- Overview
- Description
- Drawings
ABSTRACT
Provided is a method for generating a preamble sequence group. The method includes creating a preamble sequence, calculating a cross-correlation value between sequences using the created preamble sequence, determining a limit cross-correlation value using the cross-correlation value to construct a preamble set used in the communication system, calculating a preamble set that satisfies the determined limit cross-correlation value, and terminating construction of the preamble set.
Inventors:
Hyoung-Gwan Kim, Sang-Kyung Sung, Jae-Yoel Kim Joon-Goo Park Jae-Woon Park
Original Assignee:
Samsung Electronics Co., Ltd
Section: Electricity
Classification: Electric Communication Technique
PRIORITY
This application claims priority under 35 U.S.C. § 119 to an application entitled “Method for Generating Preamble Sequence Group” filed in the Korean Intellectual Property Office on Oct. 27, 2003 and assigned Serial No. 2003-75271, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a method for generating a preamble set or group in a communication system and an apparatus adopting the method, and in particular, to a method for generating an optimal preamble set using a plurality of sequences used to increase the limited number of channels, and an apparatus adopting the method.
2. Description of the Related Art
Generally, communication systems support communication services and include transmitters and receivers.
FIG. 1 is a block diagram of a general communication system. Referring to FIG. 1, a transmitter 10 and a receiver 20 provide communication services using frames. The transmitter 10 and the receiver 20 need to acquire synchronization information for accurate transmission and reception of the frames.
In order to acquire the synchronization information of the receiver 20, the transmitter 10 transmits to the receiver 20 a synchronization signal indicating the start position of a frame transmitted to the receiver 20. Upon receiving the synchronization signal and the frame transmitted from the transmitter 10, the receiver 20 detects the start position of the received frame, i.e. frame timing, using the received synchronization signal. The receiver 20 demodulates the received frame using the detected frame timing. A specific preamble sequence, which has been previously agreed upon between the transmitter 10 and the receiver 20, is used as the synchronization signal.
Various methods such as the use of a preamble or a pilot signal are used to acquire synchronization with transmitted frames in communication systems. In the case of acquiring synchronization using a preamble as mentioned above, it is a general practice to use a single preamble.
FIG. 2 illustrates a frame structure used in the general communication system. As shown in FIG. 2, a frame is composed of a preamble 30 and data 40. The preamble 30 is used for frame synchronization and channel estimation. The data 40 includes data selected and requested by a user for transmission and/or control information of the communication system.
The frame structure may have a fixed format according to the communication system as shown in FIG. 2, but in other communication systems, the preamble 30 may be positioned in the middle of or at the end of the data 40. In other words, a preamble in a frame may be positioned differently according to communication systems.
The preamble 30 shown in FIG. 2 is comprised of a first signal 32 and a second signal 34. The first signal 32 is used for frame synchronization and the second signal 34 is used for channel estimation. The structure of the preamble 30 shown in FIG. 2 can be formed by divided into two parts, i.e. the first signal 32 and the second signal 34, but may also be formed repetitively using a single signal or using several concatenated signals without dividing into two parts. In some communication systems, the first signal 32 is divided into two parts: one for frame synchronization and the other for packet synchronization.
FIG. 3 is a block diagram of a transmitter for the general communication system.
A data creator 51 receives data, creates transmission data, and transmits the created transmission data to a first multiplexer 54. A media access control (MAC) header creator 52 creates a MAC header suitable for frames and transmits the created MAC header to the first multiplexer 54. A physical (PHY) header creator 53 creates a PHY header suitable for the communication system and transmits the created PHY header to the first multiplexer 54. The first multiplexer 54 multiplexes, i.e. mixes signals transmitted from the data creator 51, the MAC header creator 52, and the PHY header creator 53, and transmits a resultant signal to a second multiplexer 57. The resultant signal is referred to as transmission data.
A preamble creator 56 creates a preamble suitable for the communication system and transmits the created preamble to the second multiplexer 57. The transmission data multiplexed by the first multiplexer 54 and the preamble created by the preamble creator 56 are input to the second multiplexer 57. The second multiplexer 57 combines the transmission data from the first multiplexer 54 with the preamble from the preamble creator 56 to convert them into a transmission frame, and transmits the transmission frame to a receiver side through a transmission antenna 58.
FIG. 4 is a block diagram of a receiver for the general communication system. Referring to FIG. 4, the frame transmitted from the transmitter of FIG. 3 is received through a reception antenna 61. The frame received through the reception antenna 61 is sent to a preamble analyzer 62 and a demultiplexer 63. The preamble analyzer 62 analyzes the preamble in the received frame and detects synchronization information and channel estimation information. The preamble analyzer 62 determines the start position of the received frame using the synchronization information and the channel estimation information.
When the start point of the received frame is detected, the demultiplexer 63 separates the PHY header, the MAC header, and the data from the transmission data of the received frame with reference to the start position of the received frame. The separated signals are input to a PHY header analyzer 64, an MAC header analyzer 65, and a data restorer 66.
The PHY header analyzer 64 analyzes the PHY header transmitted from the demultiplexer 63 and transmits the result of the header analysis to the data restorer 66. The MAC header analyzer 65 analyzes the MAC header transmitted from the demultiplexer 63 and transmits the result of the header analysis to the data restorer 66. The data restorer 66 restores the data transmitted from the demultiplexer 63 using the results of the header analysis transmitted from the PHY header analyzer 64 and the MAC header analyzer 65.
The preamble sequence, which is agreed upon between the transmitter and the receiver of the communication system, may vary from system to system, but an aperiodic recursive multiplex (ARM) sequence will be used as the preamble sequence herein as an example. The preamble sequence that can be applied to the present invention is not limited to the ARM sequence, and may include any possible sequences that can be used as preambles. The ARM sequence exhibits superior auto-correlation in an aperiodic environment where sequences are not periodically transmitted.
Superior auto-correlation indicates that auto-correlation is high when the sequences are synchronized and auto-correlation is relatively low in other cases.
FIG. 5 is a block diagram of an ARM sequence generation apparatus that can generate an ARM sequence of a length 128. As shown in FIG. 5, when one of the possible 2-bit combinations of real numbers (‘00’, ‘01’, ‘10’, or ‘11’) is input as an input signal, the input signal is also input to a first multiplexer 81. The input signal is input to a first XOR operator 71.
At the same time, a first signal generator 91 generates a signal ‘01’ or ‘10’ and outputs the generated signal to the first XOR operator 71. The first XOR operator 71 performs an exclusive or operation on the signal output from the first signal generator 91 and the input signal, and outputs a result of the XOR operation to the first multiplexer 81. The first multiplexer 81 alternatively multiplexes the input signal and a signal output from the first XOR operator 71 and creates an ARM sequence of 4 bits. The first multiplexer 81 outputs the created 4-bit ARM sequence to a second multiplexer 82 and a second XOR operator 72.
A second signal generator 92 generates a signal ‘0101’ or ‘1010’ and outputs the generated signal to the second XOR operator 72 at the same time that the 4-bit ARM sequence is input to the second multiplexer 82 from the first multiplexer 81. The second XOR operator 72 performs an XOR operation on the signal output from the second signal generator 92 and the 4-bit ARM sequence output from the first multiplexer 81, and outputs a result of the XOR operation to the second multiplexer 82. The second multiplexer 82 alternatively multiplexes the signal output from the first multiplexer 81 and the signal output from the second XOR operator 72 to create an ARM sequence of 8 bits and outputs the created 8-bit ARM sequence to a third multiplexer 83 and a third XOR operator 73.
A third signal generator 93 generates a signal ‘01010101’ or ‘10101010’ and outputs the generated signal to the third XOR operator 73 at the same time that the 8-bit ARM sequence is input to the third multiplexer 83 from the second multiplexer 82. The third XOR operator 73 performs an XOR operation on the signal output from the third signal generator 93 and the 8-bit ARM sequence output from the second multiplexer 82, and outputs a result of the XOR operation to the third multiplexer 83. The third multiplexer 83 alternatively multiplexes the signal output from the second multiplexer 82 and the signal output from the third XOR operator 73 to create an ARM sequence of 16 bits and outputs the created 16-bit ARM sequence to a fourth multiplexer 84 and a fourth XOR operator 74.
A fourth signal generator 94 generates a signal ‘0101010101010101’ or ‘1010101010101010’ and outputs the created signal to the fourth XOR operator 74 at the same time that the 16-bit ARM sequence is input to the fourth multiplexer 84 from the third multiplexer 83. The fourth XOR operator 74 performs an XOR operation on the signal output from the fourth signal generator 94 and the 16-bit ARM sequence output from the third multiplexer 83, and outputs a result of the XOR operation to the fourth multiplexer 84. The fourth multiplexer 84 alternatively multiplexes the signal output from the third multiplexer 83 and the signal output from the fourth XOR operator 74 to create an ARM sequence of 32 bits, and outputs the created 32-bit ARM sequence to a fifth multiplexer 85 and a fifth XOR operator 75.
A fifth signal generator 95 generates a signal ‘01010101010101010101010101010101’ or ‘10101010101010101010101010101010’ and outputs the created signal to the fifth XOR operator 75 at the same time that the 32-bit ARM sequence is input to the fifth multiplexer 85 from the fourth multiplexer 84. The fifth XOR operator 75 performs an XOR operation on the signal output from the fifth signal generator 95 and the 32-bit ARM sequence output from the fourth multiplexer 84 and outputs a result of the XOR operation to the fifth multiplexer 85. The fifth multiplexer 85 alternatively multiplexes the signal output from the fourth multiplexer 84 and the signal output from the fifth XOR operator 75 to create an ARM sequence of 64 bits and outputs the created 64-bit ARM sequence to a sixth multiplexer 86 and a sixth XOR operator 76.
A sixth signal generator 96 generates a signal ‘010101010101010101010101010101011010101010101010101010101010101’ or ‘1010101010101010101010101010101010101010101010101010101010101010’ and outputs the created signal to the sixth XOR operator 76 at the same time that the 64-bit ARM sequence is input to the sixth multiplexer 86 from the fifth multiplexer 85. The sixth XOR operator 76 performs an XOR operation on the signal output from the sixth signal generator 96 and the 64-bit ARM sequence output from the fifth multiplexer 85, and outputs a result of the XOR operation to the sixth multiplexer 86. The sixth multiplexer 86 alternatively multiplexes the signal output from the fifth multiplexer 85 and the signal output from the sixth XOR operator 76 to create an ARM sequence of 128 bits.
The created 128-bit ARM sequence is used for detecting frame synchronization in the preamble analyzer 62 of FIG. 4. The length of the ARM sequence is extendable by powers of 2 such as 64, 128, 256, 512, and the like. Since the ARM sequence is produced from a plurality of inputs, the number of sequences of the ARM sequence is equal to two times the length of the ARM sequence. For example, the 128-bit ARM sequence shown in FIG. 5 has a total of 256 (=128*2) sequences.
Conventional preamble signals are only used for detection of frame synchronization and channel estimation in receivers of communication systems.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a method for generating a superior sequence set from a sequence candidate group that can be used as preambles, and an apparatus adopting the method.
To achieve the above and other objects, there is provided a method for generating a preamble sequence group in a communication system having a transmitter and a receiver. The method comprises creating a preamble sequence, calculating a cross-correlation value between sequences using the created preamble sequence, determining a limit cross-correlation value using the cross-correlation value to construct a preamble set used in the communication system, calculating a preamble set that satisfies the determined limit cross-correlation value, and terminating construction of the preamble set.
According to the present invention, a preamble set useful for user or channel discrimination is provided using a plurality of preambles, thereby stabilizing user or channel discrimination.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:
FIG. 1 is a block diagram of a general communication system;
FIG. 2 illustrates a frame structure used in the general communication system;
FIG. 3 is a block diagram of a transmitter for the general communication system;
FIG. 4 is a block diagram of a receiver for the general communication system;
FIG. 5 is a block diagram of an aperiodic recursive multiplex (ARM) sequence generation apparatus;
FIG. 6 is a flowchart illustrating a method for acquiring a preamble set according to an embodiment of the present invention;
FIG. 7 is a block diagram of a transmitter of a communication system using a preamble set according to an embodiment of the present invention;
FIG. 8 is a block diagram of the preamble creator of FIG. 7 according to an embodiment of the present invention;
FIG. 9 is a block diagram of a receiver of a communication system using a preamble set according to an embodiment of the present invention; and
FIG. 10 is a block diagram of the preamble analyzer of FIG. 9 according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Several preferred embodiments of the present invention will now be described in detail with reference to the annexed drawings. In the drawings, the same or similar elements are denoted by the same reference numerals even though they are depicted in different drawings. In the following description, a detailed description of known functions and configurations incorporated herein has been omitted for conciseness.
In the present invention, a plurality of preambles is used for user or channel discrimination. A plurality of preamble signals or sequences, instead of a single preamble signal, should be used simultaneously for a communication system. Preamble signals should satisfy two conditions. First, the preamble signals should have superior characteristics. Second, the preamble signals should not be alike, that is, correlation between different preamble signals should be sufficiently low.
When a plurality of preamble sequences is used, receivers should be able to discriminate from among the preambles. When the receivers check correlation with other preamble signals except for those used for the receivers, the correlation should be sufficiently low so as to reduce the possibility that other preamble signals are regarded as those used for the receivers.
A preamble set used for user or channel discrimination can be structured in different forms. However, in the present invention, an ARM sequence having superior auto-correlation will be described. An ARM sequence set has a variable structure that provides preambles whose number is two times the length of the ARM sequence set, as shown in FIG. 5. ARM sequences are created to calculate a cross-correlation value of each of the ARM sequences. A limit correlation value is determined in relation to the number of preambles to be used for a desired communication system. Then preambles that satisfy the determined correlation value are acquired, and a preamble set is comprised of the acquired preambles.
FIG. 6 is a flowchart illustrating a method for acquiring a preamble set according to an embodiment of the present invention.
In step S110, an ARM sequence is created to acquire preamble sequences. In step S120, cross-correlation values between the preamble sequences are calculated using the created ARM sequence. In step S130, a limit correlation value is determined to provide the optimal preamble set to the communication system using the calculated cross-correlation values. In step S140, a preamble set that satisfies the determined limit cross-correlation value is constructed. In step S150, it is determined if the generated preamble set is suitable for the communication system. If the generated preamble set is suitable for the communication system, construction of the preamble set is terminated in step S160.
However, if the generated preamble set is not suitable for the communication system, the limit cross-correlation value is adjusted in step S170, and steps S140 and S150 are performed again. The generated preamble set is applied to the communication system.
FIG. 7 is a block diagram of a transmitter in a communication system using the preamble set according to an embodiment of the present invention. Referring to FIG. 7, a preamble creator 100 creates preamble signals according to an embodiment of the present invention and transmits the created preamble signals to a multiplexer 300. Transmission data 200 is transmission data to be transmitted to a receiver and includes an MAC header and a PHY header. The multiplexer 300 performs multiplexing, i.e. multiplexes the preamble signals created by the preamble creator 100 and the transmission data 200, and transmits a resultant signal to the receiver through a transmission antenna 350.
FIG. 8 is a block diagram of the preamble creator 100 of FIG. 7. Referring to FIG. 7, the preamble creator 100 includes a preamble selector 120 and a preamble generator 140. The preamble selector 120 selects one of the preambles available in a preamble set that is agreed upon between the transmitter and the receiver in the communication system, and transmits the preamble information to the preamble generator 140. The preamble generator 140 creates the selected preamble using the preamble information transmitted from the preamble selector 120 and outputs the created preamble to the multiplexer 300.
FIG. 9 is a block diagram of a receiver of the communication system using the preamble set according to an embodiment of the present invention. A frame signal transmitted from the transmitter of FIG. 7 is received through a reception antenna 410, and input to a preamble analyzer 500 and a data restorer 420.
The preamble analyzer 500 analyzes the received frame signal, detects the preamble information, synchronization information and channel estimation information, and transmits the detected information to the data restorer 420. The data restorer 420 restores the received data based on the information transmitted from the preamble analyzer 500, and outputs the restored data 430.
FIG. 10 is a block diagram of the preamble analyzer 500 of FIG. 9. Referring to FIG. 10, the preamble analyzer 500 includes a preamble generator 510, a correlation measurer 520, and a synchronization acquisition/channel estimation unit 540.
A received signal 600 received through the reception antenna 410 is a frame signal transmitted from the transmitter of FIG. 7, and is input into the correlation measurer 520. The preamble generator 510 generates preambles that are agreed upon between the transmitter and the receiver of the communication system, and inputs the preambles to the correlation measurer 520.
The correlation measurer 520 measures cross-correlation between the frame signal, i.e., the received signal 600, and the preambles generated by the preamble generator 510, and detects preambles included in the received frame signal. The correlation measurer 520 transmits information on the detected preambles to the synchronization acquisition/channel estimation unit 540. The synchronization acquisition/channel estimation unit 540 acquires synchronization information of the frame signal, i.e. the received signal 600, and estimates channels based on the information received from the correlation measurer 520. Here, the acquired information is transmitted to the data restorer 420 of FIG. 9.
As described above, the present invention provides a preamble set useful for user or channel discrimination using a plurality of preambles, thus providing more stable user or channel discrimination.
A process of acquiring a preamble set in FIG. 6 will now be described herein below. The process below is intended to acquire preamble sets each comprised of 4 preambles, using 128-bit ARM sequences. First, all of the ARM sequences are created in step S110 of FIG. 6.
Table 1 tabulates the 128-bit ARM sequences created in step S110 of FIG. 6. In Table 1, values at the left side are indices of created ARM sequences and values at the right side are the ARM sequences. The indices of the ARM sequences shown in Table 1 are used to facilitate understanding of the present invention and may be defined differently or may not be used according to the preambles. In step S120 of FIG. 6, cross-correlation values between created preamble sequences are calculated.
TABLE 1
1
:
00010010000111010001001011100010000100100001110111101101000111010001001000011101000100101110001011101101111000100001001011100010
2
:
01000111010010000100011110110111010001110100100010111000010010000100011101001000010001111011011110111000101101110100011110110111
3
:
00100001001011100010000111010001001000010010111011011110001011100010000100101110001000011101000111011110110100010010000111010001
4
:
01110100011110110111010010000100011101000111101110001011011110110111010001111011011101001000010010001011100001000111010010000100
5
:
00011101000100100001110111101101000111010001001011100010000100100001110100010010000111011110110111100010111011010001110111101101
6
:
01001000010001110100100010111000010010000100011110110111010001110100100001000111010010001011100010110111101110000100100010111000
7
:
00101110001000010010111011011110001011100010000111010001001000010010111000100001001011101101111011010001110111100010111011011110
8
:
01111011011101000111101110001011011110110111010010000100011101000111101101110100011110111000101110000100100010110111101110001011
9
:
00010010111000100001001000011101000100101110001011101101111000100001001011100010000100100001110111101101000111010001001000011101
10
:
01000111101101110100011101001000010001111011011110111000101101110100011110110111010001110100100010111000010010000100011101001000
11
:
00100001110100010010000100101110001000011101000111011110110100010010000111010001001000010010111011011110001011100010000100101110
12
:
01110100100001000111010001111011011101001000010010001011100001000111010010000100011101000111101110001011011110110111010001111011
13
:
00011101111011010001110100010010000111011110110111100010111011010001110111101101000111010001001011100010000100100001110100010010
14
:
01001000101110000100100001000111010010001011100010110111101110000100100010111000010010000100011110110111010001110100100001000111
15
:
00101110110111100010111000100001001011101101111011010001110111100010111011011110001011100010000111010001001000010010111000100001
16
:
01111011100010110111101101110100011110111000101110000100100010110111101110001011011110110111010010000100011101000111101101110100
17
:
00010010000111011110110100011101000100100001110100010010111000100001001000011101111011010001110111101101111000101110110100011101
18
:
01000111010010001011100001001000010001110100100001000111101101110100011101001000101110000100100010111000101101111011100001001000
19
:
00100001001011101101111000101110001000010010111000100001110100010010000100101110110111100010111011011110110100011101111000101110
20
:
01110100011110111000101101111011011101000111101101110100100001000111010001111011100010110111101110001011100001001000101101111011
21
:
00011101000100101110001000010010000111010001001000011101111011010001110100010010111000100001001011100010111011011110001000010010
22
:
01001000010001111011011101000111010010000100011101001000101110000100100001000111101101110100011110110111101110001011011101000111
23
:
00101110001000011101000100100001001011100010000100101110110111100010111000100001110100010010000111010001110111101101000100100001
24
:
01111011011101001000010001110100011110110111010001111011100010110111101101110100100001000111010010000100100010111000010001110100
25
:
00010010111000101110110111100010000100101110001000010010000111010001001011100010111011011110001011101101000111011110110111100010
26
:
01000111101101111011100010110111010001111011011101000111010010000100011110110111101110001011011110111000010010001011100010110111
27
:
00100001110100011101111011010001001000011101000100100001001011100010000111010001110111101101000111011110001011101101111011010001
28
:
01110100100001001000101110000100011101001000010001110100011110110111010010000100100010111000010010001011011110111000101110000100
29
:
00011101111011011110001011101101000111011110110100011101000100100001110111101101111000101110110111100010000100101110001011101101
30
:
01001000101110001011011110111000010010001011100001001000010001110100100010111000101101111011100010110111010001111011011110111000
31
:
00101110110111101101000111011110001011101101111000101110001000010010111011011110110100011101111011010001001000011101000111011110
.
.
.
234
:
10111000010010001011100010110111010001111011011110011100010110111101110000100100010111000101101110111000010010000100011101001000
235
:
11011110001011101101111011010001001000011101000111011110110100011101111000101110110111101101000111011110001011100010000100101110
236
:
10001011011110111000101110000100011101001000010010001011100001001000101101111011100010111000010010001011011110110111010001111011
237
:
11100010000100101110001011101101000111011110110111100010111011011110001000010010111000101110110111100010000100100001110100010010
238
:
10110111010001111011011110111000010010001011100010110111101110001011011101000111101101111011100010110111010001110100100001000111
239
:
11010001001000011101000111011110001011101101111011010001110111101101000100100001110100011101111011010001001000010010111000100001
240
:
10000100011101001000010010001011011110111000101110000100100010111000010001110100100001001000101110000100011101000111101101110100
241
:
11101101111000100001001011100010000100100001110100010010111000101110110111100010000100101110001011101101111000101110110100011101
242
:
10111000101101110100011110110111010001110100100001000111101101111011100010110111010001111011011110111000101101111011100001001000
243
:
11011110110100010010000111010001001000010010111000100001110100011101111011010001001000011101000111011110110100011101111000101110
244
:
10001011100001000111010010000100011101000111101101110100100001001000101110000100011101001000010010001011100001001000101101111011
245
:
11100010111011010001110111101101000111010001001000011101111011011110001011101101000111011110110111100010111011011110001000010010
246
:
10110111101110000100100010111000010010000100011101001000101110001011011110111000010010001011100010110111101110001011011101000111
247
:
11010001110111100010111011011110001011100010000100101110110111101101000111011110001011101101111011010001110111101101000100100001
248
:
10000100100010110111101110001011011110110111010001111011100010111000010010001011011110111000101110000100100010111000010001110100
249
:
11101101000111010001001000011101000100101110001000010010000111011110110100011101000100100001110111101101000111011110110111100010
250
:
10111000010010000100011101001000010001111011011101000111010010001011100001001000010001110100100010111000010010001011100010110111
251
:
11011110001011100010000100101110001000011101000100100001001011101101111000101110001000010010111011011110001011101101111011010001
252
:
10001011011110110111010001111011011101001000010001110100011110111000101101111011011101000111101110001011011110111000101110000100
253
:
11100010000100100001110100010010000111011110110100011101000100101110001000010010000111010001001011100010000100101110001011101101
254
:
10110111010001110100100001000111010010001011100001001000010001111011011101000111010010000100011110110111010001111011011110111000
255
:
11010001001000010010111000100001001011101101111000101110001000011101000100100001001011100010000111010001001000011101000111011110
256
:
10000100011101000111101101110100011110111000101101111011011101001000010001110100011110110111010010000100011101001000010010001011
Table 2 tabulates the largest cross-correlation values among the calculated cross-correlation values in Table 1. Here, a larger cross-correlation value implies that similarity between two signals is high. Such high similarity is likely to cause generation of an error during analyzing of preambles and searching of synchronization in the preamble analyzer 62 of the receiver of FIG. 4. Thus, the largest cross-correlation value among cross-correlation values between corresponding sequences is used as a representative value.
TABLE 2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
1
128
26
65
65
40
66
36
66
49
49
68
38
49
49
68
34
41
50
35
50
2
26
128
65
65
66
40
66
36
49
49
38
68
49
49
34
68
50
41
50
36
3
65
65
128
26
36
66
40
66
68
38
49
49
68
34
49
49
36
50
32
50
4
65
65
26
128
66
36
66
40
38
68
49
49
34
68
49
49
50
38
50
32
5
40
66
36
66
128
22
65
65
49
49
68
34
49
51
68
34
72
29
45
43
6
66
40
66
36
22
128
65
65
49
49
34
68
51
49
34
68
29
72
43
45
7
36
66
40
65
65
65
128
22
68
34
49
49
68
34
51
49
44
45
72
29
8
56
36
66
40
65
65
22
128
34
68
49
49
34
68
49
51
45
44
29
72
9
49
49
68
38
49
49
68
34
128
22
65
65
40
66
33
66
48
50
36
50
10
49
49
38
68
49
49
34
68
22
128
65
65
66
40
68
33
50
48
50
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11
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65
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22
33
66
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38
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22
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66
33
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13
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51
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23
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31
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17
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22
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65
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65
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27
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22
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22
128
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.
.
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.
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.
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26
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26
128
65
65
66
40
66
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26
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40
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22
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66
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22
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22
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29
200
66
36
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22
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34
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201
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22
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65
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22
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38
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22
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66
33
66
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34
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128
23
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31
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49
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23
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31
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68
34
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40
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128
22
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43
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27
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34
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40
65
65
22
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43
43
27
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209
41
50
36
50
72
29
44
45
48
50
36
50
72
31
43
43
128
22
65
65
210
50
41
50
36
29
72
45
44
50
48
50
36
31
72
43
43
22
128
65
65
211
36
50
32
50
45
43
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29
36
50
48
50
43
43
72
27
65
65
128
22
.
.
.
.
.
.
245
40
33
52
31
33
33
52
42
40
46
29
45
80
30
43
43
58
35
60
34
246
33
40
31
52
33
33
42
52
46
40
46
29
30
80
43
43
35
56
34
60
247
52
26
40
33
52
42
33
33
28
46
40
46
43
43
80
30
60
34
56
35
248
26
52
33
40
42
52
33
33
46
28
46
40
43
43
30
80
34
60
35
56
249
80
30
43
43
40
46
36
46
33
42
52
30
40
33
52
26
80
30
43
41
250
30
80
43
43
46
40
46
36
42
33
30
52
33
40
26
52
30
80
41
43
251
43
43
80
30
36
46
40
46
52
30
39
42
52
31
40
33
41
43
80
30
252
43
43
30
80
46
36
46
40
30
52
42
39
31
52
33
40
43
41
30
80
253
40
45
36
46
80
38
43
43
40
33
52
31
33
33
52
42
40
46
36
42
254
46
49
46
36
36
80
43
43
33
40
31
52
33
33
42
52
46
40
42
36
255
36
46
40
48
43
43
80
38
52
26
40
33
52
42
33
33
36
42
40
46
256
46
36
46
40
43
43
38
80
26
52
33
40
42
52
33
33
42
36
46
40
21
. . .
245
246
247
248
249
250
251
252
253
254
255
256
1
72
. . .
33
42
52
30
40
33
52
26
80
30
43
43
2
29
42
33
30
52
33
40
26
52
30
80
43
43
3
45
52
30
39
42
52
31
40
33
43
43
80
30
4
43
30
52
42
39
31
52
33
40
43
43
30
80
5
41
40
33
52
31
33
33
52
42
40
46
36
46
6
50
33
40
31
52
33
33
42
52
46
40
46
36
7
36
52
26
40
33
52
42
33
33
36
46
40
46
8
50
26
52
33
40
42
52
33
33
46
36
46
40
9
72
80
30
43
43
40
46
28
46
33
42
52
30
10
27
30
80
43
43
46
40
46
28
42
33
30
52
11
43
43
43
80
30
29
46
40
46
52
30
39
42
12
43
43
43
30
80
46
29
46
40
30
52
42
39
13
48
40
46
29
46
80
30
43
43
40
33
52
31
14
50
46
40
46
29
30
80
43
43
33
40
31
52
15
36
26
46
40
46
43
43
80
30
52
26
40
33
16
50
46
28
46
40
43
43
30
80
26
52
33
40
17
33
64
46
52
34
56
35
60
34
80
30
41
43
18
66
46
64
34
52
35
56
34
60
30
80
43
41
19
33
52
34
64
46
60
34
56
25
43
41
80
30
20
68
34
52
46
64
34
60
35
56
41
43
30
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21
128
56
35
60
34
64
34
52
46
40
42
35
46
.
.
.
.
.
.
.
.
.
193
72
. . .
40
33
52
26
80
30
43
43
40
46
36
46
194
29
33
40
26
52
30
80
43
43
45
40
46
36
195
45
52
31
40
33
43
43
80
30
35
46
40
46
196
43
31
52
33
40
43
43
30
80
46
36
46
40
197
41
33
33
52
42
40
46
36
46
80
38
43
43
198
50
33
33
42
52
46
40
46
35
38
80
43
43
199
36
52
42
33
33
36
46
40
46
43
43
80
38
200
50
42
52
33
33
46
36
46
40
43
43
38
80
201
72
40
46
28
46
33
42
52
30
40
33
52
26
202
27
46
40
46
28
42
33
30
52
33
40
26
52
203
43
29
46
40
46
52
30
39
42
52
31
40
33
204
43
48
29
46
40
30
52
42
39
31
52
33
40
205
48
80
30
43
43
40
33
52
31
33
33
52
42
206
50
30
80
43
43
33
40
31
52
33
33
42
52
207
36
43
43
80
30
52
26
40
33
52
42
33
33
208
50
43
43
30
80
26
52
33
40
42
52
33
33
209
33
56
35
60
34
80
30
41
43
40
46
36
42
210
66
35
56
34
60
30
80
43
41
46
40
42
36
211
33
60
34
56
35
43
41
80
38
36
42
40
46
.
.
. . .
.
.
.
.
.
.
.
245
64
. . .
128
25
65
65
49
49
68
34
49
51
68
34
246
34
25
128
65
65
49
49
34
68
51
49
34
68
247
52
65
65
128
19
68
34
49
49
68
34
51
49
248
46
65
65
19
128
34
68
49
49
34
68
49
51
249
40
49
49
68
34
128
23
65
65
33
66
33
66
250
42
49
49
34
68
23
128
65
65
66
33
66
33
251
36
68
34
49
49
65
65
128
22
33
66
35
66
252
46
34
68
49
49
65
65
22
128
66
33
66
35
253
80
49
51
68
34
33
66
33
66
128
26
65
65
254
30
51
49
34
68
66
33
66
33
26
128
65
65
255
43
68
34
51
49
33
66
35
66
65
65
128
26
256
41
34
68
49
51
66
33
66
35
65
65
26
128
A preamble set having the minimum value among the representative values of Table 2 should be constructed. By acquiring a limit cross-correlation value that makes the cross-correlation value to be the smallest, it is possible to minimize the possibility of the generation of an error when the preamble analyzer 62 of FIG. 4 analyzes the preambles.
To construct the preamble set of the smallest cross-correlation values in step S130 of FIG. 6, one representative value that is largest or smallest is set as the limit cross-correlation value. An appropriate preamble set is searched for using the set representative value. According to the present invention, the representative value set in step S310 of FIG. 6 is set to 31.
Table 3 tabulates a preamble set calculated using the representative value ‘31’. As shown in Table 3, there are 128 preamble sets. Here, if the representative value is lowered to 30, there is no appropriate preamble set since when any 4 sequences are selected from among the 256 sequences, the lowest limit of all cross correlation values pertaining to the selected sequence group is 31.
TABLE 3
s1
s2
s3
s4
s1:s2
s1:s3
s1:s4
s2:s3
s2:s4
s3:s4
17
47
86
108
28
31
30
30
23
29
17
47
86
172
28
31
30
30
23
29
17
47
108
150
28
30
31
23
30
29
17
47
150
172
28
31
30
30
23
29
17
86
108
239
31
30
28
29
30
23
17
86
172
239
31
30
28
29
30
23
17
108
150
239
30
31
28
29
23
30
17
150
172
239
31
30
28
29
30
23
18
48
85
107
28
31
30
30
23
29
18
48
85
171
28
31
30
30
23
29
18
48
107
149
28
30
31
23
30
29
18
48
149
171
28
31
30
30
23
29
18
85
107
240
31
30
28
29
30
23
18
85
171
240
31
30
28
29
30
23
18
107
149
240
30
31
28
29
23
30
18
149
171
240
31
30
28
29
30
23
19
45
88
106
29
31
30
30
23
28
19
45
88
170
29
31
30
30
23
28
19
45
106
152
29
30
31
23
30
28
19
45
152
170
29
31
30
30
23
28
19
88
106
237
31
30
29
28
30
23
19
88
170
237
31
30
29
28
30
23
19
106
152
237
30
31
29
28
23
30
19
152
170
237
31
30
29
28
30
23
20
46
87
105
29
31
30
30
23
28
20
46
87
169
29
31
30
30
23
28
20
46
105
151
29
30
31
23
30
28
20
46
151
169
29
31
30
30
23
28
20
87
105
238
31
30
29
28
30
23
20
87
169
238
31
30
29
28
30
23
20
105
151
238
30
31
29
28
23
30
20
151
169
238
31
30
29
28
30
23
21
43
82
112
29
31
30
30
23
28
21
43
82
176
29
31
30
30
23
28
21
43
112
146
29
30
31
23
30
28
21
43
146
176
29
31
30
30
23
28
21
82
112
235
31
30
29
28
30
23
21
82
176
235
31
30
29
28
30
23
21
112
146
235
30
31
29
28
23
30
21
146
176
235
31
30
29
28
30
23
22
44
81
111
29
31
30
30
23
28
22
44
81
175
29
31
30
30
23
28
22
44
111
145
29
30
31
23
30
28
22
44
145
175
29
31
30
30
23
28
22
81
111
236
31
30
29
28
30
23
22
81
175
236
31
30
29
28
30
23
22
111
145
236
30
31
29
28
23
30
22
145
175
236
31
30
29
28
30
23
23
41
84
110
28
31
30
30
23
29
23
41
84
174
28
31
30
30
23
29
23
41
110
148
28
30
31
23
30
29
23
41
148
174
28
31
30
30
23
29
23
84
110
233
31
30
28
29
30
23
23
84
174
233
31
30
28
29
30
23
23
110
148
233
30
31
28
29
23
30
23
148
174
233
31
30
28
29
30
23
24
42
83
109
28
31
30
30
23
29
24
42
83
173
28
31
30
30
23
29
24
42
109
147
28
30
31
23
30
29
24
42
147
173
28
31
30
30
23
29
24
83
109
234
31
30
28
29
30
23
24
83
173
234
31
30
28
29
30
23
24
109
147
234
30
31
28
29
23
30
24
147
173
234
31
30
28
29
30
23
41
84
110
215
30
23
28
29
31
30
41
84
174
215
30
23
28
29
31
30
41
110
148
215
23
30
28
29
30
31
41
148
174
215
30
23
28
29
31
30
42
83
109
216
30
23
28
29
31
30
42
83
173
216
30
23
28
29
31
30
42
109
147
216
23
30
28
29
30
31
42
147
173
216
30
23
28
29
31
30
43
82
112
213
30
23
29
28
31
30
43
82
176
213
30
23
29
28
31
30
43
112
146
213
23
30
29
28
30
31
43
146
176
213
30
23
29
28
31
30
44
81
111
214
30
23
29
28
31
30
44
81
175
214
30
23
29
28
31
30
44
111
145
214
23
30
29
28
30
31
44
145
175
214
30
23
29
28
31
30
45
88
106
211
30
23
29
28
31
30
45
88
170
211
30
23
29
28
31
30
45
106
152
211
23
30
29
28
30
31
45
152
170
211
30
23
29
28
31
30
46
87
105
212
30
23
29
28
31
30
46
87
169
212
30
23
29
28
31
30
46
105
151
212
23
30
29
28
30
31
46
151
169
212
30
23
29
28
31
30
47
86
108
209
30
23
28
29
31
30
47
86
172
209
30
23
28
29
31
30
47
108
150
209
23
30
28
29
30
31
47
150
172
209
30
23
28
29
31
30
48
85
107
210
30
23
28
29
31
30
48
85
171
210
30
23
28
29
31
30
48
107
149
210
23
30
28
29
30
31
48
149
171
210
30
23
28
29
31
30
81
111
214
236
28
31
30
30
23
29
81
175
214
236
28
31
30
30
23
29
82
112
213
235
28
31
30
30
23
29
82
176
213
235
28
31
30
30
23
29
83
109
216
234
29
31
30
30
23
28
83
173
216
234
29
31
30
30
23
28
84
110
215
233
29
31
30
30
23
28
84
174
215
233
29
31
30
30
23
28
85
107
210
240
29
31
30
30
23
28
85
171
210
240
29
31
30
30
23
28
86
108
209
239
29
31
30
30
23
28
86
172
209
239
29
31
30
30
23
28
87
105
212
238
28
31
30
30
23
29
87
169
212
238
28
31
30
30
23
29
88
106
211
237
28
31
30
30
23
29
88
170
211
237
28
31
30
30
23
29
105
151
212
238
28
30
23
31
30
29
106
152
211
237
28
30
23
31
30
29
107
149
210
240
29
30
23
31
30
28
108
150
209
239
29
30
23
31
30
28
109
147
216
234
29
30
23
31
30
28
110
148
215
233
29
30
23
31
30
28
111
145
214
236
28
30
23
31
30
29
112
146
213
235
28
30
23
31
30
29
145
175
214
236
28
31
30
30
23
29
146
176
213
235
28
31
30
30
23
29
147
173
216
234
29
31
30
30
23
28
148
174
215
233
29
31
30
30
23
28
149
171
210
240
29
31
30
30
23
28
150
172
209
239
29
31
30
30
23
28
151
169
212
238
28
31
30
30
23
29
152
170
211
237
28
31
30
30
23
29
If one preamble set is selected from among the 128 preambles sets and is used to discriminate users or channels, a preamble set having a superior auto-correlation and cross-correlation that is less than 31 can be used.
Once a preamble set is determined in a communication system, the preamble selector 120 of FIG. 8 selects one from among preambles of the preamble set and transmits the preamble information to the preamble generator 140 of FIG. 8. The preamble generator 140 generates preambles using the preamble information.
Once the preambles included in a frame are transmitted from the transmitter to the receiver, the preamble analyzer 500 of FIG. 9 analyzes the preambles. At this time, the preamble analyzer 500 detects the preambles selected by the preamble selector 120 of FIG. 8 and creates the preamble information through the correlation measurer 520 of FIG. 10.
By providing a preamble set to discriminate between users or channels using a plurality of preambles, it is possible to more stably discriminate users or channels.
According to an embodiment of the present invention, by providing a preamble set to discriminate between users or channels using a plurality of preambles, it is possible to more stably discriminate the users or channels.
By lowering cross-correlation to the smallest possible value, users or channels can be discriminated while the preambles are not affected in acquiring synchronization information.
While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
