HK1134972B - Apparatus and methods for signaling transmission with localized spreading for wireless communication - Google Patents

Description

Apparatus and method for signaling with localized spreading for wireless communication

This application claims priority from provisional U.S. application S/n.60/843,366 entitled "ACK Spreading Design," filed on 8.9.2006, assigned to the present applicant and incorporated herein by reference.

Background

I. Field of the invention

The present disclosure relates generally to communication, and more specifically to techniques for transmitting signaling in a wireless communication system.

II. background

Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, and so on. These systems may be multiple-access systems capable of supporting communication for multiple users by sharing the available system resources. Examples of such multiple-access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, orthogonal FDMA (ofdma) systems, and single carrier FDMA (SC-FDMA) systems.

A wireless communication system may include any number of base stations that may support communication for any number of terminals. Each base station may transmit data and signaling to the terminals served by the base station. Each terminal may also transmit data and signaling to its serving base station. It may be desirable for a transmitter to transmit signaling in a manner that enables the signaling to be reliably received by an intended receiver. This may be achieved by encoding and/or repeating the signaling and transmitting the encoded and/or repeated signaling on the radio resources allocated to the signaling. Signaling in this manner may improve detection performance. However, there may be specific examples of such: where the radio resources allocated to the signalling observe more interference than usual and thus the signalling may be received in error.

There is therefore a need in the art for techniques to communicate signaling in a manner that achieves good detection performance in the presence of interference variations.

Summary of the invention

Techniques for transmitting signaling with localized spreading for good detection performance are described herein. In one design, a transmitter (e.g., a base station) may spread multiple signaling symbols to obtain multiple sets of output symbols. The plurality of signaling symbols may include Acknowledgement (ACK) symbols and/or other types of signaling symbols. The transmitter may obtain each set of output symbols by spreading the plurality of signaling symbols with a spreading matrix. The transmitter may then map the multiple sets of output symbols to multiple time frequency blocks, one set of output symbols to each time frequency block. Whereby spreading can be localized to each time-frequency block. A receiver (e.g., a terminal) may perform complementary despreading to recover one or more signaling symbols of interest.

In another design, the transmitter may scale the multiple signaling symbols (which may be sent to different receivers) with multiple gains determined based on transmit powers of the multiple signaling symbols. The transmitter may descramble each scaled symbol with a respective scrambling sequence to obtain a plurality of scrambled symbols for the signaling symbol. The transmitter may form multiple sets of scrambled symbols and each set includes one scrambled symbol for each of the multiple signaling symbols. The transmitter may despread each set of scrambled symbols with a spreading matrix to obtain a corresponding set of output symbols. The transmitter may then map each set of output symbols to a respective time frequency block. The receiver may perform complementary despreading to recover one or more signaling symbols of interest.

Various aspects and features of the disclosure are described in further detail below.

Brief description of the drawings

Fig. 1 shows a wireless communication system.

Fig. 2 shows an example transmission structure.

Fig. 3 shows an example transmission of four ACK bits.

FIG. 4 illustrates localized expansion of each of a plurality of tiles.

Fig. 5 shows despreading with respect to localized spreading of each tile.

Fig. 6 illustrates transmission of ACK signaling with localized spreading.

Fig. 7 shows the mapping of the output symbols of the ACK signaling to three tiles.

Fig. 8 illustrates the reception of ACK signaling sent under localized spreading.

Fig. 9 and 10 show a procedure and an arrangement, respectively, for signaling of the carousel localized extension.

Fig. 11 and 12 show another procedure and another apparatus, respectively, for signaling of carousel localized spreading.

Fig. 13 and 14 illustrate a process and apparatus, respectively, for receiving signaling sent under localized spreading.

Fig. 15 and 16 show another process and another apparatus, respectively, for receiving signaling sent under a localized extension.

Fig. 17 shows a block diagram of a base station and a terminal.

Detailed Description

Fig. 1 shows a wireless communication system 100 with multiple base stations 110 and multiple terminals 120. A base station is a station that communicates with the terminals. A base station may also be called an access point, a node B, an enodeb, and so on. Each base station 110 provides communication coverage for a particular geographic area 102. The term "cell" can refer to a base station and/or its coverage area depending on the context in which the term is used. To improve system capacity, the base station coverage area may be divided into a plurality of smaller areas, e.g., three smaller areas 104a, 104b, and 104 c. Each smaller area may be served by a respective base station subsystem. The term "sector" can refer to the smallest coverage area of a base station and/or a subsystem serving this coverage area.

Terminals 120 can be dispersed throughout the system, and each terminal can be stationary or mobile. A terminal may also be called an access terminal, mobile station, user equipment, subscriber unit, station, or the like. The terminal may be a cellular telephone, a Personal Digital Assistant (PDA), a wireless device, a wireless modem, a handheld device, a laptop computer, or the like. A terminal may communicate with zero, one, or multiple base stations on the forward and/or reverse links at any given moment. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. The terms "terminal" and "user" are used interchangeably herein.

The techniques described herein may be used for various wireless communication systems such as CDMA, TDMA, FDMA, OFDMA and SC-FDMA systems. CDMA systems utilize Code Division Multiplexing (CDM) and send transmissions with different orthogonal codes. TDMA systems utilize Time Division Multiplexing (TDM) and transmit transmissions in different time slots. FDMA systems utilize Frequency Division Multiplexing (FDM) and send transmissions on different subcarriers. OFDMA utilizes Orthogonal Frequency Division Multiplexing (OFDM), while SC-FDMA systems utilize single-carrier frequency division multiplexing (SC-FDM). OFDM and SC-FDM partition the system bandwidth into multiple orthogonal subcarriers, which are also referred to as tones, bins, and the like. Each subcarrier may be modulated with data. In general, modulation symbols are sent in the frequency domain under OFDM and in the time domain under SC-FDM. These techniques may also be used for wireless communication systems that utilize a combination of multiplexing schemes, e.g., CDMA and OFDM or OFDM and SC-FDM, etc. For clarity, certain aspects of the techniques are described for a system utilizing OFDM on the forward link. Certain aspects of these techniques are also described with respect to a system implementing the Ultra Mobile Broadband (UMB) radio technology described in publicly available 3gpp2c.s0084-001-0 entitled "Physical Layer for Ultra Mobile Broadband (UMB) Air Interface Specification" on a date of 2007, 5, month and 18.

The techniques described herein may also be used for various types of signaling. For example, the techniques may be used for Acknowledgement (ACK) and Negative Acknowledgement (NAK) of packets, power control commands, and so on. For clarity, certain aspects of these techniques are described below for ACK/NAK signaling.

Fig. 2 shows a design of a transmission structure 200 that may be used for the forward link. The transmission timeline may be divided into frames, which may also be referred to as physical layer (PHY) frames, time slots, and so on. Each frame may span a particular period of time, which may be fixed or configurable. Each frame may span T symbol periods, where typically T ≧ 1 and in one design T ≧ 8. The symbol period is the duration of one OFDM symbol.

The system bandwidth may be divided into multiple (K) orthogonal subcarriers. All K total subcarriers may be used for transmission. Alternatively, only a subset of the K total subcarriers may be used for transmission, while the remaining subcarriers may serve as guard subcarriers to enable the system to meet spectral mask requirements. In one design, the spacing between subcarriers is fixed, and the number of subcarriers (K) depends on the system bandwidth. In one design, K may equal 128, 256, 512, 1024, or 2048 for system bandwidth of 1.25, 2.5, 5.0, 10, or 20MHz, respectively.

The available time and frequency resources of the forward link may be divided into tiles, which may also be referred to as time frequency blocks, resource blocks, etc. A tile may cover S subcarriers in T symbol periods, where S ≧ 1 and T ≧ 1 are typical. In one design, a tile covers 16 subcarriers in 8 periods. In one design, tiles may also have other S T dimensions. The S subcarriers in a tile may be consecutive subcarriers or may be distributed across the system bandwidth. A tile includes S · T resource units that can be used to transmit up to S · T symbols. A resource unit is one subcarrier in one symbol period and may be referred to as a resource element, subcarrier-symbol, etc. For a given tile, some resource units may be used for pilot symbols and the remaining resource units may be used for data and/or signaling symbols. As used herein, a data symbol is a symbol corresponding to traffic data, a signaling symbol is a symbol corresponding to signaling, a pilot symbol is a symbol corresponding to pilot, and a symbol is a complex value. The pilot is data that is known a priori to both the transmitter and the receiver.

One or more signaling channels may be defined and may be allocated a sufficient number of tiles. For example, a Forward Link Control Segment (FLCS) may be defined and may include multiple signaling/control channels, such as a forward acknowledgement channel (F-ACKCH). The FLCS may be allocated tiles distributed across time and frequency to achieve diversity. Different resource units in the tiles allocated to the FLCS may be allocated to different control channels. The signaling for each control channel may be sent on the resource units allocated to that control channel.

A control channel, such as F-ACKCH, may carry one signaling symbol or one information bit for a user in a given transmission. The information bits may have one of two possible values (e.g., 0 and 1), while the signaling symbols may have one of two or more possible real or complex values. To ensure diversity and improve reliability, signaling symbols or information bits may be repeated and transmitted on multiple resource elements, which may be distributed across multiple subcarriers and/or symbol periods.

Fig. 2 shows an example transmission of an ACK bit for one user. In this example, the ACK bits are repeated and sent on three resource elements in three tiles of FLCS. Sending ACK bits across frequency may provide frequency diversity.

The resource units for the ACK bit may observe intra-tile interference variations, which are variations in intra-tile interference. The intra-tile interference variation may correspond to the interference power on a pilot symbol in a tile being different from the interference power on another symbol within the tile. Intra-tile interference variations may be generated by high power control channels in adjacent sectors and degrade performance.

To mitigate intra-tile interference variations, the ACK bits may be spread and sent on more resource units, which may provide more averaging for the interference variations. To maintain the same overhead (e.g., three resource elements per ACK bit for the example shown in fig. 2), multiple ACK bits may be jointly spread with a spreading matrix to obtain output symbols that may be sent on the resource elements.

Fig. 3 shows a design of a transmission of a vector of four ACK bits, which may correspond to four different users or to four packets from one or more users. In this design, the four ACK bits may be spread with a 12 × 4 spreading matrix to obtain 12 output symbols that may be transmitted on 12 resource elements. In the design shown in fig. 3, the first four output symbols may be sent on four resource units in the first tile, then four output symbols may be sent in the second tile, and the last four output symbols may be sent in the third tile. Each ACK bit may be sent across 12 resource units and thus is less prone to performance degradation due to inter-tile interference variations.

In general, a transmitter may spread any number (L) of signaling symbols and obtain any number (Q) of output symbols. In one design, Q is an integer multiple of L, or Q ═ L · M, such that L output symbols may be sent on each of the M tiles. The receiver may perform complementary despreading to recover one or more signaling symbols of interest. The spreading performed by the transmitter and the complementary despreading performed by the receiver may provide averaging for interference variations within the tile. Thus, the effect of intra-tile interference variations may be mitigated.

The transmitter may perform the spreading in a manner that improves detection performance and simplifies processing by the receiver. Any Q x L spreading matrix may be selected such that each signaling symbol may be spread with a different spreading sequence of length Q. In this case, the receiver may perform equalization on all Q resource elements used to transmit Q output symbols in order to account for variations in channel response across the Q resource elements. Equalization may be based on Minimum Mean Square Error (MMSE), Least Squares (LS), or some other technique. In highly frequency selective channels, wide variations in channel response can result in large loss of orthogonality between the L spreading sequences in the Q × L spreading matrix. This loss of orthogonality leads to performance degradation, even when equalization is performed.

In an aspect, multiple signaling symbols may be spread to combat interference variations. Spreading may be localized to each tile used to send signaling symbols in order to mitigate performance degradation due to equalization losses and simplify receiver processing. In one design, the spreading is based on a spreading matrix that consists of smaller invertible matrices. In one design, the qxl total spreading matrix S may be formed by concatenating M smaller lxl base spreading matrices. The M sets of output symbols may be obtained with M base spreading matrices and may be sent on M different tiles.

In one design, a single type of base spreading matrix may be used, and the total spreading matrix S is made up of M copies of this base spreading matrix. The base-spreading matrix may be a Discrete Fourier Transform (DFT) matrix, a Walsh matrix (which is also referred to as a Hadamard matrix), a unitary matrix, or the like. In another design, the total spreading matrix S may be composed of different types of base spreading matrices. For example, L signaling symbols can be spread with a DFT matrix and sent in one tile, while the same L signaling symbols can be spread with a Walsh matrix and sent in another tile.

Fig. 4 shows a design of a signaling transmission with localized spreading for each tile. Vector a of L signalling symbols ═ a₁...A_L]^TMay be provided to M expanders 410a through 410M, where "T" denotes transpose. Each expander 410 may expand matrix S with a corresponding base_mSpreading the L signalling symbols and providing a vector z of L output symbols_m＝[Z_1m...Z_Lm]^TWhere M ∈ {1,..., M }. The L output symbols from each expander 410 may be mapped to L resource elements in the corresponding tile. Thus, each signaling symbol may be sent on M · L resource elements in the M tiles. Each signaling symbol may be spread across L resource elements in each tile based on the spreading sequence of the corresponding signaling symbol for that tile.

The spreading of the vector of L signaling symbols may be expressed as:

formula (1)

Wherein S_m-M ∈ { 1.,. M } -is the base expansion matrix for tile M, and z_m-M ∈ { 1.,. M } -is the output symbol vector for tile M.

The base expansion matrix for each tile m may be a unitary matrix with the following properties:

formula (2)

Where "H" denotes the conjugate transpose and I is the identity matrix. Equation (2) indicates that the columns of the base spreading matrix are orthogonal to each other, and each column has a unit power.

The expansion for each tile m may be expressed as:

z_m＝S_ma, wherein mE.g. { 1., M }. Formula (3)

Equation (3) can be expanded as follows:

formula (4)

Wherein A is_l-L ∈ { 1.,. L } -is the L-th signaling symbol in vector a,

S_klmto expand the matrix S_mAnd the element in the kth row and the l column, and

Z_kmk ∈ { 1., L } — the output symbol of the kth resource unit corresponding to tile m.

By using localized spreading, the receiver can obtain the L despread symbols for each tile by inverting the base spreading matrix for that tile. The despread symbols are initial estimates of the signaling symbols. For each signaling symbol, M despread symbols may be obtained from the M tiles and combined to obtain a final estimate of the signaling symbol. Alternatively, the receiver may perform equalization based on MMSE or LS, for example. In this case, the loss due to equalization may depend on the amount of channel variation within each tile, rather than across all M tiles. Thus, equalization losses may be less under localized expansion than in the case where the expansion spans all M tiles.

Fig. 5 shows a design of the reception of signaling sent under localized expansion for each tile. Vector r of L received symbols_m＝[R_1m...R_Im]^TMay be obtained from each tile used to transmit the L signaling symbols. M received symbol vectors r₁To r_MMay be obtained from the M tiles and provided to M despreaders 510a through 510M, respectively. Each despreader 510 may be based on a corresponding base-spreading matrix S_mReceives it to a symbol vector r_mVector b of despread and provided L despread symbols_m. The combiner 520 can be separately solvedSpreaders 510a to 510M receive M despread symbol vectors b₁To b_M. Combiner 520 may scale and combine the M despread symbol vectors to obtain a vector of L signaling symbol estimates

The despreading for each tile m can be expressed as:

formula (5)

Wherein S_m ^-1A despreading matrix for the corresponding tile m, which is S_mThe inverse of (c).

The receiver may be interested in only a subset of the L signaling symbols sent by the transmitter. The receiver may then give a signalling symbol a for each tile m_lDespreading is performed as follows:

formula (6)

Wherein R is_kmIs a vector r_mThe k-th received symbol of the sequence,

S′_klmfor despreading matrix S_m ^-1Of the m-th row and the l-th column, and

B_lmis a vector b_mThe first despreading symbol from the corresponding signaling symbol A in tile m_lThe despread symbols of (1).

The receiver may be directed to signalling symbol a_lSymbol combining is performed across the M tiles as follows:

formula (7)

Wherein W_lmSignaling symbol A for tile m_lA weight of, and

for signalling symbol A_lIs estimated.

Weight W of each tile_lmMay be determined based on the received signal quality for that tile. The received signal quality may be quantified in terms of signal-to-noise ratio (SNR) or some other metric. More weight may be given to despread symbols from tiles having higher received signal quality. Alternatively, the same weight may be applied to despread symbols from all M tiles.

Fig. 6 shows a block diagram of a design of a Transmit (TX) signaling processor 600 for transmitting ACK signaling with localized spreading. In this design, four ACK symbols may be spread and sent in three tiles, with the spread localized to each tile.

In one design, an ACK symbol is one of four possible values, which may be given as follows:

formula (8)

An ACK value of 0 may correspond to a NAK, which may be sent for an erroneously decoded packet. An ACK value of 1 may indicate a correctly decoded packet and may also inform the user to maintain the current resource assignment. An ACK value of 2 may indicate a correctly decoded packet and may also inform the user to relinquish the current resource assignment. An ACK value of 3 may inform the user to relinquish the current resource assignment. An ACK symbol may also be defined to have one of two possible values (e.g., 0 and 1) or some other set based on the possible values.

Scaling unit 610 may receive and scale four ACK symbols. The ACK symbols may be sent to users with different geometries or SNRs. The ACK symbol for each user may be scaled with an appropriate gain to achieve a desired SNR for the ACK symbol. Scaling unit 610 may scale four ACK symbols A'₀To A'₃Are provided to four scramblers 612a to 612d, respectively.

Each scrambler 612 may be used for ACK symbol A_lThree scrambling values Y of the scrambling sequence of the transmitted user_l0、Y_l1And Y_l2To derive its scaled ACK symbol A'_lAnd (5) scrambling. Different users may be assigned different scrambling sequences, which may be generated based on parameters such as the user's MAC ID, the sector ID of the transmitting sector, and so on. Scrambling may be used to distinguish signals from different sectors to different users with different MAC IDs. Each scrambler 612 may provide three scrambled symbols to three spreaders 614a, 614b, and 614 c.

Each spreader 614 may receive four scrambled symbols corresponding to the four ACK symbols from the four scramblers 612a through 612 d. Each spreader 614 may spread its four scrambled symbols with a spreading matrix (e.g., a 4 x 4DFT matrix) and provide four output symbols. Spreaders 614a, 614b, and 614c may provide their output symbols to symbol-to-subcarrier mappers 616a, 616b, and 616c, respectively.

Each mapper 616 may map its four output symbols to four resource units in the associated tile. Mapper 616a may map its output symbols to tile 1, mapper 616b may map its output symbols to tile 2, and mapper 616c may map its output symbols to tile 3.

The transmitter processing for each tile may be expressed as:

z_m＝DY_mga, formula (9)

Wherein a ═ a₀ A₁ A₂ A₃]^TIs a 4 x 1 vector of four ACK symbols,

g is a 4 x 4 diagonal matrix with four gains along the diagonal corresponding to four ACKs and zeros elsewhere,

Y_ma 4 x 4 diagonal matrix with four scrambling values along the diagonal for the four ACKs for tile m,

d is an extended 4 x 4DFT matrix for one tile, an

z_m＝[Z_0m Z_1m Z_2m Z_3m]^TIs a 4 x 1 vector of output symbols for the corresponding tile m.

For each ACK code element A_lThe process of (d) can be expressed as:

Z_klm＝D_klY_lmG_lA_lwherein k is 0, 3 and m is 0, 2,formula (10)

WhereinIs a gain, P_TXlIs ACK symbol A_lThe transmission power of the antenna is set to be,

Y_lmACK symbol A for tile m_lThe value of the scrambling code of (a),

D_klis an element in the kth row and the l column of the DFT matrix D, an

Z_klmACK symbol A for the kth resource unit in the corresponding tile m_lThe output symbol of (1).

Equation (10) indicates the available gain G_lTo scale ACK symbol A_lTo achieve ACK symbol A_lThe desired transmit power of. The scaled ACK symbol may then be scrambled with three scrambling values to obtain three scrambled symbols. Each scrambled symbol may be spread with four elements in a column of the DFT matrix to obtain four output symbols to be sent in one tile corresponding to the scrambled symbol. May be ACK symbol A_lA total of 12 output symbols are obtained.

The output symbols for all four ACK symbols may be combined as follows:

formula (11)

Wherein Z_kmIs the output symbol to be sent on the kth resource unit in tile m.

Fig. 7 shows 12 output symbols for four ACK symbols in three tiles. In this design, each tile covers 16 subcarriers in 8 symbol periods. In each tile, 18 resource units are reserved for pilot symbols, while the remaining resource units may be used to transmit other symbols. In one design, four output symbols Z_0m、Z_1m、Z_2mAnd Z_3mIs mapped to a cluster of four adjacent resource units in the tile. Sending four symbols close together in time-frequency causes the output symbols to observe less channel variation, which in turn may result in less loss of orthogonality. The output symbols may be mapped to different symbol periods in the three tiles as shown in fig. 7. This may allow better transmit power sharing among symbols sent on different subcarriers. Transmitting output symbols over multiple clusters in the same pair of symbol periods results in excessive transmit power being used for the output symbols, while less transmit power is available for the remaining symbols in the pair of symbol periods. These output symbols may also be mapped to resource units in other manners.

Fig. 8 shows a block diagram of a design of a Receive (RX) signaling processor 800 to receive ACK signaling sent under a localized spreading. For clarity, fig. 8 shows a scheme for recovering one ACK symbol a_lAnd (4) processing.

Symbol-to-subcarrier demappers 810a, 810b, and 810c may obtain received symbols from the three tiles used to send ACK signaling. Each demapper 810 may provide received symbols from four resource units used to send ACK signaling in an associated tile. Despreaders 812a, 812b, and 812c may obtain received symbols from demappers 810a, 810b, and 810c, respectively. The four ACK symbols may be spread with four columns of the DFT matrix. Each despreader 812 may then despread its four received symbols with four elements in the l column of an Inverse Discrete Fourier Transform (IDFT) matrix, which corresponds to the column used to spread the ACK symbol a being recovered_lColumn l of the DFT matrix. Descrambler 814 may receive three despread symbols B from despreaders 812a, 812B, and 812c, respectively_l0、B_l1And B_l2. Descrambler 814 may combine the three despread symbols with ACK symbol A_lThree scrambling values Y_l0、Y_l1And Y_l2Multiplies and provides three descrambled symbols. Combiner 816 may scale the three descrambled symbols with three weights derived for the three tiles, and may then combine the three scaled symbols as shown in equation (7) to obtain an ACK symbol estimateThis receiver processing may be repeated for each ACK symbol of interest. ACK symbol A_lRecovery may also be performed by performing equalization (e.g., MMSE or LS based) and descrambling.

In general, any gain value G_lCan be used for each ACK symbol A_l. For a flat fading channel, the four spread ACK symbols remain orthogonal at the receiver, and each ACK symbol can be recovered by despreading the received symbol. For a frequency selective channel, channel variation may result in loss of orthogonality, which then causes each ACK symbol to interfere with the remaining ACK symbols. ACK symbols transmitted at high power may cause excessive interference to ACK symbols transmitted at low power, which may subsequently degrade detection performance for low power ACK symbols. To mitigate this effect, the ratio of the highest gain to the lowest gain among the four gains corresponding to the four ACK symbols may be limited to a threshold value or lower. This may then ensure that the highest power ACK symbol does not cause excessive interference to the lowest power ACK symbol. The threshold may be selected based on various factors, such as a desired maximum amount of orthogonality loss due to channel variations, desired detection performance, and so on. The ACK symbols for different users may also be arranged into groups such that each group includes ACK symbols with similar transmit power.

The processes shown in fig. 6 and 8 may be performed in other manners or orders. For example, scrambling may be performed before spreading (as shown in fig. 6) or after spreading. The scaling may be performed first (as shown in fig. 6), or after scrambling, or at some other point. Scaling and/or scrambling may also be omitted.

For clarity, the use of these techniques for ACK signaling has been described above. These techniques may also be used for other types of signaling. For example, these techniques may also be used for power control commands, Other Sector Interference (OSI) indications, access grants, resource assignments, pilot quality indicators, start of packet indications, reverse activity bits, and so on.

Fig. 9 shows a design of a process 900 for transmitting signaling with localized spreading. Process 900 may be performed by a transmitter, such as a base station. The plurality of signaling symbols may be spread to obtain a plurality of sets of output symbols, and each set of output symbols is obtained by spreading the plurality of signaling symbols with a spreading matrix, e.g., a DFT matrix or a Walsh matrix (block 912). Multiple sets of output symbols may be mapped to multiple time frequency blocks or tiles (block 914). For example, each set of output symbols may be mapped to a cluster of adjacent resource units in one time frequency block. The plurality of signaling symbols may include ACK symbols and/or other types of signaling symbols.

Fig. 10 shows a design of an apparatus 1000 for transmitting signaling with localized spreading. The apparatus 1000 comprises: means for spreading the plurality of signaling symbols to obtain a plurality of sets of output symbols, and each set of output symbols is obtained by spreading the plurality of signaling symbols with a spreading matrix (block 1012); and means for mapping the plurality of sets of output symbols to a plurality of time frequency blocks (module 1014).

Fig. 11 shows a design of a process 1100 for transmitting signaling with localized spreading. Process 1100 may be performed by a transmitter, such as a base station. Multiple signaling symbols (e.g., ACK symbols) may be scaled with multiple gains determined based on transmit powers used for the signaling symbols (block 1112). The ratio of the maximum gain to the minimum gain may be limited to be less than a predetermined value. Each of the plurality of scaled signaling symbols may be scrambled with a respective scrambling sequence to obtain a plurality of scrambled symbols for the signaling symbol (block 1114). Sets of multiple scrambled symbols may be formed, and each set includes one scrambled symbol for each of the multiple signaling symbols (block 1116). The sets of multiple scrambled symbols may be spread (e.g., with a DFT matrix or a Walsh matrix) to obtain multiple sets of output symbols, one set of output symbols for each set of scrambled symbols (block 1118). Multiple sets of output symbols may be mapped to multiple time frequency blocks, one set of output symbols being mapped to each time frequency block (block 1120). Each set of output symbols may be mapped to a cluster of adjacent resource units in one time frequency block.

The processing in fig. 11 may be performed in other orders. Some of the processing (e.g., scaling and/or scrambling) may be omitted. Other processing may also be performed on the signaling symbols.

Fig. 12 shows a design of an apparatus 1200 for transmitting signaling with localized spreading. The apparatus 1200 includes: means for scaling a plurality of signaling symbols with a plurality of gains determined based on transmit powers of the plurality of signaling symbols (block 1212); means for scrambling each of the plurality of scaled signaling symbols with a respective scrambling sequence to obtain a plurality of scrambled symbols for the signaling symbol (module 1214); means for forming a plurality of sets of scrambled symbols, and each set including one scrambled symbol for each of a plurality of signaling symbols (module 1216); means for spreading the plurality of sets of scrambled symbols to obtain a plurality of sets of output symbols, one set of output symbols for each set of scrambled symbols (block 1218); and means for mapping the plurality of sets of output symbols to a plurality of time frequency blocks, one set of output symbols to each time frequency block (block 1220).

Fig. 13 shows a design of a process 1300 for receiving signaling. Process 1300 may be performed by a receiver, such as a terminal. A plurality of sets of received symbols may be obtained from a plurality of time frequency blocks used to transmit a plurality of band spread signaling symbols (e.g., ACK symbols) (block 1312). The multiple sets of received symbols may be despread (e.g., based on a despreading matrix such as an IFDT matrix or a Walsh matrix) to obtain multiple despread symbols (block 1314). A signaling symbol estimate for one of the multiple signaling symbols may be derived based on the multiple despread symbols (block 1316). This process may be repeated for each ACK symbol of interest.

Fig. 14 shows a design of an apparatus 1400 for receiving signaling transmitted under extension. The apparatus 1400 comprises: means for obtaining a plurality of sets of received symbols from a plurality of time frequency blocks used to transmit the plurality of signaling symbols with spreading (block 1412); means for despreading the plurality of sets of received symbols to obtain a plurality of despread symbols (block 1414); and means for deriving a signaling symbol estimate for one of the plurality of signaling symbols based on the plurality of despread symbols (block 1416).

Fig. 15 shows a design of a process 1500 for receiving signaling. Process 1500 may be performed by a receiver, such as a terminal. Multiple sets of received symbols may be obtained from multiple time frequency blocks, one set of received symbols for each time frequency block (block 1512). Each set of received symbols may be despread based on the despreading matrix to obtain despread symbols (block 1514). A plurality of despread symbols may be obtained for the plurality of sets of received symbols and may be descrambled to obtain a plurality of descrambled symbols (block 1516). The plurality of descrambled symbols may be combined to obtain a signaling symbol estimate for one of the plurality of signaling symbols (block 1518). For block 1518, a plurality of weights for a plurality of time frequency blocks may be determined, for example, based on the quality of the received signal for the time frequency blocks. The plurality of descrambled symbols may be scaled with a plurality of weights to obtain a plurality of scaled symbols. Multiple scaled symbols may then be combined to obtain a signaling symbol estimate. The processing by the receiver may depend on the processing by the transmitter.

Fig. 16 shows a design of an apparatus 1600 for receiving signaling transmitted under a localized spreading. The apparatus 1600 includes: means for obtaining a plurality of sets of received symbols from a plurality of time frequency blocks, one set of received symbols for each time frequency block (block 1612); means for despreading each set of received symbols based on a despreading matrix to obtain despread symbols (block 1614); means for descrambling the plurality of despread symbols to obtain a plurality of descrambled symbols (block 1616); and means for combining the plurality of descrambled symbols to obtain a signaling symbol estimate for one of the plurality of signaling symbols (block 1618).

The modules in fig. 10, 12, 14, and 16 may comprise processors, electronics devices, hardware devices, electronic components, logic circuits, memories, etc., or any combination thereof.

FIG. 17 shows a block diagram of a design of a base station 110 and a terminal 120, which are one of the base stations and one of the terminals in FIG. 1. At base station 110, a Transmit (TX) data and signaling processor 1710 can receive traffic data from a data source (not shown) and/or signaling from a controller/processor 1740. A processor 1710 can process (e.g., format, encode, interleave, and symbol map) traffic data and signaling and provide data and signaling symbols. Processor 1710 can also generate pilot symbols. A Modulator (MOD)1720 may process the data, signaling, and pilot symbols (e.g., for OFDM) and provide output chips. A transmitter (TMTR)1722 processes (e.g., converts to analog, amplifies, filters, and frequency upconverts) the output chip streams and generates a forward link signal, which is then transmitted from an antenna 1724.

At terminal 120, an antenna 1752 can receive forward link signals from base station 110 and other base stations and can provide a received signal to a receiver (RCVR) 1754. Receiver 1754 may condition (e.g., filter, amplify, downconvert, and digitize) the received signal and provide received samples. A demodulator (DEMOD)1760 may perform demodulation on the received samples (e.g., for the OFDM case) and provide received symbols. An RX data and signaling processor 1770 may process (e.g., symbol demap, deinterleave, and decode) the received symbols to obtain decoded data and signaling for terminal 120.

On the reverse link, at terminal 120, traffic data and signaling to be sent by terminal 120 may be processed by a TX data and signaling processor 1790, modulated by a modulator 1792, conditioned by a transmitter 1794, and transmitted via antenna 1752. At base station 110, the reverse link signals from terminal 120 and possibly other terminals may be received by antennas 1724, conditioned by receivers 1730, demodulated by a demodulator 1732, and processed by a RX data and signaling processor 1734 to recover the traffic data and signaling sent by the terminals. The processing for reverse link transmissions may be similar or different than the processing for forward link transmissions.

Controllers/processors 1740 and 1780 may direct the operation at base station 110 and terminal 120, respectively. Memories 1742 and 1782 may each store data and program codes for base station 110 and terminal 120. A scheduler 1744 may schedule terminals for forward and/or reverse link transmissions and may provide assignments of resources (e.g., tiles) for the scheduled UEs.

For signaling, processor 1710 and/or 1790 may perform the processes shown in fig. 4 or 6, process 900 in fig. 9, process 1100 in fig. 11, and/or other processes for the techniques described herein. For signaling reception, processors 1734 and/or 1770 may perform the processes shown in fig. 5 or 8, process 1300 in fig. 13, process 1500 in fig. 15, and/or other processes for the techniques described herein.

The techniques described herein may be implemented by various means. For example, these techniques may be implemented in hardware, firmware, software, or a combination thereof. For a hardware implementation, the various processing units used to perform the techniques at an entity (e.g., a base station or a terminal) may be implemented within one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, electronic devices, other electronic units designed to perform the functions described herein, a computer, or a combination thereof.

For a firmware and/or software implementation, the techniques may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The firmware and/or software instructions may be stored in a memory (e.g., memory 1742 or 1782 in fig. 17) and executed by a processor (e.g., processor 1740 or 1780). The memory may be implemented within the processor or external to the processor. The firmware and/or software instructions/code may also be stored in a computer/processor readable medium, such as Random Access Memory (RAM), Read Only Memory (ROM), non-volatile random access memory (NVRAM), Programmable Read Only Memory (PROM), electrically erasable PROM (eeprom), flash memory, floppy disks, Compact Disks (CDs), Digital Versatile Disks (DVDs), magnetic or optical data storage devices, and the like. The instructions/code may be executed by one or more processors and may cause the processors to perform certain aspects of the functions described herein.

The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (32)

1. An apparatus for wireless communication, comprising:

a first spreader configured to spread the plurality of signaling symbols based on a first base spreading matrix to obtain a first set of output symbols;

a second spreader configured to spread the plurality of signaling symbols based on a second base spreading matrix to obtain a second set of output symbols, wherein the first base spreading matrix and the second base spreading matrix are single type or different types of base spreading matrices,

a first mapper configured to map the first set of output symbols to a first time frequency block; and

a second mapper configured to map the second set of output symbols to a second time frequency block, each of the first and second time frequency blocks covering a plurality of subcarriers in a plurality of symbol periods, and each of the plurality of signaling symbols thereby being transmitted in both the first and second time frequency blocks.

2. The apparatus of claim 1, wherein the first base-spreading matrix comprises a Discrete Fourier Transform (DFT) matrix or a Walsh matrix.

3. The apparatus of claim 1, further comprising:

a scrambler configured to scramble the plurality of signaling symbols to obtain scrambled symbols, and wherein the first and second spreaders are configured to spread the scrambled symbols to obtain the first and second sets of output symbols.

4. The apparatus of claim 1, further comprising:

a scrambler configured to scramble each of the plurality of signaling symbols with a respective scrambling sequence to obtain a plurality of scrambled symbols for the signaling symbol and to form first and second sets of scrambled symbols, wherein each set includes one scrambled symbol corresponding to each of the plurality of signaling symbols, and wherein the first and second spreaders are configured to spread the first and second sets of scrambled symbols to obtain the first and second sets of output symbols, wherein spreading each set of scrambled symbols results in one set of output symbols.

5. The apparatus of claim 1, further comprising:

a scaler configured to scale the plurality of signaling symbols with a plurality of gains determined based on transmit powers of the plurality of signaling symbols.

6. The apparatus of claim 5, wherein:

a ratio of a maximum gain to a minimum gain among the plurality of gains is defined to be less than a predetermined value.

7. The apparatus of claim 1, wherein the first mapper is configured to map the first set of output symbols to clusters of adjacent resource units in the first time frequency block, and wherein the second mapper is configured to map the second set of output symbols to clusters of adjacent resource units in the second time frequency block.

8. The apparatus of claim 1, wherein the plurality of signaling symbols comprise Acknowledgement (ACK) symbols.

9. A method for wireless communication, comprising:

spreading the plurality of signaling symbols based on a first base spreading matrix to obtain a first set of output symbols;

spreading the plurality of signaling symbols based on a second base spreading matrix to obtain a second set of output symbols, wherein the first base spreading matrix and the second base spreading matrix are single type or different types of base spreading matrices;

mapping the first set of output symbols to a first time frequency block; and

mapping the second set of output symbols to a second time frequency block, each of the first and second time frequency blocks covering a plurality of subcarriers in a plurality of symbol periods, and each of the plurality of signaling symbols thereby being sent in both of the first and second time frequency blocks.

10. The method of claim 9, further comprising:

scrambling the plurality of signaling symbols to obtain scrambled symbols, and wherein the scrambled symbols are spread to obtain the first and second sets of output symbols.

11. The method of claim 9, further comprising:

scaling the plurality of signaling symbols with a plurality of gains determined based on transmit powers of the plurality of signaling symbols.

12. The method of claim 9, wherein the mapping the first set of output symbols comprises mapping the first set of output symbols to clusters of adjacent resource units in the first time frequency block, and wherein the mapping the second set of output symbols comprises mapping the second set of output symbols to clusters of adjacent resource units in the second time frequency block.

13. An apparatus for wireless communication, comprising:

means for spreading the plurality of signaling symbols based on a first base spreading matrix to obtain a first set of output symbols;

means for spreading the plurality of signaling symbols based on a second base spreading matrix to obtain a second set of output symbols, wherein the first base spreading matrix and the second base spreading matrix are single type or different types of base spreading matrices;

means for mapping the first set of output symbols to a first time frequency block; and

means for mapping the second set of output symbols to a second time frequency block, each of the first and second time frequency blocks covering a plurality of subcarriers in a plurality of symbol periods, and each of the plurality of signaling symbols thereby being sent in both the first and second time frequency blocks.

14. The apparatus of claim 13, further comprising:

means for scrambling the plurality of signaling symbols to obtain scrambled symbols, and wherein the scrambled symbols are spread to obtain the first and second sets of output symbols.

15. The apparatus of claim 13, wherein the means for mapping the first set of output symbols comprises means for mapping the first set of output symbols to a cluster of adjacent resource units in the first time frequency block, and wherein the means for mapping the second set of output symbols comprises means for mapping the second set of output symbols to a cluster of adjacent resource units in the second time frequency block.

16. An apparatus for wireless communication, comprising:

a first module configured to spread a plurality of signaling symbols based on a first base spreading matrix to obtain a first set of output symbols;

a second module configured to spread the plurality of signaling symbols based on a second base spreading matrix to obtain a second set of output symbols, wherein the first base spreading matrix and the second base spreading matrix are single type or different types of base spreading matrices;

a third module configured to map the first set of output symbols to a first time frequency block; and

a fourth module configured to map the second set of output symbols to a second time frequency block, each of the first and second time frequency blocks covering a plurality of subcarriers in a plurality of symbol periods, and each of the plurality of signaling symbols thereby being sent in both the first and second time frequency blocks.

17. An apparatus for wireless communication, comprising:

a demapper configured to obtain first and second sets of received symbols from first and second time frequency blocks used to transmit a plurality of signaling symbols under spreading, wherein the plurality of signaling symbols are spread with a first base spreading matrix to obtain a first set of output symbols and are further spread with a second base spreading matrix to obtain a second set of output symbols, wherein the first basis expansion matrix and the second basis expansion matrix are a single type or different types of basis expansion matrices, and wherein the first set of output symbols is transmitted on a first time frequency block and the second set of output symbols is transmitted on a second time frequency block, each of the first and second time frequency blocks covers a plurality of subcarriers in a plurality of symbol periods, and each of the plurality of signaling symbols is thus sent in both the first and second time frequency blocks;

a despreader configured to despread the first and second sets of received symbols to obtain a plurality of despread symbols; and

a combiner configured to derive at least one signaling symbol estimate for at least one of the plurality of signaling symbols based on the plurality of despread symbols.

18. The apparatus of claim 17, wherein the despreader is configured to despread the first set of received symbols with an inverse of the first base spreading matrix and to despread the second set of received symbols with an inverse of the second base spreading matrix to obtain at least one of the plurality of despread symbols.

19. The apparatus of claim 18, wherein the first base-spreading matrix comprises a Discrete Fourier Transform (DFT) matrix or a Walsh matrix.

20. The apparatus of claim 17, further comprising:

a descrambler configured to descramble the plurality of despread symbols to obtain a plurality of descrambled symbols, and wherein the combiner is configured to derive the at least one signaling symbol estimate based on the plurality of descrambled symbols.

21. The apparatus of claim 17, wherein the combiner is configured to determine weights for the first and second time frequency blocks, scale the plurality of despread symbols with the weights to obtain a plurality of scaled symbols, and combine the plurality of scaled symbols to obtain the at least one signaling symbol estimate.

22. The apparatus of claim 17, wherein the demapper is configured to obtain the first set of received symbols from a cluster of adjacent resource units in the first time frequency block, and to obtain the second set of received symbols from a cluster of adjacent resource units in the second time frequency block.

23. The apparatus of claim 17, wherein the plurality of signaling symbols comprise Acknowledgement (ACK) symbols.

24. A method for wireless communication, comprising:

obtaining first and second sets of received symbols from first and second time frequency blocks used to transmit a plurality of signaling symbols under spreading, wherein the plurality of signaling symbols are spread with a first base spreading matrix to obtain a first set of output symbols and are also spread with a second base spreading matrix to obtain a second set of output symbols, wherein the first base spreading matrix and the second base spreading matrix are single type or different types of base spreading matrices, and wherein the first set of output symbols are transmitted on a first time frequency block and the second set of output symbols are transmitted on a second time frequency block, each of the first and second time frequency blocks covering a plurality of subcarriers in a plurality of symbol periods, and each of the plurality of signaling symbols is thereby transmitted in both the first and second time frequency blocks;

despreading the first and second sets of received symbols to obtain a plurality of despread symbols; and

deriving at least one signaling symbol estimate for at least one of the plurality of signaling symbols based on the plurality of despread symbols.

25. The method of claim 24, further comprising:

descrambling the plurality of despread symbols to obtain a plurality of descrambled symbols; and

deriving the at least one signaling symbol estimate based on the plurality of descrambled symbols.

26. The method of claim 24, wherein the despreading the first and second sets of received symbols comprises despreading each of the first and second sets of received symbols with a despreading matrix to obtain at least one of the plurality of despread symbols.

27. The method of claim 24, wherein said deriving said at least one signaling symbol estimate comprises

Determining weights for the first and second time frequency blocks,

scaling the plurality of despread symbols with the weights to obtain a plurality of scaled symbols, an

Combining the plurality of scaled symbols to obtain the at least one signaling symbol estimate.

28. The method of claim 24, wherein the obtaining the first and second sets of received symbols comprises:

obtaining the first set of received symbols from a cluster of adjacent resource units in the first time frequency block; and

obtaining the second set of received symbols from a cluster of adjacent resource units in the second time frequency block.

29. An apparatus for wireless communication, comprising:

means for obtaining first and second sets of received symbols from first and second time frequency blocks used to transmit a plurality of signaling symbols under spreading, wherein the plurality of signaling symbols are spread with a first base spreading matrix to obtain a first set of output symbols and are further spread with a second base spreading matrix to obtain a second set of output symbols, wherein the first basis expansion matrix and the second basis expansion matrix are a single type or different types of basis expansion matrices, and wherein the first set of output symbols is transmitted on a first time frequency block and the second set of output symbols is transmitted on a second time frequency block, each of the first and second time frequency blocks covers a plurality of subcarriers in a plurality of symbol periods, and each of the plurality of signaling symbols is thus sent in both the first and second time frequency blocks;

means for despreading the first and second sets of received symbols to obtain a plurality of despread symbols; and

means for deriving at least one signaling symbol estimate for at least one of the plurality of signaling symbols based on the plurality of despread symbols.

30. The apparatus of claim 29, further comprising:

means for descrambling the plurality of despread symbols to obtain a plurality of descrambled symbols; and

means for deriving the at least one signaling symbol estimate based on the plurality of descrambled symbols.

31. The apparatus of claim 29, wherein the means for despreading the first and second sets of received symbols comprises means for despreading each of the first and second sets of received symbols with a despreading matrix to obtain at least one of the plurality of despread symbols.

32. An apparatus for wireless communication, comprising:

a first module configured to obtain first and second sets of received symbols from first and second time frequency blocks used to transmit a plurality of signaling symbols under spreading, wherein the plurality of signaling symbols are spread with a first base spreading matrix to obtain a first set of output symbols and are further spread with a second base spreading matrix to obtain a second set of output symbols, wherein the first basis expansion matrix and the second basis expansion matrix are a single type or different types of basis expansion matrices, and wherein the first set of output symbols is transmitted on a first time frequency block and the second set of output symbols is transmitted on a second time frequency block, each of the first and second time frequency blocks covers a plurality of subcarriers in a plurality of symbol periods, and each of the plurality of signaling symbols is thus sent in both the first and second time frequency blocks;

a second module configured to despread the first and second sets of received symbols to obtain a plurality of despread symbols, an

A third module configured to derive at least one signaling symbol estimate for at least one of the plurality of signaling symbols based on the plurality of despread symbols.