Determining channel configurations

Embodiments of the present disclosure describe methods, computer-readable media and system configurations for wireless communications. A method may include receiving a transmission of a series of symbols, including an index, and determining a plurality of configurations of a physical downlink channel based on the index. In various embodiments, the plurality of configurations of the physical downlink channel may include one or more antenna ports that are reserved for a reference signal. A relay node (RN) may include a processor and a memory storing a plurality of potential combinations of a plurality of configurations of a physical downlink channel. The processor may be configured to receive a transmission of a series of symbols, including an index, and match the index to one of the plurality of potential combinations. A donor evolved NodeB (DeNB) may be configured to encode such an index into a transmission. Other embodiments may be described and/or claimed.

TECHNICAL FIELD

Embodiments of the present invention relate generally to the field of wireless transmission, and more particularly, to the determination of channel configurations.

BACKGROUND

The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in the present disclosure and are not admitted to be prior art by inclusion in this section.

The 3GPP Long Term Evolution (“LTE”) Release 10 (March 2011) (the “LTE Standard”) provides for an evolved packet system (“EPS”). An EPS may include an evolved universal terrestrial radio access network (“E-UTRAN”) and an evolved packet core (“EPC”).

LTE Releases 10 and later are known as LTE Advanced (“LTE-A”). LTE-A provides for the deployment of a relay node (“RN”) in an E-UTRAN. The RN may be between user equipment (“UE”) and an evolved NodeB (“eNB”) serving the RN, called the “donor” eNB, or “DeNB.” The DeNB may in turn be in communication with components of an EPC, such as a mobile management entity (“MME”) and/or a gateway (such as a serving gateway, or “SGW”).

Various nodes of an EPS may communicate using various logical interfaces. For example, an eNB may communicate with an MME/SGW over an S1 interface. An eNB may communicate with a DeNB over an X2 interface. An RN may communicate wirelessly with a DeNB using a modified version of the E-UTRAN radio interface, called the “Un” interface.

A downlink signal may include a UE specific reference signal (“USRS”), which may be used by a UE device to demodulate downlink user and/or control data, and/or a common reference signal (“CRS”) used to determine things like channel quality. Sometimes a downlink USRS is referred to as a “downlink demodulation reference signal (“DMRS”), particularly in Release 10 of LTE and beyond.

When an RN communicates with a DeNB over the Un interface, a relay physical downlink control channel (“R-PDCCH”) may be multiplexed with a relay physical downlink shared channel (“R-PDSCH”) in a physical resource block (“PRB”) pair. However, in a non-interleaved R-PDCCH (e.g., mode 2), the Un interface's physical downlink shared channel (“PDSCH”) transmission mode may be based on a USRS, rather than a CRS. In such cases, there may be either two {7, 8} or four {7, 8, 9, 10} logical antenna ports reserved, or “unused,” for the USRS.

To determine whether two or four antenna ports are reserved for the USRS, it has been proposed that a bit may be added to a higher layer. This technique may save as many as six resource elements (“RE”) per slot, and may reduce blind decoding complexity. However, it may require modification of the LTE Standard and may add a higher signaling transmission delay.

Alternatively, it has been proposed that, in a non-interleaved R-PDCCH, the maximum number of USRS ports (four) may be assumed to be used in the R-PDCCH. This technique may avoid the added overhead associated with higher-layer signaling, but may waste REs where only two antenna ports are unused. This technique also may increase blind decoding complexity because there may be a need for more rank format detection. Moreover, it may add a blind decoding delay for rank.

DETAILED DESCRIPTION

As used herein, the term “module” 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 components that provide the described functionality.

In various embodiments, a computer-implemented method may include receiving, by a processor of a relay node, a transmission of a series of symbols, including an index. Based on the index, the processor may determine a plurality of configurations of a physical downlink channel. The plurality of configurations of the physical downlink channel may include one or more antenna ports that are reserved for a reference signal. In some embodiments, the physical downlink channel may be a relay physical downlink control channel (“R-PDCCH”).

In some embodiments, determining the plurality of configurations may include determining, by the processor, whether the R-PDCCH is interleaved. In some embodiments, determining the plurality of configurations may include determining, by the processor, a resource allocation type of the R-PDCCH. In some embodiments, determining the plurality of configurations may include determining, by the processor, a demodulation type of the R-PDCCH.

In some embodiments, determining the plurality of configurations may include determining, by the processor, whether the reference signal is a user equipment (“UE”) specific reference signal (“USRS”) or a common reference signal (“CRS”). In some embodiments, the one or more antenna ports may be antenna ports reserved for the USRS. In some embodiments, the index may be four bits long. Determining the plurality of configurations of the physical downlink channel may include determining, by the processor, three other physical downlink channel configurations in addition to the one or more antenna ports reserved for the reference signal.

In some embodiments, determining the plurality of configurations of the physical downlink channel may include matching, by the processor, the index to a first of a plurality of potential combinations of the plurality of configurations. In some embodiments, the index may be based at least in part on a codebookSubsetRestriction bitmap.

In some embodiments, a relay node (“RN”) may include a wireless network adapter, a processor and a memory storing a plurality of potential combinations of a plurality of configurations of a physical downlink channel. The processor may be configured to receive, through the wireless network adapter, a transmission of a series of symbols, including an index. The processor may further be configured to match the index to one of the plurality of potential combinations.

In some embodiments, a donor evolved Node B (“DeNB”) may include a wireless network adapter and a processor. The processor may be configured to generate a series of symbols for transmission. The series of symbols may include an index that is indicative of a plurality of configurations of a physical downlink channel, including one or more antenna ports that are reserved for a reference signal. The processor may further be configured to transmit, to an RN, through the wireless network adapter, the series of symbols.

In various embodiments, methods and/or non-transitory computer-readable media having a number of the above described operations may be practiced and/or executed. In various embodiments, apparatus and/or systems may be configured to practice such methods.

Referring toFIG. 1, an evolved packet system (“EPS”)10in accordance with various embodiments may include an evolved packet core (“EPC”)12with one or more mobile management entities (“MME”)14and one or more SGWs16. InFIG. 1, there are two computer systems in the EPC12, each functioning as both an MME14and an SGW16. EPS10may also include an evolved universal terrestrial radio access network (“E-UTRAN”)18that includes one or more evolved Node Bs (“eNB”)20to which a UE device22may connect. The UE device22also may connect to the E-UTRAN18via a DeNB24and an RN26.

Various interfaces, described in the background, may exist between the various nodes of EPS10. For example, the RN26and the DeNB24may communicate using, among other interfaces (not shown), an Un interface28. The Un interface28may include various channels, including an R-PDCCH and relay physical downlink shared channel (“R-PDSCH”).

Referring toFIG. 2, the R-PDCCH and R-PDSCH of the Un interface28may be multiplexed together in a PRB pair. The R-PDCCH may be in a first slot and the R-PDSCH may be in a second slot. While an R-PDSCH may include four antenna ports for a USRS, it may not be apparent whether two antenna ports (e.g., {7, 8}) or four antenna ports (e.g., {7, 8, 9, 10}) are reserved for the USRS of the R-PDCCH.

Rather than adding a signaling bit to a higher layer or always assuming four ports, as described in the background, combinations of existing channel configuration parameters may be jointly encoded and decoded so that, in addition to the information they previously conveyed, they also indicate a number of reserved antenna ports. For example, assume two parameters of one bit each and a third parameter of two bits are used separately to indicate three different channel configurations. With the three parameters encoded/decoded separately, only eight possible channel combinations (23) may be communicated. However, if the three parameters are jointly encoded/decoded as a single index, sixteen (24) possible channel configuration combinations may be communicated.

FIG. 3depicts an example method300of joint decoding that may be implemented by an RN, such as RN26inFIG. 1, to determine multiple configurations of a physical downlink channel such as the R-PDCCH. At302, a transmission of a series of symbols, including an index, may be received, e.g., from a DeNB such as DeNB24. At304, the RN may determine, from the index, a plurality of configurations of a physical downlink channel based on the index. For example, at306, the RN may determine, from the index, whether an R-PDCCH of a Un channel (e.g.,28) is interleaved. At308, the RN may determine, from the same index, a resource allocation type of the R-PDCCH. At310, the RN may determine, from the index, a modulation type (e.g., USRS or CRS) of the R-PDCCH. At312, the RN may determine, again from the index, one or more antenna ports reserved for a reference signal of the R-PDCCH, such as the USRS.

An index may be used to determine multiple configurations of a channel in various ways. In some embodiments, such as those where the index has four bits, the index may be an index to a database table containing up to sixteen records of channel configuration combinations.

An example of this is shown inFIG. 4. The index has four bits, and can be any number from 0 to 15 (although index=15 is not used in this example). Three legacy channel configuration parameters are shown in headers of the middle columns to illustrate what information the bits forming the index would have conveyed in the prior art, and how those bits may now be used to form an index into the table. In this example the legacy channel configuration parameters include R-PDCCH-demodulationRs (one bit), which determines an R-PDCCH's modulation type, R-PDCCH-interleaved (one bit), which indicates whether an R-PDCCH is interleaved, and R-PDCCH-resourceAllocationType (two bits), which indicates orthogonal frequency division multiplexing (“OFDM”) symbols for the R-PDCCH (e.g., 00→symbols 1-6; 01→symbols 2-6; 10→symbols 3-6). Another configuration of the channel, antenna ports reserved for a USRS, is shown in the right-most column.

Upon receiving a transmission of a series of symbols, including an index, from a DeNB, an RN may be configured to match the index to one of the plurality of potential combinations represented by the rows of the table ofFIG. 4. For example, if an RN receives a transmission that includes an index with a value of 2 (0010), then the RN may refer to the table ofFIG. 4to determine that the modulation type of the R-PDCCH is USRS, the R-PDCCH is non-interleaved, its OFDM symbols are 3-6, and there are two antenna ports {7, 8} reserved for the USRS. As another example, if an RN receives a transmission that includes an index with a value of 14 (1110), then the RN may refer to the table ofFIG. 4to determine that the modulation type of the R-PDCCH is USRS, the R-PDCCH is non-interleaved, its OFDM symbols are 3-6, and there are four antenna ports ({7, 8, 9, 10}) reserved for the USRS.

Indications of channel configurations, including antenna ports for a USRS, may be encoded using parameters other than those shown inFIG. 4. For example, in various embodiments, parameters such as codebookSubsetRestriction may be used instead. codebookSubsetRestriction is a bitmap that specifies a precoder codebook subset in which a UE device may report various pieces of information, including as a precoding matrix indicator (“PMI”), a rank indication (“RI”) and a precoding type indicator. In some embodiments, a codebook subset restriction value of 2 may indicate, in addition to what it normally indicates, that two antenna ports are reserved for the USRS. A value of 4 may indicate that four antenna ports are reserved for the USRS.

Just as RNs such as RN26may be configured to decode an index to determine combinations of channel configurations, nodes such as DeNB24may be configured to encode transmissions with indexes to communicate channel configurations.

For example, a method500depicted inFIG. 5may be implemented by a DeNB, such as DeNB24inFIG. 1, to encode a transmission to an RN with an index. At502, the DeNB may generate a series of symbols for transmission. The series of symbols may include an index that is indicative of a plurality of configurations of a physical downlink channel, including one or more antenna ports that are reserved for a reference signal. In some embodiments, the physical downlink channel may be an R-PDCCH. Similar as above, in some embodiments, the plurality of configurations indicated by the index may include one or more of whether the R-PDCCH is interleaved, a resource allocation type of the R-PDCCH, a demodulation type of the R-PDCCH, and one or more antenna ports reserved for a USRS. At504, the DeNB may transmit, to an RN, the series of symbols.

The techniques and apparatuses described herein may be implemented into a system using suitable hardware and/or software to configure as desired.FIG. 6illustrates, for one embodiment, an example system600comprising one or more processor(s)604, system control logic608coupled to at least one of the processor(s)604, system memory612coupled to system control logic608, non-volatile memory (NVM)/storage616coupled to system control logic608, and one or more communications interface(s)620coupled to system control logic608.

System control logic608for one embodiment may include any suitable interface controllers to provide for any suitable interface to at least one of the processor(s)604and/or to any suitable device or component in communication with system control logic608.

System control logic608for one embodiment may include one or more memory controller(s) to provide an interface to system memory612. System memory612may be used to load and store data and/or instructions, for example, for system600. System memory612for one embodiment may include any suitable volatile memory, such as suitable dynamic random access memory (“DRAM”), for example.

System control logic608for one embodiment may include one or more input/output (“I/O”) controller(s) to provide an interface to NVM/storage616and a wireless network adaptor(s)620.

NVM/storage616may be used to store data and/or instructions, for example. NVM/storage616may include any suitable non-volatile memory, such as flash memory, for example, and/or may include any suitable non-volatile storage device(s), such as one or more hard disk drive(s) (“HDD”(s)), one or more solid-state drive(s), one or more compact disc (“CD”) drive(s), and/or one or more digital versatile disc (DVD) drive(s) for example.

The NVM/storage616may include a storage resource physically part of a device on which the system600is installed or it may be accessible by, but not necessarily a part of, the device. For example, the NVM/storage616may be accessed over a network via the wireless network adaptor(s)620.

System memory612and NVM/storage616may include, in particular, temporal and persistent copies of control module624, respectively. In various embodiments, system memory612and NVM/storage616may also store, as indicated at626, a plurality of potential combinations of a plurality of configurations of a physical downlink channel. In some embodiments the plurality of potential channel configurations626may be in the form of a table such as that shown inFIG. 4. The control module624may include instructions that when executed by at least one of the processor(s)604result in the system600using an index and a stored plurality of potential channel configurations626to encode a transmission with an index (where system600is a DeNB) and determine channel configurations by decoding an index of a channel (where system is a RN), as described above. In some embodiments, the control module624may additionally/alternatively be located in the system control logic608and/or wireless network adapter620.

Wireless network adaptor(s)620may provide an interface for system600to communicate over one or more network(s) and/or with any other suitable device. Wireless network adaptor (s)620may include any suitable hardware and/or firmware. The wireless network adaptor (s)620may use one or more antenna(s).

For one embodiment, at least one of the processor(s)604may be packaged together with logic for one or more controller(s) of system control logic608. For one embodiment, at least one of the processor(s)604may be packaged together with logic for one or more controllers of system control logic608to form a System in Package (“SiP”). For one embodiment, at least one of the processor(s)604may be integrated on the same die with logic for one or more controller(s) of system control logic608. For one embodiment, at least one of the processor(s)604may be integrated on the same die with logic for one or more controller(s) of system control logic608to form a System on Chip (“SoC”).

The system600may be a various nodes in an EPS, such as an RN or a DeNB, as well as a desktop or laptop computer, a mobile telephone, a smart phone, or any other device adapted to receive a wireless communication signal. In various embodiments, system600may have more or less components, and/or different architectures.