Patent ID: 12244791

DETAILED DESCRIPTION

A detailed description of illustrative embodiments will now be described with reference to the various Figures. Although this description provides a detailed example of possible implementations, it should be noted that the details are intended to be exemplary and in no way limit the scope of the application.

One or more video coding devices in a video coding system may compress digital video signals, for example, to reduce the storage space and/or transmission bandwidth associated with the storage and/or delivery of such signals. A video coding device may be based on a block-based hybrid video coding framework. A multi-type tree based block partitioning structure may be employed. One or more of coding modules, for example, an intra prediction module, an inter prediction module, a transform/inverse transform module and a quantization/de-quantization module may be included. The video coding device may include in-loop filters.

The video coding device may include one or more coding tools that may provide higher coding efficiency and moderate implementation complexity. The coding tools may include one or more of the following: affine motion model, alternative temporal motion vector prediction (ATMVP), integer motion vector (IMV), generalized bi-prediction (GBi) orbi-prediction with CU-level weights (BCW), bi-directional optical flow (BDOF), combined inter merge/intra prediction, merge with motion vector difference (MMVD), pairwise average merge candidate, triangular inter prediction for inter coding; cross-component linear model (CCLM), multi-line intra prediction, current picture referencing (CPR) for intra prediction; enhanced multiple transform (EMT), dependent quantization for quantization and transform coding, and adaptive loop filtering (ALF) for in-loop filters.

An example block-based video coding system may include a block-based hybrid video coding framework.FIG.1illustrates an exemplary block diagram of a block-based hybrid video encoding system. As illustrated inFIG.1, the input video signal1002may be processed block by block. Extended block sizes (e.g., referred to as a coding unit or CU) may be used to compress high resolution (e.g., 1080p and/or beyond) video signals. A CU may include sizes of up to 128×128 pixels. Blocks may be partitioned based on quad-trees. A coding tree unit (CTU) may be split into CUs to adapt to varying local characteristics based on quad/binary/ternary-tree. A CU may or may not be partitioned into prediction units or PUs, for which separate predictions may be applied. A CU may be used (e.g., may always use) as the basic unit for prediction and transform without further partitions. In a multi-type tree structure, a (e.g., one) CTU may be partitioned (e.g., may be firstly partitioned) by a quad-tree structure. A quad-tree leaf node (e.g., each quad tree lead node) may be further partitioned by a binary and ternary tree structure. As illustrated inFIG.2, there may be one or more (e.g., five) splitting types including, for example, quaternary partitioning, horizontal binary partitioning, vertical binary partitioning, horizontal ternary partitioning, and vertical ternary partitioning.

Referring toFIG.1, an input video block (e.g., macroblock (MB) and/or a CU), spatial prediction1060and/or temporal prediction1062may be performed. Spatial prediction1060(e.g., intra prediction) may use pixels from samples of coded neighboring blocks (e.g., reference samples) in the video picture/slice to predict the current video block. The spatial prediction1060may reduce spatial redundancy, for example, that may be inherent in the video signal. Motion prediction1062(e.g., inter prediction and/or temporal prediction) may use reconstructed pixels from the coded video pictures, for example, to predict the current video block. The motion prediction1062may reduce temporal redundancy, for example, that may be inherent in the video signal. Motion prediction signals (e.g., a temporal prediction signal) for a video block (e.g., a CU) may be signaled by one or more motion vectors (MVs). The MVs may indicate the amount and/or the direction of motion between the current block and/or the current block's reference block or its temporal reference. If multiple reference pictures are supported for a (e.g., each) video block, the video block's reference picture index may be sent by an encoder. The reference picture index may be used to identify from which reference picture in a reference picture store1064the motion prediction signal may derive.

After the spatial prediction1060and/or motion prediction1062, a mode decision block1080in the encoder may determine a prediction mode (e.g., the best prediction mode), for example, based on a rate-distortion optimization. The prediction block may be subtracted from a current video block at1016, and/or the prediction residual may be de-correlated using a transform1004and/or a quantization1006to achieve a bit-rate, such as a target bit rate. The quantized residual coefficients may be inverse quantized at the inverse quantization1010and/or inverse transformed at transform1012, for example, to form the reconstructed residual, which may be added to the prediction block at1026, for example, to form a reconstructed video block. In-loop filtering (e.g., a de-blocking filter and/or adaptive loop filters) may be applied at loop filter1066on the reconstructed video block before the reconstructed video block may be put in the reference picture store1064and/or used to code video blocks (e.g., future video blocks). To form the output video bit-stream1020, coding mode (e.g., inter or intra), prediction mode information, motion information, and/or quantized residual coefficients may be sent (e.g., may all be sent) to an entropy coding module1008, for example, to be compressed and/or packed to form the bit-stream.

FIG.3illustrates a block diagram of an example block-based video decoding framework for a decoder. A video bit-stream1102(e.g., the video bit-stream1020inFIG.1) may be unpacked (e.g., first unpacked) and/or entropy decoded at an entropy decoding module1108. The coding mode and prediction information may be sent to a spatial prediction module1170(e.g., if intra coded) and/or to a motion compensation prediction module1172(e.g., if inter coded and/or temporal coded) to form a prediction block. Residual transform coefficients may be sent to an inverse quantization module1110and/or to an inverse transform module1112, e.g., to reconstruct the residual block. The prediction block and/or the residual block may be added together at1126. The reconstructed block may go through in-loop filtering at a loop filter1176, for example, before the reconstructed block is stored in a reference picture store1174. The reconstructed video1120in the reference picture store1174may be sent to drive a display device and/or used to predict video blocks (e.g., future video blocks).

One or more coding modules, for example, the coding modules associated with inter prediction, may be enhanced to improve inter coding efficiency. For example, as described herein, the coding efficiency of history-based motion vector prediction (HMVP) may be improved.

The MVs of inter-coded blocks may be signaled using one or more mechanisms as described herein. For example, the MVs of inter-coded blocks may be signaled using advanced motion vector prediction (AMVP) mode or merge mode. In the AMVP mode, the difference between the real MV and a MV predictor (MVP), a reference index, and a MVP index referring to an AMVP candidate list may be signaled. For the merge mode, a merge index referring to a merge candidate list may be signaled. The motion information associated with a merge candidate may be inherited from the signaled merge candidate. Motion information, for example for the AMVP and merge candidates, may be derived from the spatial blocks that neighbor a CU. For example, the spatial blocks may directly neighbor (e.g., be adjacent to) the current CU or a collocated block in a temporal reference picture. One or more merge candidates (e.g., up to 6 merge candidates) and one or more AMVP candidates (e.g., up to 2 AMVP candidates) may be added to a candidate list for motion vector prediction.

HMVP may be employed to explore the correlation between the MVs of neighboring blocks. For example, HMVP may be utilized to explore correlation between neighboring spatially non-adjacent blocks. Although reference is made herein to the HMVP being utilized by neighboring blocks that are spatially non-adjacent, one skilled in the art may appreciate that the neighboring blocks may also include blocks that are adjacent blocks.

A HMVP candidate may indicate the motion information of a previously coded CU. The motion information may include one or more of the MVs and the reference picture index. A table of multiple HMVP candidates may be maintained at an encoder and/or a decoder. The HMVP candidate table may be reset (e.g., reset to empty) when the coding of a new CTU line is started. After an inter CU that does not contain multiple sub-blocks (e.g., the ATMVP and affine coded CUs) is coded, the associated motion information may be added to an entry (e.g., the last entry in the HMVP candidate table) based on a rule (e.g., a constrained first-in-first-out (FIFO) rule). A redundancy check may be applied to identify whether there is an existing HMVP candidate that is identical to a new motion candidate (e.g., before adding the motion candidate into the HMVP candidate table or list). If an existing HMVP candidate that is identical to the new motion candidate is found, the identical HMVP candidate may be removed from the HMVP candidate table or list and the HMVP candidates may be moved forward by one position, for example, by reducing the HMVP candidate table index by one.FIG.4illustrates an exemplary decoding workflow when HMVP is applied to predict MVs. As illustrated inFIG.4, at402, the existing HMVP candidates may be loaded in a list of existing HMVP candidates. At404, MV associated with a current block may be decoded from the HMVP candidates. At406, the HMVP candidate list may be updated based on the decoded MV.

Generalized bi-prediction (GBi) or bi-prediction with CU-level weights (BCW) may be performed. For example, GBi or BCW may be performed to improve the efficiency of bi-prediction when one CU is predicted by two temporal prediction blocks from the reference pictures that are reconstructed. In bi-prediction mode, the prediction signal at sample x may be calculated as the average of two prediction signals, as shown in the equation (1).
P[x]=(P0[x+v0]+P1[x+v1])/2,  (1)

Referring to the equation (1): P[x] may be the resulting prediction signal of a sample x located at a picture position x, P1[x+v1] may be the motion-compensated prediction signal of x using the motion vector (MV) v1for i-th list (e.g., list 0, list 1). GBi may apply a variety of weight values (e.g., w0 and w1) to the two prediction signals from list 0 and list 1. One or more configurations of w0 and w1 may imply prediction similarities to uni-prediction and bi-prediction (e.g., the same prediction as conventional uni-prediction and bi-prediction). For example, prediction similarities to uni-prediction and bi-prediction may exist when (w0, w1) equals: (1, 0) for uni-prediction with reference list L0; (0,1) for uni-prediction with reference list L1; and (0.5, 0.5) for the conventional bi-prediction with two reference lists. In GBi, the weights applied to the prediction signals from lists L0 and L1 may be signaled per CU. A constraint may be applied so that the summation of w0 and w1 is 1, e.g., w0+w1=1. The constraint may be applied to reduce signaling overhead. Given such constraint, a single weight may be signaled, and the final bi-prediction signal when the GBi is applied may be calculated, for example, using equation (2).
P[x]=(1−w1)*P0[x+v0]+w1*P1[x+v1].  (2)

Referring to (2), w1 may be discretized, e.g., using values {−1/4, 1/4, 3/8, 1/2, 5/8, 3/4, 5/4}, so that each weight value can be indicated by an index value within a small limited range. The discretization of w1 using a small range may be utilized to reduce signaling overhead. The weight values {1/4, 3/8, 1/2, 5/8, 3/4} may be applied to an inter picture (e.g., all inter pictures) and the weight values {−1/4, 5/4} may be applied to low-delay pictures. The weight values may be applied to low-delay pictures that can be predicted by using the reference picture preceding the current picture as per the display order.

Triangle inter prediction may be performed. In some video content (e.g., nature video content), the boundaries between two moving objects may not be horizontal or vertical (e.g., purely horizontal or vertical). Such non-horizontal or non-vertical boundaries may be difficult to be accurately approximated by rectangular blocks. Triangular prediction may, therefore, be applied for example to enable triangular partitions for motion compensated prediction. As illustrated inFIG.5, triangular prediction may split a CU into one or more (e.g., two) triangular prediction units, e.g., in a diagonal direction (502) or an inverse-diagonal direction (504). A triangular prediction unit (e.g., each triangular prediction unit) in the CU may be inter-predicted using its uni-prediction motion vector and reference frame index. The uni-prediction motion vector and reference frame index may be derived from a uni-prediction candidate list.

A uni-prediction candidate list may include one or more (e.g., five) uni-prediction motion vector candidates. Uni-prediction motion vector candidates may be derived from similar (e.g., the same) spatial/temporal neighboring blocks as those that are used for a merge process (e.g., the merge process of the HEVC). Uni-prediction MV candidates may be derived from five spatially neighboring blocks and two temporally collocated blocks, as illustrated inFIG.6. Referring toFIG.6, the motion vectors of the seven neighboring blocks may be collected and stored into the uni-prediction MV candidate list in the order of the L0 motion vector of neighboring blocks, the L1 motion vector of neighboring blocks, and the averaged motion vector of the L0 and L1 motion vectors of the neighboring blocks, for example, if the neighboring blocks are bi-predicted. If the number of MV candidates is less than five, zero (0) motion vectors may be added to the MV candidate list.

FIG.7illustrates a flow chart for adding the uni-prediction MVs of merge candidates into the uni-prediction MV list of a CU that is coded by triangle prediction mode. At702, a video coding device may determine whether a merge candidate includes L0 MV. If it does, at704, the video coding device may add the L0 MV associated with the merge candidate into a uni-prediction MV list. At708, the video coding device may check whether the spatial/temporal candidate is the last in the list. At710, the video coding device may determine whether a merge candidate includes L1 MV. If it does, at712, the video coding device may add the L1 MV associated with the merge candidate into a uni-prediction MV list. At714, the video coding device may check whether the spatial/temporal candidate is the last in the list. At716, the video coding device may determine whether a merge candidate includes L0 and L1 MVs. If it does, at718, the video coding device may add the average of L0 MV and L1 MV associated with the merge candidate into a uni-prediction MV list. At720, the video coding device may check whether the spatial/temporal candidate is the last in the list.

The order of the one or more neighboring blocks (e.g., the order of how the candidate blocks may be checked and considered for addition to a candidate list) may include the one or more spatial neighboring blocks (e.g., 1 to 5) followed by one or more temporal co-located blocks (6 to 7). Referring toFIG.6, the motion vectors of the seven neighboring blocks (e.g., A1, A0, B0, B1, B2, T0, T1) may be collected and stored into a uni-prediction candidate list according to the order of uni-prediction motion vectors, L0 motion vector of bi-prediction motion vectors, L1 motion vector of bi-prediction motion vectors, and averaged motion vector of the L0 and L1 motion vectors of bi-prediction motion vectors. If the number of candidates is less than five, zero motion vector is added to the list.

HMVP coding gain may be improved, for example, by extending the application of HMVP to other coding tools, for example, generalized bi-prediction and/or triangle inter prediction. HMVP may be employed to determine the MV correlation between the neighboring blocks. For example, HMVP may be utilized to determine the MV correlation between neighboring spatially non-adjacent blocks. Although reference is made herein to the HMVP being utilized to determine the MV correlation between neighboring blocks that are spatially non-adjacent, one skilled in the art may appreciate that the neighboring blocks may include blocks that are adjacent blocks. HMVP may be utilized to determine the MV correlation by maintaining a table of one or more MV candidates. The table may be maintained at the at an encoding device and/or a decoding device. An HMVP candidate may be defined based on motion information comprising one or more of the following: a motion vector (e.g., one or more motion vectors), a reference list (e.g., one or more reference lists), or a reference picture index (e.g., one or more reference picture indices) associated with a previously coded block

In an example, a HMVP candidate may be used to derive the prediction signal of a CU with GBi disabled. In such a case, equal weights may be applied to two prediction signals associated with list 0 and list1.

In an example, HMVP and the GBi may be enabled, for example, by associating a GBi with an HMVP index. The GBi may be enabled by associating at least one GBi index with each of the HMVP entries or HMVP indexes. This may result in improvement of the coding efficiency of HMVP. GBi index may also be referred as bi-prediction weight index.

In an example, for each HMVP candidate, in addition to the motion information, the at least one GBi index may be created based on one or more of the following. When a HMVP candidate is derived from an inter CU where the GBi weight is signaled, the GBi weight of the HMVP candidate may be set to the signaled GBi weight. When a HMVP candidate is derived from a spatial merge candidate, the GBi weight of the HMVP candidate may be set to the GBi weight of the spatial candidate. When a HMVP candidate is derived from a temporal merge candidate, the GBi weight of the HMVP candidate may be set to the GBi weight of a collocated block in a temporally collocated picture. When the HMVP candidate is derived from an average merge candidate, the GBi weight of the HMVP candidate may be set to a certain fixed value (e.g., 0.5).

As described herein, pruning may be performed at one or more different stages of HMVP processing procedure. For example, pruning may be performed to remove redundant entries in an HMVP list when adding an MV candidate or an HMVP candidate to the HMVP list. In an example, pruning may be performed after determining whether an entry in the HMVP list is identical to the MV candidate or the HMVP candidate. If an identical candidate in the HMVP list is found, the identical HMVP is removed from the HMVP list. In an example, an HMVP candidate may be said to be identical to an HMVP entry in the HMVP list, if the motion information associated with the HMVP candidate is similar to the motion information associated with the HMVP entry in the HMVP list. The motion information that is compared may include one or more of: a motion vector (e.g., one or more motion vectors), a reference list (e.g., one or more reference indices, and a reference picture index (e.g., one or more reference picture indices).

In an example, in addition to the motion vector information, GBi weights may be considered in determining whether to add an HMVP candidate to a HMVP candidate listFIG.8Aillustrates an example wherein the GBi weight is considered when adding a HMVP candidate into a HMVP candidate list. As illustrated inFIG.8A, the second entry of the HMVP list and the new HMVP candidate to be added to the HMVP list may be treated as identical when the motion information and the GBi weights of the second entry of the existing HMVP list (e.g., HMV P1) are similar to the motion information and the GBi weights of the a new HMV P candidate (e.g., Ci-1). In such an example, before adding the HMVP candidate, Ci-1to the end of the HMVP list, the matched HMVP entry in the HMVP list, HMVP1may be removed from the list and HMVP entries following HMVP entries (e.g., HMVP2to HMVPi-1) may be moved forward as indicated by the arrows. This may be achieved, for example, by reducing the respective indices by one.

FIG.8Billustrates an example wherein an HMVP candidate may be treated as not identical to an entry in an HMVP list. As illustrated inFIG.88, even though the motion information of HMVP1and Ci-1is the same, HMVP1and Ci-1are said to be not identical because their respective GBi weights are unequal. A FIFO process (e.g., the default FIFO process) may be applied. As illustrated inFIG.8B, the FIFO procedure may include removing the first HMVP candidate (e.g., HMVP0) from the table, moving each entry's position by one, as indicated by the arrows inFIG.8B, to create an empty position at the end of the HMVP list, and adding the new candidate Ci-1into the empty position at the end of the HMVP list.

HMVP candidates (e.g., which may each be associated with a GBi weight, respectively) may be used as candidates for a merge mode and/or an AMVP mode. HMVP candidates (e.g., all the HMVP candidates from the last entry to the first entry in the HMVP table) may be inserted, for example, after the TMVP candidate. When HMVP is applied to the merge mode, pruning may be applied to remove the candidates with similar (e.g., the same) motion information and similar (e.g., the same) GBi weight.

GBi indices may be used for motion-compensated prediction and HMVP pruning process. The motion-compensated prediction and HMVP pruning process may improve coding gain and increase the complexity of the pruning process. The complexity of the HMVP pruning process may increase when the motion information and the GBi weight of the HMVP candidates (e.g., each HMVP candidate in the list) are checked. In an example, the GBi weight of each of the HMVP candidates (e.g., all the HMVP candidates) may be utilized for motion-compensated prediction. A subset of the HMVP candidates may be utilized for HMVP pruning process. As described herein, an HMVP candidate may be associated with a GBi index (e.g., each HMVP candidate may be associated with one GBi index). The associated GBi weight may be utilized to generate a prediction signal of a CU (e.g., rather than determining whether two HMVP candidates are identical).

FIG.9illustrates an example of adding an HMVP candidate to an HMVP list, wherein the GBi weight may not be considered when adding a HMVP candidate into a HMVP list. In the example provided inFIG.9, the GBi index of the second entry of the existing HMVP list (e.g., HMVP1) and the new HMVP candidate (e.g., Ci-1) are not the same while the motion information of the second entry of the existing HMVP list (e.g., HMVP1) and the new HMVP candidate (e.g, Ci-1) are the same. In this example, if the motion information of the second entry of the existing HMVP list (e.g., HMVP1) and the new HMVP candidate (e.g., Ci-1) are the same, and the GBi indices of the second entry of the existing HMVP list (e.g., HMVP1) and the new HMVP candidate (e.g., Ci-1) are not the same, the second entry of the HMVP list and the new HMVP candidate may be treated as identical. As illustrated inFIG.9, HMVP1may be removed from the HMVP candidate list, and the subsequent HMVP candidate (e.g., HMVP2to HMVPi-1) may be moved forward, e.g., by reducing the indices by one as illustrated by arrows. Ci-1may then be added to the end of the HMVP list.

Triangle inter prediction may be performed with the HMVP. In triangle inter prediction, the MVs in a uni-prediction candidate list may be derived from temporal and spatial neighbors. For example, the conventional spatial and temporal neighbors may be the neighbors that are used for the merge mode of the HEVC. For example, triangle inter prediction may derive the MVs in the uni-prediction candidate list from five spatial neighbors and two temporal neighbors, as illustrated inFIG.6. In an example, MV derivation may not consider the correlation between the MVs of the blocks that are not directly spatial neighbors (e.g., non-adjacent blocks). In such a case, MV derivation may not generate accurate uni-prediction MV candidates (e.g., the most accurate uni-prediction MV candidates) to capture the true motion of the two triangle partitions. In an example, the motion information of neighboring blocks along an occlusion boundary may not be correlated (e.g., due to occluding objects that may commonly exist in content, such as nature video content). If the motion information of neighboring blocks along an occlusion boundary are not correlated, the MVs from the spatial neighbors on the occlusion boundary may not be accurate (e.g., sufficiently accurate) to act as the MV predictor of a current CU. This may lower the efficiency of inter coding. In an example, HMVP candidates (e.g., besides the existing spatial and temporal MV candidates) may be used to derive a uni-prediction MV candidate list for the triangle prediction mode, for example, to explore the correlation between the MVs of one or more neighboring blocks (e.g., spatially non-adjacent blocks).

The uni-prediction MVs of HMVP candidates may be placed at different positions of a candidate list (e.g., a final candidate list) of the uni-prediction MVs for the triangle mode. In an example, the uni-prediction MVs associated with one or more HMVP candidates may be checked and inserted in a list after spatial and/or temporal candidates. The MVs associated with an HMVP candidate may be checked (e.g., check whether the MV of a HMVP candidate is identical to an MV in the uni-prediction MV list) and inserted in the uni-prediction candidate list (e.g., after the spatial and the temporal candidates). The MVs of the candidate blocks may be collected in order of the five spatial neighbors (e.g., A1, A0, B1, B0 and B2) followed by the two temporal neighbors (e.g., T0 and T1) as illustrated inFIG.6and the N HMVP candidates.

The uni-prediction MVs that are used for the triangle mode may be generated as described herein. In an example, the uni-prediction MVs used for the triangle mode may be generated by adding the L0 MVs associated with one or more of the spatial/temporal and HMVP candidates. In an example, the uni-prediction MVs used for the triangle mode may be generated by adding the L1 MVs associated with one or more spatial/temporal and HMVP candidates. In an example, the uni-prediction MVs used for the triangle mode may be generated by adding average of L0 and L1 MVs of the spatial/temporal and HMVP candidates, for example, if the HMVP candidate is bi-predicted.

FIG.10illustrates an example associated with inserting the uni-prediction MVs of merge candidates into the uni-prediction MV list of a triangle CU. As illustrated inFIG.10, at1030a video coding device may determine if a candidate (e.g., an i-th merge candidate) includes an L0 MV. If yes, at1032, the video coding device may add the L0 MV associated with the candidate to a uni-prediction MV list. At1034, the video coding device may check whether the spatial/temporal, or the HMVP candidate is the last in the list. At1036, the video coding device may determine whether the candidate includes an L1 MV. If yes, at1038, the video coding device may add the L1 MV of the candidate into the uni-prediction MV list. At1040, the video coding device may check whether the spatial/temporal, or HMVP candidate is the last in the list. At1042, the video coding device may determine whether the candidate includes the L0 and L1 MVs. If yes, at1044, the video coding device may add the average of L0 and L1 MVs of the candidate into the uni-prediction MV list. At1046, the video coding device may check whether the spatial/temporal, or HMVP candidate is the last in the list.

The motion (e.g., the motion information) of spatial and temporal neighbors may be correlated with the motion (e.g., the motion information) of a current CU (e.g., more correlated than the motion of HMVP candidates). The uni-prediction MVs of the spatial and temporal candidates may be given higher priorities than the uni-prediction MVs of the HMVP candidates (e.g., to reduce the overhead of signaling candidate MVs). In examples, the uni-prediction MVs of spatial/temporal candidates may be interleaved with the uni-prediction MVs of the HMVP candidates.

A uni-prediction MV list (e.g., the final uni-prediction MV list) of a triangle CU may be generated. In an example, the uni-prediction MV list of a triangle CU may be generated by inserting the L0 MV of each spatial/temporal candidate in the uni-prediction MV list. In an example, the uni-prediction MV list of a triangle CU may be generated by inserting the L1 MV of each spatial/temporal candidate in the uni-prediction MV list. In an example, the uni-prediction MV list of a triangle CU may be generated by inserting the L0 MV of each HMVP candidate in the uni-prediction MV list. In an example, the uni-prediction MV list of a triangle CU may be generated by inserting the L1 MV of each HMVP candidate in the uni-prediction MV list.

In an example, the uni-prediction MV list of a triangle CU may be generated by inserting the average of L0 and L1 MV of the spatial/temporal candidate (e.g., each spatial/temporal candidate, if the candidate is bi-predicted) in the uni-prediction MV list. In an example, the uni-prediction MV list of a triangle CU may be generated by inserting the average of L0 and L1 MVs of the HMVP candidate (e.g., each HMVP candidate, if the candidate is bi-predicted) in the uni-prediction MV list.

FIG.11illustrates an example of generating the uni-prediction MV list of triangle mode when the uni-prediction MVs of spatial/temporal candidates and the HMVP candidates are interleaved. As illustrated inFIG.11, at1130a video coding device may determine if a candidate (e.g., an i-th merge candidate) includes an L0 MV. If yes, at1132, the video coding device adds the L0 MV associated with the candidate to a uni-prediction MV list. At1134, the video coding device may check whether the spatial/temporal candidate is the last in the list. At1136the video coding device may determine if a candidate includes an L1 MV. If yes, at1138, the video coding device may add the L1 MV associated with the candidate to a uni-prediction MV list. At1140, the video coding device may check whether the spatial/temporal candidate is the last in the list. At1142the video coding device may determine if a candidate includes an L0 MV. If yes, at1144, the video coding device may add the L1 MV associated with the candidate to a uni-prediction MV list. At1146, the video coding device may check whether the HMVP candidate is the last in the list. At1148the video coding device may determine if a candidate includes an L1 MV. If yes, at1150, the video coding device may add the L1 MV associated with the candidate to a uni-prediction MV list. At1152, the video coding device may check whether the HMVP candidate is the last in the list. At1154the video coding device may determine if a candidate includes L0 and L1 MVs. If yes, at1156, the video coding device may add the average of the L0 and L1 MVs associated with the candidate to a uni-prediction MV list. At1158, the video coding device may check whether the spatial/temporal candidate is the last in the list. At1160the video coding device may determine if a candidate includes L0 and L1 MVs. If yes, at1162, the video coding device may add the average of the L0 and L1 MVs associated with the candidate to a uni-prediction MV list. At1164, the video coding device may check whether the HMVP candidate is the last in the list.

FIG.12Ais a diagram illustrating an example communications system100in which one or more disclosed embodiments may be implemented. For example, one or more of the features associated with the video coding device as described herein may be included in one or more of the WTRUs102a,102b,102cand102dof the communications system100. The communications system100may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system100may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems100may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

As shown inFIG.12A, the communications system100may include wireless transmit/receive units (WTRUs)102a,102b.102c.102d, a RAN104/113, a CN106/115, a public switched telephone network (PSTN)108, the Internet110, and other networks112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs102a,102b,102c,102dmay be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the WTRUs102a,102b.102c.102d, any of which may be referred to as a “station” and/or a “STA”, may be configured to transmit and/or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. Any of the WTRUs102a,102b,102cand102dmay be interchangeably referred to as a UE.

The communications systems100may also include a base station114aand/or a base station114b. Each of the base stations114a,114bmay be any type of device configured to wirelessly interface with at least one of the WTRUs102a,102b,102c,102dto facilitate access to one or more communication networks, such as the CN106/115, the Internet110, and/or the other networks112. By way of example, the base stations114a,114bmay be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller, an access point (AP), a wireless router, and the like. While the base stations114a,114bare each depicted as a single element, it will be appreciated that the base stations114a,114bmay include any number of interconnected base stations and/or network elements.

The base station114amay be part of the RAN104/113, which may also include other base stations and/or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station114aand/or the base station114bmay be configured to transmit and/or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station114amay be divided into three sectors. Thus, in one embodiment, the base station114amay include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station114amay employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and/or receive signals in desired spatial directions.

The base stations114a,114bmay communicate with one or more of the WTRUs102a,102b,102c,102dover an air interface116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface116may be established using any suitable radio access technology (RAT).

More specifically, as noted above, the communications system100may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station114ain the RAN104/113and the WTRUs102a,102b,102cmay implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface115/116/117using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink (DL) Packet Access (HSDPA) and/or High-Speed UL Packet Access (HSUPA).

In an embodiment, the base station114aand the WTRUs102a,102b,102cmay implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface116using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/or LTE-Advanced Pro (LTE-A Pro).

In an embodiment, the base station114aand the WTRUs102a,102b,102cmay implement a radio technology such as NR Radio Access, which may establish the air interface116using New Radio (NR).

In an embodiment, the base station114aand the WTRUs102a,102b,102cmay implement multiple radio access technologies. For example, the base station114aand the WTRUs102a,102b,102cmay implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs102a,102b,102cmay be characterized by multiple types of radio access technologies and/or transmissions sent to/from multiple types of base stations (e.g., an eNB and a gNB).

In other embodiments, the base station114aand the WTRUs102a,102b,102cmay implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

The base station114binFIG.12Amay be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. In one embodiment, the base station114band the WTRUs102c.102dmay implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station114band the WTRUs102c,102dmay implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station114band the WTRUs102c,102dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. As shown inFIG.12A, the base station114bmay have a direct connection to the Internet110. Thus, the base station114bmay not be required to access the Internet110via the CN106/115.

The RAN104/113may be in communication with the CN106/115, which may be any type of network configured to provide voice, data, applications, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs102a,102b,102c,102d. The data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN106/115may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and/or perform high-level security functions, such as user authentication. Although not shown inFIG.12A, it will be appreciated that the RAN104/113and/or the CN106/115may be in direct or indirect communication with other RANs that employ the same RAT as the RAN104/113or a different RAT. For example, in addition to being connected to the RAN104/113, which may be utilizing a NR radio technology, the CN106/115may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

The CN106/115may also serve as a gateway for the WTRUs102a,102b,102c,102dto access the PSTN108, the Internet110, and/or the other networks112. The PSTN108may include circuit-switched telephone networks that provide plain old telephone service (POTS). The Internet110may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and/or the internet protocol (IP) in the TCP/IP internet protocol suite. The networks112may include wired and/or wireless communications networks owned and/or operated by other service providers. For example, the networks112may include another CN connected to one or more RANs, which may employ the same RAT as the RAN104/113or a different RAT.

Some or all of the WTRUs102a,102b,102c,102din the communications system100may include multi-mode capabilities (e.g., the WTRUs102a,102b,102c,102dmay include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU102cshown inFIG.12Amay be configured to communicate with the base station114a, which may employ a cellular-based radio technology, and with the base station114b, which may employ an IEEE 802 radio technology.

FIG.12Bis a system diagram illustrating an example WTRU102. As shown inFIG.12B, the WTRU102may include a processor118, a transceiver120, a transmit/receive element122, a speaker/microphone124, a keypad126, a display/touchpad128, non-removable memory130, removable memory132, a power source134, a global positioning system (GPS) chipset136, and/or other peripherals138, among others. It will be appreciated that the WTRU102may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

The processor118may be a general-purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor118may perform signal coding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRU102to operate in a wireless environment. The processor118may be coupled to the transceiver120, which may be coupled to the transmit/receive element122. WhileFIG.12Bdepicts the processor118and the transceiver120as separate components, it will be appreciated that the processor118and the transceiver120may be integrated together in an electronic package or chip.

The transmit/receive element122may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station114a) over the air interface116. For example, in one embodiment, the transmit/receive element122may be an antenna configured to transmit and/or receive RF signals. In an embodiment, the transmit/receive element122may be an emitter/detector configured to transmit and/or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit/receive element122may be configured to transmit and/or receive both RF and light signals. It will be appreciated that the transmit/receive element122may be configured to transmit and/or receive any combination of wireless signals.

Although the transmit/receive element122is depicted inFIG.12Bas a single element, the WTRU102may include any number of transmit/receive elements122. More specifically, the WTRU102may employ MIMO technology. Thus, in one embodiment, the WTRU102may include two or more transmit/receive elements122(e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface116.

The transceiver120may be configured to modulate the signals that are to be transmitted by the transmit/receive element122and to demodulate the signals that are received by the transmit/receive element122. As noted above, the WTRU102may have multi-mode capabilities. Thus, the transceiver120may include multiple transceivers for enabling the WTRU102to communicate via multiple RATs, such as NR and IEEE 802.11, for example.

The processor118of the WTRU102may be coupled to, and may receive user input data from, the speaker/microphone124, the keypad126, and/or the display/touchpad128(e.g., a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit). The processor118may also output user data to the speaker/microphone124, the keypad126, and/or the display/touchpad128. In addition, the processor118may access information from, and store data in, any type of suitable memory, such as the non-removable memory130and/or the removable memory132. The non-removable memory130may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory132may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor118may access information from, and store data in, memory that is not physically located on the WTRU102, such as on a server or a home computer (not shown).

The processor118may receive power from the power source134and may be configured to distribute and/or control the power to the other components in the WTRU102. The power source134may be any suitable device for powering the WTRU102. For example, the power source134may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

The processor118may also be coupled to the GPS chipset136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU102. In addition to, or in lieu of, the information from the GPS chipset136, the WTRU102may receive location information over the air interface116from a base station (e.g., base stations114a,114b) and/or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU102may acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment.

The processor118may further be coupled to other peripherals138, which may include one or more software and/or hardware modules that provide additional features, functionality and/or wired or wireless connectivity. For example, the peripherals138may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs and/or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a Virtual Reality and/or Augmented Reality (R/AR) device, an activity tracker, and the like. The peripherals138may include one or more sensors, the sensors may be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, alight sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and/or a humidity sensor.

The WTRU102may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the UL (e.g., for transmission) and downlink (e.g., for reception) may be concurrent and/or simultaneous. The full duplex radio may include an interference management unit to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor118). In an embodiment, the WRTU102may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception).

FIG.12Cis a system diagram illustrating the RAN104and the CN106according to an embodiment. As noted above, the RAN104may employ an E-UTRA radio technology to communicate with the WTRUs102a,102b,102cover the air interface116. The RAN104may also be in communication with the CN106.

The RAN104may include eNode-Bs160a,160b,160c, though it will be appreciated that the RAN104may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs160a,160b,160cmay each include one or more transceivers for communicating with the WTRUs102a,102b,102cover the air interface116. In one embodiment, the eNode-Bs160a,160b,160cmay implement MIMO technology. Thus, the eNode-B160a, for example, may use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU102a.

Each of the eNode-Bs160a,160b,160cmay be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, and the like. As shown inFIG.12C, the eNode-Bs160a,160b,160cmay communicate with one another over an X2 interface.

The CN106shown inFIG.12Cmay include a mobility management entity (MME)162, a serving gateway (SGW)164, and a packet data network (PDN) gateway (or PGW)166. While each of the foregoing elements are depicted as part of the CN106, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator.

The MME162may be connected to each of the eNode-Bs162a,162b,162cin the RAN104via an S1 interface and may serve as a control node. For example, the MME162may be responsible for authenticating users of the WTRUs102a,102b,102c, bearer activation/deactivation, selecting a particular serving gateway during an initial attach of the WTRUs102a,102b,102c, and the like. The MME162may provide a control plane function for switching between the RAN104and other RANs (not shown) that employ other radio technologies, such as GSM and/or WCDMA.

The SGW164may be connected to each of the eNode Bs160a,160b,160cin the RAN104via the S1 interface. The SGW164may generally route and forward user data packets to/from the WTRUs102a,102b,102c. The SGW164may perform other functions, such as anchoring user planes during inter-eNode B handovers, triggering paging when DL data is available for the WTRUs102a.102b,102c, managing and storing contexts of the WTRUs102a,102b,102c, and the like.

The SGW164may be connected to the PGW166, which may provide the WTRUs102a,102b,102cwith access to packet-switched networks, such as the Internet110, to facilitate communications between the WTRUs102a,102b,102cand IP-enabled devices.

The CN106may facilitate communications with other networks. For example, the CN106may provide the WTRUs102a,102b,102cwith access to circuit-switched networks, such as the PSTN108, to facilitate communications between the WTRUs102a,102b,102cand traditional land-line communications devices. For example, the CN106may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN106and the PSTN108. In addition, the CN106may provide the WTRUs102a,102b,102cwith access to the other networks112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers

Although the WTRU is described inFIGS.12A-12Das a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

In representative embodiments, the other network112may be a WLAN.

A WLAN in Infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have an access or an interface to a Distribution System (DS) or another type of wired/wireless network that carries traffic in to and/or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA. The traffic between STAs within a BSS may be considered and/or referred to as peer-to-peer traffic. The peer-to-peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11e LS or an 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an ‘ad-hoc’ mode of communication.

When using the 802.11ac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) may be implemented, for example in in 802.11 systems. For CSMA/CA, the STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed/detected and/or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

High Throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.

Very High Throughput (VHT) STAs may support 20 MHz, 40 MHz, 80 MHz, and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, may be passed through a segment parser that may divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, may be done on each stream separately. The streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration may be reversed, and the combined data may be sent to the Medium Access Control (MAC).

Sub 1 GHz modes of operation are supported by 802.11af and 802.11ah. The channel operating bandwidths, and carriers, are reduced in 802.11af and 802.11ah relative to those used in 802.11n, and 802.11ac. 802.11af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support Meter Type Control/Machine-Type Communications, such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and/or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

WLAN systems, which may support multiple channels, and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and/or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.11ah, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes. Carrier sensing and/or Network Allocation Vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available.

In the United States, the available frequency bands, which may be used by 802.11ah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11ah is 6 MHz to 26 MHz depending on the country code.

FIG.12Dis a system diagram illustrating the RAN113and the CN115according to an embodiment. As noted above, the RAN113may employ an NR radio technology to communicate with the WTRUs102a,102b,102cover the air interface116. The RAN113may also be in communication with the CN115.

The RAN113may include gNBs180a,180b,180c, though it will be appreciated that the RAN113may include any number of gNBs while remaining consistent with an embodiment. The gNBs180a,180b,180cmay each include one or more transceivers for communicating with the WTRUs102a,102b,102cover the air interface116. In one embodiment, the gNBs180a,180b,180cmay implement MIMO technology. For example, gNBs180a,108bmay utilize beamforming to transmit signals to and/or receive signals from the gNBs180a,180b,180c. Thus, the gNB180a, for example, may use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU102a. In an embodiment, the gNBs180a,180b,180cmay implement carrier aggregation technology. For example, the gNB180amay transmit multiple component carriers to the WTRU102a(not shown). A subset of these component carriers may be on unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs180a,180b,180cmay implement Coordinated Multi-Point (CoMP) technology. For example, WTRU102amay receive coordinated transmissions from gNB180aand gNB180b(and/or gNB180c).

The WTRUs102a,102b,102cmay communicate with gNBs180a,180b,180cusing transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and/or OFDM subcarrier spacing may vary for different transmissions, different cells, and/or different portions of the wireless transmission spectrum. The WTRUs102a,102b,102cmay communicate with gNBs180a,180b,180cusing subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing varying number of OFDM symbols and/or lasting varying lengths of absolute time).

The gNBs180a,180b,180cmay be configured to communicate with the WTRUs102a,102b,102cin a standalone configuration and/or a non-standalone configuration. In the standalone configuration, WTRUs102a,102b,102cmay communicate with gNBs180a,180b,180cwithout also accessing other RANs (e.g., such as eNode-Bs160a,160b,160c). In the standalone configuration, WTRUs102a,102b,102cmay utilize one or more of gNBs180a,180b,180cas a mobility anchor point. In the standalone configuration, WTRUs102a,102b,102cmay communicate with gNBs180a,180b,180cusing signals in an unlicensed band. In a non-standalone configuration WTRUs102a,102b,102cmay communicate with/connect to gNBs180a,180b,180cwhile also communicating with/connecting to another RAN such as eNode-Bs160a,160b,160c. For example, WTRUs102a,102b,102cmay implement DC principles to communicate with one or more gNBs180a,180b,180cand one or more eNode-Bs160a,160b,160csubstantially simultaneously. In the non-standalone configuration, eNode-Bs160a,160b,160cmay serve as a mobility anchor for WTRUs102a,102b,102cand gNBs180a,180b,180cmay provide additional coverage and/or throughput for servicing WTRUs102a,102b,102c.

Each of the gNBs180a,180b,180cmay be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards User Plane Function (UPF)184a,184b, routing of control plane information towards Access and Mobility Management Function (AMF)182a,182band the like. As shown inFIG.12D, the gNBs180a,180b,180cmay communicate with one another over an Xn interface.

The CN115shown inFIG.12Dmay include at least one AMF182a,182b, at least one UPF184a,184b, at least one Session Management Function (SMF)183a,183b, and possibly a Data Network (DN)185a,185b. While each of the foregoing elements are depicted as part of the CN115, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator.

The AMF182a,182bmay be connected to one or more of the gNBs180a,180b,180cin the RAN113via an N2 interface and may serve as a control node. For example, the AMF182a,182bmay be responsible for authenticating users of the WTRUs102a,102b,102c, support for network slicing (e.g., handling of different PDU sessions with different requirements), selecting a particular SMF183a,183b, management of the registration area, termination of NAS signaling, mobility management, and the like. Network slicing may be used by the AMF182a,182bin order to customize CN support for WTRUs102a,102b,102cbased on the types of services being utilized WTRUs102a,102b,102c. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, and/or the like. The AMF162may provide a control plane function for switching between the RAN113and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and/or non-3GPP access technologies such as WiFi.

The SMF183a,183bmay be connected to an AMF182a,182bin the CN115via an N11 interface. The SMF183a,183bmay also be connected to a UPF184a,184bin the CN115via an N4 interface. The SMF183a,183bmay select and control the UPF184a,184band configure the routing of traffic through the UPF184a,184b. The SMF183a,183bmay perform other functions, such as managing and allocating UE IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type may be IP-based, non-IP based, Ethernet-based, and the like.

The UPF184a,184bmay be connected to one or more of the gNBs180a,180b,180cin the RAN113via an N3 interface, which may provide the WTRUs102a,102b,102cwith access to packet-switched networks, such as the Internet110, to facilitate communications between the WTRUs102a,102b,102cand IP-enabled devices. The UPF184,184bmay perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

The CN115may facilitate communications with other networks. For example, the CN115may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN115and the PSTN108. In addition, the CN115may provide the WTRUs102a,102b,102cwith access to the other networks112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers. In one embodiment, the WTRUs102a,102b,102cmay be connected to a local Data Network (DN)185a,185bthrough the UPF184a,184bvia the N3 interface to the UPF184a,184band an N6 interface between the UPF184a,184band the DN185a,185b.

In view ofFIGS.12A-12D, and the corresponding description ofFIG.12A-12D, one or more, or all, of the functions described herein with regard to one or more of: WTRU102a-d, Base Station114a-b, eNode-B160a-c, MME162. SGW164, PGW166, gNB180a-c, AMF182a-b, UPF184a-b, SMF183a-b, DN185a-b, and/or any other device(s) described herein, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and/or to simulate network and/or WTRU functions.

The emulation devices may be designed to implement one or more tests of other devices in a lab environment and/or in an operator network environment. For example, the one or more emulation devices may perform the one or more, or all, functions while being fully or partially implemented and/or deployed as part of a wired and/or wireless communication network in order to test other devices within the communication network. The one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented/deployed as part of a wired and/or wireless communication network. The emulation device may be directly coupled to another device for purposes of testing and/or may performing testing using over-the-air wireless communications.

The one or more emulation devices may perform the one or more, including all, functions while not being implemented/deployed as part of a wired and/or wireless communication network. For example, the emulation devices may be utilized in a testing scenario in a testing laboratory and/or a non-deployed (e.g., testing) wired and/or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and/or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and/or receive data.

The processes and techniques described herein may be implemented in a computer program, software, and/or firmware incorporated in a computer-readable medium for execution by a computer and/or processor. Examples of computer-readable media include, but are not limited to, electronic signals (transmitted over wired and/or wireless connections) and/or computer-readable storage media Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as, but not limited to, internal hard disks and removable disks, magneto-optical media, and/or optical media such as CD-ROM disks, and/or digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, terminal, base station, RNC, and/or any host computer.