KR100913979B1 - Method, system and receiver for receiving a multi-carrier transmission - Google Patents

Abstract

Mobile terminals receiving DVB transmissions require relatively low power consumption and TDM-based transmissions can be used to save power in the terminals. To obtain a pilot carrier position, at least one symbol is accessed, which is adapted to establish a corresponding pattern for pilot carriers made up of the matrix of symbols. The carriers of the symbol are subjected to power accumulation sum within the matrix to determine a power accumulation sum maximum for indicating a pilot carrier position.

Description

Method, system and receiver for receiving a multi-carrier transmission

The present invention relates to receivers, mobile terminals, subassemblies, chipsets, methods and computer programs for receiving multi-carrier transmissions.

Services used in mobile terminals require relatively low bandwidth. The estimated maximum bit rate for streaming video using advanced compression techniques such as MPEG-4 is on the order of hundreds of kilobits per second.

Terrestrial Digital Video Broadcasting (DVB-T) transmission systems typically provide data rates above 10 Mbps. This provides the ability to significantly reduce average DVB-T receiver power consumption by introducing a schema that can be based on time division multiplexing (TDM). The introduced scheme may be referred to as time slicing.

The concept of time slicing is to transmit data in bursts at a moment using a fairly high bandwidth. The time slicing allows the receiver to remain active for only some time while receiving bursts of the required service. An example of such time slicing may be as shown in FIG. 1. So the original maybe streaming data can be sent as a burst using a high bandwidth load. Two time slice bursts 100 and 101 are shown and each burst has a synchronization portion 102 of each of the bursts and a data portion 103 carrying the service.

The received data can be buffered. For example, if an applicable and constant low bit rate is required at the mobile terminal, this may be provided through buffering of the received bursts. Thus, the data used in the final application can be applied even as one stream by unpacking the data in the buffer (s).

If the representative burst size is 2 Mbit and the DVB-T bit rate is 15 Mbps, the burst duration is 146 ms. When the constant bit rate (the bit rate at which the burst is read from the buffer) is 350 kbps (eg, when one streaming service has high quality video), the average time between bursts is 6.1 s.

Since the total on time is the sum of the burst duration plus the synchronization time, the synchronization time of the handheld receiver should be severely minimized to better exploit the potential of time slicing.

Thus, technical use of TDM-based systems, such as time slicing to reduce power consumption to the right quantities, is becoming popular in DVB handheld environments. Therefore, in order to better utilize the potential power savings, the synchronization time of such receivers should be shortened. Faster synchronization is desirable.

An approach to multi-carrier transmission synchronization according to the prior art will be described below.

Typical DVB-T Synchronization According to Prior Art

Typical DVB-T synchronization schemes up to Channel Estimation can be found in the 'Standard Publication: "DVB", ETS 300 744, standardization publication: "Digital Video Broadcasting," incorporated herein by reference. (DVB) ", ETS 300 744, chapter 4.4 '. This typical synchronization scheme is shown in Figure 2. After initiation, the first step of synchronization is the pre-FFT (Fast Fourier Transform). Synchronization 200. Since all the metrics in this stage are obtained from guard interval correlation, the typical synchronization time of two Orthogonal Frequency Division Multiplex (OFDM) symbols is unique.

For subsequent post-FFT synchronization 201, considering that the first OFDM symbol is provided for post-FFT synchronization after the latency of the FFT (typically three OFDM symbols), 4-5 The typical synchronization time of an OFDM symbol is related to this phase.

After carrier and timing synchronization has been made, the location of the scattered pilot carriers within an OFDM symbol must be determined before allowing channel estimation to commence. Since the position of the disturbed pilot carrier is directly related to the number of OFDM symbols in the OFDM frame, no dedicated disturbed pilot carrier synchronization is included in the prior art DVB-T receivers, and instead available TPS- anyway. Bit-based OFDM frame synchronization 202 is typically included in prior art DVB-T receivers. As a result, this inevitably involves a variable minimum synchronization time of 17 to 68 OFDM symbols. For the purposes of DVB-H (DVB in mobile terminal environment) time slicing, this means that 68 OFDM symbol synchronization times must be reserved because the receiver must be prepared for later symbols. Generally speaking, this leads to 75 OFDM symbol synchronization times until allowing channel estimation (CHE) 203 to be initiated. Assuming 8k mode, this is 69-84 ms, depending on the length of the guard interval. If only this portion of the synchronization time is taken (channel estimation is omitted), this 84 ms is already quite good compared to the 146 ms burst duration. 37% of the total on time is solely for the synchronization of this part, most of which results from Transmission Parameter Signaling (TPS) synchronization 202.

Given the various limitations of synchronization to multi-carrier transmission, it would be desirable to avoid or mitigate these and other problems associated with the prior art. Therefore, a quick synchronization is needed.

Currently, receivers, mobile terminals, subassemblies, chipsets, methods, systems and computer programs are generally invented which quickly synchronize to multi-carrier transmissions or parts thereof.

In accordance with embodiments of the present invention, a receiver, a terminal, a subassembly of a terminal, and a method for receiving a multicarrier transmission, wherein the multicarrier transmission includes multiple symbols, each symbol including a plurality of carriers A receiver, a terminal, a subassembly of a terminal, and a method for receiving a carrier transmission are provided, and a receiver, a terminal, a subassembly, and a method for receiving a multicarrier transmission,

Means and corresponding operations for accessing at least one symbol, the at least One symbol comprises means for establishing an identifiable power based pattern for pilot carriers within the at least one symbol and corresponding operations;

Means and corresponding operations for setting power accumulation sums for possible pilot carriers of the symbol based on the pattern, and

Means for determining a power accumulation sum maximum magnitude of said sums indicating pilot carrier position and corresponding operations.

With some embodiments of the present invention, the position of the disturbed pilot carriers in the OFDM symbol can be quickly obtained.

Several embodiments of the present invention propose to use power-based fast disturbed pilot carrier synchronization to reduce the time required for disturbed pilot carrier synchronization even to a minimum limit of only one symbol, such as only one OFDM symbol. Various embodiments employ predetermined dishonest raster pilot carriers arranged in the symbol in that the disturbed pilot carriers are boosted at a higher amplitude than the data carriers.

By sensing all possible disturbed pilot raster carrier positions through power accumulation, the current position of the disturbed pilot carriers can be obtained.

In various embodiments, synchronization may be based on realizing that certain identifiable carriers, such as disturbed pilot carriers, may be obtained at the same standardized locations (ie, the same carrier index) inherent in the symbol. have. Moreover, certain identifiable carriers, such as disturbed pilot carriers, may be obtained at certain standardized locations (ie, specific standardized locations with specific carrier indexes) within all standardized symbols. This may, for example, be seen as a diagonal offset pattern for pilot carriers in some examples. The pilot carriers are boosted at high amplitudes, while other carriers, such as data carriers, are not boosted at high amplitudes. By detecting possible raster positions of the pilot carriers via power accumulation, a clear individual power sum maximum magnitude can be obtained for the current pilot carrier position. Specific symbols may be identified based on the pilot carrier location.

Through various embodiments of the present invention, a very fast way of obtaining identifier (s) for a particular number of symbols in a multi-carrier transmission stream is provided. This is sufficient to proceed with the additional channel estimation and synchronization process. As a whole result, it is possible to reduce all the synchronization phases of the receiver quite dramatically. In various embodiments, this is advantageous for mobile receivers operating in a TDM based power saving mode. Moreover, several embodiments of the present invention are very robust to Doppler frequency based interference.

In various embodiments of the present invention, it is possible to make the synchronization time (ie, the synchronization time up to channel estimation) considerably shorter. Various embodiments are feasible in various related channel conditions making these embodiments feasible. In some embodiments, the robustness of the process may be improved through rapid disrupted pilot carrier synchronization based on cumulative power.

In various additional embodiments, the cumulative power sum may be defined for consecutive symbols, for example. However, this maintains the speed of the process and provides better robustness. Of course, any symbol other than the neighboring symbol may also be selected.

Thus, various embodiments of the present invention can be safely used in place of prior art TPS based OFDM synchronization. In addition, the complexity required for the various embodiments of the present invention may be relatively low because most of the computational resources required are somehow available and applicable from post FFT acquisition resources. However, the post FFT acquisition computational resources are not essential implementations. For example, more specific designs may also be applied and other used circuitry of the receiver may be applied.

In addition to the present invention, for a better understanding of other and further objects of the present invention, reference is made to the following description in conjunction with the accompanying drawings, in which the scope of the present invention will be set forth in the appended claims.

The invention will now be described by way of example only with reference to the accompanying drawings.

1 shows an example of a time slicing concept according to the prior art.

2 shows an example of a DVB-T synchronization sequence according to the prior art.

3 is a functional block diagram illustrating a portion of a receiver for receiving a signal in accordance with some embodiments of the present invention.

4 is a functional block diagram illustrating a portion of a receiver for receiving a signal in accordance with some embodiments of the present invention.

5 is a functional block diagram illustrating a part of a receiver for receiving a signal according to another embodiment of the present invention.

FIG. 6 is a schematic diagram illustrating an example of disturbed pilot carrier positions where the carrier power sums are adapted to be applied in accordance with some embodiments of the present invention.

FIG. 7 is a diagram schematically illustrating an example of disturbed pilot carrier positions in which cumulative carrier power sums are applied according to some embodiments of the present invention.

8 is a functional block diagram illustrating a portion of a receiver receiving a transmission in accordance with some embodiments of the present invention.

9 is a functional block diagram illustrating a portion of a receiver for receiving a transmission in accordance with some embodiments of the present invention.

10 is a simplified block diagram illustrating the first half of a receiver for receiving a transmission in accordance with some embodiments of the present invention.

11 shows the overall structure of a system to which some principles of some embodiments of the invention may be applied.

Accordingly, in the following description of the various embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration various embodiments in which the invention may be practiced. It is to be understood that other embodiments may be employed and structural and functional modifications may be made to the invention without departing from the scope of the invention.

Multicarrier Signal Reception and Power-Based Fast Disrupted Pilot Carrier Synchronization

3 is a functional block diagram illustrating a portion of a receiver 300 that receives a signal in accordance with some embodiments of the present invention. In FIG. 3 some parts of the receiver 300 are shown to include functional blocks therein and some other parts of the receiver are omitted for clarity. The functional block may be adapted to perform the corresponding method of the receiver. The receiver 300 includes means for receiving multiple carriers (not shown) and means for performing a Fast Fourier Transform (FFT) on the signal received at block 301.

Various embodiments of the present invention apply a method and corresponding means for receiving a multi-carrier signal, such as an OFDM signal. In various embodiments, this is advantageous because the multi-carrier transmission has generated a lot of interest. The multi-carrier transmission may have a particular disturbed pilot raster carrier location scheme. Multiple carriers, such as OFDM signals, can be used in DVB. Moreover, the multi-carrier signal also applies to other systems such as mobile telephony techniques, such as other digital television systems such as Integrated Services Digital Broadcasting (ISDB) and Digital Audio Broadcasting (DAB). It is possible. In some cases, the multicarrier transmission, e.g., OFDM, is embodied in a mobile DVB or in an IP over a mobile DVB environment. The embodied mobile DVB environment may be referred to as DVB-H (DVB handheld) or previously sometimes referred to as DVB-X. The multicarrier transmission is received at the receiver. Because of the power saving phases, the time slicing concept is applied to save power in the receiver, which may be a mobile receiver. In the time slicing, the transmission is in the form of a burst. Thus, the receiver may possibly receive some bursts and adopt them. Synchronization in bursts must be very fast and reliable. Some embodiments of the present invention relate to the disturbed pilot carrier scheme of DVB-T / DVB-H. Also, the same principle can be applied to similar pilot carrier schemes.

In some receivers and receiving methods applying some embodiments of the present invention, during synchronization of the receivers, the number of symbols (eg 0 to 67 in OFDM) must be obtained. For all symbol numbers, the positions of the disturbed pilot carriers are defined. Disrupted pilot carriers are used for channel estimation and fine timing. Therefore, these operations can only be initiated after the location of the disturbed pilot carriers is known. So during synchronization of the receiver, the position of the disturbed pilot carriers in the symbols must be determined to initiate channel estimation. The receiver includes means for determining the position of the disturbed pilot carriers in the symbol.

Thus, in various embodiments of the multi-carrier signal reception, after carrier and timing synchronization has been made, the position of the disturbed pilot carriers in one OFDM symbol must be determined before the start of channel estimation is allowed. Since the position of the disturbed pilot carrier is directly related to the number of OFDM symbols in the OFDM frame, it is typical that no dedicated disturbed pilot carrier synchronization is included in standard DVB-T receivers.

Referring again to the example of FIG. 3, after the FFT of the means 301, the receiver comprises means for obtaining a symbol at block 302.

In various embodiments of multi-carrier transmission systems, transmitters, and transmission methods, the symbols are transmitted in a particular predetermined sequence manner, typically based on standards. Various embodiments of the present invention relate to a method and means for receiving symbols and to how symbols are processed. The symbol can be received and saved. The symbols are transmitted continuously so that the received symbol is related to a particular point in time and another point is related to another symbol.

Various embodiments of the present invention provide a method and means for determining a disturbed pilot carrier position through a fixed synchronization time of an OFDM symbol. It should be noted here that only one symbol can be applied. Therefore, the synchronization time is very fast.

Thus, the above embodiments allow for channel estimation and subsequent tasks while OFDM frame synchronization can still be performed.

For example, in some embodiments, by examining all possible disturbed raster positions through power accumulation, the current position of the disturbed pilot carriers can be obtained. In some additional embodiments, some of the possible disturbed pilot raster carrier positions may be applied based on a predetermined pattern in which the pilot carriers were generated and the present invention is not limited to the total number of possible pilot carriers.

Referring again to FIG. 3, the receiver includes means 303 for calculating power accumulation for a particular carrier of the symbol.

The selection of candidate carriers in the symbol may be based on an identification pattern for pilot carriers of the symbol. Possible carriers may also be mentioned when indicating an applied carrier. Thus, such a candidate carrier represents an applied carrier and a possible carrier represents a pilot carrier or vice versa. For example, the carrier may be selected as a candidate for possible pilot carrier location. The selection may be based on a similar position of a pilot carrier obtained from the outer pattern of the pilot carriers within a certain quantity of symbols.

Several embodiments of the present invention propose a power-based fast disturbed pilot carrier synchronization to reduce the time required for a disturbed pilot carrier synchronization even down to the minimum limit of one symbol. Various embodiments employ the fact that disturbed pilot carriers are boosted at higher amplitudes than data carriers. The position of the disturbed pilot carriers in the symbol may be based on a certain predetermined pattern. The positioning of the disturbed pilot carriers within the symbol may vary from one symbol to another. However, for example, the change between two consecutive symbols is predetermined. For example, the disturbed pilot carriers can be found in a typical diagonal offset structure.

Referring again to FIG. 3, the receiver includes means 304 for storing the calculation result. The result of the means 303 can be stored therein. In one embodiment of the invention, the storage means 304 in which the result can be stored is an accumulating means, such as an accumulator, which may alternatively be referred to as a power accumulator.

In some embodiments, there is one accumulator for each possible disturbed pilot carrier location (eg, four in DVB-T / DVB-H). It should be noted here that the stored result may be something different from the appearance pattern of the pilot carriers. Thus, the power sum result may be added to only one of those in which the carrier tested in the present embodiments is included.

와 같은 최종적이거나 결과적인 전력 합 인덱스에 이르렀는지를 테스트하는 수단(305)을 포함한다. 그래서 동작 루프는 블록들(303,304,305)이 실행하도록 채택되고 계산 프로세스가 특정의 결과적인 인덱스에 이르게 될 때까지 수행될 경우에 설정된다.

와 같은 최종적이거나 결과적인 전력 합 인덱스에 이르지 않을 경우, 다른 어떤 반송파들에 대한 다음 전력 합이 수단(303,304)에 따라 계산되도록 채택된다. 여러 실시예에서, 전력 합들의 개수 및 최종적인 전력 합 인덱스는 특정한 소정의 알려진 대응 패턴이 이러한 심벌의 반송파들을 포함하는 매트릭스로 이루어진 파일럿 반송파들(위치들)용으로 사용되는 방식으로 선택된다. 따라서, 최종적인 전력 합의 개수 및 전력 합들의 수량은 한 심벌의 반송파들을 지니는 매트릭스로 이루어진 파일럿 반송파들(위치들)에 대한 알려진 대응 패턴을 기반으로 할 수 있다.Referring again to the examples of FIG. 3, the receiver

Means 305 for testing whether a final or resulting power sum index has been reached. So the operation loop is set if blocks 303, 304, 305 are adopted to execute and performed until the computational process reaches a particular resulting index.

If the final or resulting power sum index does not reach, then the next power sum for any other carriers is adapted to be calculated according to the means 303,304. In various embodiments, the number of power sums and the final power sum index are selected in such a way that a certain known corresponding pattern is used for pilot carriers (locations) consisting of a matrix containing carriers of this symbol. Thus, the final number of power sums and the quantity of power sums may be based on a known correspondence pattern for pilot carriers (locations) consisting of a matrix with one symbol of carriers.

Various embodiments are based on the concept that disturbed pilot carriers of a multi-carrier signal can be obtained at certain same locations (specific carrier indices) in the symbol. For example, certain carrier indices may indicate the location of a pilot carrier. The spacing between the pilot carriers is known. Also, the pilot carrier repetition pattern in one symbol is repeatable after a certain symbol quantity, for example every fourth symbol. Thus certain symbols have a similar pilot carrier location pattern. Moreover, the positioning of pilot carriers in other symbols may have a similar pattern but different starting points. Thus, although the pilot carriers are located at different positions relative to neighboring symbols, the positioning of the pilot carriers within the symbol is still predetermined to some extent. These disturbed pilot carriers are boosted to a higher amplitude than the data carriers in the symbol.

In some additional embodiments, power accumulation sums for specific carriers (pair) may be calculated. The result is stored in memory. The condition of the resulting carrier index is checked. For example, the maximum K-mode index id is adapted to be checked by the receiver. If the resulting carrier index is not reached, calculation and storage continue. For example, numerical values of various carriers of the symbol are processed. When the resulting index is reached, memory is processed. Thus, based on power accumulation metrics, a final quantity of power accumulation of a certain quantity is calculated. The final power accumulations can be calculated in such a way that certain power accumulation sums (sometimes referred to as pairs) are summed. The power accumulation result with the maximum magnitude selected from the final power accumulations represents the pilot carrier position.

Referring again to FIG. 3, the receiver includes means 306 for determining a maximum magnitude that is the highest magnitude from the calculated power accumulation sums. An identifiable power sum maximum magnitude indicative of the current disturbed pilot raster carrier position can be obtained for the power accumulation sum. Determination of the highest magnitude through the means 306 is performed on the sum of power (s) calculated by the means 303, 304, 305.

Thus, by detecting or inspecting all possible disturbed pilot raster carrier positions through power accumulation, a maximum magnitude is obtained that is an identifiable magnitude indicative of the current position of the disturbed pilot raster carrier positions.

For example, specific and substantially similar disturbed pilot raster carrier positions are periodic in OFDM symbols. The same raster pilot carrier pattern in one symbol is repeated, for example, every fourth OFDM symbol in some multicarrier systems and methods. The symbols between them have a specific known pilot carrier location pattern in which five OFDM symbols establish a known pattern for pilot carriers. By examining the four possible disturbed pilot carriers (or positions) in one symbol, the current disturbed pilot raster carrier position is determined to be the largest of these four disturbed pilot carriers.

Referring again to FIG. 3, the receiver also includes channel estimation (CHE) means 307.

Some embodiments of the present invention provide a fairly fast way of obtaining two least significant bits (LSB) of the number of OFDM symbols in a DVB-T / DVB-H data stream. Two LSBs are sufficient to go through an additional channel estimation and synchronization process.

In various embodiments, the overall result is a dramatic reduction in the time for all synchronization phases of the receiver. This is particularly important for DVB-H receivers, especially when the DVB-H receivers are operating in time slice mode and where power saving is very important for DVB-H receivers. Thus, various specified synchronization techniques, such as power-based fast disrupted pilot carrier synchronization, can dramatically accelerate the synchronization time of a DVB-T / H receiver. For example, if the DVB-H receiver is operating in time slice mode, this represents a notable reduction in power consumption. Power-based fast disrupted pilot carrier synchronization can be used as a substitute for TPS-based OFDM frame synchronization. The ability to use time slicing can be better used because the synchronization time of the receiver is significantly minimized.

4 is a functional block diagram of a portion of a receiver 300 ′ that receives signals in accordance with some embodiments of the invention. In FIG. 4, some parts of the receiver 300 ′ are shown to include functional blocks therein, and some other parts of the receiver are omitted for clarity. The functional blocks may be adapted to perform the corresponding method of the receiver. The receiver 300 'may be adapted to perform the functions and means mentioned in FIG. The receiver includes means for receiving multiple carriers and means for performing a Fast Fourier Transform (FFT) on the signal received at block 301 '. The receiver further includes means 302 'for obtaining a symbol, such as an OFDM symbol. The receiver also includes means 401 for obtaining or receiving another symbol.

As mentioned in various embodiments of multi-carrier transmission systems, transmitters or transmission methods, symbols are typically transmitted in a certain predetermined sequence manner based on a standard. Various embodiments of the present invention relate to a method and means for receiving symbols and to how symbols are processed. The symbol can be received and saved. The symbols are transmitted continuously so that the received symbol is related to a particular point in time and another point is related to another symbol.

In some additional embodiments of the present invention, consecutive symbols may be applied. In some embodiments of the invention two consecutive symbols are applied. However, accessed or selected symbols may also be selected differently. Thus the accessed or selected symbols may be different from successive symbols and three or more symbols may be selected to further improve robustness.

Thus, noise robustness can be improved in these embodiments. Of course, consecutive symbols may be set to be current and previous symbols or current and next symbols according to an embodiment. Disturbed pilots (or distorted pilot raster carrier positions) of successive OFDM symbols may be examined to detect distorted pilot raster carrier positions. Thus, the disturbed pilot raster carrier position can additionally identify specific symbols of transmission / reception.

In addition, in some additional embodiments of the present invention, a symbol pair different from a pair of neighboring symbols may be used. The robustness can also be further increased using three or more symbols, for example a plurality of symbols. In such a case, the processing time may be long.

Referring back to FIG. 4, the receiver determines whether it has reached a means 303 'for calculating power accumulation for a particular carrier (pair) within one symbol, means for storing the result of the calculation 304', and the resulting index. Means for determining 305 '. Thus the operation loop is established if blocks 303, 304, 305 are adapted to execute and the computation process can be performed on the candidate carriers of the symbol. For example, the first symbol is processed and then another symbol is processed as well. In another example, four possible dishonest pilot raster carrier positions are processed in one symbol and four possible dishonest pilot raster carrier positions are processed in another symbol.

The receiver of FIG. 4 also includes means 402 for calculating cumulated power sums (CPSs). Thus, for example, in order to improve robustness, also positions for distorted raster pilot carriers of two or more symbols may possibly be investigated and obtained. The cumulative power sum uses the power accumulation sum of the first symbol and the power accumulation sum of the other symbol. The selection of the power accumulation sum for the cumulative power accumulation sum may be made such that a corresponding pattern of pilot carriers is employed. The selection of the relevant power sum is thus made according to the appearance of the pilot carriers inherent in the two symbols. Thus, pilot carriers in other symbols have a match to indicate high power accumulation. For example, disturbed raster pilot carriers are investigated and employed based on their typical 'diagonal' offset structure.

The receiver of FIG. 4 also includes means 306 ′ for determining the maximum magnitude that is the highest magnitude from the cumulative power sums. Such peak size determines the current disturbed pilot raster carrier position. The receiver also includes channel estimation (CHE) means 307 '.

5 is a functional block diagram illustrating a portion of a receiver 300 "for receiving a signal in accordance with some other embodiments of the present invention. In FIG. 5, some portions of the receiver 300" are functional blocks therein. And other portions of the receiver are omitted for clarity. Some functional blocks of FIG. 5 may be employed to perform the corresponding method of the receiver. The receiver 300 "of Figure 5 may be adapted to perform the functions and means mentioned in Figure 3. The receiver may be adapted to the means for receiving multiple carriers (not shown) and to the signal received at block 301". Means for performing a Fast Fourier Transform (FFT) for the data. The receiver further comprises means for obtaining a symbol, such as an OFDM symbol, 302 ". The receiver also includes means for obtaining another symbol 401 '. In FIG. 302 ", to obtain the symbol. The receiver is also adapted to determine the power accumulation sum (s) of the particular carrier (s) for the first symbol in the means 303 ", 304 ", 305 ". It is possible to determine the four power sums for possible dishonest pilot carrier positions within the receiver of Figure 5. The receiver of Fig. 5 may also determine a particular carrier for another symbol in the means 401 ', 303 "', 304" ', 305' '. It is adapted to obtain and determine the power accumulation sum (s) of the (s). For example, the receiver can determine four power sums for possible dishonest pilot raster carrier positions in another symbol.

The receiver of FIG. 5 further includes means 402 ′ for calculating cumulative power sums. Thus, for example, to improve robustness, also two or more symbols of disturbed raster pilot carriers may possibly be investigated and obtained. The cumulative power sum uses the specific power accumulation sum of the first symbol and the specific power accumulation sum of the other symbol. The power accumulation sums for the cumulative power accumulation sums are selected such that a corresponding pattern of disturbed raster carrier positions is employed. Thus, the pilot carriers in other symbols have a match to indicate high power accumulation. Disrupted raster pilot carriers, for example, are investigated and used based on their typical 'diagonal' offset structure.

The receiver of Figure 5 also includes means for determining a maximum magnitude that is the highest magnitude from the cumulative power sums. The maximum magnitude determines the current disturbed pilot raster carrier position. The receiver also determines channel estimation (CHE). ) Means 307 ".

Multi-power distorted pilot carrier synchronization

FIG. 6 is a diagram schematically illustrating an example of disturbed pilot carrier positions where carrier power sums are adapted to be applied in accordance with some embodiments of the present invention. According to various embodiments of the present invention which proposes a power-based fast disturbed pilot carrier synchronization, two LSBs of the position of the disturbed pilot carriers in the OFDM symbol, consequently the number of OFDM symbols are obtained in only one OFDM symbol. . Since synchronization can only proceed after such a location has been acquired, significant acceleration is achieved over TPS-based solutions. In the case of time slicing, this is relevant because the DVB-H time slicing receiver must be prepared for the worst case delay considered to ensure synchronization.

Thus, in some additional embodiments of the present invention, it is proposed to use power-based fast disturbed synchronization to reduce the time required for pilot carrier synchronization disturbed with only one OFDM symbol. Such a process and receiver employ the fact that the disturbed pilot carriers are boosted relative to the data carriers.

The location of the disturbed pilot carriers can be provided, for example, in the standard publication "Digital Video Broadcasting (DVB)", ETSI ETS 300 744, which is hereby incorporated by reference in its entirety.

For symbols at index l (range 0 to 67), index k is a subset

가 0(제로)보다 크거나 0(제로)과 동일한 모든 가능한 값들을 취하는 정수이며,

에 대한 결과적인 값이 유효 범위(

)를 초과하지 않는다고 규정된다.

은 0이고

는 2k 모드에 대하여 1704이며, (4k 모드에 대하여 3408이고), 그리고 8k 모드에 대하여 6816이다.Carriers included in the scattered pilot carriers. In the above formula,

Is an integer that takes all possible values greater than 0 (zero) or equal to 0 (zero),

The resulting value for is a valid range (

It is prescribed not to exceed).

Is 0

Is 1704 for the 2k mode (3408 for the 4k mode) and 6816 for the 8k mode.

6 illustrates the locations of the disturbed pilot carriers (indicated by the black dots). Data carriers are shown as circles in this example. The horizontal axis represents frequency f. Thus, the entire horizontal row represents one symbol, symbol 610. The vertical axis represents time t. Vertical rows represent carriers with the same index (K). For example, carriers 60Kmin have an index Kmin and carriers 60Kmax have an index Kmax. So the transmission and reception of symbols is time dependent and the different carriers in one symbol have different frequencies.

), 4k 모드(

), 및 8k 모드(

)에 있을 수 있다.In some DVB standardized examples, there are symbols ranging from 0 to 67 (of 68 symbols in total). The symbols are indexed by number. So they reach another time. In the DVB example, the K-value depends on the applicable modes and for example 2K mode (

), 4k mode (

), And 8k mode (

Can be).

As shown, in the example of FIG. 6 a pattern is set on the pilot carriers (black dots). This appears as if the pilot carriers appear diagonally in FIG. Moreover, some indices of carriers of other symbols have a similar appearance in their respective symbols.

Some embodiments of the power based fast disheveled pilot carrier synchronization employ the fact that disheveled pilot carriers are boosted relative to data carriers.

In this example, by detecting power all four possible disturbed pilot raster carrier positions through power accumulation, the current position of the disturbed pilot carriers can be obtained.

,

,

,

,

)(가능한 파일럿 반송파 위치들)의 단지 몇몇 위치들만이 나타나 있다는 것이다. 다른 위치들은 인덱스 p를 부가적으로 적용하는 주어진 식들을 기반으로 하여 획득될 수 있다. 4개의 전력 합이 다음과 같이 제공될 수 있다.Still referring to FIG. 6, S (n, c) represents the c-th subcarrier of the current OFDM symbol (index n) as a complex number. In Fig. 6, examples S (n, 0) and S (n, 12) are shown to represent some of the following equations. It should be noted here that for clarity, the power sums according to the above equations (

,

,

,

,

Only a few positions of () (possible pilot carrier positions) are shown. Other locations may be obtained based on given equations that additionally apply index p. Four power sums may be provided as follows.

는 2k 모드에 대하여 141이고 4k 모드에 대하여 283이며 8k 모드에 대하여 567이다.In the above formula,

Is 141 for 2k mode, 283 for 4k mode, and 567 for 8k mode.

Through the definition of these power sums, all four consider the same number of carriers.

를 다음과 같이 정의하는 것이다.Another variation is

Is defined as

Thus, by detecting all four possible raster positions of the disturbed pilot carriers, an apparent individual maximum magnitude, i.e.

Is the current disturbed pilot raster carrier position (SPRP),

Can be obtained for.

The SPRP identifiably indicates the location of the pilot carrier so that one symbol can be recognized. Thus, providing the highest magnitude determines the current disturbed pilot raster carrier position.

,

,

',

,

)의 예들을 통해 실수 값들이 획득될 수 있다. 그러나, 몇몇 부가 실시예에서는 복소수 및/또는 그러한 수치값들이 적용될 수 있다. 다시 말하면, 상기 값들은 i/q-매개변수들의 절대값들을 나타낼 수 있다.The above equations (

,

,

',

,

Real values can be obtained through the examples. However, in some additional embodiments complex numbers and / or such numerical values may be applied. In other words, the values may represent absolute values of i / q-parameters.

The indices in the above equations may be adapted to correspond with the disturbed pilot raster carrier positions of the applied pattern. Thus, only one example is shown in FIG. 6 and the invention is not limited to the particular pattern of FIG. 6. In addition, pilot carrier positioning may be such that several identical carrier indices in the symbol do not necessarily correspond, and consequently do not necessarily have boosted power, that is, carrier indices with any other repetition pattern in the symbol correspond. Can be done. All that is needed is any conventional known pattern for dishonest pilot raster carrier positions that may be employed in any conventional known pattern to which the above equations relate.

,

)은 최대 크기를 지닌다. 따라서, 특정 심벌은 이러한 현저한 특징(highlighting)을 기반으로 하여 현재 수신된 심벌이도록 추론될 수 있다.In the illustrated example of FIG. 6, the power accumulation sum (s) (

,

) Has the maximum size. Thus, a particular symbol can be inferred to be the currently received symbol based on this highlighting.

The time required for some embodiments of power based fast disturbed pilot carrier synchronization may be only one OFDM symbol. Compared to standard TPS synchronization, this is a significant improvement.

가 또한 다른 한 심벌로서 언급될 수 있는 이웃하는 심벌을 나타낸다.7 is a diagram illustrating an example of dishonest pilot carrier positions where cumulative carrier power sums (CPSs) are employed to be applied in accordance with some embodiments of the present invention. The example of FIG. 7 is based on similar principles than in FIG. 6. In addition to FIG. 6, the indicated carriers represent cumulative power sums (CPSs) in FIG. 7. It should be noted here that for clarity only some of the possible pilot carrier positions according to the following equations are shown. The example of FIG. 7 provides better robustness against noise and can make the process and receiver more reliable. To improve noise robustness, also disturbed pilot carriers of two or more OFDM symbols can be investigated and used. For example, two consecutive OFDM symbols can be applied as follows, in which case

Denotes a neighboring symbol that may also be referred to as another symbol.

Disrupted pilot carriers are examined in their 'typical' diagonal offset structure. The example of FIG. 7 can be extended to consider more OFDM symbols.

Thus, the cumulative power sum (CPS) providing the maximum magnitude indicates the current disturbed pilot raster carrier position (SPRP) and indicates the associated symbol.

Several additional implementations

)은 누산기 1(804)에 상주해 있을 수 있다.8 is a functional block diagram of a portion of a receiver receiving a transmission in accordance with some embodiments of the present invention. Thus, the number of symbols is known and the location of the disturbed pilot carriers may also be known, which may be one purpose of the receiver and operations. Decision block 808 is meaningful for performing the full size survey. Some embodiments of the receiver may be adapted to perform the means and processes for the example of FIGS. 3-7. The receiver includes an FFT block 801 for performing FFT on a received multicarrier signal, such as an OFDM signal. The FFT block 801 is connected to the power accumulation sum block 902. One symbol is obtained and received by the FFT block 801. The power accumulation sum block 802 is adapted to calculate a power accumulation sum for specific carriers of the symbol. Carriers for the power sum are selected in such a way that possible pilot carrier positions are selected. The power accumulating sum block 802 is connected to accumulators 1 to 4 having the reference numerals 804-807 through the demultiplexer 803, respectively. The accumulators 804-807 are adapted to store the respective power accumulation sum calculation results. For example, sum of power (

) May reside in accumulator 1 804.

Also referring to FIG. 8, the decision block 808 is adapted to test the power sum results of the accumulators 804-807. The control logic for terminating the accumulation of the power sums is omitted in FIG. 8 for reasons of simplicity. It should be noted here that the number of each accumulator and power sum is not limited to four as in the above example.

Also, referring to FIG. 8, the decision block 808 may calculate or obtain a maximum power accumulation magnitude with respect to the calculated power accumulation sum. The identifiable power accumulating maximum magnitude indicative of pilot carrier indices is obtained for the power accumulating sum because the disturbed pilot carriers are boosted with amplitudes greater than the data carriers.

Thus, by sensing possible raster positions of the disturbed pilot carriers, an identifiable power accumulation maximum magnitude is obtained for the current disturbed pilot raster carrier position.

Also, referring to FIG. 8, the decision block may be connected to a channel estimator CHE 809.

9 is a functional block diagram illustrating a portion of a receiver that receives a transmission in accordance with cumulative power sum embodiments of the present invention. 9 is a diagram illustrating some of the cumulative power sum embodiments. The receiver includes two branches, one for symbol S (n) 902 and the other for symbol S (n-1) 903. The branch 902 may be equivalent to the branch of FIG. 8. In branch 903, an FFT block 801 ′ is coupled to a delay block 901. An FFT block 901 is coupled to a power sum 802 ". One symbol is obtained and received by the FFT block 801 '. The delay block 901 is received to some extent in a time-dependent manner. The received symbol may be delayed up to a certain other symbol, and the delay block 901 may then obtain another symbol, such as a consecutive symbol.

Referring to the example of FIG. 9, the branches 902 and 903 may operate through another symbol as shown with reference to FIG. 8. It should be noted here that the number of each accumulator and the sum of the carriers is not limited to four as in the above example. The number of carriers and corresponding symbols is obtained in such a way that a certain predetermined known corresponding pattern is established for the pilot carriers (locations) consisting of a matrix comprising these two symbols of carriers.

Referring to FIG. 9, the decision block 808 ′ may calculate the cumulative power sum based on the S (n) branch 902 and the S (n−1) branch 903. Furthermore, the decision block 808 ′ may obtain a cumulative power accumulation maximum size for the calculated cumulative power sums. A very robust and identifiable cumulative power maximum magnitude indicative of pilot carriers (locations) is obtained for the cumulative power sums, since disturbed pilot carriers are boosted with a larger amplitude than data carriers.

Thus, by detecting all possible disturbed pilot raster carrier positions through power accumulation, the current position of the disturbed pilot carriers can be obtained.

In addition, referring to FIG. 9, the decision block may be connected to a channel estimation block (CHE) 809 ′.

와 동일한 누산기에

를 추가함으로써 지능적으로 제어되도록 적용될 수 있다. (예컨대, 심벌(n-1) 이후에 심벌(n)이 나오는) 일렬 순서로 여하튼 심벌들이 FFT로부터 나오기 때문에, 어떠한 전용의 지연 블록(901)이 반드시 필요하지 않다.There are several embodiments for calculating cumulative power sums (CPSs). For example, FIG. 8 shows that the demultiplexer 803 of FIG.

On the same accumulator with

It can be applied to control intelligently by adding. Any dedicated delay block 901 is not necessary because the symbols come from the FFT anyway (e.g., after the symbol n-1, followed by the symbol n).

Some embodiments have been of interest and may relate to DVB-T derived standards referred to as DVB-H (DVB handheld), which, among other things, supports the features of time-slicing. This is an important enabler to support DVB-H in small and portable devices such as mobile phones.

The complexity required to implement various embodiments of the synchronization scheme is quite small because most of the computational resources needed are somehow provided from post FFT acquisition. Of course, the computational resources of post FFT acquisition are not just essential implementations. For example, more specific designs may also be applied and other used circuitry of the receiver may be applied.

Embodiments of the present invention may be implemented in various DVB-T / DVB-H receivers. In some embodiments of the invention, this may be done, for example, in an ASIC. Accordingly, the chipset for receiving multi-carrier transmissions according to the embodiments may be one or more ASICs.

In some of the various embodiments, the block containing the disturbed pilot carrier synchronization may be a buffer block (BUF) of the receiver. This buffer block may be used to store data carriers and disturbed pilot carriers of several OFDM symbols so that channel estimation (CHE) can span several OFDM symbols.

Therefore, at the output of the FFT there is a demultiplexer that divides the carriers into data carriers, continuous pilot carriers, disturbed pilot carriers, and possibly TPS carriers. To do this, the locations of the disturbed pilot carriers (their carrier indexes) must be known. The location of everything else is constant.

As mentioned in the prior art, the conventional approach has been to use TPS synchronization, which otherwise determines the number of OFDM symbols in an OFDM frame. So this mode of operation can be replaced by embodiments of the present invention.

10 shows the first half of the receiver in a functional block diagram. The illustrated receiver 1000 may be used in any or all of the various embodiments. The receiver includes a processing unit 1003, a multi-carrier signal receiver 1001, such as an OFDM signal receiver, and a user interface (UI). The user interface includes a display 1004 and a keyboard 1005. In addition, the UI includes an audio input 1006 and an audio output 1007. The processing unit 1003 includes a microprocessor (not shown), possibly a memory (not shown) and software (not shown). The processing unit 1003 is based on the software for receiving a signal, receiving a data stream, receiving a symbol, possibly receiving another symbol, setting up power accumulation sums of possible disturbed pilot carriers of the symbol (s), Controls operations of the receiver 1000, such as comparing power accumulation results, determining a disturbed pilot raster carrier position, and calculating related symbols. Various operations and means are mentioned in the examples of FIGS. 3-9.

10, alternatively, middleware or software implementations may be applied (not shown). The receiver 1000 may be a handheld device or a mobile device that a user can conveniently carry. Advantageously, the receiver 1000 may be a mobile phone comprising a multi-carrier signal receiver 1001 such as an OFDM receiver for receiving an OFDM signal. The receiver can talk to service providers.

Various embodiments of the present invention can be applied to the system of FIG. The receiver 1100 preferably operates within the scope of a digital broadcast network (DBN) 1101 that employs, for example, OFDM wireless signal based transmission. The receiver is capable of receiving transmissions provided by the DBN and receives the OFDM based signal. The operations of the receiver may include receiving a signal, receiving a data stream, receiving a symbol, for example receiving another symbol, perhaps through a delay in receiving, power accumulation summating carriers of the symbol (s), comparison of the results, It may be a determination of a disturbed pilot raster carrier position, a determination of an associated symbol. Various operations and means are mentioned in the examples of FIGS. 3-9.

Effect and range

While what has been described as being preferred embodiments of the invention has been described so far, those skilled in the art will recognize that other and additional changes and modifications to the invention may be implemented without departing from the spirit of the invention and are within the true scope of the invention. It will be appreciated that all such changes and modifications are intended to be claimed.

Claims (34)

A receiver for receiving a multi-carrier transmission, the multi-carrier transmission comprising various symbols, each symbol receiving a multi-carrier transmission comprising a plurality of carriers, the receiver comprising: Means for accessing the at least one symbol to establish an identifiable power based pattern for pilot carriers in at least one symbol; Means for setting power accumulations for potential pilot carriers of the symbol based on the pattern; And Means for determining a power accumulation sum of the maximum magnitude among the power accumulation sums indicating a pilot carrier location; Receiver for receiving a multi-carrier transmission comprising a. 2. The receiver of claim 1 wherein a pilot carrier of one of the potential pilot carriers includes a maximum magnitude in a predetermined pattern for the pilot carriers in the symbol. The method of claim 1, The position of the potential pilot carriers is determined based on the pattern in such a way that carrier indices having pilot carriers in a matrix of a certain number of symbols are selected, thereby selecting a corresponding carrier index in the accessed symbol. A receiver for receiving multi-carrier transmissions. 2. The receiver of claim 1 wherein all predetermined carriers of the symbol are selected for means for setting the power accumulation sums. 5. A receiver as claimed in claim 4, wherein the receiver is selected for means for setting the power accumulation sums for every fourth carrier of the symbol. 2. The receiver of claim 1 wherein the identifiable power-based pattern comprises pilot carriers boosted relative to the data carriers of the symbol. delete The apparatus of claim 1, wherein the means for setting power accumulation sums comprises: Means for performing first power accumulation on the first potential pilot carrier positions of the symbol; Means for performing a second power accumulation for the second potential pilot carrier positions of the symbol; Means for performing third power accumulation on third potential pilot carrier positions of the symbol, and Means for performing a fourth power accumulation on the fourth potential pilot carrier positions of the symbol, Means for determining the power accumulation of the maximum magnitude Means for detecting a maximum power accumulation sum of the first power accumulation sum, the second power accumulation summation, the third power accumulation summation, and the fourth power accumulation sum to indicate a current disturbed pilot raster carrier position. And a receiver for receiving multi-carrier transmissions. The method of claim 8, wherein the first power accumulation sum is

Calculated based on the equation, where S (n, c) represents the c-th subcarrier of the current symbol

Is a receiver for receiving multi-carrier transmissions, depending on the transmission mode used. The method of claim 8, wherein the second power accumulation sum is

Calculated based on the equation, where S (n, c) represents the c-th subcarrier of the current symbol

Is a receiver for receiving multi-carrier transmissions, depending on the transmission mode used. The method of claim 8, wherein the third power accumulation sum is

Calculated based on the equation, wherein S (n, c) represents the c-th subcarrier of the current symbol

Is a receiver for receiving multi-carrier transmissions, depending on the transmission mode used. The method of claim 8, wherein the fourth power accumulation sum is

Calculated based on the equation, wherein S (n, c) represents the c-th subcarrier of the current symbol

Is a receiver for receiving multi-carrier transmissions, depending on the transmission mode used. The method of claim 8, wherein the first power accumulation sum is

Calculated based on the equation, wherein S (n, c) represents the c-th subcarrier of the current symbol

Is a receiver for receiving multi-carrier transmissions, depending on the transmission mode used. 9. The apparatus of claim 8, wherein the means for detecting the maximum accumulated power accumulation is

Based on an expression,

Represents each of the first, second, third and fourth power accumulation sums,

Determines pilot carrier positions that identify a particular symbol, The current disturbed pilot raster carrier position (SPRP) is

Based on the expression,

Represents each of the first, second, third and fourth power accumulation sums,

And a receiver for determining pilot carrier locations identifying a particular symbol. The method of claim 1 wherein said means for accessing Means for obtaining a first symbol of the transmission, and Means for obtaining a second symbol associated with the first symbol. The method of claim 15, And wherein the accessed symbols comprise a currently received symbol and a predetermined specific symbol that comes before or after the currently received symbol. The method of claim 15, The accessed symbols include a currently received symbol and a predetermined specific symbol that comes before or after the currently received symbol. And a corresponding pattern is established between pilot carriers of the symbols for potential carrier locations in the matrix of symbols. 17. The receiver of claim 16 wherein the predetermined other predetermined symbol comprises a consecutive symbol that comes before or after the currently received symbol. 16. The apparatus of claim 15, wherein the means for setting power accumulation sums comprises: Means for setting first power accumulations for potential pilot carriers of the first symbol, wherein the receiver comprises: Means for setting second power accumulations for potential pilot carriers of the second symbol, and Means for setting cumulative power sums from the first power accumulation sums and the second power accumulation sums; Means for determining the power accumulation sum of the maximum size, Means for detecting a power accumulation sum of the maximum magnitudes of the cumulative power sums to indicate a current pilot carrier position. The method of claim 19, Means for setting the first power accumulation sums Means for performing a first power accumulation on the first potential pilot carrier positions of the first symbol; Means for performing a second power accumulation for the second potential pilot carrier positions of the first symbol; Means for performing a third power accumulation on the third potential pilot carrier positions of the first symbol, and Means for performing a fourth power accumulation on the fourth potential pilot carrier positions of the first symbol, Means for setting the second power accumulation sums Means for performing a first power accumulation on the first potential pilot carrier positions of the second symbol; Means for performing a second power accumulation for the second potential pilot carrier positions of the second symbol; Means for performing a third power accumulation for the third potential pilot carrier positions of the second symbol, and Means for performing a fourth power accumulation for the fourth potential pilot carrier positions of the second symbol. 20. The apparatus of claim 19, wherein in means for setting the cumulative power sums, the power accumulation sums of each of the first and second symbols are selected such that pilot carriers of the symbols correspond to the respective power accumulation sums. A receiver for receiving multi-carrier transmissions. 21. The apparatus of claim 20, wherein the means for setting the cumulative power sums comprises: Means for performing a first cumulative power sum on a first power accumulation sum of the first symbol and a fourth power accumulation sum of the second symbol; Means for performing a second cumulative power sum on a second power accumulation sum of the first symbol and a first power accumulation sum of the second symbol; Means for performing a third cumulative power sum on the third power accumulation sum of the first symbol and the second power accumulation sum of the second symbol, and Means for performing a fourth cumulative power sum on a fourth power accumulation sum of the first symbol and a third power accumulation sum of the second symbol. 2. The method of claim 1, wherein the multi-carrier transmission comprises OFDM transmission using time slicing, the symbol comprises an OFDM symbol and the plurality of carriers comprises data carriers and disturbed pilot carriers. Receiver receiving a carrier transmission. 2. The method of claim 1, wherein the multi-carrier transmission includes a burst-based time slicing based power saving function, wherein the synchronization of the receiver on a burst basis is based on the indicated pilot position to obtain an index of the received symbol. A receiver for receiving a multi-carrier transmission, characterized in that. 10. The method of claim 1, wherein the multi-carrier transmission comprises DVB transmission over burst based time slicing, wherein synchronization in bursts is based on the indicated pilot position to obtain an indicator representing an OFDM symbol. A receiver for receiving multi-carrier transmission. The method of claim 1, wherein the receiver Fast Fourier transform (FFT) means for performing a Fast Fourier Transform (FFT) on the received transmission to obtain the symbol, Accumulator means for accumulating power accumulation results, and And channel estimation means (CHE) for additionally continuing to receive the transmission. 2. The multi-carrier transmission of claim 1, wherein computational resources for performing operations of at least one of the means comprise identical computational resources for performing post-FFT acquisition at the receiver. Receiver. 2. The receiver of claim 1 wherein the buffer means of the receiver comprises all of the means. A mobile terminal for receiving a multicarrier transmission, wherein the multicarrier transmission includes various symbols, each symbol receiving a multicarrier transmission including a plurality of carriers, the mobile terminal comprising: Means for accessing at least one symbol, wherein the at least one symbol establishes an identifiable power based pattern for pilot carriers in the at least one symbol; Means for setting power accumulations for potential pilot carriers of the symbol based on the pattern, and And means for determining a power accumulation sum of the maximum magnitude among the power accumulation sums indicating a pilot carrier location. A subassembly of a terminal receiving a multi-carrier transmission, wherein the multi-carrier transmission includes several symbols, each symbol of the terminal receiving a multi-carrier transmission comprising a plurality of carriers, The subassembly of the terminal, Means for accessing at least one symbol, wherein the at least one symbol establishes an identifiable power based pattern for pilot carriers in the at least one symbol; Means for setting power accumulations for potential pilot carriers of the symbol based on the pattern, and And a means for determining a power accumulation sum of the largest of the power accumulation sums indicating a pilot carrier location. A chip set for receiving a multi-carrier transmission, wherein the multi-carrier transmission includes several symbols, each symbol receiving a multi-carrier transmission comprising a plurality of carriers, wherein the chip set comprises: Means for accessing at least one symbol, the at least one symbol establishing an identifiable power-based pattern for pilot carriers in the at least one symbol; Means for setting power accumulations for potential pilot carriers of the symbol based on the pattern, and And means for determining a power accumulation sum of the maximum magnitude among the power accumulation sums indicating a pilot carrier location. A method of receiving a multi-carrier transmission, wherein the multi-carrier transmission includes multiple symbols, wherein each symbol comprises a plurality of carriers, the method comprising: Accessing at least one symbol, the at least one symbol establishing an identifiable power-based pattern for pilot carriers in the at least one symbol; Setting power accumulations for potential pilot carriers of the symbol based on the pattern, and Determining a power accumulation sum of the largest of the power accumulation sums indicating a pilot carrier location. A computer-readable recording medium having recorded thereon a program storing computer program code for executing the method of claim 32 on a computer. delete

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