Client Docket No. P45698-US1
`Attorney Docket No. 4015-9080
`
`[0020)
`
`In at least some embodiments,
`
`the method is performed for only one group. This
`
`single group in one embodiment includes all precoders in the codebook.
`
`[0021)
`
`In another embodiment. of coiurse, the single group includes only a portion of the
`
`precoders in the codebook, such that the signaling approach is adopted for only this portion,
`
`while other signaling approaches (e.g., the conventional bitmap) is adopted for other portions.
`
`[0022)
`
`In other embodiments, the meithod is performed for multiple different groups that
`
`respectively include different portions of the precoders in the codebook. In one such
`
`ernbodime11t, the signaling indicates the actual configurations for the groups in a defined order.
`
`In one embodiment, the one or more reference configurations for any given group includes the
`
`actual configuration, if any. signaled Immediately before that of the given group (according to
`
`the defifled order).
`
`[0023]
`
`Consider a s1mple example with an arbitrary codebook of size N, where the single
`
`group includes all N precoders. A certain configuration out of the zN possible codebook subset
`
`restriction configurations for the single group is deemed more probable. This configuration is
`
`represented by a single bit, '1'. The other zN -1 configurations are represented by a '0',
`
`followed by a bitmap of size N. One of th,e configurations is then represented by ·1 bit, while the
`
`other configurations are represented by N + 1 bits. Since the configuration represented by one
`
`bit is more frequently signaled, accord.ingi to the assumption, the aver.age number of bits
`
`required to convey the codebook subset restriction may be much less than N.
`
`[0024)
`
`However, if the assumption that one of the possible codebook subset restriction
`
`configurations was more likely than the others was incorrect for !he actual usage of codebook
`
`subset restriction configurations.
`
`the ave1rage number of bits required to convey a codebook
`
`subset restriction to a UE may be larger than N bits. One or more embodiments herein
`
`therefore aim to choose the representations of the 2N configurations well. Various methods may
`
`8
`
`IPR2022-00464
`Apple EX1002 Page 142
`
`

`

`Client Docket No. P45698-US1
`Attorney Docket No. 4015-9080
`
`represent the zN configurations differently depending on which sets of precoders are more likely
`
`to be restricted.
`
`[0025)
`
`Consider for example embodiments where the codebook is defined for a multi-
`
`dimensional (e.g., two-dimensional) anteinna array. Such antenna arrays may be (partly)
`
`described by the number of antenna columns corresponding to the horizontal dimension M11., the
`
`number of antenna rows corresponding to tne vertical dimension M., and the number of
`
`to different polarizations M,, The total number of antennas is thus
`dimensions corresponding
`M = M11 M,,Mp. It should be pointed out thtat the concept of an antenna is non-limiting in the
`
`sense that it can refer to any vfrtuali2:atio1n (e.g., linear mapping) of the physical antenna
`
`elements. For example, pairS of physical sub-elements could be fed the same signal, ·and hence
`
`share the same virtualized antenna port.
`
`[0026)
`
`An example of a 4x4 array wit:h cross-polarized antenna elements is illustrated in
`
`Figure 3. Specifically, Figure 3 shows a two-dimensional antenna array of cross-polarized
`
`antenna elements (Mp= 2), with Mn= 4 horizontal antenna elements and Mv; 4 vertical
`
`antenna elements, assuming one antenna element corresponds to one antenna port.
`
`[0027)
`
`Precoding may be interpreted as multiplying the signal with different beamforming
`
`weights for each antenna pdor to transmi1ssion. A typical approach is to tailor the precoder to the
`
`antenna form factor, i,e. taking into account M11., Mu and Mv when designing the precoder
`
`codebook.
`
`[0028)
`
`According to some embodirne1nts, a precoder codebook Js tailored for 20 antenna
`
`arrays by combining precoders tailored f()r a horizontal array and a vertical array respective'ly by
`
`means of a Kronecker product. This mecins that (at least part of) the precoder can be described
`
`as a function of
`
`9
`
`IPR2022-00464
`Apple EX1002 Page 143
`
`

`

`Client Docket No. P45698-US1
`Attorney Docket No. 4015-9080
`
`where WH is a horizontal precoder taken from a (sub)-codebook XH containing NH codewords
`
`and similarly Wv is a vertical precoder taken from a (sub)-codebook Xv containing Nv
`
`codewords. The joint codebook. denoted XH®Xv,
`thus contains Nlf • Nv codewords. The
`elements of XH are indexed with k = o, ... , NH - 1, the elen1ents of Xv are indexed with I=
`o, ... , Nv -1 and the elements of the joint codebook X H®X v are indexed with rn = Nv • k + l
`meaning that m = 0, ... , NH • Ny -1.
`
`(0029)
`
`In some embodiments, for example, the (sub)-codebooks of the Kronecker codebook
`
`consist of DFT-precoders. In this case, the horizontal codebook can be expressed as X~ =
`
`ovet'Sampling factor and Ll1t can take on value in the interval O to 1 so as to "shift" the beam
`
`pattern (LI,~ =0.5 could be an interesting value for creating symmetry of beams with respect to
`
`the broadsTde of an array). And the vertical codebook can be expressed as
`
`.2
`x~ = 1 e 1
`r
`
`tl-.11~
`TlMvQv
`
`'? CMu-1)1+.1,,]T
`'" e 1
`-"'
`MvQv
`
`, l = 0, ... , MvQ,, - 1, where Q.,,is an integer vertical
`
`oversampling factor and ii,, is similarly defined as above.
`
`[0030)
`
`It should be pointed out that a precoder codebook may be defined in several ways.
`
`For example, the above mentioned Kronecker codebook may be interpreted as one codebook
`
`indexed with a single PMI m. Alternatively, it may be interpreted as a single codebook indexed
`
`with two PMls k and I. It may also be interpreted as two separate codebooks, indexed with k
`
`and l respectivly. Further, the Kronecker codebook discussed above may only describe a part of
`
`the precoder, i.e. the precoder may be a function of other parameters as well. In a such
`
`example, the precoder isa function also of another PMI n. Again, this can be interpreted as
`
`three separate codebooks with indices k. land n respectively, or two separate codebooks with
`
`indices m = Nv · k +land n respectivly. It may also be interpreted as a single joint codebook
`
`10
`
`Samsung Ex. 1002
`144 of 409
`
`IPR2022-00464
`Apple EX1002 Page 144
`
`

`

`Client Docket No. P45698-US1
`Attorney Docket No. 4015-9080
`
`with a joint PMI. Embodiments herein should be considered agnostic with respect to how a
`
`codebook is defined.
`
`[0031)
`
`With this understanding, the codebook at issue in Figure 2 may be a Kronecker
`
`codebook that comprises different precoders indexed (at least in part) by different possible
`
`values of a single index parameter (e.g., index parameter m = O, ... , NH · Nv -
`
`l). In this case.
`
`the different possible values of the single index pa.rameter are divided into different clusters of
`
`consecutively ordered values. And precoders in the different groups are respectively indexed (at
`
`least in part) by the different clusters of consecutively ordered values. For example, precoders
`indexed by the cluster m = 0, ·-· ml belonig to a first group, precoders indexed by the cluster
`m = mZ. , .. m3 belong to a second group, precoders indexed by the cluster m = m4, ... mS
`
`belong to a third group, and so on. As an even more specific example, one or more
`
`embodiments exploit the Kronecker struc;ture of the precoder by mapping the inde:xl m to indices
`k and las m = N,,k + l and grouping the precoders such that m = O, .•• ~Nv-·1 is the first group,
`m=-Nv' ..... 2Nv-1 is the second group, etc.
`
`[0032]
`
`In another embodiment, by contrast, the Kronecker codebook comprises different
`
`precoders indexed (at least in part) by di1ferent pairs of possible values for a first-dimension
`index parameter (e.g., k = o, ... , NH -1) and a second-dimension
`
`index parameter (e.g ..
`
`L = 0, •. -.Nv - 1). In ibis case, precoders in each of !he different groups are indexed (at least in
`
`part) by pairs (k, l) that have tt,e same value for the fi.rst-dimenslon index parameter k and/or
`
`the second-dimension
`
`index parameter l..
`
`[0033)
`
`Two different embodiments in this regard, referred lo as a "similar rows embodiment"
`
`arid a "similar columns embodiment". will now be illustrated in the context of a Kronecker
`
`codebook and where only a single reference configuration is defined for a group. The Kronecker
`
`codebook in this example consists of precoders wlth different angular directions, spanning a
`
`two~dimensional angular area as seen from the transmitter. An important use case for codebook
`
`11
`
`IPR2022-00464
`Apple EX1002 Page 145
`
`

`

`Client Docket No. P45698-US1
`Attorney Docket No. 4015-9080
`
`subset restriction in such an embodimen1i may be to restrict precoders in a certain angular area
`
`or angle interval, e.g. corresponding to a direction where a user hotspot of an adjacent cell is
`
`located. The eNodeB would then reduce interference to said adjacent cell and particular the
`
`hotspot area if precoders corresponding to beams pointing at that direction were restdcted. This
`
`is beneficial from a system capacity pers1Pective.
`
`[0034)
`
`In the following. consider the i;pecific example where codebook subset restriction is
`
`used on a Kronecker codebook in order to understand how different embodiments can be used
`
`to reduce the signaling overhead. In this scenario, a 4x4 antenna array with a mechanical
`
`downtilt of 18° is used. The Kronecker co•debook consists of 8 vertical and 8 horizontal
`
`precoders, i.e. Nu = Nv = 8. The angular pointing directions of the precoders in the codebook
`
`are illustrated In Figure 4.
`
`[0035)
`
`Codebook subset restriction is applied to restrict beams with pointing directions in
`
`the zenith interval (85°, 95° J (illustrated with dotted lines). That is. codebook subset restriction is
`applied in the angular Interval 85° < 0 < 95". meaning that the precoders with indices (k, l) =
`
`(0,4), (3,5), (4,5), (7,4-) are restricted. These restricted beams are illustrated with an 'o' while the
`
`unrestricted beams are illustrated with an 'x'. The beam index k in the horfzontal codebook and
`
`l in the vertical codebook is written next to the beams as (k, l). If this configuration of codebook
`subset restriction would be signaled with a conventional bitmap. /V = tv11 · Ny ~ 64 bits would be
`used.
`
`"Similar rows embodiment"
`
`[0036)
`
`In one embodiment, by using compressing of the CSR signalling, a scheme is
`
`designed taking into consideration the hypothesis that precoders (le, l) with adjacent l-indices
`
`(i.e. (lc,l 0 -1),
`
`(Jc, 10) and (k, L0 + 1)) are likely to have the same restriction setting. meaning
`
`that lf (le. l0)
`
`is restricted, Ck. lo+ 1) is likely to be restricted as well and vice versa. The scheme
`
`works as follows:
`
`12
`
`IPR2022-00464
`Apple EX1002 Page 146
`
`

`

`Client Docket No. P45698-US1
`Attorney Docket No. 4015-9080
`
`[0037)
`
`First, a bitmap of NH blts are sent, indicating the codebook subset restriction for the
`
`"row" of precoders where l = O (c.f. Figure 4), Le the precoders (le, L) = (0,0), (1,0), ... , (NH -
`
`1,0).
`
`[0038)
`
`Then, the codebook subset reistriction for the second "row" of precoders, where l = 1
`is sent. If the restriction is the same as for the previous row of precoders, a '1' is sent. If the
`
`restriction for this row differs from the restriction of the previous row, a 'O' is sent, followed by a
`
`bitmap indicating the restriction for this row.
`
`[0039]
`
`The previous step is then repoated for each of the Nv "rows" of precoders.
`
`[0040)
`
`We illustrate this embodiment with an example, considering the codebook subset
`
`restriction setting illustrated in Figure 4, i .. e. the restriction of precoders with indices (k, l) =
`
`(0,4), (3,S), (4,S), (7,4) should be signaled.
`
`[0041)
`
`For l = O:
`
`No precoders with l-inde>< 0 should be restricted, therefore the bitmap '00000000' is
`
`sent.
`
`[0042)
`
`For I= 1:
`
`The restriction of this row is identiical to the restriction of the previous row. the bit '1' is
`
`For L = 2:
`
`The restriction of this row 1s identi1cal to the restriction of the previous row, the bit ·1· is
`
`Fpr l = 3:
`
`The restriction of this row -fs identl,cal to the restriction of the previous row, the bit '1' is
`
`sent.
`
`[0043)
`
`sent.
`
`[0044)
`
`sent.
`
`[0045]
`
`For l = 4:
`
`13
`
`IPR2022-00464
`Apple EX1002 Page 147
`
`

`

`Client Docket No. P45698-US1
`Attorney Docket No. 4015-9080
`
`The restriction of this row is not identical to the restriction of the previous row, therefore
`
`the bit 'O' is sent. The bitmap indicating the restriction for this row should now be sent.
`
`Precoders (0,4) and (7,4) should be rest1'.icted. Therefore, the bitmap '10000001'
`
`is sent.
`
`[0046]
`
`For l = 5:
`
`The restriction of this row is not idlentical to the re.striction of the previous row, therefore
`
`the bil 'O' is sent. The bitmap indicating the restriction for this row should now be sent.
`
`Precoders (3,5) and ('1,5) should be rest,icted. Therefore,
`
`the bitmap '00011000'
`
`is sent.
`
`[0047)
`
`For l = 6:
`
`The restriction .of this row Is not idlentica I to the restriction of the previous row, therefore
`
`the bit 'O' Is sent. The bitmap indicating the restriction for this row should now be sent. No
`
`precoder should be restricted. Therefore.
`
`the bitmap '00000000'
`
`is sent.
`
`[0048)
`
`For l = 7:
`
`The restriction of this row is identilcal to the restriction of the previous row, the bit '1' is
`
`sent.
`
`[0049]
`
`The string of bits to be signaled is thus
`
`0000000001110100000010000110000000000001
`
`', consisting of 39 bits. Generally. the number
`
`of bits required With this scheme Is
`
`[0050]
`
`transmitted,
`
`Wl1ere M is the number of times the rows change and a bitmap for a row has to be
`'M = 4 in the example. Analyzing
`This means that for some of the zN = zNwNv possible codebook subset restrictions,
`
`the above expression, we note that 1 s; M $ Nv.
`
`the number
`
`of bits required to signal the codebook subset restriction Wilh this scheme is smaller than N,
`while for others, such as when M = Nv, tlhe number of bits required is larger than N.
`
`(0051)
`
`It should be noted that 'this is .a small example for the sake of illustrating the
`
`embodiment.
`
`If a larger codebook
`
`is used, say Nu = Nv = 30, and M = 4 the number of bits
`
`14
`
`IPR2022-00464
`Apple EX1002 Page 148
`
`

`

`Client Docket No. P45698-US1
`Attorney Docket No. 4015-9080
`
`required with this scheme would be Nb,r.s = M ·NH+ Nv - 1 = 149 compared to N =NH· Nv =
`
`900 in the case of just transmitting the entire bitmap; this is hence a substantial reduction in tile
`
`number of required bits.
`
`[0052)
`
`Finally, it is pointed out that all possible codebook subset restriction configurations
`
`can be represented by this encoding/decoding scheme. thereby providing full flexibility.
`
`"Similar columns" embodiment
`
`[0053)
`
`In another embodiment,
`
`the s,cheme discussed in the previous embodiment
`
`is
`
`modified by instead taking into consideration
`
`the hypothesis that precoders (k, l) with adjacent
`
`k-indices {i.e. (k 0 - 1, 0, (lc0 , l) and (k 0 + 1, l) ) are likely to have the same restriction setting,
`meaning that if (k 0, l) is restricted, (/c0 + 1, L) is likely to be restricted as well and vice versa. The
`
`construction of the string of bits to be sig1naled would then work similarly as in the previously
`
`discussed embodiment, except that the precoders "columns" k will b~ used instead.
`
`[0054)
`
`In another embodiment an exitra initial bit is inserted where '1' indicates that
`
`encod.ing is done under the assumption
`
`that precoders (I<, l) with adjacent /-indices (i.e_
`
`l0 - 1), (le, l 0 ) and (I,, l 0 + 1) ) are likely to have the same restriction, hence the encbding is
`CJ<,
`
`done row wise. whereas a 'O' indicates thtat precoders (Tc, l) with adjacent k-indices (i.e_
`
`(k 0 - 1, /), (k 0 , l) and (/<0 + l, L) ) are likely to have the same restriction setting, hence encoding
`
`is done column wise,.
`
`[0055)
`In another embodiment an ini1tial bit is inserted where '1' indicates that no precoders
`are restricted, a ·o· indicates that some pirecoders are restricted and the ·o· is followed by a
`
`number of bits representing
`
`the codebook subset restriction.
`
`[0056)
`
`Accordingly, different "compression"
`
`techniques (whether based on similar rows,
`
`columns, or otherwise) may be adopted for different groups of precoders in the same codebook,
`
`where the particular technique ,is indicate:d to the device so that the device can decode the
`
`sighaling. Alternatively,
`
`the same "compression"
`
`technique may be adopted for each of the
`
`15
`
`IPR2022-00464
`Apple EX1002 Page 149
`
`

`

`Client Docket No. P45698-US1
`Attorney Docket No. 4015-9080
`
`groups of precoders, but the network evailuates different possible techniques to identify the one
`
`that provides the best compression and then adopts that approach (and indicates it to the
`
`device).
`
`[0057)
`
`Of course, the embodiments shown in Figure 2, and variations thereof, may be used
`
`for signaling a restricted subset of precoders in any given codebook, whether Kronecker
`
`structured or not. Moreover, the signalin~J may be rank-specific, meaning that different signaling
`
`restricts different rank-specific codebooks.
`
`[0058)
`
`According to other embodiments shown in Figure 5, a method is implemented in a
`
`network node (e.g., a base station) for si1~naling to a wireless communication device which
`
`precoders In a codebook are restricted frorn being used (e.g., which Kronecker product
`
`precoders are restricted), As shown, the method includes generating codebook subset
`
`restriction signaling that, for each of one or more groups of precoders, jointly restricts the
`
`precoders in the group, e.g., with a singlei signaling bit (Block 210). In at least some
`
`embodiments,
`
`this signaling (i) is rank-a!;1nostic so as to restrict precoders irrespective of their
`
`transmission rank; and/or (ii) jointly restrk,ts a group of precoders by restricting a certain
`
`component that those precoders have in common. Regardless, the method then includes
`
`sending the generated signaling to the wireless communication device (Block 220).
`
`[0059]
`
`Consider embodiments
`
`that jointly restrict a group of precoders by restricting a
`
`certain component that those precoders lhave in common. Precoders have a certain component
`
`in common if the precoders are derived flrom or are otherwise a function of that same
`
`component.
`
`In one embodiment,
`
`for example, a ,group of precoders W(b)
`
`that have a certain
`
`component b in common are jointly restricted by restricting that component b. Restriction of this
`
`component b may be signaled for instance in tem,s of one or more indices for the component
`
`(e.g., m where the component
`
`is indexed ·as b,,, or (k, l) where the component is indexed as b1;.,,
`
`with m, !G, and I being indices for a Kronecker-structured codebook as described above).
`
`16
`
`IPR2022-00464
`Apple EX1002 Page 150
`
`

`

`Client Docket No. P45698-US1
`Attorney Docket No. 4015-9080
`
`[0060)
`
`Note that embodiments herein contemplate a precoder having one or more different
`
`"components" at any level of granularity. For example, a precoder may comprise one or more
`
`different components b at one level of granularity. At a finer level of granularity, though, each of
`
`these components b may in turn be derived from or otherwise be a function of multiple
`
`sub-components xH and Xv such that b(xH,xv ). In this case. a group of precoders W(xH,xv)
`
`that
`
`have a certain component xH or xv in common may be jointly restricted by restricting that
`
`component xH or xv. Restriction of this component xH or xv may be Signaled for instance in
`
`terms of an index ror the component (e.g., /( or l where the component xH is indexed as xt and
`
`the component xv is indexed as xi, with xH and xv being horizontal and vertical beamforming
`
`vectors, respectively, and willl k and l bE!ing indices for a Kronecker-structured codebook as
`
`described above).
`
`[0061}
`
`In some embodiments, a precoder at one level of granularily .consists of one or more
`
`different components that are referred to as one or more so-called ''beam precoders". Each
`
`precoder Win this regard consists of one or more beamforming vectors b0 , b1 , ... , bx that are
`
`referred to as beam precoders. One or more embodiments herein jointly restrict a group of
`
`precoders W that have a certain beam pl'ecoder in common, by restricting that beam precoder.
`
`With restriction of precoders W as a wholle founded on restriction of one or more of their
`
`constituting beam precoders, these embodiments advantageously generate the CSR signaling
`
`in terms of beam-specific restrictions (i.e,., restrictions of certain beam precoders), rather than In
`
`terms of precoder-specific
`
`restrictions (i.e., restrictions on precoders Was a whole). In some
`
`embodiments,
`
`the device shall assume that a precoder W is restricted if one or more of its beam
`
`precoders are restricted. In other embodiments. each beam precoder must be restricted for the
`
`device to assume that the total precoder W is restricted.
`
`[0062)
`
`ln one embodiment, a beam precoder is the beamforming vector used to transmit on
`
`a particular layer, where different scaled versions of that beamforming vector are transmitted on
`
`17
`
`IPR2022-00464
`Apple EX1002 Page 151
`
`

`

`Client Docket No. P45698-US1
`Attorney Docket No. 4015-9080
`
`different poiarizations. Different layers ar,e transmitted on different beam precoders. A precoder
`
`W in this case can be expressed as:
`
`t>
`ob
`[
`<Pc, o
`Here, W is a N x L precoder matrix. whe1re N is the number of transmit antenna ports, L the
`
`W=et•
`
`transmission rank (i.e. the number of transmitted spatial streams), b0 , b1, •••• bL-J are~ x 1
`
`beamforming vectors (denoted beam pre coders), <po, <p1 , ... , 'Pt-l and a are arbitrary complex
`
`numbers. In some embodiments,
`the first~ antenna ports are mapped to antennas with one
`polarization whlle the latter "i' antenna ports are mapped to antennas with the same positions as
`
`the first antennas. but with an orthogonal polarizatton. In such embodiments. for each column of
`
`w (Le. the precoder for each spatial layer), a beam precoder bis transmitted on one
`
`polarization and a scaled version of the s.ame beam precoder <pb is transmitted on :a second
`
`polarization,
`
`[0063]
`
`In another embodiment. a beam precoder is the beamforming vector used to transmit
`
`on multiple different layers, where the layers are sent on orthogonal polarizations.
`
`In this case, a
`
`precoder W can be expressed as:
`
`W =a•
`
`b
`0
`[
`</,1obo
`
`Accordingly, it should be noted that the beam precoders for each spatial layer b0,b 1, .... l>L- i
`
`may be different beam precoders, or. some subsets of the beam precoders may be identical, for
`
`example b 0 may be equal to b 1 .
`
`[0064)
`
`In yet another embodiment, a beam precoder is the beamforming vector used to
`
`transmit on a particular layer and on a pc:lrticular polarlzation. That is, a beam precoder may be
`
`defined in a slightly clifferent way than the definitior.i above. The definition of a beam precoder
`
`may for example allow different beam pmcoders to be transmitted on the different polarizations
`
`of the same layer. such as
`
`18
`
`IPR2022-00464
`Apple EX1002 Page 152
`
`

`

`Client Docket No. P45698-US1
`Attorney Docket No. 4015-9080
`
`[0065]
`
`Jn still another embodiment, the beam precoders may be defined by disregarding the
`
`polarization as
`
`[0066)
`
`Note that the beam precoders b0, b1 , ... , bL-, may be chosen explicitly from a set of
`
`beam precoders (a codebook) or they may be implicitly chosen when- selecting the (total)
`
`precoder w from a codebook X. It shoulcl be noted that the selection of the (total) precoder W
`
`may be made with one or several PM ls. In the case where selection of the total precoder w is
`
`made with several PMls, the resulting beam precoders for each layer may be a functfon of only
`
`a subset of the PMls or they may be a function of all PMls.
`
`[0067)
`
`Irrespective of the particular way a beam precoder is defined, though, one or more
`
`embodiments herein jointly restrict a group of precoders W that have a certain beam precoder in
`
`common, by restricting that beam precoder. That is, in some embodiments, codebook subset
`
`restriction (CSR) may be signalled basedl on the set of possible beam precoders b, instead of
`
`CSR signalled on the set of possible (tot,~I) precoders W. In some such embodiments,
`
`the UE
`
`shall assume that a precoder w is restric,ted if one or more of the beam precoders b0 , b1 ; ... , bi._1
`
`of each layer are restricted. In other such! embodiments, each layers' beam precoder must be
`
`restricted for the UE to assume that the t,otal precoder w is restricted.
`
`[0068]
`
`Consider a specific example ior an 8TX codebook with transmission rank 2. In some
`
`embodiments,
`this codebook is defined a1s shown tn Figure 6. Defined in this way, each
`precoder Wis formed in part from a beam precoder v,,, . The beam precoder index mis the
`
`same for some precoders W, including for instance precoders whose subcodebook
`
`index i 2 is
`
`equal to 0, 1, 8, 9, 12 or 13 (since for those precoders m = 2i 1 ). This means that those
`
`precoders W have the same beam precoder Um in common. Accordingly, sbme embodiments
`
`herein jointly restrict a group of precoders w that have a particular beam precoder 11m in
`
`19
`
`IPR2022-00464
`Apple EX1002 Page 153
`
`

`

`Client Docket No. P45698-US1
`Attorney Docket No. 4015-9080
`
`common, by restricting that beam precoder ·v,n, e.g., with a single bit. Restriction of this beam
`
`precoder vm may be signaled for·instance in terms of index m. (e.g., beam precoders indexed
`
`with a particular value of m. are restrictecJ). Signaling in this case may constitute a bitmap of m.
`
`values, with different bits in the bitmap re·spectively dedicated to indicating whether or not beam
`
`precoders Indexed with different of m values are restricted from use.
`
`[0069)
`
`In alternative embodiments not shown in Figure 6, the beam precoder v 111 is replaced
`
`by beam precoder vk.l • which is a Kronecker product of a vertical beamforming vector xv with
`
`index k and a horizontal beamforming ve·ctor xH with index l. Restriction of beam precoder vk,t
`
`may be signaled ih terms of the Index palir (k. l). Signaling in this case may constitute a bitmap
`
`of (I<, l) value pairs, with different bits in the bitmap respectively dedicated to indicating whether
`
`or not beam precoders indexed with different (k, l) value pairs are restricted from use.
`
`[0070]
`
`Instead of such a bitmap, restriction of one or more beam precoders vk,I
`
`in some
`
`embodiments
`
`Is jointly signaled in terms ,of a "rectangle" defined by two (k, l) value pairs:
`
`namely, (k 0 , l 0 ) and (lc1, l 1 ). In this case, beam precoders v1,. 1 with lndides k0 < k < k 1 and
`
`10 < L < l 1 are restricted.
`
`[0071)
`
`As yet another alternative. restriction of one or more beam precoders JJk.l in some
`
`embodiments
`
`is signaled in terms of a bitmap of k value-sand/or a bitmap of l values. If signaled
`
`as only a bitmap of k values, the device (n some embodiments assumes that any beam
`
`precoders vk.l with certain le values are ri3stricted, irrespective of those precoders' l values. If
`
`signaled as only a bitmap of l values, the, device in some embodiments assumes that any beam
`
`precoders vk,t with certain l values are restricted, irrespective of those precoders' k values. If
`
`signaled as both a bitmap of le values and a bitmap of l values. the device in some
`
`embodiments assumes that only beam precoders v,<.l with certain (le, l) value pairs as
`
`collectively defined by those bitmaps are restricted.
`
`20
`
`IPR2022-00464
`Apple EX1002 Page 154
`
`

`

`Client Docket No. P45698-US1
`Attorney Docket No. 4015-9080
`
`[0072]
`
`That said, restrictions specified in term of k and/or L Values may in some sense be
`
`deemed as restrictions at a finer level of igranularity than even the beam precoders themselves,
`
`Indeed, as noted above, each beam precoder v11,1, is in some embodiments a Kronecker
`
`product of a verlical beamfomiing vector xv with index k and a horizontal beamforming vector
`
`xH with index l. Accordingly, signaling the restriction as I< and/or
`
`l values effectively amounts
`
`to restricting (sub)components xH or .xv.
`
`[0073]
`
`Consider a simple example of' these finer-granularity embodiments where codebook
`
`subset restriction is to be applied to beam precoders with l values of 3 or 4. If this configuration
`
`of codebook subset restriction would be signaled with a conventional bitmap, N =NH• Nv = 64
`
`bits would be used. By contrast, the scheme in these finer-granularity embodiments consic;ler
`
`restriction of entire precodet "rows", i.e alll precoders that are formed from beam precoders with
`
`the same L-indet< is either I\Jrned on or off. To signal the codebook subset restriction in this
`
`example, therefore, the bitmap '00011000' of l values, consisting of Nv = 8 bits, may be senL
`
`With this scheme, a. large requction of th,~ number of bits required to signal the codebook subset
`
`restriction is seen. However. not all of tho 2N possible codebook subset res1rictions may be
`
`signaled.
`
`[0074]
`
`In a similar embodiment,
`
`the restriction is applied on the precoder "columns" k and
`
`the codebook subset restriction
`
`is signaled with a NH bit long bitmap, indicating restrictions of
`
`entire precoder "columns".
`
`[0075]
`
`In another embodiment an exItra initial bit is inserted where '1' Indicates that
`
`encoding is done as above "row wise"; Whereas a '0' indicates is done "column Wise".
`
`[0076)
`
`In yet another embodiment, tlhe device shall assume that a precoder 'W ts restricted
`
`if both the vertical and the horizontal precoder in the Kronecker structure are restricted. If only
`
`one of1he vertical and horizontal precoders are restricted, then the UE shall not assume that the
`
`resulting precoder after Kronecker operation is restricted.
`
`21
`
`IPR2022-00464
`Apple EX1002 Page 155
`
`

`

`Client Docket No. P45698-US1
`Attorney Docket No. 4015-9080
`
`[0077)
`
`Thus, one or more embodiments herein advantageously exploit a codebook's
`
`Kronecker structure to generate the sign;3ling of Figure 5 1n terms of indices le, l, and/or m. In
`
`some embodiments, for example, the signaHng is generated to jointly restrict, e.g-, with a single
`
`bit, a group of precoders that either (i) ha1ve the same value of index le: (ii) have the same value
`
`of index l; or (iii) have the same pair of values for indices (k, l).
`
`[0078)
`
`In some embodiments, signalling that jointly restricts a group of ptecoders by
`
`restricting a certain component (e.g., bea1m precoder) that those precoders have in common is
`
`rank-agnostic. That is, the signafing jointly restricts the group of precoders regardless of the
`
`precoders' transmission rank (i.e., regardlless of which rank-specific codebook they belong to).
`
`For example, embodiments that restrict z1 single beam precoder h0 can be extended so that all
`
`precoders across all ranks that contain the restrlcted beam precoder h0 are restricted. Hence. all
`
`precoders across all ranks that contain a certain beam precoder h0 is a precoder group that can
`
`be restricted jointly_ According to some embodiments,
`
`therefore, an advantage of signaling CSR
`
`based on beam precoders is that one does not need to signal a separate CSR for precoders
`
`with different rank (precoders with different rank are restdcted with the same CSR). This
`
`reduces signaling overhead.
`
`[0079)
`
`Signaling that jointly restricts a group of precoders by restricting a certain component
`
`that those precoders have in common also pr.aves effective for restricting precoders that
`
`transmit jn whole or in part towards certain angular pointing directions. Indeed, according to
`
`some embodiments herein, the network node jointly restricts a group of precoders that transmit
`
`at least in part towards a certain angular pointing direction, by restricting a certain component
`
`(e.g., beam precoder) which has that an~Iular pointing direction. In this way, the network node
`
`avoids transmitting energy in a certain diirection, by signaling to the device by means of CSR
`
`that the device shall not compute feedba•ck for that particular direction,
`
`22
`
`IPR2022-00464
`Apple EX1002 Page 156
`
`

`

`Client Docket No. P45698-US1
`Attorney Docket No. 4015-9080
`
`[0080)
`
`More specifically in this regard, when each precoder W is formed from multipie beam
`
`precoders, the precoder W in some sense has multiple angular pointing directions
`
`corresponding to the angul