PADDING BITS FOR CSI REPORT CODING
Described herein are methods and apparatus for jointly encoding components of a a channel state information (CSI) report into a single codeword. Padding bits are added to equalize payload size for different CRI/RI cases and yo allow encoding of all parts of CSI into one codeword without payload ambiguity.
This application is a continuation of U.S. patent application Ser. No. 16/245,825, filed Jan. 11, 2019, entitled “Padding Bits for CSI Report Coding”, which claims priority to U.S. Provisional Patent Application Ser. No. 62/617,030 filed on Jan. 12, 2018, which are incorporated herein by reference in their entirety.
The claims in the instant application are different than those of the parent application or other related applications. The Applicant therefore rescinds any disclaimer of claim scope made in the parent application or any predecessor application in relation to the instant application. The Examiner is therefore advised that any such previous disclaimer and the cited references that it was made to avoid, may need to be revisited. Further, any disclaimer made in the instant application should not be read into or against the parent application or other related applications.
TECHNICAL FIELDEmbodiments described herein relate generally to wireless networks and communications systems. Some embodiments relate to cellular communication networks including 3GPP (Third Generation Partnership Project) networks, 3GPP LTE (Long Term Evolution) networks, 3GPP LTE-A (LTE Advanced), and 3GPP fifth generation (SG) or new radio (NR) networks, although the scope of the embodiments is not limited in this respect.
BACKGROUNDIn Long Term Evolution (LTE) and next generation new radio (NR) systems, a mobile terminal (referred to as a User Equipment or UE) connects to the cellular network via a base station (referred to as an evolved Node B or eNB or as a next generation Node B or gNB). The present disclosure relates to methods and apparatus by which a UE may more efficiently transmit channel state information (CSI) to a gNB.
In Long Term Evolution (LTE) and 5G systems, a mobile terminal (referred to as a User Equipment or UE) connects to the cellular network via a base station (BS), referred to as an evolved Node B or eNB in LTE systems and as a next generation evolved Node B or gNB in 5G or NR systems.
In order to perform scheduling and other link adaptation functions, the BS needs to know the downlink channel from the BS to the UE. LTE and NR provides reference signals that may be used by a UE to obtain downlink channel state information (CSI) for a transmitting cell, referred to as channel state information reference signals (CSI-RSs). The UE may then feedback the CSI thus obtained to the serving cell in the form of a CSI report. CSI-RS are transmitted using particular time-frequency resource element (REs) of an orthogonal frequency division multiple access (OFDMA) transmission scheme over the physical downlink shared channel (PDSCH) with a configurable periodicity and spanning the entire transmit band. Multiple sets of CSI-RSs may be transmitted by a cell with each set corresponding to a different antenna port. A UE may use the CSI-RSs to estimate the channel and produce a CSI report that is fed back to the serving cell either multiplexed with data over the PDSCH or via the physical uplink control channel (PUCCH). For periodic CSI reporting, the CSI report is encoded with a forward error correction (FEC) such as a polar code and sent over the PUCCH. A channel state information report may include a channel quality indicator (CQI) that represents the highest modulation and coding scheme that could be used in the channel without exceeding a specified error rate, a rank indicator (RI) that represents the number of spatial multiplexing layers that could be used in the channel, a precoding matrix indicator (PMI) that represents a preferred antenna weighting scheme for transmitting to the UE, a sub-band (SB) indicator that represents the subcarriers preferred by the UE, and a CSI-RS resource indicator (CRI) to indicate a preferred antenna beam. The NR standard adds a layer indicator (LI) to the list. In order to configure a UE to receive and process reference signals and to provide appropriate feedback in the form of CSI reports, the eNB signals the UE using the radio resource control (RRC) protocol to send what are referred to herein as higher layer parameters. An RRC message that transmits CSI-RS configuration information from an eNB to a UE originates in the RRC layer of the eNB and, after traversing the protocol layers, is then transmitted to the UE via the PDSCH. The UE then processes the message at its corresponding RRC layer.
In LTE, due to dependency between CSI components, coding of CRI/RI and PMI/CQI using a forward error correction (FEC) code is carried out independently from each other. The bitwidth of CRI/RI is typically known by the base station based on the higher layer configuration and/or derived from CSI-RS antenna port configuration and reported UE capability. Based on the decoded CRI/RI, the UE determines the payload size of PMI/CQI report. In particular, for LTE, if the reported RI is 1, the single CQI. report should be assumed in the UCI, otherwise there are two CQI reports. In addition, the bitwidth of the PMI report also depends on the reported RI.
The LTE approach supports separate coding of CRI/RI and CQI/PMI in two codewords, where payload of CQI/PMI report is decided after decoding of the CRI/RI codeword. Separate coding of CSI components, however, is less efficient than joint one from channel coding perspective.
From an NR channel coding perspective, it is desirable to use the common coding for all CSI components. However, the dependency of the PMI/CQI payload on the current RI/CRI value may lead to payload size ambiguity on the decoder side. It is possible to avoid this by adding a certain amount of padding hits to the CSI payload. The number of padding bits may be made to depend on the current RI/CRI value and higher layer configuration. Described below are methods and apparatus to determine the padding bits quantity for joint CSI coding. The padding bits equalize payload size for different CRI/RI cases and allow encoding of all parts of CSI in one codeword without payload ambiguity.
In one embodiment, padding bits are appended to a CSI payload of size ACSI to make a result bit sequence, which is then passed to encoder input. The padding bits may be zeroes or any other fixed values. The amount of padding bits should be such that the result sequence is of size AmaxCSI (where AmaxCSI is the maximum possible CSI payload over all CRI/RI values with the current higher-layer MIMO configuration). The padding bits can be placed in continuous or non-continuous block at different positions inside CSI payload as illustrated in
-
- Alt1—padding bits are placed at the start of result sequence
- Alt2—padding bits are placed at the end of result sequence
- Alt3—padding bits are placed in the middle of result sequence
Simulation results have shown that Alt3 is preferable since it gives some additional coding gain under sequential decoding, e.g., polar SCL decoding. For polar coding, the gain obtained can be described as follows. With Alt1, CRI/RI is decoded after all padding bits. Given this, it is not possible to determine the amount of padding bits prior to their decoding. They have to be decoded as information bits that leads to worst-case coding gain (same as with maximum payload AmaxCSI in current MIMO configuration). With Alt2, CRI/RI is decoded before the padding bits. This allows a decoder to treat padding bits as frozen bits, which could increase the coding gain. However, this increase is negligible since these frozen appear after all the info bits are already decoded. Therefore, their impact on info bits BER is very limited. Alt3 provides the ability to decode CRI/RI before the padding bits, compute their quantity, treat padding bits as frozen and then decode other part of CSI payload. Implementation of such advanced decoding approach may provide significant coding gain. In one embodiment, the components of the CSI payload are ordered as follows: CRI, RI, LI, padding bits, PMI, and CQI.
In one embodiment, the amount of padding bits that is needed to be added to the CSI payload ACSI is specified depending on current CRI/RI value and higher layer configuration. The amount of padding bits to equalize the payload size over all CRI/RI values may be calculated as:
Apadding=AmaxCSI−ACSI
where AmaxCSI=AmaxRI+AmaxCRI+AmaxLI+AmaxPMI+AmaxCQI.
The following symbols are defined as follows:
In one embodiment, the maximum CSI payload is defined as a maximum payload possible under current RI_Restriction and ResourseSetBittnap parameters as configured by higher layers:
AmaxRI=┌log2nRI┐32 ARI
AmaxCTI=┌log2KsCSI-RS┐=ACRI
Bitwidths ALI, APMI and ACQI are usually defined in tables with each row corresponding to some combination of RI value and higher layer parameters. Therefore AmaxLI,AmaxPMI and AmaxCQI can be found as a maximum over the rows corresponding to the allowed rank values set BRI and current higher layer configuration as shown in
Similarly, LI and CQI maximum sizes can be found as the maximums over the table rows corresponding to the allowed rank values set BRI.
In another embodiment, the maximum CSI payload is defined as a maximum CSI payload possible in the standard:
The total padding bits quantity may then be defined as:
In some situations, a base station may request a UE to transmit several CSI reports. In other embodiments, multiple CSI payloads representing multiple CSI reports are encoded as described above. Such methods allow encoding of these multiple CSI reports into one codeword which is more efficient than separate coding.
Apadding #1=AmaxCSI#1−ACSI#1
The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments that may be practiced. These embodiments are also referred to herein as “examples.” Such examples may include elements in addition to those shown or described. However, also contemplated are examples that include the elements shown or described. Moreover, also contemplate are examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.
Publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference(s) are supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.
In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to suggest a numerical order for their objects.
The embodiments as described above may be implemented in various hardware configurations that may include a processor for executing instructions that perform the techniques described. Such instructions may be contained in a machine-readable medium such as a suitable storage medium or a memory or other processor-executable medium.
The embodiments as described herein may be implemented in a. number of environments such as part of a wireless local area network (WLAN), 3rd Generation Partnership Project (3GPP) Universal Terrestrial Radio Access Network (UTRAN), or Long-Term-Evolution (LTE) or a Long-Term-Evolution (LTE) communication system, although the scope of the disclosure is not limited in this respect. An example LTE system includes a number of mobile stations, defined by the LTE specification as User Equipment (UE), communicating with a base station, defined by the LTE specifications as an eNodeB.
Antennas referred to herein may comprise one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas or other types of antennas suitable for transmission of RF signals. In some embodiments, instead of two or more antennas, a single antenna with multiple apertures may be used. In these embodiments, each aperture may be considered a separate antenna. In some multiple-input multiple-output (MIMO) embodiments, antennas may be effectively separated to take advantage of spatial diversity and the different channel characteristics that may result between each of antennas and the antennas of a transmitting station. In some MIMO embodiments, antennas may be separated by up to 1/10 of a wavelength or more.
In some embodiments, a receiver as described herein may be configured to receive signals in accordance with specific communication standards, such as the Institute of Electrical and Electronics Engineers (IEEE) standards including IEEE 802.11-2007 and/or 802.11(n) standards and/or proposed specifications for WLANs, although the scope of the disclosure is not limited in this respect as they may also be suitable to transmit and/or receive communications in accordance with other techniques and standards. In some embodiments, the receiver may be configured to receive signals in accordance with the IFEE 802.16-2004, the IFEE 802.16(e) and/or IEEE 802.16(m) standards for wireless metropolitan area networks (WMANs) including variations and evolutions thereof, although the scope of the disclosure is not limited in this respect as they may also be suitable to transmit and/or receive communications in accordance with other techniques and standards. In some embodiments, the receiver may be configured to receive signals in accordance with the Universal Terrestrial Radio Access Network (UTRAN) LTE communication standards. For more information with respect to the IEEE 802.11 and IEEE 802.16 standards, please refer to “IEEE Standards for information Technology—Telecommunications and Information Exchange between Systems”—Local Area Networks—Specific Requirements—Part 11 “Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY), ISO/IEC 8802-11: 1999”, and Metropolitan Area Networks—Specific Requirements—Part 16: “Air Interface for Fixed Broadband Wireless Access Systems,” May 2005 and related amendments/versions. For more information with respect to UTRAN LTE standards, see the 3rd Generation Partnership Project (3GPP) standards for UTRAN-LTE, release 8, Mar. 2008, including variations and evolutions thereof.
The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with others. Other embodiments may be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. However, the claims may not set forth every feature disclosed herein as embodiments may feature a subset of said features. Further, embodiments may include fewer features than those disclosed in a particular example. Thus, the following claims are hereby incorporated into the Detailed Description, with a claim standing on its own as a separate embodiment. The scope of the embodiments disclosed herein is to be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. cm 1-20. (canceled)
Claims
21. A user equipment (UE), the UE comprising:
- one or more memory mediums; and
- one or more processors coupled to the one or more memory mediums, wherein the one or more processors are configured to cause the UE to: encode reported components of one or more channel state information (CSI) payloads that each represent a CSI report into a single codeword for transmission over a physical uplink control channel (PUCCH), wherein the one or more memory mediums are configured to store the one or more CSI payloads; wherein the reported CSI payload components that are encoded include one or more of: a CSI reference signal (CSI-RS) resource indicator (CRI), a rank indicator (RI), a layer indicator (LI), a precoding matrix indicator (PMI), and a channel quality indicator (CQI); add a number of padding bits as necessary to the CSI payload before encoding to make the bitwidth of the CSI payload equal to a maximum allowable CSI payload bitwidth, wherein the number of padding bits Apadding is calculated as: Apadding=AmaxCSI−ACSI where ACSI is the bitwidth of the reported components of the CSI payload and AmaxCSI is the maximum allowable CSI payload bitwidth; and, wherein the bitwidth of the reported components of the CSI payload ACSI is a function of the reported RI and wherein the maximum allowable CSI payload bitwidth AmaxCSI is a function of a set of allowed RI values reported to a next generation Node B (gNB).
22. The UE of claim 21, wherein said encoding reported components comprises using a forward error correction code (FEC) to jointly encode the reported components.
23. The UE of claim 21, wherein said encoding is performed for all reported components.
24. The UE of claim 21, wherein the maximum allowable CSI payload bitwidth is determined by parameters to be received from a next generation Node B (gnB), wherein the parameters that determine the maximum allowable CSI payload bitwidth include a set of allowed RI values as indicated by higher layer parameter ri_restriction.
25. The UE of claim 21, wherein the maximum allowable CSI payload bitwidth is determined by parameters to be received from a next generation Node B (gnB), wherein the parameters that determine the maximum allowable CSI payload bitwidth include a CSI-RS resource set to be used for CSI reporting and the number of resources in the CSI-RS resource set
26. The UE of claim 21, wherein the maximum allowable CSI payload bitwidth is determined by parameters to be received from a next generation Node B (gnB), wherein the parameters that determine the maximum allowable CSI payload bitwidth include the number of CSI-RS ports.
27. The UE of claim 21, wherein the maximum allowable CSI payload bitwidth AmaxCSI is calculated as: where max(APMI(r)+ACQI(r)+ALI(r)))) is the maximum of the sum of the PMI bitwidth APMI(r), the CQI bitwidth ACQI(r), and the LI bitwidth ALI(r) over a set of rank values allowed to be reported.
- AmaxCSI=max(APMI(r)+ACQI(r)+ALI(r))
28. An apparatus, comprising:
- one or more processors configured to cause a user equipment (UE) to: encode reported components of one or more channel state information (CSI) payloads that each represent a CSI report into a single codeword for transmission over a physical uplink control channel (PUCCH), wherein the one or more memory mediums are configured to store the one or more CSI payloads; wherein the reported CSI payload components that are encoded include one or more of: a CSI reference signal (CSI-RS) resource indicator (CRI), a rank indicator (RI), a layer indicator (LI), a precoding matrix indicator (PMI), and a channel quality indicator (CQI); add a number of padding bits as necessary to the CSI payload before encoding to make the bitwidth of the CSI payload equal to a maximum allowable CSI payload bitwidth, wherein the number of padding bits Apadding is calculated as: Apadding=AmaxCSI−ACSI where ACSI is the bitwidth of the reported components of the CSI payload and AmaxCSI is the maximum allowable CSI payload bitwidth; and, wherein the bitwidth of the reported components of the CSI payload ACSI is a function of the reported RI and wherein the maximum allowable CSI payload bitwidth AmaxCSI is a function of a set of allowed RI values reported to a next generation Node B (gNB).
29. The apparatus of claim 28, wherein said encoding reported components comprises using a forward error correction code (FEC) to jointly encode the reported components.
30. The apparatus of claim 28, wherein said encoding is performed for all reported components.
31. The apparatus of claim 28, wherein the maximum allowable CSI payload bitwidth is determined by parameters to be received from a next generation Node B (gnB), wherein the parameters that determine the maximum allowable CSI payload bitwidth include a set of allowed RI values as indicated by higher layer parameter ri_restriction.
32. The apparatus of claim 28, wherein the maximum allowable CSI payload bitwidth is determined by parameters to be received from a next generation Node B (gnB), wherein the parameters that determine the maximum allowable CSI payload bitwidth include a CSI-RS resource set to be used for CSI reporting and the number of resources in the CSI-RS resource set
33. The apparatus of claim 28, wherein the maximum allowable CSI payload bitwidth is determined by parameters to be received from a next generation Node B (gnB), wherein the parameters that determine the maximum allowable CSI payload bitwidth include the number of CSI-RS ports.
34. The apparatus of claim 28, wherein the maximum allowable CSI payload bitwidth AmaxCSI is calculated as: where max(APMI(r)+ACQI(r)+ALI(r)) is the maximum of the sum of the PMI bitwidth APMI(r), the CQI bitwidth ACQI(r), and the LI bitwidth ALI(r) over a set of rank values allowed to be reported.
- AmaxCSI=max(APMI(r)+ACQI(r)+ALI(r))
35. A non-transitory computer accessible memory medium storing program instructions executable by a processor of a user equipment (UE) to:
- encode reported components of one or more channel state information (CSI) payloads that each represent a CSI report into a single codeword for transmission over a physical uplink control channel (PUCCH), wherein the one or more memory mediums are configured to store the one or more CSI payloads;
- wherein the reported CSI payload components that are encoded include one or more of: a CSI reference signal (CSI-RS) resource indicator (CRI), a rank indicator (RI), a layer indicator (LI), a precoding matrix indicator (PMI), and a channel quality indicator (CQI);
- add a number of padding bits as necessary to the CSI payload before encoding to make the bitwidth of the CSI payload equal to a maximum allowable CSI payload bitwidth, wherein the number of padding bits Apadding is calculated as: Apadding=AmaxCSI−ACSI
- where ACSI is the bitwidth of the reported components of the CSI payload and AmaxCSI is the maximum allowable CSI payload bitwidth; and,
- wherein the bitwidth of the reported components of the CSI payload ACSI is a function of the reported RI and wherein the maximum allowable CSI payload bitwidth AmaxCSI is a function of a set of allowed RI values reported to a next generation Node B (gNB).
36. The non-transitory computer accessible memory medium of claim 35, wherein said encoding reported components comprises using a forward error correction code (FEC) to jointly encode the reported components.
37. The non-transitory computer accessible memory medium of claim 35, wherein said encoding is performed for all reported components.
38. The non-transitory computer accessible memory medium of claim 35, wherein the maximum allowable CSI payload bitwidth is determined by parameters to be received from a next generation Node B (gnB), wherein the parameters that determine the maximum allowable CSI payload bitwidth include a set of allowed RI values as indicated by higher layer parameter ri_restriction.
39. The non-transitory computer accessible memory medium of claim 35, wherein the maximum allowable CSI payload bitwidth is determined by parameters to be received from a next generation Node B (gnB), wherein the parameters that determine the maximum allowable CSI payload bitwidth include a CSI-RS resource set to be used for CSI reporting and the number of resources in the CSI-RS resource set
40. The non-transitory computer accessible memory medium of claim 35, wherein the maximum allowable CSI payload bitwidth AmaxCSI is calculated as: where max(APMI(r)+ACQI(r)+ALI(r)) is the maximum of the sum of the PMI bitwidth APMI(r), the CQI bitwidth ACQI(r), and the LI bitwidth ALI(r) over a set of rank values allowed to be reported.
- AmaxCSI=max(APMI(r)+ACQI(r)+ALI(r))
Type: Application
Filed: Aug 6, 2020
Publication Date: Dec 3, 2020
Inventors: Dmitry Dikarev (Nizhny Novgorod), Victor Sergeev (Nizhny Novgorod), Ajit Nimbalker (Fremont, CA), Alexei Vladimirovich Davydov (Nizhny Novgorod), Gregory Ermolaev (Nizhny Novgorod)
Application Number: 16/986,616