KR20200007727A - Apparatus and Method for Waveform Technology of Payload Communications operating at frequency adjacent with CNPC in Unmanned Aircraft System (UAS) - Google Patents

Abstract

The present invention relates to a data transmission method of a wireless communication system using a single transmission wave transmission method performed in a radio station with an unmanned aerial vehicle (UAV). The data transmission method comprises the steps of: receiving a control frame; and transmitting a payload frame to a terrestrial radio station by a radio station with a UAV based on the control frame. The payload frame is determined based on the control frame, and the payload frame is composed of a first subframe and a second subframe of a preset length, and a pilot is disposed in consideration of a value above a preset speed of a UAV and a preset delay spread value.

Description

Apparatus and Method for Waveform Technology of Payload Communications operating at frequency adjacent with CNPC in Unmanned Aircraft System (UAS)}

The present invention relates to a physical layer design and communication scheme of a drone mission communication operating in an adjacent band of a control frequency band for mission data transmission of the drone.

The present invention relates to a physical layer design and communication scheme of a drone mission communication operating in an adjacent band of a control frequency band for mission data transmission of the drone.

The data link of the drone system can be divided into a control communication link and a mission communication link. Mission datalinks are data links associated with mission performance and are generally broadband compared to control communications links. On the other hand, the control communication link is defined as a link for transmitting data related to drone flight control, condition monitoring, and system management.

LTE mobile communication technology is currently being considered as the main communication link for drone control and mission data transmission for the stable operation and operation of disaster-safe drones to improve national safety through disaster prevention and response using drones. LTE mobile communication technology has the advantage of greater coverage and QoS management compared to the existing unlicensed low-power communication technology such as WiFi, which is widely used in existing drones.

However, LTE mobile communication technology also has a problem that communication is cut off outside the coverage of the existing mobile communication networks such as mountain, sea. Considering that drone operation should be possible in anytime and anywhere in the national security situation, an auxiliary communication link is essential for stable control and mission performance even in areas where LTE mobile communication of the main communication link cannot be used.

Unlicensed band communication technology, such as WiFi, which is widely used in existing drones, can be considered, but it is difficult to guarantee coverage limitations and stable communication links due to small power limitation and interference. Accordingly, in Korea, the C-band frequency has been distributed by the drone control and mission licensed frequency bands for the stable operation and expansion of the drone operation.

The control communication C band frequency distributed in Korea is the 5030-5091 MHz band and is a harmonized frequency newly distributed internationally as the control communication frequency for stable entry into the international airspace of the UAV from the ITU-R WRC-12.

On the other hand, mission-communication C band frequency was allocated 5091-5150 MHz band for domestic use. It is possible to secure more stable communication link than communication in low-power unlicensed band and to consider the UAV frequency policy.It is the auxiliary communication link of LTE main communication link of disaster drone. The communication link in the frequency band is considered.

Unlike the C-band control communication technology, mission communication is currently a band allocated to the unmanned mission communication frequency in Korea only, and has not been standardized until now. Therefore, mission communication needs to derive new waveform technology that can be miniaturized and lightened to be suitable for small drones.

Unlike the C-band control communication technology, mission communication is currently a band allocated to the unmanned mission communication frequency in Korea only, and has not been standardized until now. Therefore, mission communication needs to derive new waveform technology that can be miniaturized and lightened to be suitable for small drones.

Considering the mission scenario of the disaster-safe drone to derive new waveform technology, the following requirements should be considered. Accordingly, the present invention proposes a physical layer design and communication scheme of an unmanned aerial vehicle communication that operates in an adjacent band of a control frequency band for transmitting mission data of an unmanned aerial vehicle satisfying certain characteristics.

Technical problems to be achieved in the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the following description. Could be.

The present invention relates to a data transmission method and apparatus for a wireless communication system using a single transmission wave transmission method performed in an unmanned radio station.

According to an embodiment of the present invention, the unmanned mission communication waveform technology may have a 50 ms frame structure composed of two GPS-based subframes similar to the TDD frame structure of the control 5030-5091 MHz band communication standard technology.

According to an embodiment of the present invention, the UAV mission communication waveform technology supports downlink transmission from an unmanned radio station to a terrestrial radio station, and can apply the SC-FDE scheme for low complexity operation even in a low PAPR and multiple fading environment. have.

According to an embodiment of the present invention, the communication waveform technology for the drone mission supports pilot deployment considering a drone speed of 150 km / h or more and 1 to 2us multipath delay spread, and has excellent PAPR and auto and cross to reduce inter-cell interference. Preamble sequences with good correlation properties are used, and various modulation and demodulation methods can be supported to support various transmission rates.

Unlike the C-band control communication technology, mission communication is currently a band allocated to the unmanned mission communication frequency in Korea only, and has not been standardized until now.

The mission communication waveform technology of the present invention operates without interference from the drone communication in the adjacent band for the drone control communication and can be mounted on a small and light drone.

Effects obtained in the present invention are not limited to the above-mentioned effects, and other effects not mentioned above may be clearly understood by those skilled in the art from the following description. will be.

1 is a diagram summarizing the main features of the drone mission communication Waveform technology according to an embodiment of the present invention.
2 shows a diagram of a One Radio frame according to an embodiment of the present invention.
3 is a diagram illustrating a structure of a subframe according to an embodiment of the present invention.
4 illustrates a diagram for an nth slot according to an embodiment of the present invention.
5 is a diagram illustrating an m-th block according to an embodiment of the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the following description of embodiments of the present invention, when it is determined that detailed descriptions of well-known structures or functions may obscure the gist of the present invention, detailed descriptions thereof will be omitted. In the drawings, parts irrelevant to the description of the present invention are omitted, and like reference numerals designate like parts.

In the present invention, the components distinguished from each other to clearly describe each feature, and does not necessarily mean that the components are separated. That is, a plurality of components may be integrated into one hardware or software unit, or one component may be distributed into a plurality of hardware or software units. Therefore, even if not mentioned otherwise, such integrated or distributed embodiments are included in the scope of the present invention.

In the present disclosure, components described in various embodiments are not necessarily required components, and some may be optional components. Therefore, an embodiment composed of a subset of components described in an embodiment is also included in the scope of the present invention. In addition, embodiments including other components in addition to the components described in the various embodiments are included in the scope of the present invention.

The present invention proposes a mission communication waveform technology capable of being mounted on a small and light drone without interference with the drone control communication in a drone control communication adjacent band. The proposed scheme mainly targets drone communication systems operating in the C band, but can be applied to other systems with similar operational concepts.

1 is a diagram summarizing the main features of the drone mission communication Waveform technology according to an embodiment of the present invention.

In consideration of the mission performance scenario of the disaster-safe drone in order to derive a new waveform technology according to an embodiment of the present invention, it is necessary to consider the requirements as shown in Table 1 below.

As mentioned earlier, when considering the light and light UAV mission scenario, the new Waveform technology of UAV mission communication must satisfy the requirements of the following table.

Classification Content (requirements) Transmission speed 7 Mbps or higher Communication radius 30 km Maximum supported drones 4 units Operation required in low altitude drone Consider multipath fading Operation required in low altitude drone Consider multipath fading Compatible with C band communication link for control Interference issue with adjacent control frequencies Variable bit rate support - Requires small, lightweight, low power design PAPR and Low Complexity Receiver Design Unidirectional communication link -

In view of the requirements as shown in Table 1, the present invention proposes a Waveform technology having the main features as shown in FIG.

According to Figure 1, the communication waveform technology for a more drone mission proposed in the present invention is as follows.

According to an embodiment of the present invention, a data transmission method of a wireless communication system performed by an unmanned aerial station includes a step of receiving a control frame and transmitting a payload frame to the terrestrial radio station by the unmanned radio station based on the control frame. It may include the step.

In the claims of the present invention, the payload frame may be used as a term referring to a mission frame. In addition, in the claims of the present invention, a control frame may be used as a term referring to a control frame.

In this case, the payload frame may be determined based on the control frame according to an embodiment of the present invention. In this case, the payload frame may have a GPS-based 50 ms frame structure identical to that of the control C band communication standard technology. In more detail, the payload frame may be determined as a GPS-based 50 ms frame similar to the TDD frame structure of the control 5030-5091 MHz band communication standard technology.

In this case, according to an embodiment of the present invention, it is possible to support downlink transmission from the drone-mounted radio station to the terrestrial radio station.

In this case, the payload frame may include a first subframe and a second subframe having a preset length. More specifically, the payload frame may consist of two subframes having a length of 24.3 ms and 25.7 ms, respectively. In this case, as shown in FIG. 2, the first subframe may correspond to subframe 0 having a length of Tsf0 = 24.3 ms. In this case, as shown in FIG. 2, the second subframe may correspond to subframe 1 having a length of Tsf1 = 25.7 ms.

According to an embodiment of the present invention, a waveform may be selected in a single transmission wave method in consideration of amplifier nonlinearity in terms of SWaP of a small unmanned aerial vehicle. At this time, PAPR characteristics can be excellent compared to the existing multi-carrier system such as WiFi. In addition, the waveform may apply a Single Carrier-Frequency Domain Equalization (SC-FDE) scheme for low complexity operation even in a multi-fading channel environment.

According to an embodiment of the present invention, a pilot may be arranged in consideration of a value over a preset speed of the drone and a preset delay spread value. At this time, according to an embodiment of the present invention, the preset speed of the drone may be 150 km / h, and the pilot may be disposed in consideration of the drone speed of 150 km / h or more.

At this time, according to an embodiment of the present invention, the predetermined delay spread value may be 1 to 2 us, and the pilot may be arranged in consideration of the 1 to 2 us multipath delay spread value.

According to an embodiment of the present invention, the preamble may use a preamble sequence having excellent PAPR and good auto and cross correlation properties to reduce inter-cell interference. In this case, according to an embodiment of the present invention, the preamble may apply a Zadoff-Zu sequence having excellent PAPR characteristics.

According to one embodiment of the present invention, a communication waveform technique for an unmanned mission can support various modulation and demodulation schemes to support various transmission rates.

In this case, according to an embodiment of the present invention, a modulation scheme may use QPSK, 16QAM (or 8PSK), but is not limited thereto.

In this case, the encoding scheme may use Punctured Turbo Coding according to an embodiment of the present invention, but is not limited thereto.

In this case, according to an embodiment of the present invention, the MCS mode may support various encoding modes. (Minimum 0.4 Mbps, up to 7 Mbps or more)

In addition, according to an embodiment of the present invention, transmission filtering may be applied to improve transmission spectrum characteristics.

2 shows a diagram of a One Radio frame according to an embodiment of the present invention.

The multiple access scheme for a physical uplink payload channel (PUPCH) for uplink missions is based on a single carrier-frequency domain equalization (SC-FDE) scheme with a cyclic prefix. Time division duplex (hereinafter referred to as TDD) is applied as a duplication scheme.

In the present invention, unless stated otherwise, the size of various fields in the time domain is expressed in time units of Ts = 1 / (15000 × 2048) seconds. Only downlink is present and consists of a 50 ms long radio frame with two subframes having a length of 24.3 ms and 25.7 ms, respectively.

Each radio frame has a length of Tf = 50 ms, and may be composed of subframe 0 having a length of Tsf0 = 24.3 ms and subframe 1 having a length of Tsf1 = 25.7 ms. The first subframe (No. 0, # 0) is used by the indication of the upper layer. When the first subframe is not used, subframe # 0 is not transmitted. Further, according to an embodiment of the present invention, the frame starts transmission when the radio frame number corresponding to an integer multiple of every 20 corresponds to an integer multiple of 1 second in UTC time.

3 is a diagram illustrating a structure of a subframe according to an embodiment of the present invention.

Subframe 0 and subframe 1 may have a length of T _sf0 = 24.3 ms and T _sf1 = 25.7 ms, respectively. In addition, subframe 0 and subframe 1 may be configured with a data segment interval and a guard time.

3A and 3B, the data segment section includes a front guard symbol section, one or two preamble SC-FDE sections, at least one slot section (N _{sf, slot} ), and a tail guard symbol section. Can be. In addition, the data segment may have the same structure and length regardless of the subframe number.

According to an embodiment of the present invention, in the case of guard time, subframe 0 may have a length of 1.3 ms and subframe 1 may have a length of 2.7 ms.

[Table 2] is a table of the structure of the subframe, and more specifically, the number of slots (N _{sf, slot} ) that can be included in each subframe is shown in [Table 2]. The configuration of the subframe is determined by the higher layer.

According to an embodiment of the present invention, when the subframe # 0 is shown in Table 2, the number of slots N _{sf and slot} included in the subframe may correspond to 34. In addition, in the first subframe, the number of slots N _{sf and slot} included in the subframe may correspond to 34.

According to FIG. 3, the length Tslot of one slot may be calculated as in Equation 1 below.

In addition, the slot may be _composed of N _{slot, data_blocks} SC-FDE data blocks and N _{slot, pilot_blocks} SC-FDE pilot blocks.

[Table 3] is a table of the structure of the subframe, and more specifically, it may correspond to the number of SC-FDE blocks constituting the slot of each subframe. Supported configurations are shown in [Table 3] below.

According to an embodiment of the present invention, when subframe # 0 is shown in [Table 3], the number of SC-FDE blocks (N _{slot, SC-FDE_blocks} ) in a slot is 24, and the number of pilot SC-FDE blocks in a slot is shown. (N _{slot, pilot_blocks} ) may be configured as 4 and the number of data SC-FDE blocks (N _{slot, data_blocks} ) in the _slot may be 20. In the case of subframe 1, the number of SC-FDE blocks (N _{slot, SC-FDE_blocks} ) in the slot is 18, the number of pilot SC-FDE blocks (N _{slot, pilot_blocks} ) in the _slot is three and the data SC in the slot. The number of FDE blocks (N _{slot, data_blocks} ) may be 15.

4 illustrates a diagram for an nth slot according to an embodiment of the present invention. In more detail, FIG. 4 shows data and pilot SC-FDE block positions constituting slots of a subframe.

In the slot, the SC-FDE Pilot block may be inserted after every five SC-FDE data blocks as shown in FIGS. 4A and 4B. The location of the SC-FDE Pilot block according to the configuration is shown in the following [Table 4]. [Table 4] is a table showing the structure of a subframe, and corresponds to a diagram showing data and pilot SC-FDE block positions constituting slots of a subframe.

4A and 4, according to an embodiment of the present invention, the position of the SC-FDE Pilot block at the time of subframe 0 can be confirmed. More specifically, in subframe 0, the interval between the SC-FDE pilot blocks is 6, the position of the first SC-FDE pilot in the slot is 5, the position of the second SC-FDE pilot in the slot is 11, and the third in the slot. The position of the SC-FDE pilot is 17, and the position of the fourth SC-FDE pilot in the slot may correspond to 23.

4B and Table 4, according to an embodiment of the present invention, it is possible to check the position of the SC-FDE Pilot block when the first subframe. More specifically, in subframe 1, the interval between the SC-FDE pilot blocks is 6, the position of the first SC-FDE pilot in the slot is 5, the position of the second SC-FDE pilot in the slot is 11, and the third in the slot. The position of the SC-FDE pilot may correspond to 17.

5 is a diagram illustrating an m-th block according to an embodiment of the present invention.

SC-FDE data / Pilot block divided into SC-FDE Pilot and data block has a length of T _Block , and the length (T _Block ) of SC-FDE data / Pilot block can be calculated using Equation 2. have.

The SC-FDE data / Pilot block is composed of N _cp CP samples (T _s length unit samples), N _block, and sample block samples, and can transmit M _{block and} symbol modulation symbols.

Since SC-FDE Pilot and data block have the same structure, T _Block = T _{Data_Block} = T _{Pilot_Block} , N _{block, samples} = N _{Data_block, samples} = N _{Pilot_block, samples} , and M _{block, symbols} = M _{Data_block, symbols} = M _{Pilot_block} Can have a value of _{, symbols} .

In this case, T _{Data_Block} may correspond to the length of the SC-FDE data block, and T _{Pilot_Block} may correspond to the length of the SC-FDE Pilot block. N _{Data_block, samples} may correspond to the number of SC-FDE data block samples, and N _{Pilot_block, samples} may correspond to the number of SC-FDE Pilot block samples. In addition, M _{Data_block, symbols} may correspond to the number of SC-FDE data block modulation symbols, and M _{Pilot_block, symbols} may indicate the number of SC-FDE Pilot block modulation symbols.

SC-FDE data / Pilot block configuration according to configuration is shown in [Table 5]. That is, according to [Table 5], the number of symbols and samples of the data and pilot SC-FDE block constituting the slot of the subframe can be checked.

SC-FDE Pilot block has a _length of T _{pilot_Block} = (N _{cp, samples} + N _{pilot_block, samples} ) T _s and can be composed of N _{cp, samples} CP samples and N _{pilot_block, samples} Pilot samples, and M _{Pilot_block, symbols} Pilot symbol sequences may be delivered.

SC-FDE data block has _length T _{data_Block} = (N _{cp, samples} + N _{data_block, samples} ) T _s and can be composed of N _{cp, samples} CP samples and N _{data_block, samples} data samples, and M _{data_block, symbols} Data symbol sequences may be transferred.

The first SC-FDE preamble block consists of T _{1st_preamble_block} = (N _{1st_preamble_CP_block, samples} + N _{1st_preamble_block, samples} ) T _s length and _{consists of} N _{1st_preamble_CP_block, samples} CP samples and N _{1st_preamble_block, samples} preamble block samples. _{1st_preamble_block, symbols} symbol sequence is delivered. According to the configuration, the first SC-FDE preamble block configuration is shown in [Table 6]. That is, in [Table 6], the number of symbols and samples of the SC-FDE block constituting the first preamble of the subframe can be checked.

Two consists of a second SC-FDE preamble block is _{T 2nd_preamble_block = (N CP, samples} + N 2nd_preamble_block, samples) N CP, samples of CP samples and N _{2nd_preamble_block, samples} of preamble block sample has a T _s length, M _{2nd_preamble_block, symbols} symbol sequence is delivered. According to the configuration, the second SC-FDE preamble block configuration is shown in [Table 7]. That is, in [Table 7], the number of symbols and samples of the SC-FDE block configuring the second preamble of the subframe can be checked.

The Front Guard symbol has a length of T _frontGuard = N _{frontGuard, samples} T _s . According to Configuration, Front Guard symbol configuration is shown in [Table 8]. That is, the front guard symbols in the subframe structure according to the embodiment of the present invention may have the number shown in [Table 8].

The Tail Guard symbol has a length of T _TailGuard = N _{TailGuard, samples} T _s . The Front Guard symbol configuration is shown in [Table 9] according to the configuration.

The first SC-FDE 'preamble block sequence is determined by a Zadoff-Chu sequence with a prime number length as in the case of Configuration 0, or by a Zadoff-Chu sequence with even lengths as in the case of Configuration 1. . In addition, the second SC-FDE preamble and the pilot block sequence may be defined by a Zadoff-Chu sequence having an even number length. Finally, the data block sequence may be generated from the bit sequence encoded by channel coding.

The first SC-FDE preamble block sequence minority, as in the case of Configuration 0 (Prime Number) length of q _1th root Zadoff-Chu or defined by a sequence, q _1th root Zadoff-Chu having an even length as in the case of Configuration 1 The sequence may be generated as shown in [Equation 3]. Where q ₁ may have any fixed value. That is, as shown in [Equation 3], the first preamble block sequence may generate a preamble by generating a root sequence in association with a Cell ID.

The second SC-FDE preamble block and the pilot block sequence are an even number length q _{2, i} th root Zadoff-Chu sequence having the length M _{2nd_preamble_block, symbols} = M _{pilot_block, symbols} defined as in Equation 4. Can be generated via

That is, according to an embodiment of the present invention, the second preamble and pilot block sequence is a group hopping applied differently according to Cell ID, slot number and pilot block number through a group having 30 root sequences having good auto and cross correlation properties. Preamble generation method characterized in that to generate one of the 30 root sequence by applying the pattern

Here, q _{2, i} may have various values or may have a fixed value such as q _{2, i} = 127.

The generated q _{2, i} th root Zadoff-Chu sequence is divided into a group of u = {u ₀ , u ₁ , ..., u ₂₉ } and can have a value of the i th group, u _i = q _{2, i} have. The second preamble and the pilot block sequence group x may be defined as shown in [Equation 5] according to the following group hopping pattern from the generated Zadoff-Chu sequence group u.

Here, f _gs (n _s ) and f _ss may be defined as shown in Equation 6.

Here, c may be obtained from a Gold sequence generator having a length of 31 initialized by c _init derived as shown in [Equation 7].

Here, the second preamble block sequence has a value of n _s = 0, and the j (0 ≦ j ≦ 3) th pilot block sequence of the i th (0 ≦ i ≦ 33) slot has a value of n _s = 4xi + j + 1. May have

The data symbol sequence may be generated through the following process.

For each codeword q, the bit blocks b ^(q) (0), ..., b ^(q) (M ^(q) bit-1) transmitted in codeword q in one slot, where M ^(q) bit means the number of bits transmitted in codeword q) must be scrambled with a cell specific scrambling sequence before modulation. The scrambled bit blocks b ^'(q) (0), ..., b ^{' (q)} (M ^(q) bit-1) may be defined as shown in [Equation 8].

Here, the scrambling sequence c ^(q) (i) is defined at the bottom. The scrambling sequence generator defined at the bottom is initialized with c _init = n _RNTI · 2 ¹⁵ + n _s · 2 ⁸ + N _{Cell_ID} at the beginning of each slot. Here, n _RNTI is a value corresponding to RNTI related to PDPCH transmission transmitted from a higher layer, and n _s means a slot number. At this time, the two variables may have any fixed value, unlike the meaning mentioned.

One codeword is transmitted in each slot.

For each codeword q, the modulation of the scrambled bit blocks b ^'(q) (0), ..., b ^{' (q)} (M ^(q) block, bit-1) is a PSK series modulation such as QPSK, 8PSK. Or can be modulated by a QAM-based modulation scheme such as 16QAM or 64QAM.

According to an embodiment of the present invention, in order to use a low-power high-power amplifier in consideration of on-board wireless station SWaP (Size, Weight and Power), etc., a modulation scheme QPSK or 8PSK having good linearity may be selected. In addition, according to an embodiment of the present invention, higher-order modulation such as 16QAM and 64QAM may be applied when considering a data transmission rate. According to an embodiment of the present invention, QPSK and 16QAM modulation are applied in consideration of both the onboard wireless station SWaP and the required transmission rate for HD-class video transmission, but are not limited thereto.

The generated plurality of symbol blocks d ^(q) (0), ..., d ^(q) (M ^(q) _{data_block, symbols} -1) may be mapped to SC-FDE data blocks in each slot. For each codeword q, the mapped SC-FDE data block sequence a ^data _{m, l} may be defined as shown in [Equation 9].

The pseudo noise sequence for scrambling is defined by a Gold sequence having a length of 31. For n = 0, 1, ..., M _PN -1, the output sequence c (n) having the length of MPN is defined as shown in [Equation 10].

At this time, it may correspond to N _c = 1600. In addition, the first m sequence x ₁ may be initialized to x ₁ (n) = 0 for x ₁ (0) = 1, n = 1, 2, ..., 30. The second m sequence x ₂ can be initialized by c _init with the value (Σ ³⁰ _i = 0 x ₂ (i) x2 ⁱ ) depending on the application in which the Gold sequence is used. For example, if a Gold sequence is used for scrambling, the second m sequence may be initialized with c _init = n _RNTI · 2 ¹⁵ + n _s · 2 ⁸ + N _{Cell_ID} in association with the Cell ID.

For the first SC-FDE preamble block of each subframe, the time sequential signal s _{1st_preamble} (t) for the first SC-FDE preamble block in a range of time t may be defined as shown in [Equation 11]. Can be.

(-M _filt N _{symbol, oversamples} T _s / 2 ≤ t <(N _{cp, samples} + N _{1st_preamble_block, samples} ) T _s + M _filt N _{symbol, oversamples} T _s / 2)

In this case, s _{1st_preamble} (t) may mean a time continuous signal for the first SC-FDE preamble block. N _{symbol, oversamples} means the number of samples per modulation symbol and may have a value of 4. M _filt may mean the length of the transmission filter pulse p (t) for the modulation symbol. In addition, the x _q1 sequence means the first SC-FDE preamble block sequence, and the modulation symbol period T may be defined as T = N _{symbol, oversamples} xT _s .

The transmission filter pulse p (t) for the modulation symbol may be defined as a root-raised-cosine filter (RRC filter) as shown in [Equation 12]. In the present invention, root-raised-cosine (RRC) filtering may be applied as a digital filtering method to reduce PAPR and out-of-band emiision.

p (t) may represent a transmit filter pulse for a modulation symbol. Β may correspond to a value of 0.3 as a roll-off factor. In addition, the modulation symbol period T may be defined as T = N _{symbol, oversamples} xT _s .

Next, for the second SC-FDE preamble and pilot block of each subframe, the time sequential signal s _{2nd_preamble / pilot} (t) for the second SC-FDE preamble or pilot block in a constant time t range is represented by Equation 13] can be defined as.

(-M _filt N _{symbol, oversamples} T _s / 2 ≤ t <(N _{cp, samples} + N _{2nd_preamble / pilot_block, samples} ) T _s + M _filt N _{symbol, oversamples} T _s / 2)

In this case, s _{2nd_preamble / pilot} (t) may mean a time continuous signal for the second SC-FDE preamble or pilot block. In addition, N _{symbol, oversamples} means the number of samples per modulation symbol and may have a value of 4. M _filt may mean the length of the transmission filter pulse p (t) for the modulation symbol. Here, the x _q2 sequence may mean a second SC-FDE preamble and a pilot block sequence generated according to a method for generating a second SC-FDE preamble and a pilot block sequence.

Next, for the l-th SC-FDE data block of each subframe, the time sequential signal s _{data, l} (t) for the l-th SC-FDE data block in a constant time (t) range is expressed by Equation 14 below. Can be defined as:

(-M _filt N _{symbol, oversamples} T _s / 2 ≤ t <(N _{cp, samples} + N _{data_block, samples} ) T _s + M _filt N _{symbol, oversamples} T _s / 2)

In this case, s _{data, l} (t) may mean a time continuous signal for the l-th SC-FDE data block. In addition, N _{symbol, oversamples} means the number of samples per modulation symbol and may have a value of 4. M _filt may mean the length of the transmission filter pulse p (t) for the modulation symbol.

Here, the a _{m, l} sequence may mean the m-th modulation symbol sequence of the l-th SC-FDE data block in the slot as shown in [Equation 15].

Next, the time continuous signal for the front guard symbol may be defined as a time continuous signal corresponding to a predetermined time period of the time continuous signal s _{1st_preamble} (t) for the first SC-FDE preamble block. In this case, the preset time period may correspond to -M _filt N _{symbol, oversamples} T _s / 2≤t <0.

Finally, the time continuous signal for the Tail Guard symbol is defined as a time continuous signal corresponding to a preset time period of the time continuous signal s _pilot (t) for the last SC-FDE Pilot block. At this time, the predetermined time period according to an embodiment of the present invention is (N _{cp, samples} + N _{2nd_preamble / pilot_block, samples} ) T _s ≤ t <(N _{cp, samples} + N _{2nd_preamble / pilot_block, samples} ) T _s + M _filt N _{symbol and oversamples} T _s / 2.

The symbol rate R _mod has a 7,680,000 sps (symbols per second), and when the roll-off index 0.3 of the root-raised cosine symbol transmission filter is considered, the transmission bandwidth may have 9,984,000 Hz.

The guard interval does not transmit a signal for the following number of sample intervals after the Tail Guard symbol of the first subframe and the second subframe, respectively.

In the encoding of the information bits coming down from the upper layer, data of one transport block type is transmitted to a coding unit in each slot, and is encoded through the following steps as in the turbo coding scheme of the existing LTE.

CRC insertion in the transport block

Split code block and add CRC to code block

Turbo coding

Rate matching

Code block concatenation

-Multiplexing

The bits encoded through the above steps may additionally apply the channel interleaver of the following process. Input vector sequences to the channel interleaver may be defined as g ₀ , g ₁ , g ₂ , g ₃ , ..., g _H'-1 . Here, H 'may mean the total number of modulation symbols in the slot. The output bit sequence from the channel interleaver can be derived as follows.

(1) The number of rows in the matrix, C _mux , has the value C _mux = N _{slot, data_blocks} . The rows of the matrix are numbered 0, 1, ..., C _mux -1 from the left row. N _{slot, data_blocks} means the number of SC-FDE data blocks in a slot.

(2) The number of columns in the matrix, R _mux, has a value of R _mux = (H '· Q _m ) / C _mux , and defines R' _mux as R ' _mux = R _mux / Q _m . The columns of the square matrix are numbered 0, 1, ..., R _mux -1 from above.

(3) Write the input vector sequence g _k (k = 0, 1, ..., H'-1) in the matrix (C _mux xR _mux ) in units of sets of Q _m columns. At this time, the vector y _o from the 0 to the (Q _m -1) column of the matrix 0 starts, and the matrix item already input is skipped.

The related pseudocode is as follows.

Set i, k = 0.

               while k <

                   k = k + 1

                   i = i + 1

               end while

(4) The output of the block interleaver is a bit sequence read into column by column of the (C _mux xR _mux ) matrix. Vector sequences after channel interleaving are defined as h ₀ , h ₁ , h ₂ , h ₃ , ..., h _H'-1 .

The modulation order and transport block size (TBS) may be determined as shown in Table 10 below according to a modulation and coding scheme. The index IMCS for the modulation and coding scheme is given in the upper layer. In this case, according to an embodiment of the present invention, [Table 10] corresponds to a modulation order and a transport block size for applying the adaptive modulation and demodulation, and may use the corresponding value to determine the MCS mode.

The power control may control transmission power of a downlink mission physical channel (PDPCH) in an onboard radio station (ARS). The power control scheme may be selectively applied.

When the ARS does not transmit the PDPCH channel simultaneously with the downlink control physical channel (PDCCH) in the subframe i, the ARS transmission power for the PDPCH transmission may be defined as shown in Equation 17.

When ARS transmits a PDPCH channel simultaneously with a downlink control physical channel (PDCCH) in subframe i, ARS transmission power for PDPCH transmission may be defined as shown in Equation 18.

, P_{O_PDPCH}, PL는 각각 linear 값으로 상위 계층에서 주어지는 ARS 송신 전력 및 PDCCH 채널 송신 전력, 그리고 상위계층에서 주어지는 서빙 지상무선국 (GRS)에서 수신되는 목표 PDPCH 수신 전력에 대한 파라미터, ARS에서 계산되는 서빙 GRS에 대한 dB 스케일 하향링크 경로 손실 추정값을 의미할 수 있다. Where P _CMAX ,

, P _{O_PDPCH} and PL are linear values, respectively, parameters for ARS transmit power and PDCCH channel transmit power given in the upper layer, target PDPCH received power received in the serving ground radio station (GRS) given in the upper layer, and serving calculated in the ARS. It may mean a dB scale downlink path loss estimate for the GRS.

In this case, the path loss value PL may be calculated as PL = PUCCH_RSTP-PUCCH_RSRP. Here, PUCCH_RSTP may mean a PUCCH reference signal transmission power value provided by an upper layer, and PUCCH_RSRP may correspond to a PUCCH reference signal reception power value provided by an upper layer.

Claims (1)

In a data transmission method of a wireless communication system using a single transmission wave transmission method performed in an unmanned radio station
Receiving a control frame; And
And transmitting, by the drone-based radio station, a payload frame to the terrestrial radio station based on the control frame.
The payload frame is determined based on the control frame,
The payload frame includes a first subframe and a second subframe having a preset length.
A pilot is disposed in consideration of a value over a preset speed of the drone and a preset delay spread value.

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