure; and

a control circuit configured to determine channel state information, CSI, based on the received first CSI-RS symbol,

wherein the self-contained subframe structure comprises a type 1 self-contained subframe structure, and wherein the type 1 self-contained subframe structure comprises a physical downlink control channel, PDCCH, and a physical downlink shared channel, PDSCH, from a base station to the UE, and an acknowledgement, ACK, of data transmitted in the PDSCH, from the UE to the base station, and wherein a gapped region is provided between the PDSCH and the ACK in the type 1 self-contained subframe structure; alternatively, the first and second electrodes may be,

the self-contained subframe structure comprises a type 2 self-contained subframe structure, and wherein the type 2 self-contained subframe structure comprises a physical downlink control channel, PDCCH, from a base station to the UE, a physical uplink shared channel, PUSCH, from the UE to the base station, and an acknowledgement, ACK, from the base station to the UE of data sent in the PUSCH, and wherein a gap region is provided between the PDCCH and the PUSCH and between the PUSCH and the ACK in the type 2 self-contained subframe structure.

15. The apparatus of claim 14, wherein the indication of the configuration of the CSI-RS comprises one of: downlink control information, DCI; or radio resource control RRC signaling.

16. The apparatus of claim 14 or claim 15, wherein the self-contained subframe structure comprises the type 1 self-contained subframe structure, and wherein the first CSI-RS is mapped to at least one of:

symbols between the PDCCH and the PDSCH in the type 1 self-contained subframe structure; and

a symbol between a gap region after the PDSCH in the type 1 self-contained subframe structure and the ACK.

17. The apparatus of claim 14 or claim 15, wherein the self-contained subframe structure comprises the type 2 self-contained subframe structure, and wherein the first CSI-RS is mapped to at least one of:

18. The apparatus of claim 14 or claim 15, wherein the configuration of the CSI-RS comprises an indication that no CSI-RS is present in the allocated symbols of a subframe, and the control circuitry is further configured to: in response to the indication of the absence of CSI-RS, treating the allocated symbols as gap regions.

19. The apparatus of claim 14 or claim 15, wherein the configuration of the CSI-RS comprises an indication of symbols to be allocated for CSI reporting in subframes reserved for CSI-RS when no CSI-RS is to be transmitted,

the apparatus also includes transmit circuitry configured to transmit a CSI report in the allocated symbols of the subframe.

20. The apparatus of claim 14, wherein the self-contained subframe structure comprises the type 1 self-contained subframe structure, and wherein the configuration of the CSI-RS comprises an indication of: the first CSI-RS is mapped to symbols between the PDCCH and the PDSCH in the type 1 self-contained subframe structure and a second CSI-RS is mapped to symbols between a gap region after the PDSCH in the type 1 self-contained subframe structure and the ACK.

21. The apparatus of claim 20, wherein the configuration of the CSI-RS comprises an indication of: when no CSI-RS is to be transmitted, the symbols reserved for the first CSI-RS in a subframe will provide periodic CSI reporting, and the symbols reserved for the second CSI-RS will provide aperiodic CSI reporting.

22. The apparatus of claim 14 or claim 15, wherein the first CSI-RS is mapped to a first number of symbols of the self-contained subframe structure, the first number of symbols comprising one of: a predetermined number of symbols; or a plurality of symbols configured using radio resource control, RRC, signaling.

23. A computer readable storage medium comprising computer program code which when executed implements the steps of:

generating a first channel state information reference signal (CSI-RS);

transmitting the mapped first CSI-RS symbol,

wherein the self-contained subframe structure comprises a type 1 self-contained subframe structure, and wherein the type 1 self-contained subframe structure comprises a physical downlink control channel, PDCCH, and a physical downlink shared channel, PDSCH, from a base station to a user equipment, UE, and an acknowledgement, ACK, of data transmitted in the PDSCH, from the UE to the base station, and wherein a gapped area is provided between the PDSCH and the ACK in the type 1 self-contained subframe structure; alternatively, the first and second electrodes may be,

the self-contained subframe structure comprises a type 2 self-contained subframe structure, and wherein the type 2 self-contained subframe structure comprises a physical downlink control channel, PDCCH, from a base station to a user equipment, UE, a physical uplink shared channel, PUSCH, from the UE to the base station, and an acknowledgement, ACK, from the base station to the UE of data sent in the PUSCH, and wherein a gap region is provided between the PDCCH and the PUSCH and between the PUSCH and the ACK in the type 2 self-contained subframe structure.

24. A computer readable storage medium comprising computer program code which when executed implements the steps of:

receiving an indication of a configuration of channel state information reference signals, CSI-RSs, wherein the CSI-RSs comprise a first CSI-RS;

determining channel state information based on the received first CSI-RS symbol,

25. A user equipment, UE, comprising the apparatus of claim 14, the UE further comprising at least one of a display, a keyboard, and a touchscreen.