TW201105073A - Method of generating preamble sequence for wireless local area network device - Google Patents

Abstract

A method of generating preamble sequence for a wireless local area network (WLAN) device is disclosed. A channel used by the WLAN device may be divided into four sub-channels, and the method includes forming a preamble sequence of a first sub-channel, making three replicas of the preamble sequence of the first sub-channel, each replica with a phase rotation of a first angle, a second angle, and a third angle respectively, for forming each preamble sequence of a second sub-channel, a third sub-channel, and a fourth sub-channel, and arranging the preamble sequences of the first, the second, the third, and the fourth sub-channels to form a preamble sequence of the channel.

Description

201105073 VI. Description of the Invention: [Technical Field] The present invention relates to a method for generating a Preamble sequence for a wireless local area network device, especially a wireless area for complying with the ffiEE8〇211ac standard. A method of generating a preamble sequence in a network device. [Prior Art] Wireless Local Area Network (WLAN) technology is one of the popular wireless communication technologies. It was first used in military applications and has been widely used in various consumer electronic products in recent years, such as desktop computers and notes. A computer or personal digital assistant that provides the convenience and speed of Internet communication for the general public. The IEEE802.il series of wireless LAN communication protocols is developed by the International Institute of Electrical and Electronics Engineers.

Developed by Electrical and Electronics Engineers (IEEE), it evolved from the early EE 802.11a, IEEE 802.11b, IEEE 802.11g, etc. to the current mainstream EE 802.11 η. The IEEE 802.11 a/g/n standard adopts 正交rth〇g〇nal Frequency-Division Multiplexing (OFDM) modulation, which has the advantages of high spectrum utilization and resistance to multipath transmission (MultipathPr).讯pagati〇n) caused by the signal attenuation effect, etc. However, for the signal transmitter in the wireless local area network system, it is easy to change the peak-to-average power ratio (peak-t〇-Average Power Ratio) Too high, the modulation signal is also easy to produce when the RF circuit of the signal transmitter is processed. 201105073

Distortion, resulting in a lower probability of the signal receiver correctly detecting the packet. Different from the EE 802.11a/g standard, the ΐΕΕΕ802·11η standard uses Multiple Input Multiple Output (ΜΙΜΟ) technology and other new functions to greatly improve data rate and throughput (Throughput), and channel bandwidth. Increased from 20MHz to 40MHz. Please refer to FIG. 1, which is a schematic diagram of a packet format of the conventional IEEE 802.11n standard. The packet transmitted by the WLAN system is a combination of Preamble _ and the data to be transmitted. The pre-data is located at the forefront of each packet and continues to be the data to be transmitted. The pre-data shown in the figure is a mixed format, which is compatible with IEEE8G2.lla/g. There is no county network device. The towel contains _ bits in the traditional short training position L-STF (Legacy). Short Training Field), Legacy Long Training Field, Legacy Signal Field, High Signaling HT_SI〇 (High_Thr〇ughput Signal Field), High Throughput Short Training block HT_STF (High ThiOughput (10) • Training Field) and N high-throughput long training fields ht ltf (High-Throughput Long Training Field). Traditional short training field l stf for Start-of-packetDetection, Automatic Gain Contrd (AGC) 'Frequency Offset Estimation (Time Synchronization); Training The field L-LTF is used for precise frequency offset estimation and time synchronization; the traditional signal shelf L-SIG carries information on data rate and packet length. High-throughput signal rotten HT alone carries (four) rate tfL, and secret automatic _ packet belongs to mixed format 201105073 or traditional 袼; high throughput short training block HT_STF for automatic gain control; high throughput long training block The HT-LTF is used for channel estimation of multiple inputs and multiple outputs. According to the current IEEE 802.11n standard, in the 40MHz channel pre-data, the second half of the 20MHz channel pre-data is the same as the IEEE 802.11 a/g standard pre-data, and the upper half of the 20MHz channel pre-data is copied. The data is placed before the second half of the 2 〇 MHz channel and the phase is rotated by 90. This can reduce the peak-to-average power ratio when transmitting the pre-data to improve the probability of the signal receiver successfully detecting the packet. In order to achieve higher quality wireless LAN transmission, the relevant units are developing a new generation of IEEE 802.11ac standard, which is a wireless WLAN standard for Very ffigh Thr〇ughput (VHT). The channel bandwidth is 4 〇MHz is increased to. If the IEEE 802.11ac standard is intended to be backward compatible with the old standard EE 8〇2 wireless local area network device, the IEEE 802.11ac standard must be designed to use either a 2 〇 MHz channel or a 40 MHz channel. Therefore, the design of the pre-data must not only take into account the downward compatibility of the channel bandwidth, but also the problem that the peak-to-peak average power ratio may be too high. SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to provide a method for generating a preamble sequence for a wireless local area network device such that the IEEE 〇 211 ac standard can be phased down to the IEEE 802.Ua/g/n standard. Wireless local area network devices and reduce the peak-to-average power ratio. 201105073 This is a method for generating a pre-sequence data sequence for a wireless local area network. The channel used by the wireless local area network device can be divided into a first sub-channel, a first sub-channel, a third sub-channel and a sub-channel, the pre-data sequence generation method package 3 has a pre-data sequence forming one of the first sub-channels; and replicating the pre-data sequence of the first sub-channel to generate a a first copy sequence, and a first angle is obtained by the memory of the wireless local area network device, and the phase of the first copy sequence is rotated by the first degree to form a preamble sequence of the second subchannel; Copying the preamble sequence of the first dice channel to generate a second replica sequence, and taking the second angle of the memory to rotate the phase of the second replica sequence to the second angle to form the third a preamble sequence of the subchannel; copying the preamble sequence of the first subchannel to generate a second replica sequence, and obtaining a third angle from the memory, rotating the phase of the second replica sequence third And forming a preamble sequence of the fourth subchannel; and arranging according to the order of the frequency bands corresponding to the first subchannel, the second subchannel, the third subchannel, and the fourth subchannel The preamble data sequence of the first subchannel, the preamble data sequence of the second subchannel, the preamble data sequence of the third subΦ channel, and the preamble data sequence of the fourth subchannel are A preamble sequence of one of the channels is formed. [Embodiment] Please refer to FIG. 2, FIG. 2 is a schematic diagram of an 80 MHz channel preamble (Preamble) sequence in a frequency domain (Frequency Domain) in a packet conforming to the EE 802 1 lac standard according to an embodiment of the present invention. The 80MHz channel can be divided into four 2〇MHz sub-channels (sub-channel) according to the frequency band from low to high, respectively labeled A, B, ^, d. 201105073 One of the pre-data sequences of sub-channel A is the same as the pre-data sequence of the 20MHz channel of the conventional IEEE 802.11 a standard; each sub-channel of sub-channels B, C, and D is preceded by a data sequence, respectively The copy sequence of the heart of the data sequence before the channel A is rotated by different angles, and the sub-channel B pre-data sequence is & χεχρ() 2πθι), and the sub-channel C pre-data sequence is ^〇χ6χΡ (/2πθ2). ), the sub-channel d pre-set data sequence is 5οχεχρ(_/2πθ3). Please refer to FIG. 3, FIG. 3 is a schematic diagram of a process 3 of the embodiment of the present invention, and the process 30 is used for a wireless local area network device conforming to the EE 802.11ac standard for generating an 80 MHz channel preamble sequence, for example, Figure 2 shows the sequence of data before. The wireless local area network device can be a wireless local area network card and a wireless local area network access point (Access)

Point), computer and mobile communication devices such as mobile phones or personal digital assistants. The process 30 package contains the following steps: Step 300: Start. Step 302: Select a sub-channel X from the four 20 MHz sub-channels, and use the 20 MHz channel pre-data sequence of the ieee 802.1 la standard as one of the pre-data sequences of the sub-channel X. Step 304: Replicating the sub-channel X to pre-set the data sequence to generate a first copy sequence, and rotating the phase of the first copy sequence by a first angle ' to form the four 20-MHz sub-channels, except for the sub-channel X One of the sub-channels Y is a pre-data sequence. Step 306: Replicating the sub-channel X to pre-set the data sequence to generate a second copy sequence, and rotating the phase of the second copy sequence by a second angle of 201105073 degrees to form the four 20-MHz sub-channels, except for the sub-channel Ζ One of the sub-channels 前 one of the pre-data sequences. Step 308: Replicating the sub-channel X to pre-set the data sequence to generate a third copy sequence, and rotating the phase of the third copy sequence by a third angle to form the four 20-MHz sub-channels, except for the sub-channel χ One of the sub-channels W is a pre-data sequence. Step 310: Arranging the sub-channel X pre-data sequence, the sub-channel γ pre-data sequence, and the sub-channel X pre-data sequence according to the high and low lure sequences of the sub-channels γ, γ, z, and w respectively. And the sub-channel W is set as a negative data sequence to form a pre-data sequence of one of the 80 MHz channels. Step 312: End. According to step 302, a sub-channel X is selected from the four 2 〇 MHz sub-channels divided by the 80 MHz channel, and the pre-data sequence of the 20 MHz channel of the IEEE 802.11a standard is used as one of the sub-channels X. The data sequence S〇. The IEEE 802.1 la standard 20 MHz channel preamble sequence is pre-stored in a memory of the wireless local area network device. Please note that the process 30 does not limit which band the sub-channel X must correspond to, and the implementation is freely configurable. After the sub-channel X pre-sequence data sequence S0 is formed according to step 302, the following steps 304, 306, and 308 are performed simultaneously, without a specific order; the sub-channels Y, Z, and W are in the four 20-MHz sub-channels. There is no limitation on the level of the sub-channels Y, Z, and W to which the three sub-channels other than the sub-channel X are located. 201105073 Steps 304 to 308 are used to generate three pre-data sequences s 复制 replication sequence ' and phase-rotate the three replication sequences separately to form three sub-channel pre-data sequences except sub-channel X . In detail, step 3〇4 copies the preamble sequence S〇, and rotates the phase of the preamble sequence to generate a first angle′, which is expressed as 2 redundancy 0 to form a subchannel γ. A pre-data sequence Si ' & = heart xexpW^). Step 306 is also to copy the preamble sequence S〇, and then to rotate the preamble sequence to rotate a second angle, represented by 2πθζ as a diameter to form a preamble sequence s2 of the subchannel z, A = &;χεχρ()2πθ2). Step 308 also copies the preamble sequence S〇, and rotates the preamble sequence to a third angle, expressed as 2πθ3 in diameter, to form a preamble sequence s3 of the subchannel W, & = 4 xexp(y.2ne3). The values of the first angle, the second angle, and the third angle are stored in advance in the memory of the wireless local area network device. Finally, according to step 310, the preamble data sequences S〇, Si, S2 and S3 are arranged according to the order of the frequency bands of the corresponding subchannels to form a preamble sequence S of one of the 80 MHz channels. As can be seen from the above, the process 3 〇 selects one of the four 20 MHz sub-channels, and designs the sub-channel pre-data sequence to conform to the IEEE 802.11a standard 20 MHz channel pre-data sequence, and fixes the pre-data sequence. Phase (can be seen as a rotation of 0.) 'The phase rotation angle of the other three subchannels before the data sequence is relative to the phase of the previous data sequence. Taking the 80 MHz channel preamble data sequence shown in FIG. 2 as an example, the sub-channel A pre-data sequence located in the lowest frequency band is formed according to step 302 of the process 201105073 30; the other sub-channels B, c, and D are based on Step 304 to step 308 are formed. Please note that the process 30 can form a plurality of different 8 〇 MHz channel pre-data sequences, and FIG. 2 is only one of them; the process 3 〇 step 3 〇 2 can also be used to form the sub-low frequency sub-channel B The sub-channel c of the sub-high frequency band or the sub-channel D of the highest frequency band is preceded by a data sequence. In order to reduce the complexity of implementation, an embodiment of the present invention defines θι, 02 or 03 as a multiple of 0.25, ie 〇, 0.25, 0.5 or 0.75, such that the first angle, the first angle or the The two angles are 90. Multiples, that is, 〇. 9, 〇. 18〇. Or 270. . In this way, when performing step 304 to step 308, the pre-data sequence s〇 only needs to be multiplied by + 1, one, one, or -j, which can effectively improve the system operation speed. The sub-channel Y, Z, and W pre-data sequences in Flow 30 are represented as follows: A 4. X αρ(/2πθ,·) ’ Θ, e {〇, 〇.25, 〇 5, 〇 75}" = U 3. Based on the flow 30, only three sub-channels are placed before the data sequence rotation and Θ!, one 2 and one 3 are the definitions of multiples of 〇·25, and the present invention only needs *4〗=64 groups (θι, θ2, θ3 In the permutation combination, the combination of (m) having the smallest peak-to-average power ratio can be searched for the 8 〇mHz channel, that is, the first angle and the second angle are searched for. The combination of the best, without having to search for 44=256 groups, the system computing load is greatly reduced. Progressively, the applicant of this case searched according to the format of the 80MHz channel pre-data sequence shown in Figure 2. 64 groups (01, 02, ~), find 8 groups to make the 11 201105073 channel pre-data sequence have the minimum peak-to-average power ratio (θ"θ2, θ3). Please refer to Figure 4, Figure 4 for the aforementioned 8 _ is a list of the corresponding rotation angles, and the 8 groups (0^02, 03) are (0, 〇, 0.5), (〇, 〇5, 〇), (〇25, 〇, 〇, respectively) 75), (〇25, 〇5 0.25), (0.5, 0, 0) ' (0.5, 0.5, 0.5), (〇.75, 〇, 0.25), (0.75, 0.5, 0.75); -angle The combination of the first angle and the third angle is (〇., 〇., 180.), (0〇, 180〇, 0〇), (90〇, 〇., 270.), (90〇, respectively). 18〇〇, 90.), (180〇, 〇' 〇〇), (180., 180°, 180°), (270., 〇〇, 90.), (270〇, 180°, 270.) The values of the above eight groups (θΐ, θ2, θ3) are stored in the disco body of the wireless local area network. In addition, the applicant in the case simulates according to the above-mentioned eight sets of rotation angle combinations to verify the wireless area network. Whether the signal receiver of the road system can correctly detect the use of these 8 sets of rotation angle pre-data, the analog channel environment is the IEEE 802.11n standard channel model B (Channel ModelΒ) 'signal transmitter transmits 1000 only contains The 80MHz channel pre-data sequence of Figure 2 and the phase rotation packet according to the optimal angle combination shown in Figure 4 are received by the signal receiver of the 4 〇 MHz channel and the signal receiver of the 80 MHz channel, respectively. And calculate the probability of correct packet detection. Lu 80MHz channel can be divided into 4 non-overlapping 20MHz sub-channels A, B C, D, as shown in Figure 2; the 80MHz channel can be further divided into three partially overlapping 40MHz sub-channels {A, B), {B, C} and {C, D}. Please refer to Figure 5, Figure 5 One of the 40MHz channels, one of the signal receivers, has an Autocorrelation Detector on each 40MHz subchannel {A, B}, {B, C}, {C, D} and each Transmit Chain. The minimum value of the Packet Detection Probability measured based on the Signal-to-Noise Ratio (SNR) of 12 201105073. Please refer to Figure 6, the sixth chart shows one of the 40MHz channels, one of the signal receivers, the Cross-correlation Detector in each 40MHz sub-channel {a,, {BC}, {C, D} and Under each transmission chain, the packets measured based on different signal-to-noise ratios successfully detect the probability of a small value. It can be seen from Fig. 5 and Fig. 6 that the minimum value of the successful side rate of the packet measured by the signal receiver of the 40 MHz channel is within an acceptable range, which means that even if the signal receiver of the wireless local area network does not support IEEE 8 〇 2 Uac standard, signal connection

The receiver can also successfully detect the 8 〇 MHz channel preamble sequence generated according to the process 30. Please refer to Figure 7 for the successful detection of packets based on the different signal-to-noise ratios. Minimum value. Please refer to Figure 8. The 8th chart shows one of the 8QMHz channels, one of the signal receivers, the cross-correlation detector is below each transmission chain, and the packet detection probability is the smallest based on the signal-to-noise ratio of different calls. value. It can be seen from Fig. 7 and Fig. 8 that the minimum value of the successful side rate of the packet measured by the signal receiver of the 80 MHz channel is as high as 1%, which means that before the 8 〇 MHz channel generated according to the process 3〇 The data sequence ' can be successfully detected by the signal receiver of the 8 〇 MHz channel. In summary, the present invention proposes a process for generating a pre-data sequence, which can form a pre-data sequence of the IEEE8〇2.llac standard, and form a pre-data sequence that is backward compatible! EEE8〇2 lla/g/n standard wireless local area network device. Preferably, the present invention further searches for the optimal phase angle of the pre-data sequence of each sub-channel to optimize the peak-to-average power ratio of the pre-data phase. The above description is only a preferred embodiment of the present invention, and the scope of the invention is in accordance with the scope of the invention. [Simple Description of the Drawing] Fig. 1 is a schematic diagram of a packet format of the conventional IEEE802.11n standard. FIG. 2 is a schematic diagram of an 80 MHz channel preamble sequence in a frequency domain in a packet conforming to the IEEE 802.11ac standard according to an embodiment of the present invention. FIG. 3 is a schematic diagram of a process of an embodiment of the present invention. Figure 4 is a list of the best rotation angles found based on the format of the 80 MHz channel preamble sequence in Figure 2. Figure 5 is the minimum of the probability of successful detection of packets based on the different signal-to-noise ratios of one of the 40MHz channels, one of the autocorrelation detectors in each 40MHz sub-channel and each transmission chain. List. Figure 6 is the minimum correlation of the probability of successful detection of packets based on different signal-to-noise ratios under one of the 40MHz sub-channels and each transmission chain. List. Figure 7 is a list of the minimum value of the probability of successful packet detection based on the different signal-to-noise ratios of one of the 80 MHz channels of the auto-correlation detector under each transmission chain. Figure 8 is a list of the minimum value of the success rate of one of the 80MHz channels, one of the signal-receiving detectors in each of the 201105073 transmission chains. Traditional short training position Traditional long training position Traditional signal field To the throughput signal field To the short throughput training field To the throughput long training position Subchannel

[Main component symbol description] L-STF L-LTF L-SIG HT-SIG Lu HT-STF HT-LTF A, B, C, D 30 300, 302, 304, 306, 308, 310, 312 Steps. ' ^oXexpO^ej) ' S0xQxp(j2nQ2) ' *^〇x 6χρ(7*2πθ3) pre-sequence sequence stomach

15

Claims (1)

201105073 VII. Patent application scope: 1. - Kind of hiding - No, __ Pre-set data (Preambie) sequence generation method 'One channel used by the wireless area network can be divided into a first sub-channel a second sub-channel, a second sub-parameter; a clean-up; a concatenated sub-channel and a fourth sub-channel, the pre-data sequence generating method comprises: forming a pre-data sequence of one of the first sub-channels; Copying the preamble sequence of the first sub-channel to generate a first copy sequence, and obtaining a first angle from a memory of the S-H wireless network device, rotating the phase of the first copy sequence Forming a preamble sequence of the second subchannel at an angle; copying the preamble sequence of the first subchannel to generate a second replica sequence, and obtaining a second angle from the δ海S memory Rotating the phase of the second replica sequence to the second angle to form a preamble sequence of the third subchannel; copying the preamble sequence of the first subchannel to generate a third replica sequence, and Memory acquisition Deriving a third angle 'rotating the phase of the third copy sequence to the third angle to form a preamble sequence of the fourth subchannel; and according to the first subchannel, the second subchannel, the third The order of the frequency bands corresponding to the sub-channels and the fourth sub-channels respectively 'arrange the pre-data sequence of the first sub-channel, the pre-data sequence of the second sub-channel, and the front of the third sub-channel The data sequence and the pre-funded 201105073 sequence of the fourth sub-channel are set to form a pre-data sequence of the channel. 2. The preamble sequence generation method according to claim 1, wherein the frequency band of the first subchannel is the lowest one of the frequency bands of the first to the fourth subchannels. 3. The method according to claim 2, wherein the first angle, the second angle, and the third angle are 0°, 0°, and 180°, respectively. 4. The method according to claim 2, wherein the first angle, the second angle, and the third angle are 0°, 180°, and 0°, respectively. 5. The method according to claim 2, wherein the first angle, the second angle, and the third angle are 90°, 0°, and 270°, respectively. 6. The method according to claim 2, wherein the first angle, the second angle, and the third angle are 90°, 180°, and 90°, respectively. 7. The method according to claim 2, wherein the first angle, the second angle, and the third angle are 180°, 0°, and 0°, respectively. 8. The method according to claim 2, wherein the first angle, the second angle, and the third angle are 180 respectively. , 180°, 180. . 9. The method according to claim 2, wherein the first angle, 17 201105073, the second angle and the third angle are respectively 270. , 0〇, 90. . 10. The method according to claim 2, wherein the first angle, the second angle, and the third angle are 270, respectively. 180. 270. . 11. The method according to claim 1, wherein the bandwidth of the channel of the wireless local area network device is 80 MHz, and the bandwidth of each of the first to the fourth subchannels. It is 20MHz. 12. The method according to claim 1, wherein the no-line area and the line device are in accordance with one of the IEEE 802.11ac standards, and the wireless area network is located in the area network. 18