US008036197B2
`
`(12) United States Patent
`Pajukoski et a1.
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 8,036,197 B2
`Oct. 11, 2011
`
`(54) SIGNALLING
`
`OTHER PUBLICATIONS
`
`(75) Inventors: Kari Pajukoski, Oulu (FI); Esa Tiirola,
`Kempele (F1)
`
`(73)
`
`Assignee: Nokia Corporation, Espoo (FI)
`
`(*)
`
`Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 885 days.
`
`(21)
`
`(22)
`
`(65)
`
`(30)
`
`Appl. N0.: 11/726,877
`
`Filed:
`
`Mar. 23, 2007
`
`Prior Publication Data
`
`US 2008/0080467 A1
`
`Apr. 3, 2008
`
`Foreign Application Priority Data
`
`Oct.3, 2006 (GB) ................................. .. 06195309
`
`Int. Cl.
`(2006.01)
`H04B 7/216
`US. Cl. ...................................... .. 370/342; 370/344
`
`Field of Classi?cation Search ................ .. 370/344,
`370/342, 343, 335
`See application ?le for complete search history.
`
`(51)
`
`(52)
`(58)
`
`(56)
`
`TSG-RAN WGl; R1-080510; “Multiplexing of ACK/NACK and
`Scheduling Request on PUCCH”, Ericsson; Sevilla, Spain; Jan.
`14-28, 2008.
`3GPP TSG RAN WGl #42 on LTE; R1-050851; “Orthogonal Pilot
`Channel in the Same Node B in Evolved UTRA Uplink”, NTT
`DoCoMo, NEC, Sharp; London, UK; Aug. 29-Sep. 2, 2005.
`Xiaoming Peng et al.; “A Simpli?ed Transceiver Structure for Cyclic
`Extended CDMA System with Frequency Domain Equalization”,
`IEEE; Sep. 2005.
`Guangliang Ren et al.; “Synchronization Method Based on a New
`Constant Envelop Preamble for OFDM Systems”, IEEE Transactions
`on Broadcasting, vol. 51, No. 1, Mar. 2005; pp. 139-143.
`Liru Le et a1; “Extended Orthogonal Polyphase Codes for Multicar
`rier CDMA System”, IEEE Communications Letters, vol. 8, No. 12,
`Dec. 2004; pp. 700-702.
`3GPP TR 25.814, V7.0.0 (Jun. 2006), 3rd Generation Partnership
`Project; Technical Speci?cation Group Radio Access Network;
`Physical layer aspects for evolved Universal Terrestrial Radio Access
`(UTRA) (Release 7), pp. 67-78.
`TSG-RAN WGl LTE AdHoc, R1-061862, Ericsson, “Uplink Non
`data-associated Control Signalling”, Cannes, France, Jun. 27-30,
`2006, 3 pgs.
`3GPP TSG RAN1 #46, R1-062065, Motorola, “L 1/L2 Uplink Con
`trol Mapping & Numerology”, Tallinn, Estonia, Aug. 28-Sep. 1,
`2006, 5 pgs.
`
`(Continued)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`Primary Examiner * Lester Kincaid
`Assistant Examiner * Isaak Jama
`(74) Attorney, Agent, or Firm * Harrington & Smith
`
`2006/0274842 A1 12/2006 Pan et al. .................... .. 375/260
`2006/0291431 Al * 12/2006 Pajukoski et al.
`370/335
`2007/0004465 Al *
`1/2007 Papasakellariou et a1.
`455/571
`2007/0171995 A1* 7/2007 Muharemovic et al. .... .. 375/260
`2007/0195906 A1* 8/2007 Kim et al. ................... .. 375/267
`2008/0049708 A1* 2/2008 Khan et al.
`. 370/343
`2008/0123616 A1* 5/2008 Lee ............................. .. 370/344
`
`FOREIGN PATENT DOCUMENTS
`WO WO-2007/084840 A2
`7/2007
`WO WO-2007/149290 A2 12/2007
`WO WO-2008/035955 A2
`3/2008
`
`(57)
`
`ABSTRACT
`
`A network element may provide a plurality of user equip
`ments with a dedicated pilot sequence for uplink reference
`signal transmission. A user equipment may, after receipt of a
`dedicated pilot sequence, spread the pilot sequences using a
`block spreading method.
`
`18 Claims, 3 Drawing Sheets
`
`ALLOCATE TO EACH OF A PLURALITY OF H
`UEs IN A CURRENT CELL A UNIQUE
`SPREADING CODE Wn
`
`/ :02
`
`I
`
`DETERMINE WHICH OF THE UNIQUE
`SPREADING CODES ARE SIMULTANEOUSLY
`ALLOCATED TO A LIE OF AN ADJACENT CELL
`
`/ 304
`
`I
`
`DETERMINE A CAZAC MATRIX E'Y WHICH
`INDMDUAL UEs WILL MULTIPLY T0
`GENEIATE A PILOT SEQUENCE
`
`/ 306
`
`I
`
`FOR EACH OF THE SIMULTANEOUSLY-ALLOCATED
`SPREADING CODES, SHIFT TNE CAZAC MATRIX
`DIFFERENTLY THAN WAS SHIFI'ED FOR THE UE
`OF THE ADJACENT CELL ALLOCATED THE SAME
`SPREADING DUDE
`
`I
`
`fsoa
`
`FOR EACH OF THE REMAINING SFREADING CODES,
`SHIFT THE CAZAC CODE IN A MANER UNIQUE
`TO EACH UE IN THE CURRENT CELL
`
`K310
`
`I
`
`PROVIDE TO EACH or THE F'LURALI‘I'Y OF n
`us: In THE CURRENT CELL A umnu: PILOT
`SEQUENCE GENERATED FROM MULTIPLYING on:
`smnm CAZAC con: WITH THE SPREADING
`cons ALLOCATED THAT n'" u:
`
`/312
`
`BlackBerry Exhibit 1004, pg. 1
`
`

`

`US 8,036,197 B2
`Page 2
`
`OTHER PUBLICATIONS
`
`3GPP TSG RAN WGl LTE Ad Hoc, Rl-06l674, NTT DoCoMo,
`Fujitsu, NEC, Sharp, Toshiba Corp., “Single-Carrier Based Multi
`plexing of Uplink Ll/L2 Control Channel”, Cannes, France, Jun.
`27-30, 2006, 9 pgs.
`3GPP TSG RAN WGl LTD Ad Hoc, Rl-06l675, NTT DoCoMo,
`Sharp, Toshiba Corp., “Data-non-associated L l/L2 Control Channel
`Structure for E-UTRA Uplink”, Cannes, France, Jun. 27-30, 2006, 6
`
`3GPP RANl LTE Ad Hoc, R1 -06l699, “Uplink ACK/NACK signal
`ing: FDM vs. TDM”, Cannes, France, Jun. 27-30, 2006, 9 pgs.
`3GPP TSG RAN WGl LTE Ad Hoc, Rl-06l779, “Multiplexing of
`Control Signalling in E-UTRA Uplink”, Cannes, France, Jun. 27-30,
`2006, 5 pgs.
`3GPP TSG RANl LTE Ad Hoc, Rl-06l802, “Multiplexing and Link
`Analysis of CQI Channel in UL”, Cannes, France, Jun. 27-30, 2006,
`6 pgs.
`Chang, Y et al., “Synchronization Method Based on a New Constant
`Envelop Preamble for OFDM Systems”, IEEE Transactions on
`Broadcasting, IEEE Service Center, PiscataWay, NJ, US, vol. 51, No.
`1, Mar. 2005, sections III and IV.
`
`Dubey, V K et al., “Extended Orthogonal Polyphase Codes for
`Multicarrier CDMA System”, IEEE Communications Letters, IEEE
`Service Center, PiscataWay, NJ, US, vol. 8, No. 12, Dec. 2004, pp.
`700-702, sections I, II, and V.
`“On Allocation of Uplink Pilot Sub-Channels in EURA SC-FDMA”,
`3GPP TSG RAN WGl Ad Hoc on LTE, R1 -050822, Aug-Sep. 2005,
`7 pgs.
`“Cubic Metric properties of CAZAC sequences”, 3GPP TSG RAN
`WG1#45, Rl-06l284, May 2006, 4 pgs.
`“Coherent vs. non-coherent ACK/NAK signaling in E-UTRA
`uplink”, 3GPP TSG RAN WG! Meeting #48, R1 -070749, Feb. 2007,
`7 pgs.
`3GPP TR 25,814, V.7.0.0 (Jun. 2006), 3rd Generation Partnership
`Project; Technical Speci?cation Group Radio Access Network;
`Physical layer aspects for evolved Universal Terrestrial Radio Access
`(UTRA) (Release 7), pp. 67-78.
`“Rl -060925: Comparison of Proposed Uplink Pilot Structures for
`SC-OFDMA”, 3GPP TSG RAN WGl#44bis, Mar. 2006, 15 pgs.
`
`* cited by examiner
`
`BlackBerry Exhibit 1004, pg. 2
`
`

`

`1102191f“c0
`
`Sheet 1 0f 3
`
`US. Patent
`
`US 8,036,197 B2
`
`\
`
`T’l‘loomEmdumzéulmnm—ll;
`EHgmEEEEEEEEE{aBEE
`
`BlackBerry Exhibit 1004, pg. 3
`
`

`

`US. Patent
`
`0a. 11, 2011
`
`Sheet 2 of3
`
`US 8,036,197 B2
`
`ALLOCATE TO EACH OF A PLURALITY OF n f 302
`UEs IN A CURRENT CELL A UNIQUE
`SPREADING CODE Wn
`
`II
`
`DETERMINE WHICH OF THE UNIQUE
`SPREADING CODES ARE SIMULTANEOUSLY
`ALLOCATED TO A UE OF AN ADJACENT CELL
`
`/ 304.
`
`I
`
`DETERMINE A CAZAC MATRIX BY WHICH
`INDIVIDUAL UEs WILL MULTIPLY TO
`GENERATE A PILOT SEQUENCE
`
`/ 306
`
`308
`FOR EACH OF THE SIMULTANEOUSLY-ALLOCATED
`SPREADING CODES, SHIFT THE CAZAC MATRIX /
`DIFFERENTLY THAN WAS SHIFI'ED FOR THE UE
`OF THE ADJACENT CELL ALLOCATED THE SAME
`SPREADING CODE
`
`I
`
`FOR EACH OF THE REMAINING SPREADING CODES, /- 31o
`SHIFT THE CAZAC CODE IN A MANER UNIQUE
`TO EACH UE IN THE CURRENT CELL
`
`PROVIDE To EACH OF THE PLURALITY OF ,7
`UEs IN THE CURRENT CELL A UNIQUE PILOT
`SEQUENCE GENERATED FROM MULTIPLYING oNE / 312
`SHIFTED CAZAC CODE wITH THE SPREADING
`CODE ALLOCATED THAT nth UE
`
`FIG.3
`
`BlackBerry Exhibit 1004, pg. 4
`
`

`

`Oct. 11, 2011
`
`Sheet 3 0f 3
`
`US 8,036,197 B2
`
`ox<z<o<z
`
`I?ozEfiEm
`
`US. Patent
`
`Eaglmnm5mm“.F
`
`
`
`
`
`{9.ENE”.smEm
`
`BlackBerry Exhibit 1004, pg. 5
`
`

`

`US 8,036,197 B2
`
`1
`SIGNALLING
`
`CROSS REFERENCE TO RELATED
`APPLICATION
`
`This application claims priority to UK Patent Application
`Serial No., GB 06195309, ?led Oct. 3, 2006. That priority
`application is hereby incorporated by reference.
`
`FIELD OF THE INVENTION
`
`The invention relates to signalling in a communication
`system, and in particular, but not exclusively, to uplink refer
`ence signal sequences.
`
`BACKGROUND
`
`2
`The user equipment (UE) within one of the cells of the
`cellular system can be controlled by a node providing con
`troller function. Examples of the controller nodes include a
`base station controller (BSC) and a radio network controller
`(RNC). The controller can be connected further to a gateway
`or linking node, for example a gateway GPRS support node
`(GGSN) or gateway mobile switching center (GMSC), link
`ing the controller nodes to other parts of the communication
`system and/or to other communication networks, such as to a
`PSTN (Public Switched Telecommunications Network) or to
`a data network, such as to a X. 25 based network or to a
`TCP/IP (Transmission Control Protocol/Internet Protocol)
`based network. The network may also include nodes for stor
`ing information of mobile stations subscribing the networks
`or visiting the networks, such as appropriate home location
`registers (HLR), visitor location registers (VLR) and home
`subscriber servers (HSS).
`A proposal for the developed communication systems
`comprises a third generation partnership project (3GPP) long
`term evolution (LTE) packet-switched only access scheme. In
`a proposed 3GPP long term evolution (LTE) access scheme, a
`?at architecture is provided by an evolved Node B (eNB) and
`an access Gateway (aGW) that are involved in controller
`functions. 3GPP is also performing a feasibility study asso
`ciated with streamlining the 3GPP packet switched network
`architecture to be used for the access.
`In the uplink (UL) part of a such communications system,
`reference signal sequences are transmitted between a user
`equipment (U E) and a network element or node. However, a
`problem still to be adequately addressed is how to enable
`reference signal transmission with suf?cient orthogonality
`between the reference signals of multiple user equipments in
`a certain cell or in multiple cells. In particular, there is a need
`to improve the pilot signal’s resistivity against intra- or inter
`cell interference.
`
`BRIEF SUMMARY
`
`Embodiments of the invention aim to address one or more
`of the above problems. In particular, embodiments of the
`invention aim to provide enhanced orthogonality between the
`reference signals of multiple user equipments.
`According to one embodiment, a plurality of user equip
`ments is provided with a dedicated pilot sequence for uplink
`reference signal transmission.
`A user equipment may, after receipt of a dedicated pilot
`sequence, spread the pilot sequences using a block spreading
`method.
`According to another embodiment, an apparatus at a net
`work includes a pilot sequence generator for generating a
`dedicatedpilot sequence for uplink reference signal transmis
`sion for each of a plurality of user equipments. A sequence
`spreader in a user equipment may then spread the pilot
`sequences using a block spreading method.
`According to another embodiment, an apparatus includes a
`pilot sequence generating means for generating a dedicated
`pilot sequence for uplink reference signal transmission for
`each of a plurality of user equipments. A user equipment may
`comprise a sequence spreading means for spreading the pilot
`sequences using a block spreading method.
`According to another embodiment, a communication sys
`tem includes a network element and a plurality of user equip
`ments, wherein the network element is con?gured to perform
`a channel estimation operation based on time averaging,
`wherein an averaging length of a channel estimation ?lter is
`siZed according to length of block-level code.
`
`20
`
`25
`
`30
`
`35
`
`Communication networks typically operate in accordance
`with a given standard or speci?cation which sets out what the
`various elements of the network are permitted to do and how
`that shouldbe achieved. For example, the standard may de?ne
`whether the user or more precisely, user equipment is pro
`vided with a circuit switched service or a packet switched
`service. The standard may also de?ne the communication
`protocols which shall be used for the connection. The given
`standard also de?nes one or more of the required connection
`parameters. The connection parameters may relate to various
`features of the connection. The parameters may de?ne fea
`tures such as the maximum number of traf?c channels, qual
`ity of service and so on. Features that relate to multi-slot
`transmission may also be de?ned.
`In other words, the standard de?nes the “rules” and param
`eters on which the communication within the communication
`system can be based. Examples of the different standards
`and/ or speci?cations include, without limiting to these, speci
`?cations such as GSM (Global System for Mobile commu
`nications) or various GSM based systems (such as GPRS:
`General Packet Radio Service), AMPS (American Mobile
`Phone System), DAMPS (Digital AMPS), WCDMA (Wide
`band Code Division Multiple Access) or CDMA in UMTS
`40
`(Code Division Multiple Access in Universal Mobile Tele
`communications System) and so on.
`The user equipment i.e. a terminal that is to be used for
`communication over a particular communication network has
`to be implemented in accordance with the prede?ned “rules”
`of the network. A terminal may also be arranged to be com
`patible with more than one standard or speci?cation, i.e. the
`terminal may communicate in accordance with several dif
`ferent types of communication services. These user equip
`ment are often called multi-mode terminals, the basic
`example thereof being a dual-mode mobile station.
`A communication network is a cellular radio network con
`sisting of cells. In most cases the cell can be de?ned as a
`certain area covered by one or several base transceiver sta
`tions (BTS) serving user equipment (UE), such as mobile
`stations (MS), via a radio interface and possibly connected to
`a base station subsystem (BSS). Several cells cover a larger
`area, and form typically a radio coverage area referred to as a
`location area (LA) or in some standards as a routing area
`(RA). It shouldbe appreciated that the siZe of the location area
`or routing area depends on the system and circumstances, and
`may equal to one cell or be even smaller, such a part of a
`coverage area of a base station. A feature of the cellular
`system is that it provides mobility for the mobile stations, i.e.
`the mobile stations are enabled to move from a location area
`to another, and even from a network to another network that is
`compatible with the standard the mobile station is adapted to.
`
`45
`
`50
`
`55
`
`60
`
`65
`
`BlackBerry Exhibit 1004, pg. 6
`
`

`

`US 8,036,197 B2
`
`3
`According to another embodiment, a communication sys
`tem includes a network element and a plurality of user equip
`ments Wherein the netWork element is con?gured to perform
`a despreading operation combined With a channel estimation
`operation.
`According to another embodiment, a computer program
`product includes a set of instructions Which When executed by
`a processor in a netWork element of a communications sys
`tem, causes the netWork element to provide each of a plurality
`of user equipments With a dedicated pilot sequence for uplink
`reference signal transmission.
`According to yet another embodiment, a computer pro
`gram product includes a set of instructions Which When
`executed by a processor in a communication device, causes
`the communication device to spread pilot sequences using a
`block spreading method based on a dedicated pilot sequence
`for uplink reference signal transmission as received from a
`netWork element.
`In one embodiment, the pilot sequences are spread using
`orthogonal codes, for example Hadamard codes. Each dedi
`cated pilot sequence may comprise a Constant Amplitude
`Zero AutoCorrelation (CAZAC) sequence, and each CAZAC
`sequence may have a dedicated frequency pin allocation and/
`or a de?ned cyclic shift of a single CAZAC code. In another
`embodiment, the dedicated pilot sequences may comprise
`multiple CAZAC codes.
`In another embodiment, an uplink transmission interval in
`the method consists of tWo sub-frames. The method may be
`performed in a Universal Mobile Telecommunications Sys
`tem Terrestrial Radio Access Network long term evolution
`(UTRAN LTE) netWork.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The foregoing and other aspects of these teachings are
`made more evident in the folloWing Detailed Description,
`When read in conjunction With the attached DraWing Figures,
`Wherein:
`FIG. 1 illustrates format of a subframe for uplink in accor
`dance With 3GPP LTE Which may use embodiments to advan
`tage.
`FIG. 2 is a schematic block diagram of user equipments
`and various netWork elements that employ aspects of the
`invention.
`FIG. 3 is a process How diagram shoWing steps according
`to an aspect of the invention.
`FIG. 4 shoWs a physical resource block of tWo sub-frames
`in further detail.
`
`DETAILED DESCRIPTION
`
`The invention Will noW be further described by Way of
`example only, With reference to the folloWing speci?c
`embodiments.
`In the 3GPP long term evolution (LTE) system, intra-cell
`interference related to the pilot signals exists When reference
`signals from multiple user equipments (U Es) share the same
`frequency and time resource. This may happen, for example,
`With channel dependent scheduling and virtual MIMO (mul
`tiple input multiple output). Also the smallest bit rates like
`data-non-associated control, including the reference signals,
`are multiplexed into the same frequency and time resource.
`With respect to the inter-cell interference of reference sig
`nals, in order to minimiZe the cross-correlation properties of
`the Constant Amplitude Zero AutoCorrelation (CAZAC)
`codes, different CAZAC sequences should be used in differ
`ent cells. The number of CAZAC sequences is basically
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
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`65
`
`4
`decided by the length of the sequence. The number of
`CAZAC sequences is the number of integers relatively prime
`to the sequence length. Assuming that the uplink resource
`allocation consists of only one physical resource block
`(PRB), the length of a short block (SB) in an uplink sub-frame
`is only 6 symbols. This means that the number of CAZAC
`sequences With SB of one PRB is equal to only four. As
`mentioned, in order to minimiZe the cross-correlation prop
`erties of the CAZAC codes, different CAZAC sequences
`should be used in different cells. HoWever, When the number
`of CAZAC sequences is small, the re-use planning of the
`sequences becomes very dif?cult. This also indicates that
`there is a need for improving the orthogonality betWeen dif
`ferent cells.
`FIG. 1 shoWs one sub-frame 110 in a format for 3GPP LTE
`UL. There are tWo blocks reserved for pilot signal in the
`current frame format (3GPP LTE UL) as can be seen in FIG.
`1. The blocks reserved for the pilot signal are designated as
`SB1 101 and SB2 102. Other blocks of the subframe 110
`include long blocks LBs and cyclic pre?xes CPs.
`In 3GPP LTE, the uplink TTI (Transmission Interval) con
`sists of tWo consecutive sub-frames 110. Thus, the pilot
`resource actually consists of four short blocks (SBs). The
`CAZAC sequence has been agreed to be a pilot sequence for
`3GPP LTE UL. CAZAC sequences can be de?ned by the
`equation:
`
`Where k is the sample index and NG is length of CAZAC
`sequence.
`Both the code division multiplexing (CDM) and frequency
`division multiplexing (FDM) types of pilot structure have
`been proposed as multiplexing schemes for pilot signals allo
`cated to the same time and frequency resource. A combina
`tion of FDM and CDM has also been proposed for standard
`iZing reference signals. For example, pilot signals having
`equal bandWidth could be separated using CDM While the
`different bandWidth pilots are separated using distributed
`FDM.
`The CDM type of multiplexing based on usage of cyclic
`shift provides almost complete orthogonality betWeen differ
`ent cyclic shifts if the length of cyclic shift is larger than delay
`spread of the radio channel. For example With an assumption
`of 5 us delay spread in the radio channel, 6 orthogonal cyclic
`shifts inside one short block (SB) can be achieved.
`In frequency selective (delay dispersive) channels the
`cross-correlation properties of CAZAC sequences are not
`exactly Zero, thus in practice the codes often interfere With
`each other. The orthogonality properties depend on the num
`ber of cyclic shifts. Together With poWer differences the
`cross-correlation of CAZAC sequences could result in sev
`eral near/far problems in LTE uplink.
`In certain embodiments the pilot sequence can be opti
`miZed in terms of intra- and inter-cell orthogonality appli
`cable for extended TTI length, e.g. tWo sub-frames. Accord
`ing to one embodiment, the pilot sequences are generated as
`a combination of existing CAZAC codes and Hadamard
`codes (i.e., block-Wise spreading). Each user device may have
`a dedicatedpilot sequence (CAZAC) corresponding to a dedi
`cated frequency pin allocation (FDM multiplexing) and/or a
`certain cyclic shift of a CAZAC code (CDM multiplexing).
`Hadamard codes are used to perform the orthogonal spread
`ing for the existing pilot signals. This is done in order to
`
`BlackBerry Exhibit 1004, pg. 7
`
`

`

`US 8,036,197 B2
`
`5
`improve the orthogonality (i.e., cross correlation properties)
`of pilot signals between user devices allocated to the same
`bandwidth. As a result of this arrangement, “double protec
`tion” against the intra/inter-cell interference of the pilot sig
`nals can be provided.
`In non-synchronized networks the pilot signals are typi
`cally designed to be orthogonal within the cell. According to
`embodiments of the invention, the orthogonality properties
`between the pilot signals may be improved without any deg
`radation on the properties of the pilot signal.
`In synchroniZed networks, embodiments of the invention
`may provide an additional degree of freedom to provide inter
`cell orthogonality between different cells. The improved
`inter-cell orthogonality may also be useful in non-synchro
`niZed networks.
`The following example shows one embodiment of the
`invention using cyclic-shifted CAZAC codes (CDM
`approach). This embodiment employs two well known matri
`ces C and W:
`
`6
`The orthogonal matrix W can be generated, for example,
`by using well known Walsh-Hadamard codes or cyclic GCL
`(generalized chirp-like) sequences.
`Embodiments of the invention may improve the channel
`estimation since the majority of the inter cell interference of
`pilot signal is cancelled out using the proposed scheme. The
`gain depends on the averaging length of the channel estima
`tion ?lter. Typically, at the receiver site, the channel estimate
`is averaged over several pilot blocks for improving perfor
`mance against noise. In one embodiment the averaging length
`of channel estimation ?lter is siZed according to length of
`block-level code. In practice suitable averaging length for the
`channel estimation ?lter equals to N><length of the block-level
`code, where, NIP/2, 1, 2, 3 .
`.
`. ].
`The best gain obtained could be in the region of 0-50 km/h.
`The orthogonality properties between the pilot signals may be
`improved without any degradation on the properties of the
`pilot signal.
`
`1-1 —1
`
`—1—11
`
`1.0000 — 0.0000i
`
`0.8660 — 0.5000i
`
`—0.5000—0.8660i
`
`—0.0000 +1.0000i
`
`—0.5000—0.8660i 0.8660-0.5000i
`
`0.8660 — 0.5000i
`
`1.0000 — 0.0000i
`
`0.8660 — 0.5000i
`
`—0.5000 — 0.8660i
`
`—0.0000 +1.0000i —0.5000 — 0.8660i
`
`—0.5000 — 0.8660i 0.8660 — 0.5000i
`
`1.0000 — 0.0000i
`
`0.8660 — 0.5000i
`
`—0.5000 — 0.8660i —0.0000 +1.0000i
`
`—0.0000 +1.0000i —0.5000 — 0.8660i 0.8660 — 0.5000i
`
`1.0000 — 0.0000i
`
`0.8660 — 0.5000i —0.5000 — 0.8660i
`
`—0.5000 — 0.8660i —0.0000 +1.0000i
`
`—0.5000 — 0.8660i 0.8660 — 0.5000i
`
`1.0000 — 0.0000i
`
`0.8660 — 0.5000i
`
`0.8660 — 0.5000i —0.5000 — 0.8660i
`
`—0.0000 +1.0000i
`
`—0.5000 — 0.8660i 0.8660 — 0.5000i
`
`1.0000 — 0.0000i
`
`35
`
`In the above W is the 4x4 Hadamard matrix and C is the
`matrix including the cyclic shifts of one CAZAC code. Each
`row of the table above represents a cyclic shift of the CAZAC
`code as compared to the previous row. The siZe of the Had
`amard matrix is equal to the number of short blocks (SBs) in
`TTI whereas the siZe of matrix C is equal to the number of
`pilot carriers in minimum physical resource block (6 in 180
`kHZ PRB). In a typical case the number of cyclic shifted
`CAZAC codes is larger than the number of Walsh codes.
`Pilot sequences, e.g., for the nth user device, are spread by
`multiplying the cyclic shifted CAZAC code by the orthogonal
`matrix W.:
`
`40
`
`45
`
`a
`ZMICWW...
`where n is user device index and m is Walsh code index [1, 2,
`3, 4]. This can be done because the number of Walsh codes in
`matrix W equals the number of SBs in TTI. This is structured
`in such way that the different Walsh codes are used at least for
`adjacent cyclic shifted codes. Mathematically speaking this
`can be realiZed as:
`
`50
`
`55
`
`60
`
`65
`
`where the superscript refers to a user device.
`
`FIG. 2 is a schematic diagram showing one user device,
`referred to below as user equipment (UE) 210 in communi
`cation over a wireless link 202 with a network, where the
`network includes an evolved Node B e-NB 220 and an access
`gateway aGW 230. The e-NB 220 may be for example a base
`transceiver station, and the aGW 230 is a higher network
`entity that controls multiple e-NBs, as a radio network con
`troller controls multiple Node Bs in certain wireless net
`works. Allocation of the pilot sequences among multiple UEs
`is determined in the network, by either orboth of the eNB 220
`and the aGW 230. It is noted that the e-NB 220 allocates
`resources to multiple UEs 210 within its cell though only one
`UE 210 is shown, and intra-cell interference can be managed/
`mitigated according to aspects of this invention by coordinat
`ing among e-NBs 220 of adjacent cells, by an aGW 230 that
`controls those adjacent-cell e-NBs 220, or by some combi
`nation of those approaches.
`Referring to the user devices above represented as Z1,
`Z2, .
`.
`. Z6, assume that Z1 through Z3 are in a ?rst cell and Z4
`through Z6 are in a second cell adjacent to the ?rst cell. Note
`that the same spreading code W1 is allocated to each of Z1 and
`Z4. Their pilot sequences do not interfere despite being in
`adjacent cells because the associated CAZAC sequences Cl
`and C4 are shifted differently. The same applies to Z3 and Z6.
`Analogously, if two user equipments in adjacent cells used
`the same shifted CAZAC sequence, their uplink signals
`would not interfere because those user equipments would be
`allocated different spreading codes.
`The user equipment 210 includes a digital processor 212
`for executing computer program instructions 214 (software)
`that are stored in a local memory 216. Wireless communica
`
`BlackBerry Exhibit 1004, pg. 8
`
`

`

`US 8,036,197 B2
`
`7
`tion from the link 202 is received at and transmitted from one
`or more antennas 218 coupled to a transceiver 219, which
`includes a transmitter, a receiver, and a switch or diplex ?lter
`or similar switching means between the two. The user equip
`ment receives its dedicated pilot sequences from the network,
`generated as above. The user equipment 220 then inserts
`those dedicated pilot signals into the short blocks of sub
`frames for an uplink transmission to the network, as detailed
`above and shown in FIG. 1.
`The e-NB 22 also includes a digital processor 222 for
`executing computer program instructions 224 (software) that
`are stored in a local memory 226. Wireless communication
`from the link 202 is received at and transmitted from one or
`more antennas 228 coupled to a transceiver 229, which
`includes a transmitter, a receiver, and a switch or diplex ?lter
`or similar switching means between the two. The e-NB 220
`allocates to each of a plurality of user equipments 210 a
`spreading code, unique among all allocated spreading codes
`in the cell. For each user equipment 210, the network allo
`cates a unique combination of spreading sequence and
`CAZAC code (preferably the CAZAC codes differ only in a
`cyclic shift) so that each UE’s dedicated pilot sequence does
`not interfere with that of any other user equipment in the same
`or an adjacent cell. On the uplink, the e-NB 220 receives a
`message with the dedicated pilot sequence from a particular
`user equipment 210, and determines characteristics of the
`channel/ link 202 from that received dedicated pilot sequence.
`The e-NB 220 knows the dedicated pilot sequence in advance
`because it allocated the spreading code and shifted CAZAC
`code to the user equipments 210 in its cell, so comparing to
`the received dedicated pilot sequences gives an indication of
`channel quality (CQI) to the e-NB 220. The e-NB 220 can
`also adjust the length of its ?lter used in estimating the chan
`nel based on the length of the block level code.
`The aGW 230 includes similar components as the e-NB
`220, but is typically not in wireless communication so its link
`204 to the e-NB 220 is hardwired, such as a lub or lur link. The
`aGW 230 includes a digital processor 232 for executing com
`puter program instructions 234 (software) that are stored in a
`local memory 236. Generally, the aGW 230 allocates spread
`ing codes as a block resource to the eNBs 220, and the e-NBs
`220 allocate individual spreading codes to individual user
`equipments 210 in their cell. To ensure a unique combination
`of spreading code and shifted CAZAC code to each user
`equipment 210 in any pair of adjacent cells (e.g., different
`e-NBs 220), some coordination between the involved e-NBs
`220 may occur. That coordination may be through the aGW
`230 or the aGW 230 may direct an allocation of shifted
`CAZAC code with a particular spreading code for a particular
`cell/e-NB 220 to ensure uniqueness over a dedicated pilot
`signal allocated to another user equipment 210 in an adjacent
`cell.
`FIG. 3 shows process steps according to an embodiment.
`At block 302, the e-NB 220 allocates to each of a plurality of
`n user equipments a unique spreading code. Whereas each
`e-NB 220 is responsible for resource allocation within its cell,
`note that user equipments 210 in adjacent cells may be allo
`cated the same spreading code by their respective e-NBs 220.
`To resolve/prevent any inter-cell interference, it is determined
`at block 304 if any user equipments in an adjacent cell are
`simultaneously allocated a same spreading code as was allo
`cated to a user equipment 210 in the current cell at block 302.
`At block 306, it is determined a CAZAC matrix by which
`individual user equipment, to which a spreading code was
`allocated at block 302, will use to generate their dedicated
`pilot sequence. In an embodiment, all the CAZAC matrices
`are distinguished from one another by cyclic shifting. At
`
`50
`
`55
`
`60
`
`65
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`8
`block 308, for each of the spreading codes determined at
`block 304 to be simultaneously allocated in an adjacent cell,
`a CAZAC matrix for that user equipment in the present cell is
`shifted/determined so as to ensure that it is not identical to a
`CAZAC code associated with the user equipment in the adja
`cent cell using the same spreading code. At block 310, for all
`other CAZAC codes allocated in the current cell, a CAZAC
`code is determined so that no two user equipments are asso
`ciated with the same spreading code and CAZAC code. As
`seen at block 310, it is advantageous to ensure that all user
`equipments in the current cell are assigned a uniquely shifted
`CAZAC code. At block 312, then to each of the n user equip
`ments in the current cell is provided a unique pilot sequence,
`each unique pilot sequence being the product of the spreading
`code allocated to the user equipment and the shifted CAZAC
`code allocated to that same user equipment.
`The end result is that no two user equipments, in any pair of
`adjacent cells, simultaneously are assigned the same spread
`ing code and the same shifted CAZAC code. It can be seen
`that the decisional processes to arrive at that result are readily
`implemented in software and executed by the processors
`described, or in hardware such as an integrated circuit (e.g.,
`an application speci?c integrated chip (ASIC)).
`FIG. 4 shows a speci?c example of one TTI having a
`duration of 1.0 ms made from two of the sub-frames shown in
`FIG. 1. In this non-limiting example some type of spreading
`scheme is employed, such as but not limited to Hadamard
`spreading, and is applied for the four middle LBs and the two
`SBs of the LTE uplink sub-frame. The spreading factor is
`equal to four in this non-limiting example.
`It should be noted, however, that this particular arrange
`ment is just one non-limiting example and that in other exem
`plary embodiments the spreading can be applied for more or
`less than four LBs/two SBs. It should be further