RU2445745C1 - Wireless communication system with multiple transmitting antennae using pilot signal subcarrier allocation - Google Patents

Abstract

FIELD: information technology.

SUBSTANCE: disclosed is a method of allocating pilot signal subcarriers in a resource block for a broadband wireless mobile communication system with multiple transmitting antennae using orthogonal frequency-division multiplexing (OFDM). According to the method, pilot signal subcarriers are allocated to a resource block consisting of five (5) or seven (7) OFDM symbols such that, only four (4) OFDM symbols of the resource blocks are allocated for the pilot signal carriers.

EFFECT: efficient allocation of pilot signal subcarriers in a wireless communication system, high efficiency of channel estimation.

24 cl, 28 dwg

Description

Technical field

The present invention relates to a wireless communication system. In particular, the present invention relates to a method for allocating pilot subcarriers in a wireless communication system including an antenna system with multiple inputs and multiple outputs (MIMO).

State of the art

The Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard provides broadband wireless access technology and an appropriate protocol. Standardization has evolved since 1999, and IEEE 802.16-2001 was adopted in 2001. It was established based on the physical layer of a single carrier, referred to as "WirelessMAN-SC." In IEEE 802.16a, which was adopted in 2003, WirelessMAN-OFDM and WirelessMAN-OFDMA were added to the physical layer in addition to WirelessMAN-SC. Upon completion of the development of the IEEE 802.16a standard, the revised IEEE 802.16-2004 was adopted in 2004. To correct the shortcomings and errors of IEEE 802.16-2004, IEEE 802.16-2004 / Cor1 was formulated as a "typo list" in 2005.

MIMO antenna technology improves data transmission / reception efficiency using multiple transmit antennas and multiple receive antennas. MIMO technology has been introduced into the IEEE 802.16a standard and is continuously updated.

MIMO technology is divided into a spatial multiplexing method and a spatial diversity method. According to the spatial multiplexing method, since different data is transmitted simultaneously, data can be transmitted at high speed without increasing the system bandwidth. According to the spatial diversity method, due to the fact that the same data is transmitted through multiple transmitting antennas to benefit from spatial diversity, the reliability of the data is increased.

The receiver needs to evaluate the channel to recover the data transmitted from the transmitter. Channel estimation indicates the process of compensating for signal distortion, which occurs due to rapid changes in the environment due to attenuation and restoration of the transmitted signal. In general, for channel estimation, the transmitter and receiver must know the pilot signals.

In a MIMO system, a signal experiences a channel corresponding to each antenna. Accordingly, it is necessary to configure the pilot signals taking into account multiple antennas. Although the number of pilot signals increases with the number of antennas, it is not possible to increase the number of antennas to increase the data rate.

According to the prior art, various pilot allocation structures have been developed which are used according to permutation methods (dispersion / AMC / PUSC / FUSC). The fact is that the permutation methods are separated from each other along the time axis in the IEEE 802.16e system, and thus, the structures can be optimized differently according to the permutation methods. However, if the permutation methods coexist at some point in time, a unified basic data extraction structure is needed.

According to the prior art, due to the significant pilot overhead, the transmission rate is reduced. In addition, since the same pilot structure is applied to neighboring cells or sectors, a conflict may arise between cells or sectors. Accordingly, a method is needed for efficiently allocating pilot subcarriers in a MIMO system.

SUMMARY OF THE INVENTION

Technical problem

An object of the present invention is to provide a method for efficiently allocating pilot subcarriers in a wireless communication system including a MIMO system regardless of uplink / downlink and specific permutation schemes. In particular, the present invention is intended to improve channel estimation performance in a communication system supporting a subframe consisting of 5 OFDMA symbols or 7 OFDMA symbols. The present invention is applicable to new wireless communication systems, for example, IEEE 802.16m.

Technical solution

The object of the present invention is solved by a number of aspects of the present invention described below.

In one aspect of the present invention, a method for allocating pilot subcarriers in a resource block for a multiple band antenna system using orthogonal frequency division multiple access (OFDMA) modulation comprises allocating pilot subcarriers to a resource block such that only four (4) OFDMA symbols of the resource block are allocated for pilot subcarriers, and the resource block has seven (7) OFDMA symbols.

Preferably, the plurality of OFDMA symbol index numbers of the four (4) OFDMA symbols is one of (0, 1, 5, 6), (0, 1, 4, 5) and (1, 2, 5, 6), the plurality of index numbers (o, p, q, r) indicates the (o + 1) th OFDMA symbol, (p + 1) th OFDMA symbol, (q + 1) th OFDMA symbol and (r + 1) th OFDMA symbol in resource block. Preferably, the multiple transmit antennas consist of four (4) transmit antennas, the resource block consists of 18 subcarriers, and each of the OFDMA symbols allocated to the pilot subcarriers includes a pilot subcarrier for the first transmit antenna, a pilot subcarrier for a second transmit antenna, a pilot subcarrier for a third transmit antenna, and a pilot subcarrier for a fourth transmit antenna of four (4) transmit antennas. Preferably, the multiple transmit antennas consist of four (4) transmit antennas, the resource block consists of 18 subcarriers, and each of the OFDMA symbols allocated to the pilot subcarriers includes a pilot subcarrier for the first transmit antenna, a pilot subcarrier for a second transmit antenna, a pilot subcarrier for a third transmit antenna, and a pilot subcarrier for a fourth transmit antenna of four (4) transmit antennas. Preferably, the multiple transmit antennas consist of two (2) transmit antennas, and each of the OFDMA symbols allocated to the pilot subcarriers includes a pilot subcarrier for the first transmit antenna, and a pilot subcarrier for the second transmit antenna of two ( 2) transmitting antennas. Preferably, the resource block consists of 4 subcarriers or 6 subcarriers.

In another aspect of the present invention, a method for allocating pilot subcarriers in a resource block for a multiple band antenna transmission broadband wireless mobile communication system using frequency division multiple access (OFDMA) modulation comprises allocating pilot subcarriers to a resource block such that only four (4) OFDMA symbols of the resource block are allocated for pilot subcarriers, wherein the resource block has five (5) OFDMA symbols.

Preferably, the OFDMA symbol index numbers of the four (4) OFDMA symbols are 0, 1, 3, and 4, with the index number p indicating the (p + 1) th OFDMA symbol in the resource block. Preferably, the resource block consists of 18 subcarriers, the multiple transmit antennas consist of four (4) transmit antennas, and each of the OFDMA symbols allocated to the pilot subcarriers includes a pilot subcarrier for the first transmit antenna, a pilot subcarrier for a second transmit antenna, a pilot subcarrier for a third transmit antenna, and a pilot subcarrier for a fourth transmit antenna of four (4) transmit antennas. Preferably, the multiple transmit antennas consist of two (2) transmit antennas, and each of the OFDMA symbols allocated to the pilot subcarriers includes a pilot subcarrier for the first transmit antenna and a pilot subcarrier for the second of two (2) transmit antennas ) transmitting antennas. Preferably, the resource block may consist of 4 subcarriers or 6 subcarriers.

In yet another aspect of the present invention, there is provided a wireless communication system having multiple transmit antennas using orthogonal frequency division multiple access (OFDMA) modulation, the wireless communication system comprising an antenna with multiple inputs and multiple outputs (MIMO); OFDMA modulator, operatively connected to the MIMO antenna; and a processor operatively connected to the OFDMA modulator, the processor being configured to allocate pilot subcarriers to the resource block such that only four (4) OFDMA symbols of the resource block are allocated to pilot subcarriers, the resource block having seven (7) OFDMA symbols , the plurality of index numbers of OFDMA symbols of four (4) OFDMA symbols is one of (0, 1, 5, 6), (0, 1, 4, 5) and (1, 2, 5, 6), and the plurality of index numbers (o, p, q, r) indicates the (o + 1) th OFDMA symbol, (p + 1) th OFDMA symbol, (q + 1) th OFDMA symbol and (r + 1) th OFDMA symbol in resource block.

In yet another aspect of the present invention, there is provided a wireless communication system having multiple transmit antennas using orthogonal frequency division multiple access (OFDMA) modulation, the wireless communication system comprising an antenna with multiple inputs and multiple outputs (MIMO); OFDMA modulator, operatively connected to the MIMO antenna; and a processor operatively coupled to the OFDMA modulator, the processor being configured to allocate pilot subcarriers to the resource block such that only four (4) OFDMA symbols of the resource block are allocated to pilot subcarriers in which the resource block has five (5) symbols OFDMA, OFDMA symbol index numbers of four (4) OFDMA symbols are 0, 1, 3, and 4, with the index number p indicating the (p + 1) th OFDMA symbol in the resource block.

Preferred Results

According to the present invention, pilot subcarriers can be efficiently allocated in a MIMO system.

Brief Description of the Drawings

The accompanying drawings, which are included to provide a better understanding of the invention, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

Figure 1 is a block diagram of a transmitter having multiple antennas.

Figure 2 is a block diagram of a receiver having multiple antennas.

Figure 3 - frame structure.

Figure 4 - the traditional configuration of the pilot signals of two transmitting antennas in the partial use of subchannels (PUSC).

5 is a traditional pilot configuration of two transmit antennas with full use of subchannels (FUSC).

6 is a traditional pilot configuration of four transmit antennas in a PUSC.

7 is a traditional pilot configuration of four transmit antennas in FUSC.

Figs. 8-11 are illustrative conventional structures used to extract pilot signals for a communication system with 2 transmit antennas for a normal subframe consisting of 6 OFDMA symbols.

12 is an illustrative conventional structure used to extract pilot signals for a communication system with 4 transmit antennas for a normal subframe consisting of 18 subcarriers and 6 OFDMA symbols.

13 is a pilot allocation structure for a mosaic tile consisting of 5 OFDMA symbols according to one embodiment of the invention.

Fig. 14 illustrates a pilot allocation structure for a tile consisting of 7 OFDMA symbols according to one embodiment of the invention.

15 and 16 are pilot allocation structures for a tile consisting of 7 OFDMA symbols according to one embodiment of the invention.

17 and 18 are pilot allocation structures for a subframe consisting of 5 OFDMA symbols according to one embodiment of the invention.

FIGS. 19 and 20 are pilot allocation structures for a subframe consisting of 7 OFDMA symbols according to one embodiment of the invention.

21-24 are pilot allocation structures for a subframe consisting of 7 OFDMA symbols according to one embodiment of the invention.

25 is a pilot allocation structure for a subframe consisting of 5 OFDMA symbols according to one embodiment of the invention.

26 is a pilot allocation structure for a subframe consisting of 7 OFDMA symbols according to one embodiment of the invention.

FIGS. 27 and 28 are pilot allocation structures for a subframe consisting of 7 OFDMA symbols according to one embodiment of the invention.

Embodiments of the invention

In the following detailed description, reference is made to the accompanying drawings, which form part thereof, in which, by way of illustration, specific embodiments of the invention are shown. It will be apparent to those skilled in the art that other embodiments may be used and structural, electrical as well as procedural changes may be made without departing from the scope of the present invention. If possible, the same conventions will be used throughout the drawings to indicate the same or similar elements.

The technology described below can be used in various wireless communication systems. A wireless communication system is widely used to provide various communication services, for example voice communication and packet data. This technology can be used on the downlink or on the uplink. In general, a downlink indicates a transmission from a base station (BS) to a user equipment (UE), and an uplink indicates a transmission from a UE to a BS. The BS generally indicates a fixed station communicating with the UE, and may also be called node-B, base transceiver system (BTS), or access point. The UE may be fixed or mobile and may also be called a mobile station (MS), a user terminal (UT), a subscriber station (SS), or a wireless device.

Next, we describe the effective pilot structure for the new system. The new system will be described using the IEEE 802.16m system as an example, but the same principles can be applied to other systems.

A communication system can be a system with many inputs and many outputs (MIMO) or a system with many inputs and one output (MISO). A MIMO system uses a plurality of transmit antennas and a plurality of receive antennas. The MISO system uses a combination of transmit antennas and one receive antenna.

Figure 1 shows a block diagram of a transmitter having multiple antennas. 1, a transmitter 100 includes a channel encoder 120, a display unit 130, a MIMO processor 140, a subcarrier allocation unit 150, and an orthogonal frequency division multiple access (OFDMA) modulator 160. The channel encoder 120, the display unit 130, the MIMO processor 140, and the subcarrier allocation unit 150 may be implemented as separate components or may be combined in a single processor of the transmitter 100.

Channel encoder 120 encodes the input stream according to a predetermined encoding method and creates an encoded word. The display unit 130 maps the encoded word to a symbol representing a position in the signal vector diagram. The modulation scheme of the display unit 130 is not limited and may include an m-ary phase shift keying (m-PSK) scheme or an m-ary quadrature amplitude modulation (m-QAM) scheme.

The MIMO processor 140 processes the input symbol according to the MIMO method using a combination of transmit antennas 190-1, ..., and 190-Nt. For example, the MIMO processor 140 may perform precoding based on a codebook.

A subcarrier allocator 150 allocates an input symbol and pilot signals to subcarriers. The pilot signals are arranged according to the transmit antennas 190-1, ..., and 190-Nt. Pilot signals are known to transmitter 100 and receiver (200 in FIG. 2), which is used for channel estimation or demodulation of data, and they are also referred to as reference signals.

An OFDMA modulator 160 modulates the input symbol and outputs OFDMA symbols. The OFDMA 160 modulator can perform the inverse fast Fourier transform (IFFT) on the input symbol and optionally insert a cyclic prefix (CP) after the implementation of the IFFT. OFDMA symbols are transmitted through transmit antennas 190-1, ... and 190-Nt.

Figure 2 shows a block diagram of a receiver having multiple antennas. 2, the receiver 200 includes an OFDMA demodulator 210, a channel estimation unit 220, a MIMO post processor 230, a mapper 240 and a channel decoder 250. A channel estimator 220, a MIMO post processor 230, a mapper 240 and a channel decoder 250 may be implemented as separate components or may be combined in one processor of the receiver 200.

Signals received through receive antennas 290-1, ... and 290-Nr undergo fast Fourier transform (FFT) on an OFDMA 210 demodulator. Channel estimator 220 estimates the channels using pilot signals. The MIMO 230 post-processor performs post-processing corresponding to the MIMO 140 processor. The mapper 240 removes the mapping of the input character into the encoded word. Channel decoder 250 decodes the encoded word and restores the original data.

Figure 3 shows an example frame structure. A frame is a sequence of data over a fixed period of time used by a physical specification that refers to section 8.4.4.2 of the IEEE 802.16-2004 standard "Part 16: Air Interface for Fixed Broadband Wireless Access Systems" (hereinafter referred to as reference document 1, the contents of which are in full included here by reference).

3, a frame includes a downlink (DL) frame and an uplink (UL) frame. Time Division Duplex (TDD) is a scheme in which transmissions on the uplink and downlink are separated in the time dimension, but use the same frequency. Typically, a DL frame precedes a UL frame. A DL frame consists, in that order, of a preamble, a frame check header (FCH), Downlink (DL) -MAP, Uplink (UL) -MAP and pulse regions (pulse DL # 1-5 and pulse UL # 1-5). A guard interval separating the DL frame and the UL frame from each other is inserted both in the intermediate part of the frame (between the DL frame and the UL frame) and in the last part of the frame (after the UL frame). A Transmit / Receive Transition Clearance (TTG) is a gap defined between a downlink pulse and a subsequent uplink pulse. The transmit / receive transition gap (RTG) is the gap defined between the uplink pulse and the subsequent downlink pulse.

The preamble is used for initial synchronization between the BS and the UE, cell search, frequency offset estimation, and channel estimation. The FCH includes information regarding the length of the DL-MAP message and the DL-MAP coding scheme. DL-MAP is the area where the DL-MAP message is transmitted. The DL-MAP message specifies the access channel downlink. The DL-MAP message includes a downlink channel descriptor (DCD) configuration change counter and a BS identifier (ID). The DCD describes a downlink pulse profile applied to the current frame. The downlink pulse profile refers to the property of the physical downlink channel, and the DCD is periodically transmitted by the BS through the DCD message.

UL-MAP is the area where the UL-MAP message is transmitted. The UL-MAP message specifies uplink channel access. The UL-MAP message includes an uplink channel descriptor (UCD) configuration change counter and an effective initial uplink allocation time specified by the UL-MAP. UCD describes the uplink pulse profile. The uplink impulse profile refers to the property of the physical uplink channel, and the UCD is periodically transmitted by the BS through the UCD message.

Further, a slot is called the minimum unit of data allocation, and it is set by time and subchannel. The number of subchannels depends on the size of the FFT and the time-frequency display. A subchannel includes a plurality of subcarriers, and the number of subcarriers per subchannel varies according to a permutation method. The permutation indicates the mapping of the logical subchannel to the physical subcarrier. The subchannel includes 48 subcarriers with full use of subchannels (FUSC) and the subchannel includes 24 or 16 subcarriers with partial use of subchannels (PUSC). A segment indicates at least one plurality of subchannels.

The mapping of data to physical subcarriers at the physical level is usually carried out in two stages. In a first step, data is mapped to at least one data slot on at least one logical subchannel. In a second step, the logical subchannel is mapped to the physical subchannel. This is called a permutation. Reference document 1 discloses a permutation method, for example, FUSC, PUSC, Optimal-FUSC (O-FUSC), Optional-PUSC (O-PUSC) and adaptive modulation and coding (AMC). A plurality of OFDMA symbols using the same permutation method is called a permutation zone, and one frame includes at least one permutation zone.

FUSC and O-FUSC are used only for downlink transmission. FUSC consists of one segment, which includes all groups of subchannels. Subchannels are mapped to physical subcarriers distributed across all physical channels. The display changes according to the OFDMA symbols. The slot consists of one subchannel on one OFDMA symbol. The methods for extracting pilot signals in O-FUSC and FUSC are different from each other.

PUSC is used for downlink transmission and uplink transmission. On the downlink, each physical channel is divided into clusters comprising 14 consecutive subcarriers on two OFDMA symbols. The physical channel is displayed in units of six groups. In each group, pilot signals are allocated to clusters in fixed positions. On the uplink, subcarriers are divided into tiles consisting of four consecutive physical subcarriers on three OFDMA symbols. The subchannel includes six mosaic elements. Pilot signals are allocated to the corners of the mosaic elements. O-PUSC is used only for uplink transmission, and the tile consists of three consecutive physical subcarriers on three OFDMA symbols. Pilot signals are allocated to the centers of mosaic elements.

Figures 4 and 5 show a conventional pilot configuration of two transmit antennas in PUSC and FUSC, respectively. Figures 6 and 7 show the traditional pilot configuration of four transmit antennas in PUSC and FUSC, respectively. These relate to Section 8.4.8.1.2.1.1, Section 8.4.8.1.2.1.2, Section 8.4.8.2.1, and Section 8.4.8.2.2 of the IEEE 802.16-2004 / Cor1-2005 "Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems; Amendment 2: Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands and Corrigendum 1 "(hereinafter referred to as Reference Document 2, the entire contents of which are hereby incorporated by reference).

4-7, the pilot overhead is large when the subcarrier is allocated according to PUSC or FUSC. In particular, the overhead is greater when using one transmit antenna than when using at least two transmit antennas, taking into account the overhead of the pilot signals per transmitter antenna.

Table 1 shows the pilot overhead according to the number of transmit antennas in each permutation method.

Table 1 Number of Transmitting Antennas PUSC FUSC O-FUSC one 14.28% (14.28%) 9.75% (9.75%) 11.1% (11.1%) 2 14.28% (7.14%) 9.75% (4.78%) 11.1% (5.55%) four 28.55% (7.14%) 18.09% (4.52%) 22.21% (5.55%)

Pilot overhead is the value obtained by dividing the number of subcarriers allocated to the pilot signals by the total number of subcarriers used. The value in parentheses indicates the overhead of the pilot signals per transmitter antenna. In addition, according to Reference Document 2, when using four or three transmit antennas, data is displayed in subchannels after perforation or truncation with respect to channel-encoded data.

In a conventional pilot allocation method, pilot signals are allocated for a normal subframe of 6 OFDMA symbols, known as a regular subframe. In the prior art, there are only irregular subframes consisting of 5 or 7 OFDMA symbols, but they are not allocated pilot signals.

FIGS. 8–11 show illustrative conventional structures used to extract pilot signals for a communication system with 2 transmit antennas for a normal subframe of 6 OFDMA symbols. 12 shows an illustrative conventional structure used to extract pilot signals for a communication system with 4 transmit antennas for a normal subframe of 6 OFDMA symbols. 8-12, the horizontal axis (index symbol 'j') indicates a plurality of OFDMA symbols in the time dimension, and the vertical axis (index symbol 'i') indicates subcarriers in the frequency dimension. In addition, P0, P1, P2, and P3 denote pilot subcarriers corresponding to antennas 1, 2, 3, and 4, respectively.

FIG. 8 shows an illustrative conventional method for allocating pilot signals for a single resource block in the form of an 18 * 6 matrix structure representing 18 subcarriers and 6 OFDMA symbols.

FIG. 9 shows an illustrative conventional method for extracting pilot signals for a mosaic tile in the form of a 6 * 6 matrix structure representing 6 subcarriers and 6 OFDMA symbols.

10 and 11 show the first and second traditional illustrative methods for extracting pilot signals for a mosaic tile in the form of a 4 * 6 matrix structure representing 4 subcarriers and 6 OFDMA symbols, respectively.

12 shows an illustrative conventional method for allocating pilot signals for a single resource block in the form of an 18 * 6 matrix structure representing 18 subcarriers and 6 OFDMA symbols.

Traditional pilot extraction methods only support a normal 6-OFDMA subframe. However, the new version of IEEE 802.16m defines a subframe consisting of 5 OFDMA symbols (hereinafter also referred to as an "irregular subframe" of the "abbreviated subframe") or a subframe consisting of 7 OFDMA symbols (hereinafter also referred to as an "irregular subframe" or an "extended subframe"). Accordingly, it is necessary to provide new methods for extracting pilot signals to optimize channel estimation performance in new communication systems.

Effective pilot allocation structures according to embodiments of the present invention are described below for a subframe with 5 OFDMA symbols or 7 OFDMA symbols other than a normal subframe with 6 OFDMA symbols. In the following embodiments, the horizontal axis (index symbol 'j') indicates a sequence of OFDMA symbols in the time dimension, and the vertical axis (index symbol 'i') indicates subcarriers in the frequency dimension. P0, P1, P2, and P3 denote pilot subcarriers corresponding to antenna 1, antenna 2, antenna 3, and antenna 4, respectively. Pilot signals for antennas can exchange positions without departing from the principles of the embodiment. In addition, the present invention can be applied to an MBS system (broadcast multicast system), as well as to a unicast service system.

Embodiments for a Tx 2 System

Consider embodiments 1-6 for a 2 Tx system.

For a communication system with 2 transmit antennas, the pilot allocation methods for the aforementioned extended / reduced subframes according to the present invention are slightly modified schemes compared to the pilot extraction methods for a normal subframe shown above. If the communication system simultaneously supports a large number of methods and modules for channel estimation, service loads increase unnecessarily. Therefore, the methods for allocating pilot signals for a normal subframe need not be significantly modified to introduce a method for allocating pilot signals for extended / reduced subframes.

According to the present invention, when a subframe consists of a number of OFDMA symbols other than 6 OFDMA symbols, the pilot allocation method for the extended / reduced subframe is implemented by adding a “OFDMA symbol column” in the pilot allocation structure of the normal subframe or by removing one “column OFDMA symbol "in the normal subframe pilot allocation structure (hereinafter, the term" OFDMA symbol column "indicates a plurality of OFDMA symbol subcarriers in a resource block for allocating pilot signals). Thus, in the case of a subframe consisting of 7 OFDMA symbols (i.e., an extended subframe), the conventional pilot allocation of a normal subframe is applied to the extended subframe, except that an "OFDMA symbol column" is inserted or added to it. In another case, for a subframe consisting of 5 OFDMA symbols (i.e., an abbreviated subframe), the conventional pilot allocation of a normal subframe is applied to the abbreviated subframe, except that the "OFDMA symbol column" is removed from it. Further, the term “column” is used to describe in this application instead of the term “OFDMA symbol column” for convenience and clarity.

To construct a subframe consisting of 7 OFDM symbols (i.e., an extended subframe), the pilot extraction method according to an embodiment of the present invention may include the step of copying the 'column' that is allocated to the pilot subcarriers from the normal pilot extraction structure subframe, and the step of adding the copied 'column' to the first OFDMA symbol of the normal subframe pilot allocation structure or after the last OFDMA symbol of the normal subframe pilot allocation structure. Preferably, the first “column” or the last “column” is not selected for copying, because if the first or last column is copied and added before the first OFDMA symbol or after the last OFDMA symbol, two pilot subcarriers are sequentially allocated along the time axis on the same subcarrier, in a subframe or between two adjacent subframes, resulting in reduced channel estimation performance. Therefore, preferably a second OFDMA symbol or a fifth OFDMA symbol is selected for copying.

To construct a subframe consisting of 7 OFDMA symbols (i.e., an extended subframe), the pilot allocation method according to an embodiment of the present invention may comprise the step of copying a 'column' that is not allocated to pilot subcarriers from the pilot allocation structure a normal subframe, and the step of adding the copied 'column' to the first OFDMA symbol of the normal subframe pilot allocation structure or after the last OFDMA symbol of the normal subframe pilot allocation structure.

Obviously, simply adding a column that is not allocated for pilot subcarriers leads to the same structure as before.

To construct a subframe consisting of 7 OFDMA symbols (i.e., an extended subframe), the pilot allocation method according to an embodiment of the present invention may comprise the step of copying a 'column' that is not allocated to pilot subcarriers from the pilot allocation structure a normal subframe, and the step of adding the copied 'column' to any place between the first OFDMA symbol and the last OFDMA symbol of the pilot subframe allocation structure of the normal subframe.

Incidentally, it is obvious that simply adding a column that is not reserved for pilot subcarriers leads to the same structure as before.

A “basic mosaic element” in the form of a 6 * 6 matrix structure representing 6 subcarriers and 6 OFDMA symbols is defined for embodiments 1-3 for description. The mosaic element shown in FIG. 9 serves as a basic mosaic element of size 6 * 6 for embodiments 1-3. In these embodiments, the “OFDMA symbol column” (hereinafter referred to as the “column”) in the 6 * 6 base mosaic element is copied and then added or pasted into the 6 * 6 base mosaic element to construct a mosaic element consisting of 7 OFDMA symbols (t .e. expanded mosaic element); otherwise, the 'column' is removed from the base mosaic element of size 6 * 6 to construct a mosaic element consisting of 5 OFDMA symbols (i.e., a shortened mosaic element).

<Embodiment 1>

13 shows a pilot allocation structure for a tile consisting of 5 OFDMA symbols (i.e., abbreviated tile).

To construct a mosaic element consisting of 5 OFDMA symbols (i.e., abbreviated mosaic element), the method for extracting pilot signals according to an embodiment of the present invention may include the step of removing the 'column' from the above described 6 * 6 mosaic base element. In this case, the third or fourth column is removed from the base mosaic element of size 6 * 6.

In the pilot allocation structure shown in FIG. 13, the position where the pilot signals are allocated for each antenna is presented in detail as follows:

<Pilot allocation index for FIG. 13>

Antenna 1 -

I (k) = 6k, for OFDMA symbols, where s is 0

I (k) = 6k + 5, for OFDMA symbols, where s is 1

I (k) = 6k, for OFDMA symbols, where s is 3

I (k) = 6k + 5, for OFDMA symbols, where s is 4

Antenna 2 -

I (k) = 6k + 5, for OFDMA symbols, where s is 0

I (k) = 6k, for OFDMA symbols, where s is 1

I (k) = 6k + 5, for OFDMA symbols, where s is 3

I (k) = 6k, for OFDMA symbols, where s is 4

where I (k): subcarrier index (k = 0, 1, ...),

s: [OFDMA symbol index j] mod 5

(OFDMA symbol index j = 0, 1, 2, ...)

<Embodiment 2>

14 shows a pilot allocation structure for a tile consisting of 7 OFDMA symbols (i.e., an extended tile).

To construct a mosaic element consisting of 7 OFDMA symbols (i.e., an extended mosaic element), the pilot extraction method according to an embodiment of the present invention may include the step of inserting a 'column' that is not allocated for the pilot subcarrier anywhere between the second OFDMA symbol and the fifth OFDMA symbol of the base mosaic element 6 * 6.

In the pilot allocation structure shown in FIG. 14, the position where the pilot signals are allocated for each antenna is presented in detail as follows:

<Pilot allocation index for Fig. 14>

Antenna 1 -

I (k) = 6k, for OFDMA symbols, where s is 0

I (k) = 6k + 5, for OFDMA symbols, where s is 1

I (k) = 6k, for OFDMA symbols, where s is 5

I (k) = 6k + 5, for OFDMA symbols, where s is 6

Antenna 2 -

I (k) = 6k + 5, for OFDMA symbols, where s is 0

I (k) = 6k, for OFDMA symbols, where s is 1

I (k) = 6k + 5, for OFDMA symbols, where s is 5

I (k) = 6k, for OFDMA symbols, where s is 6

where I (k): subcarrier index (k = 0, 1, ...),

s: [OFDMA symbol index j] mod 7

(OFDMA symbol index j = 0,1,2, ...)

<Embodiment 3>

FIGS. 15 and 16 show pilot allocation structures for a tile consisting of 7 OFDMA symbols (i.e., an extended tile).

To construct a tile consisting of 7 OFDMA symbols (i.e., an extended tile), the pilot extraction method according to an embodiment of the present invention may include the step of adding a 'column' that is not allocated for the pilot subcarrier before the first OFDMA symbol patterns of allocation of pilot signals of the basic mosaic element of size 6 * 6 (Fig. 16) or after the last OFDMA symbol of the structure of the allocation of pilot signals of the basic mosaic element of size 6 * 6 (Fig. 15).

Alternatively, the pilot extraction method may include the step of copying the 'column' that is not allocated for the pilot subcarriers from the pilot extraction structure of the 6 * 6 base tile, and the step of adding the copied 'column' to the first OFDMA symbol of the allocation structure the pilot signals of the base mosaic element of size 6 * 6 (Fig. 16) or after the last OFDMA symbol of the allocation structure of the pilot signals of the basic mosaic element of size 6 * 6 (Fig. 15).

In the pilot allocation structure shown in FIGS. 15 and 16, the position where the pilot signals are allocated for each antenna is presented in detail as follows:

<Pilot allocation index for Fig. 15>

Antenna 1 -

I (k) = 6k, for OFDMA symbols, where s is 0

I (k) = 6k + 5, for OFDMA symbols, where s is 1

I (k) = 6k, for OFDMA symbols, where s is 4

I (k) = 6k + 5, for OFDMA symbols, where s is 5

Antenna 2 -

I (k) = 6k + 5, for OFDMA symbols, where s is 0

I (k) = 6k, for OFDMA symbols, where s is 1

I (k) = 6k + 5, for OFDMA symbols, where s is 4

I (k) = 6k, for OFDMA symbols, where s is 5

where I (k): subcarrier index (k = 0, 1, ...),

s: [OFDMA symbol index j] mod 7

(OFDMA symbol index j = 0, 1, 2, ...)

<Pilot allocation index for Fig. 16>

Antenna 1 -

I (k) = 6k, for OFDMA symbols, where s is 1

I (k) = 6k + 5, for OFDMA symbols, where s is 2

I (k) = 6k, for OFDMA symbols, where s is 5

I (k) = 6k + 5, for OFDMA symbols, where s is 6

Antenna 2 -

I (k) = 6k + 5, for OFDMA symbols, where s is 1

I (k) = 6k, for OFDMA symbols, where s is 2

I (k) = 6k + 5, for OFDMA symbols, where s is 5

I (k) = 6k, for OFDMA symbols, where s is 6

where I (k): subcarrier index (k = 0, 1, ...),

s: [OFDMA symbol index j] mod 7

(OFDMA symbol index j = 0, 1, 2, ...)

As a result, embodiments 1-3 of the present invention shown in FIGS. 13-16 are improvements of the conventional pilot allocation scheme shown in FIG. 9.

A normal subframe in the form of a 4 * 6 matrix structure representing 4 subcarriers and 6 OFDMA symbols is defined for embodiments 4-6 for description. The subframe shown in FIGS. 10 or 11 serves as a normal subframe for embodiments 4-6. In these embodiments, the “OFDMA symbol column” (hereinafter referred to as the “column”) of a normal 6 * 6 subframe is copied and then added or pasted into a normal 6 * 6 subframe to construct a subframe consisting of 7 OFDMA symbols (i.e., extended subframe); otherwise, the 'column' is removed from the normal 6 * 6 subframe to construct a subframe consisting of 5 OFDMA symbols (i.e., a shortened subframe).

<Embodiment 4>

17 and 18 show pilot allocation structures for a subframe consisting of 5 OFDMA symbols (i.e., a shortened subframe).

To construct a subframe consisting of 5 OFDMA symbols (i.e., an abbreviated subframe), a pilot extraction method according to an embodiment of the present invention may include the step of removing the 'column' from the above normal subframe. In this case, the third or fourth column of the normal subframe is deleted from the normal subframe. The pilot allocation shown in FIG. 17 is constructed from the pilot allocation shown in FIG. 10, and the pilot allocation shown in FIG. 18 is constructed from the pilot allocation shown in FIG. 11.

According to FIG. 17, provided that l indicates OFDMA symbols in a subframe that contains 5 OFDMA symbols, a pilot subcarrier allocated on the i- th antenna, an OFDMA symbol with index l and s -th tile are defined as follows:

In the pilot allocation structure shown in FIG. 18, the position where the pilot signals are allocated for each antenna is represented in detail as follows:

<Pilot allocation index for Fig. 18>

Antenna 1 -

I (k) = 4k, for OFDMA symbols, where s is 0

I (k) = 4k + 2, for OFDMA symbols, where s is 1

I (k) = 4k + 1, for OFDMA symbols, where s is 3

I (k) = 4k + 3, for OFDMA symbols, where s is 4

Antenna 2 -

I (k) = 4k + 1, for OFDMA symbols, where s is 0

I (k) = 4k + 3, for OFDMA symbols, where s is 1

I (k) = 4k, for OFDMA symbols, where s is 3

I (k) = 4k + 2, for OFDMA symbols, where s is 4

where I (k): subcarrier index (k = 0, 1, ...),

s: [OFDMA symbol index j] mod 5

(OFDMA symbol index j = 0, 1, 2, ...)

<Embodiment 5>

19 and 20 show pilot allocation structures for a subframe consisting of 7 OFDMA symbols (i.e., an extended subframe).

To construct a subframe consisting of 7 OFDMA symbols (i.e., an extended subframe), the pilot extraction method according to an embodiment of the present invention may include the step of inserting a 'column' that is not allocated for the pilot subcarrier to any place between the second an OFDMA symbol and a fifth OFDMA symbol of a normal subframe.

Alternatively, the pilot extraction method according to an embodiment of the present invention may include a 'column' copy step that is not allocated for pilot subcarriers from the normal subframe pilot extraction structure, and a step of pasting the copied 'column' anywhere between the second character OFDMA and the fifth OFDMA symbol of a normal subframe.

The pilot allocation shown in FIG. 19 is constructed from the pilot allocation shown in FIG. 10, and the pilot allocation shown in FIG. 20 is constructed from the pilot allocation shown in FIG. 11.

According to FIG. 19, provided that l indicates OFDMA symbols in a subframe that contains 5 OFDMA symbols, the pilot subcarrier allocated on the i- th antenna, the l- th OFDMA symbol and the s- th tile are defined as follows:

In the pilot allocation structure shown in FIG. 20, the pilot allocation indices for antennas can be represented in detail as follows.

<Pilot allocation index for Fig. 20>

Antenna 1 -

I (k) = 4k, for OFDMA symbols, where s is 0

I (k) = 4k + 2, for OFDMA symbols, where s is 1

I (k) = 4k + 1, for OFDMA symbols, where s is 5

I (k) = 4k + 3, for OFDMA symbols, where s is 6

Antenna 2 -

I (k) = 4k + 1, for OFDMA symbols, where s is 0

I (k) = 4k + 3, for OFDMA symbols, where s is 1

I (k) = 4k, for OFDMA symbols, where s is 5

I (k) = 4k + 2, for OFDMA symbols, where s is 6

where I (k): subcarrier index (k = 0, 1, ...),

s: [OFDMA symbol index j] mod 7

(OFDMA symbol index j = 0, 1, 2, ...)

<Embodiment 6>

21-24, pilot allocation structures for a subframe consisting of 7 OFDMA symbols (i.e., an extended subframe) are shown.

To construct a subframe consisting of 7 OFDMA symbols (i.e., an extended subframe), the pilot allocation method according to an embodiment of the present invention may comprise adding a 'column' that is not allocated for the pilot subcarrier to the first OFDMA symbol of the structure normal pilot subframe allocation (FIG. 23 or FIG. 24) or after the last OFDMA symbol of the normal subframe pilot allocation structure (FIG. 21 or 22).

Alternatively, the pilot extraction method according to an embodiment of the present invention may comprise a 'column' copy step that is not allocated for pilot subcarriers from the normal subframe pilot extraction structure, and a step of adding the copied 'column' to the first OFDMA symbol of the allocation structure the normal subframe pilot (FIG. 23 or FIG. 24) or after the last OFDMA symbol of the normal subframe pilot allocation structure (FIG. 21 or 22).

The pilot allocations shown in FIGS. 21 and 23 are constructed from the pilot allocations shown in FIG. 10, and the pilot allocations shown in FIGS. 22 and 24 are constructed from the pilot allocations shown in FIG. .eleven.

In the pilot allocation structure shown in FIGS. 21-24, the pilot allocation indices for antennas can be represented in detail as follows.

As shown in FIG. 21, provided that l indicates OFDMA symbols in a subframe that contains 7 OFDMA symbols and l ∈ {0,1,4,5}, the pilot subcarrier allocated on the i- th antenna, l- th symbol and OFDMA tile s s are defined as follows:

In the pilot allocation structure shown in FIG. 22, the position where the pilot signals are allocated for each antenna is presented in detail as follows:

<Pilot allocation index for Fig. 22>

Antenna 1 -

I (k) = 4k, for OFDMA symbols, where s is 0

I (k) = 4k + 2, for OFDMA symbols, where s is 1

I (k) = 4k + 1, for OFDMA symbols, where s is 4

I (k) = 4k + 3, for OFDMA symbols, where s is 5

Antenna 2 -

I (k) = 4k + 1, for OFDMA symbols, where s is 0

I (k) = 4k + 3, for OFDMA symbols, where s is 1

I (k) = 4k, for OFDMA symbols, where s is 4

I (k) = 4k + 2, for OFDMA symbols, where s is 5

where I (k): subcarrier index (k = 0, 1, ...),

s: [OFDMA symbol index j] mod 7

(OFDMA symbol index j = 0, 1, 2, ...)

23, provided that l indicates OFDMA symbols in a subframe that contains 7 OFDMA symbols and l ∈ {1,2,5,6}, the pilot subcarrier allocated on the i- th antenna, l- th symbol and OFDMA tile s s are defined as follows.

<Pilot allocation index for Fig. 23>

Antenna 1 -

I (k) = 4k, for OFDMA symbols, where s is 1

I (k) = 4k + 2, for OFDMA symbols, where s is 2

I (k) = 4k, for OFDMA symbols, where s is 5

I (k) = 4k + 2, for OFDMA symbols, where s is 6

Antenna 2 -

I (k) = 4k + 1, for OFDMA symbols, where s is 1

I (k) = 4k + 3, for OFDMA symbols, where s is 2

I (k) = 4k + 1, for OFDMA symbols, where s is 5

I (k) = 4k + 3, for OFDMA symbols, where s is 6

where I (k): subcarrier index (k = 0, 1, ...),

s: [OFDMA symbol index j] mod 7

(OFDMA symbol index j = 0, 1, 2, ...)

In the pilot allocation structure shown in FIG. 24, the position where the pilot signals are allocated for each antenna is presented in detail as follows:

<Pilot allocation index for Fig. 24>

Antenna 1 -

I (k) = 4k, for OFDMA symbols, where s is 1

I (k) = 4k + 2, for OFDMA symbols, where s is 2

I (k) = 4k + 1, for OFDMA symbols, where s is 5

I (k) = 4k + 3, for OFDMA symbols, where s is 6

Antenna 2 -

I (k) = 4k + 1, for OFDMA symbols, where s is 1

I (k) = 4k + 3, for OFDMA symbols, where s is 2

I (k) = 4k, for OFDMA symbols, where s is 5

I (k) = 4k + 2, for OFDMA symbols, where s is 6

where I (k): subcarrier index (k = 0, 1, ...),

s: [OFDMA symbol index j] mod 7

(OFDMA symbol index j = 0, 1, 2, ...)

In summary, the embodiments of the present invention shown in FIGS. 17, 19, 21, 23 are enhancements to the conventional pilot allocations shown in FIG. 10; and the embodiments of the present invention shown in FIGS. 18, 20, 22 and 24 are enhancements to the conventional pilot allocations shown in FIG. 11.

Embodiments for a 4 Tx System

Consider embodiments 7-9 for a 4 Tx system.

A normal subframe in the form of an 18 * 6 matrix structure representing 18 subcarriers and 6 OFDMA symbols is defined for embodiments 10-12 for description. The subframe shown in FIG. 12 serves as a normal subframe for embodiments 7-9. In these embodiments, the “OFDMA symbol column” (hereinafter referred to as the “column”) of a normal 6 * 6 subframe is copied and then added or pasted into a normal 6 * 6 subframe to construct a subframe consisting of 7 OFDMA symbols (i.e., extended subframe); otherwise, the 'column' is removed from the normal 6 * 6 subframe to construct a subframe consisting of 5 OFDMA symbols (i.e., a shortened subframe).

<Embodiment 7>

25 shows a pilot allocation structure for a subframe consisting of 5 OFDMA symbols (i.e., a shortened subframe).

To construct a subframe consisting of 5 OFDMA symbols (i.e., an abbreviated subframe), a pilot extraction method according to an embodiment of the present invention may include the step of removing the 'column' from the above normal subframe. In this case, the third or fourth column is removed from the normal subframe.

In the pilot allocation structure shown in FIG. 25, the pilot allocation indices for antennas can be represented in detail as follows.

With the proviso that l indicates OFDMA symbols in the subframe that comprises of 5 OFDMA symbols, and l ∈ {0,1,3,4}, the pilot subcarrier allocated to i -th antenna, l -th OFDMA symbol, and k - th PRUs are defined as follows:

If

If

<Embodiment 8>

26 shows a pilot allocation structure for a subframe consisting of 7 OFDMA symbols (i.e., an extended subframe).

To construct a subframe consisting of 7 OFDMA symbols (i.e., an extended subframe), the pilot extraction method according to an embodiment of the present invention may include the step of inserting a 'column' that is not allocated for the pilot subcarrier to any place between the second OFDMA symbol and fifth OFDMA symbol.

Alternatively, the pilot extraction method according to an embodiment of the present invention may include a 'column' copy step that is not allocated for pilot subcarriers from the normal subframe pilot extraction structure, and a step of pasting the copied 'column' anywhere between the second character OFDMA and the fifth OFDMA symbol of a normal subframe.

In the pilot allocation structure shown in FIG. 26, the pilot allocation indices for antennas can be represented in detail as follows.

With the proviso that l indicates OFDMA symbols in the subframe that comprises 7 OFDMA symbols and l ∈ {0,1,5,6}, the pilot subcarrier allocated to i -th antenna, l -th OFDMA symbol, and k - th PRUs are defined as follows:

If

If

<Embodiment 9>

FIGS. 27 and 28 show pilot allocation structures for a subframe consisting of 7 OFDMA symbols (i.e., an extended subframe).

To construct a subframe consisting of 7 OFDMA symbols (i.e., an extended subframe), the pilot allocation method according to an embodiment of the present invention may comprise adding a 'column' that is not allocated for the pilot subcarrier to the first OFDMA symbol of the structure allocating the pilot signals of the normal subframe (FIG. 28) or after the last OFDMA symbol of the pilot allocation structure of the normal subframe (FIG. 27).

Alternatively, the pilot extraction method according to an embodiment of the present invention may comprise a 'column' copy step that is not allocated for pilot subcarriers from the normal subframe pilot extraction structure, and a step of adding the copied 'column' to the first OFDMA symbol of the allocation structure normal subframe pilot (FIG. 28) or after the last OFDMA symbol of the normal subframe pilot allocation structure (FIG. 27).

In the pilot allocation structure shown in FIGS. 27 and 28, the pilot allocation indices for antennas can be represented in detail as follows.

27, provided that l indicates OFDMA symbols in a subframe that contains 7 OFDMA symbols, and l ∈ {0,1,4,5}, the pilot subcarrier allocated on the i- th antenna, l- th symbol OFDMA and k- th PRU are defined as follows:

According to FIG. 28, provided that l indicates OFDMA symbols in a subframe that contains 7 OFDMA symbols, and l ∈ {1,2,5,6}, the pilot subcarrier allocated on the i- th antenna, l- th symbol OFDMA and k- th PRU are defined as follows:

As a result, embodiments 7-9 of the present invention shown in FIGS. 25-28 are enhancements to the conventional pilot allocations shown in FIG. 12. These enhancements are shown in Table 2.

table 2 Number of antennas Fig.25 Fig.26 Fig.27 Fig.28 one 4.444% 3,174% 3,174% 3,174% 2 8.888% (4.444% per flow) 6.348% (3.174% per flow) 6.348% (3.174% per flow) 6.348% (3.174% per flow) four 17.776% (4.444% per flow) 12.696% (3.174% per flow) 12.696% (3.174% per flow) 12.696% (3.174% per flow)

In addition, the pilot allocation structure shown in FIG. 27 provides better performance than the pilot allocation structure shown in FIG. 26, since the distance between the pilot symbols does not increase, and thus the channel estimate does not deteriorate. In addition, the pilot allocation structure shown in FIG. 27 is easier to implement than the pilot allocation structure shown in FIG. 28 with respect to interoperability / simplification with respect to backward compatibility with conventional pilot allocations.

For all of the above embodiments of the present invention, a portion of the pilot subcarriers for the transmit antennas can be used for the common pilot signal, and another portion of the pilot subcarriers for the transmit antennas can be used for the dedicated pilot signal. Alternatively, all pilot subcarriers for transmitting antennas can be used for a common pilot, otherwise, all pilot subcarriers for transmitting antennas can be used for a dedicated pilot.

In addition, the use of data subcarriers other than pilot subcarriers, which are sequentially allocated, allows sequentially pairing the data subcarriers by a value (s) of a multiple of 2. As a result, the MIMO scheme for SFBC (space-frequency block code) can be easily applied. ) and common pilots and dedicated pilots are effectively applied. Thus, by separating the pilot symbols according to at least one of the above embodiments, the SFBC scheme can be applied. In addition, by grouping the pilot signals as even pairs in the time dimension, a space-time block code (STBC) scheme can be applied.

The above discussion included a reference to OFDMA modulation. However, the present invention is also applicable to orthogonal frequency division multiplexing (OFDM) scenarios.

The above functions can be performed by a processor, for example, a microprocessor, a controller, a microcontroller, or a specialized integrated circuit (ASIC), which is encoded to carry out the functions. The design, development and implementation of the code is obvious to those skilled in the art based on the description of the present invention.

The pilot subcarrier allocation method of the present invention is applicable to an IEEE 802.16m system. As described above, a basic principle, for example, the configuration of the pilot signals to evenly transmit the transmit power to the antennas or the generation of a pilot-shifted pattern, is also applicable to other wireless communication systems in the same way.

Specialists in the art can propose various modifications and variations of the present invention without going beyond the essence or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Industrial application

The present invention can be used for a network device of a wireless mobile communication system.

Claims (24)

1. A communication method with a wireless communication device, comprising the steps of:
receiving an orthogonal frequency division multiple access (OFDMA) signal transmitted from an antenna system with multiple inputs and multiple outputs (MIMO), wherein the OFDMA signal is received using one or more resource blocks, with each resource block having an 18 × 7 matrix form representing 18 subcarriers and 7 OFDMA symbols; and
perform channel estimation based on four pilot signals corresponding to four streams, and four pilot signals are distributed only on the 1st, 2nd, 5th and 6th OFDMA symbols of 7 OFDMA symbols,
wherein in each OFDMA symbol containing pilot subcarriers, the first and second emerging pilot subcarriers are separated by four subcarriers, the second and third emerging pilot subcarriers are divided by six subcarriers, and the third and fourth emerging pilot subcarriers are divided by four subcarriers,
moreover, in each OFDMA symbol containing pilot subcarriers, the first to fourth emerging pilot subcarriers correspond to four antennas. 2. The method of claim 1, wherein the four pilot subcarriers include pilot subcarriers P0, P1, P2, and P3, the pilot subcarriers P0, P1, P2, and P3 being the first, second, third, and fourth emerging pilot subcarriers in the first OFDMA symbol. 3. The method according to claim 2, in which the pilot subcarriers P2, P3, P0 and P1 are the first, second, third and fourth arising pilot subcarriers in the second OFDMA symbol. 4. The method of claim 1, wherein the four pilot subcarriers include pilot subcarriers P0, P1, P2, and P3, and the pilot subcarriers P1, P0, P3, and P2 are the first, second, third, and fourth emerging pilot subcarriers in the fifth OFDMA symbol. 5. The method according to claim 4, in which the pilot subcarriers P3, P2, P1 and P0 are the first, second, third and fourth arising pilot subcarriers in the sixth OFDMA symbol. 6. The method of claim 1, further comprising MIMO post-processing the output of the channel estimation execution step. 7. A method of communication with a wireless communication device, comprising the steps of:
receiving an orthogonal frequency division multiple access (OFDMA) signal transmitted from an antenna system with multiple inputs and multiple outputs (MIMO), wherein the OFDMA signal is received using one or more resource blocks, with each resource block having the form of an 18 × 5 matrix representing 18 subcarriers and 5 OFDMA symbols; and
perform channel estimation based on four pilot signals corresponding to four streams, and four pilot signals are distributed only on the 1st, 2nd, 4th and 5th OFDMA symbols of 5 OFDMA symbols,
wherein in each OFDMA symbol containing pilot subcarriers, the first and second occurring pilot subcarriers are divided by four subcarriers, the second and third arising pilot subcarriers are divided by six subcarriers, and the third and fourth arising pilot subcarriers are divided by four subcarriers, and in each OFDMA symbol containing pilot subcarriers , the first to fourth emerging pilot subcarriers correspond to four antennas. 8. The method according to claim 7, in which the four pilot subcarriers include the pilot subcarriers P0, P1, P2 and P3, and the pilot subcarriers P0, P1, P2 and P3 are the first, second, third and fourth arising pilot subcarriers in the first OFDMA symbol. 9. The method of claim 8, wherein the pilot subcarriers P2, P3, P0, and P1 are the first, second, third, and fourth emerging pilot subcarriers in the second OFDMA symbol. 10. The method of claim 7, wherein the four pilot subcarriers include the pilot subcarriers P0, P1, P2, and P3, and the pilot subcarriers P1, P0, P3, and P2 are the first, second, third, and fourth emerging pilot subcarriers in the fifth OFDMA symbol. 11. The method of claim 10, wherein the pilot subcarriers P3, P2, P1, and P0 are the first, second, third, and fourth arising pilot subcarriers in the sixth OFDMA symbol. 12. The method according to claim 7, further comprising MIMO post-processing the output of the channel estimation execution step. 13. A wireless mobile communication device comprising
a receiver for receiving an orthogonal frequency division multiple access (OFDMA) signal transmitted from an antenna system with multiple inputs and multiple outputs (MIMO), wherein the OFDMA signal is received using one or more resource blocks, each resource block having an 18 × form 7 matrix representing 18 subcarriers and 7 OFDMA symbols; and
a channel estimation unit operatively connected to the receiver and designed to estimate the channel characteristics based on four pilot signals corresponding to four streams, and four pilot signals are distributed only on the 1st, 2nd, 5th and 6th OFDMA symbols of 7 OFDMA characters,
wherein in each OFDMA symbol containing pilot subcarriers, the first and second emerging pilot subcarriers are separated by four subcarriers, the second and third emerging pilot subcarriers are divided by six subcarriers, and the third and fourth emerging pilot subcarriers are divided by four subcarriers,
moreover, in each OFDMA symbol containing pilot subcarriers, the first to fourth emerging pilot subcarriers correspond to four streams. 14. The wireless mobile communications apparatus of claim 13, wherein the four pilot subcarriers include pilot subcarriers P0, P1, P2, and P3, the pilot subcarriers P0, P1, P2, and P3 being the first, second, third, and fourth emerging pilot subcarriers in the first OFDMA character. 15. The wireless mobile communications apparatus of claim 14, wherein the pilot subcarriers P2, P3, P0, and P1 are the first, second, third, and fourth emerging pilot subcarriers in the second OFDMA symbol. 16. The wireless mobile communications device of claim 13, wherein the four pilot subcarriers include the pilot subcarriers P0, P1, P2 and P3, the pilot subcarriers P1, P0, P3 and P2 being the first, second, third and fourth emerging pilot subcarriers in the fifth OFDMA symbol. 17. The wireless mobile communications device according to clause 16, in which the pilot subcarriers P3, P2, P1 and P0 are the first, second, third and fourth arising pilot subcarriers in the sixth OFDMA symbol. 18. The wireless mobile communications device according to item 13, further comprising
MIMO post-processor, operatively connected to the channel estimation block and intended for post-processing the output of the channel estimation block. 19. A wireless mobile communications device containing
a receiver for receiving an orthogonal frequency division multiple access (OFDMA) signal transmitted from an antenna system with multiple inputs and multiple outputs (MIMO), wherein the OFDMA signal is received using one or more resource blocks, each resource block having an 18 × form 5 matrices representing 18 subcarriers and 5 OFDMA symbols; and
a channel estimation unit operatively connected to the receiver and designed to estimate channel characteristics based on four pilot signals corresponding to four streams, and four pilot signals are distributed only on the 1st, 2nd, 4th and 5th OFDMA symbols of 5 OFDMA characters,
wherein in each OFDMA symbol containing pilot subcarriers, the first and second emerging pilot subcarriers are separated by four subcarriers, the second and third emerging pilot subcarriers are divided by six subcarriers, and the third and fourth emerging pilot subcarriers are divided by four subcarriers,
moreover, in each OFDMA symbol containing pilot subcarriers, the first to fourth emerging pilot subcarriers correspond to four streams. 20. The wireless mobile communications apparatus of claim 19, wherein the four pilot subcarriers include pilot subcarriers P0, P1, P2, and P3, the pilot subcarriers P0, P1, P2, and P3 being the first, second, third, and fourth emerging pilot subcarriers in the first OFDMA character. 21. The wireless mobile communications device of claim 20, wherein the pilot subcarriers P2, P3, P0, and P1 are the first, second, third, and fourth emerging pilot subcarriers in the second OFDMA symbol. 22. The wireless mobile communications apparatus of claim 19, wherein the four pilot subcarriers include pilot subcarriers P0, P1, P2, and P3, the pilot subcarriers P1, P0, P3, and P2 being the first, second, third, and fourth emerging pilot subcarriers in the fifth OFDMA symbol. 23. The wireless mobile communications device of claim 22, wherein the pilot subcarriers P3, P2, P1, and P0 are the first, second, third, and fourth emerging pilot subcarriers in the sixth OFDMA symbol. 24. The wireless mobile communications device according to claim 19, further comprising
MIMO post-processor, operatively connected to the channel estimation block and intended for post-processing the output of the channel estimation block.

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