KR20060055072A - High quality local area wireless multimedia signal transmission technique for portable terminal - Google Patents

Abstract

The present invention relates to a technique for transmitting digital multimedia signals with high quality despite the interference between users in short-range wireless communication using a mobile terminal.

Various low power wireless devices around the world are being developed using the ISM Band band, which can be used without permission. In Korea, the 2.4GHz and 5.7GHz bands have been opened for unlicensed power for a variety of purposes as long as they meet the relevant standards of the Radio Law.

Therefore, product development is being actively conducted in the field of wireless multimedia transmission that can transmit wireless audio signals such as wireless headphones, wireless microphones and wireless speakers, and wireless video signals such as wireless surveillance cameras and wireless internet broadcasts. Since this frequency band is allowed to be used without a license by anyone without any use restrictions, various application products can be used in the same region, and when used for wireless multimedia signal transmission, severe transmission quality degradation occurs due to frequency interference between users. .

In addition, even if there is no interference between users, the wavelength of the used frequency band is less than 15cm, and the transmission quality is seriously degraded due to fading due to the multipath signal of the reflected wave by surrounding facilities and furniture.

In addition, due to the characteristics of wireless transmission, there is a limitation of the transmission speed due to the limitation of the available bandwidth, so in order to transmit high quality digital multimedia signals, only the source signal can be compressed and sent. In Decoding, it is necessary to decode and decompress the compressed signal. If an error occurs in the transmission process, the error does not affect only the corresponding section, but the error spreads over various sections necessary for signal processing.

For the above reasons, in order to transmit wireless multimedia signals with high quality in the short-range, unlicensed radio frequency band, there is a need for a technology that overcomes frequency interference between users and a technique that overcomes fading due to multipath. There should be no mismatching. In addition, even if an error occurs in the transmission signal due to a poor environment, it should be prevented from affecting the signal in the section other than the section in which the error occurred.

The present invention uses the frequency hopping technique by maintaining the network unit of the cycle unit for this purpose, there is no time delay or transmission quality deterioration due to the synchronization process even in the case of crowded users and severe frequency collision and user interference, fading phenomenon Even under severe conditions, the orthogonal leap technique is maintained, and frequency and time diversity are possible, and high quality wireless multimedia signals can be transmitted by reconstructing and reproducing transmission data on a frame basis.

Description

High Quality Local Area Wireless Multimedia Signal Transmission Technique for Portable Terminals

1 is a conceptual diagram of a transmission quality degradation phenomenon due to frequency collision;

2 is a change in received signal strength due to fading phenomenon;

3 is a structure diagram of a data transmission cycle according to an embodiment of the present invention;

4 is an orthogonal hopping frequency allocation method according to an embodiment of the present invention;

5 is a cycle structure diagram of the equipment making the orthogonal leap according to an embodiment of the present invention

6 is a diagram illustrating a frequency and time diversity frame structure according to an embodiment of the present invention;

7 is a block diagram of equipment manufactured according to an embodiment of the present invention;

8 is a group full frame structure diagram configured according to an embodiment of the present invention

♣ Explanation of symbols for the main parts of the drawing ♣

30: Cycle 31: Synchronous control section

32: user section 33: super cycle

41: frequency table 42: jump sequence generator

The present invention relates to a technique for transmitting digital multimedia signals with high quality despite the interference between users in short-range wireless communication using a mobile terminal.

Various low-power wireless devices have been developed and used using the ISM Band band, which can be used without permission worldwide. In Korea, the 2.4GHz and 5.7GHz bands have been opened for unlicensed power for a variety of purposes under conditions that meet the criteria set out in the Radio Law.

Therefore, product development is being actively conducted in the field of wireless multimedia transmission that can transmit wireless video signals such as wireless headphones, wireless microphones, wireless speakers, wireless surveillance cameras, and wireless Internet broadcasting using this frequency band.

Since this frequency band is allowed to be used without a license by anyone without any use restrictions, various application products can be used in the same area, and when used for the transmission of wireless multimedia signals, severe transmission quality degradation occurs due to frequency interference between users. .

In addition, even when used as a single device without interference between users, the wavelength of the used frequency band is less than 15cm, and the transmission quality is seriously degraded due to fading due to the multipath signal of the reflected wave by surrounding facilities and furniture.

In addition, due to the characteristics of wireless transmission, there is a limitation of the transmission speed due to the limitation of the available bandwidth. Therefore, in order to transmit high quality digital multimedia signals, the source signal must be compressed and sent. It is necessary to decode and decompress the compressed signal again. Therefore, if an error occurs in the transmission process, the error does not affect only the corresponding section, but the error spreads over several sections necessary for signal processing.

Representative technologies of short range wireless multimedia transmission method used in 2.4GHz ISM Band band so far are Bluetooth and wireless LAN, but Bluetooth technology uses frequency hopping method to prevent transmission quality deterioration due to mutual interference. Even if there is an advantage, it is possible to transmit data by changing the frequency of use.However, in case of a frequency collision between users in real time multimedia signal transmission, the retransmission method is not suitable for high quality multimedia transmission because the transmission quality cannot be solved. Wireless LAN technology also has a variable frame multiple access structure, which is not suitable for high-quality multimedia transmission due to its weak function of maintaining constant speed at all times, and is not suitable for use in mobile terminals with limited power capacity due to high power consumption. This wide problem has a problem of limiting the number of users that can be used simultaneously in the same area.

Bluetooth technology has been developed to prevent the frequency interference between users by improving the performance of the frequency hopping method to avoid frequency collision with the wireless LAN, but random frequency selection and frame selection when the frequency hopping Since the transmission time is different between users, the frequency collision between Bluetooth users cannot be prevented, making it difficult to use for high quality wireless audio transmission.

For example, to listen to digital music from a portable MP3 player using stereo wireless headphones, a high quality wireless audio transmission technique is required.However, if there are several users in the same area with existing Bluetooth technology, sound degradation may occur due to mutual interference. In addition, wireless LAN technology is not suitable for use in mobile terminals due to high battery consumption, and both technologies have limited ability to recover errors in real-time multimedia signals caused by frequency collisions between users and interference signals on transmission lines. High quality wireless audio transmission is a difficult problem.

In the present invention, to improve the wireless multimedia transmission quality,

First, in order to overcome the interference between users, orthogonal frequency hopping technique that excludes frequencies already used by peripheral devices and selects only clean frequencies to use the existing Adaptive Frequency Hopping technique, but does not cause frequency collision between users. Hopping) to prevent frequency collision between users, thereby preventing transmission quality deterioration; At the same time, the technology invented can be used together with data transmission such as equipment remote control, sensor network, and home security to be used as the basic technology of home network. .

Second, in order to prevent the transmission signal from being broken due to fading due to multipath, orthogonal leaps between users can be maintained while using frequency diversity and time diversity, thereby preventing frequency collision between users and overcoming fading. will be.

Third, in case that an error occurs in the transmission signal of a certain section due to poor transmission environment even though frequency collision is avoided and fading is overcome, the error that occurs affects only that section and is not spread to other sections. In addition, the section in which the error occurs is detected in advance at the start of each section, and the section in which the error occurs is restored using the signal of the previous section.

In order to achieve the above technical problem, a technique for overcoming frequency interference between users and a technique for overcoming fading due to multipaths is required, and an error occurs even when an error occurs in a transmission signal due to a poor environment. There is a need for a technique of preventing influence on signals in sections other than the generated section.

Finally, there is no mis-matching between technologies when implementing the technologies used. Therefore, all technologies must be implemented at the same time so that wireless multimedia signals can be transmitted with high quality in the short-range, unlicensed radio frequency band. shall.

The first technical challenge,

In order to achieve the purpose of preventing the frequency collision between users by the orthogonal frequency hopping technique and shortening the synchronization time during operation, all mobile terminals using the present technology periodically transmit data structures repeatedly in the same cycle unit. By maintaining synchronization between all mobile terminals on a cycle basis, orthogonal leaps on a cycle basis are possible.

At this time, in order to maintain synchronization in cycle units, a frame for synchronization control and a user frame are allocated every cycle. Synchronous control frame is prohibited for general users and is used only for system maintenance and synchronization between devices. General users implement the transport protocol using only user frames.

Each group automatically or manually selects the group master equipment that is responsible for synchronizing, and the equipment selected as the group master examines the reception status of each individual frequency to determine the frequency status in the area, which is the most interference-free. Pick a good frequency and make a frequency table.

The group master equipment manages the "supercycle" consisting of the number of cycles considering the equipment and spare equipment operating in each group, the first cycle is used by itself and the remaining cycles are assigned sequentially to the equipment operating in the group. do.

The group master device transmits a control signal for propagating a frequency table to each group device or managing devices by using a frame for synchronization control in a cycle allocated to it once every supercycle period. In this way, devices in the same group all use the same frequency table.

General devices under the control of the group master device transmit signals related to the synchronizer and the device control to the group master device or other devices in the group by using the frame for synchronous control of the assigned cycle.

In principle, the devices in all groups can use any frequency because they do not transmit radio waves at the same time during the synchronous control frame period, but in the user frame period, radio waves can be freely overlapped with each other. Must use the specified frequency.

All equipment in the group must change the frequency of the user frame every cycle by a predetermined method, and the method of selecting the frequency every cycle is performed by changing the address of the frequency table generated by the group master equipment.

After each appointment, the frequency selection algorithm generates an address in the frequency table and uses the frequency value stored at that address as the transmission frequency.

In this case, in order for the devices in the group to use different frequencies during the cycle of the same time zone, each device in the group uses the same frequency table created by the group master, and the addresses of the frequency table have different values at the same time. Different frequencies are assigned.

In order for different devices in the group to have different frequency table addresses, the devices in the group use an algorithm that generates the same frequency table address, but they use the generated value by adding different offset values assigned to each device. In this way, different devices can always use different frequencies at the same time.

For example, the offset value of the group master device is set to '0' and the other device is assigned an offset value by the group master device, and the device assigned an offset value of '1' is selected from the frequency table used by the group master device. Use '1' plus the address value.

If you express this as

F _add (n, t) = Mod (K; F _add (0, t) + n);

F _add (0, t) = 0, 1, 2, ... (K-1);

    n = 1,2, ..., (K-1):

Where F _add (0, t) is the address of the frequency table of the t-th cycle created by the frequency selection algorithm of the group master equipment, K is the number of frequencies used in the frequency table, and n is the number of frequencies used by the group master equipment. Offset value to assign. F _add (n, t) indicates the frequency table address of the tth cycle of the equipment with Offset specified as 'n'.

Mod (K; x) is the remainder of x divided by K.

For example, if the number of frequencies 'K' used in the frequency table is 16, the address 'F _add (0, t)' used by the group master equipment at any given time t is any of '0' through '15'. It will be an integer. At this time, if the address of the group master device is set to '7', the address 'F _add (12, t)' of the device assigned the 12th Offset becomes '7 + 12 = 19' and Mod (16; 19) is 19 Is divided by 16 and the remaining integer value is '3', which is the frequency used by the frequency value stored in the address '3'.

Using this "net-space orthogonal leap technique", the frequency of the synchronization frame and the user frame can be managed separately so that the devices in the group (limited to the number of frequencies used in the frequency table) are not orthogonal to each other without frequency collision. Since it is possible to jump and the transmission quality is not degraded by mutual interference, and synchronization is always performed in cycle units during operation, the time required for synchronization is possible in cycle period units (eg: 10 msec), and the longest time is It has a characteristic of not exceeding a period (for example, 680 msec).

The second technical challenge,

In order to achieve the object of preventing the degradation of the transmission signal due to fading phenomenon while maintaining orthogonal leap,

In the same way as above, all devices are synchronized on a cycle basis, and the user interval in a cycle is divided into several frames so that different frequencies can be used. In this case, considering that each user frame is broken by a fading phenomenon, each user frame has a structure capable of maintaining its own synchronization.

Therefore, each frame has a lock time that provides a predetermined time required by the frequency synthesizer to stabilize the converted frequency when converting frequency values separately, a synchronization area (Preamble) where information can be found for each frame, and information. It consists of a data area for transmitting the data and a dummy area for protecting the last data of the frame. In this case, when only time diversity is used without using frequency and time diversity at the same time, there is no need to change the frequency, so the lock time, which is a stabilization time required for the frequency synthesizer, is not used.

In addition, since the frequency used in one cycle varies depending on the application field, the offset of the frequency table used when determining the frequency is assigned differently according to the application field. For example, a device using only time diversity and not using frequency diversity is assigned only one offset, and a device using frequency diversity three times is assigned three offsets, thereby dividing the user interval within one cycle into three frames. Use a frequency with a different offset address in each frame.

For example, the number of frequencies 'K' used in the frequency table is 16, and some equipment wants to use 3 frequency diversity so that 3 offsets, 3, 6, and 10 Assume that it is assigned. If the address 'F _add (0, t)' used by the group master device is set to '7' at any given cycle time t, the device that wants frequency diversity has three frames for the user interval corresponding to cycle t. Divide each frame's frequency table address by 'F _add (3, t)' = 7 + 3 = 10, 'F _add (6, t)' = 7 + 6 = 13, and 'F _add (10, t)' = 7 + 10 = 17 = 1, using a frequency table address of 10,13,1.

In general, three or more frequencies are not used when performing frequency diversity. Even if a plurality of frequencies are used in each cycle, the sum of the used frequencies should not exceed K in the frequency table.

When using the "Programmable Frequency Change Frame Allocation Technique", which enables frequency change in frame units within a synchronized cycle, time, frequency, and diversity can be achieved without frequency collision or user interference, the transmission signal is faded by fading. Even when damaged at a certain time or frequency, it maintains synchronization among users and maintains perfect transmission quality by using intact signals transmitted at different time or frequency.

The third technical task,

Even if an error occurs in a transmission signal of a certain section due to a poor transmission environment, an error that occurs only affects the section and prevents spreading in another section. To achieve the purpose,

Encoding block and length of user frame in each transmission cycle are used to encode multimedia source signal. Preamble that detects error in transmission signal is installed every frame and received by using Correlation value of this preamble. It is to determine whether there is an error in the source signal contained in the frame.

In this case, the cycle length cannot be changed according to the application. Therefore, the section allocated for users in each cycle is divided into frame units according to the block section of the source. When dividing the frame according to the block of the source signal according to the block of the source signal, the segment allocated for the user may not be divided correctly, and the section remaining as a border may occur, but this part may be used for various special purposes at the system level.

In this way, the user can use the "frame-based source data processing technique" that allows the length of the block that processes the multimedia source signal to match the frame length and detects an error on a frame-by-frame basis to copy and play the multimedia signal on a block-by-block basis. It is characterized by the fact that the transmitted data do not feel broken.

Hereinafter, the technical problem will be described in detail with reference to the accompanying drawings.

1 is a conceptual diagram illustrating a degradation of transmission quality due to frequency collision.

1 (a) shows a random frequency hopping of the conventional Bluetooth system.

The frequency hopping pattern in the figure shows that the horizontal axis represents the time axis and the vertical axis represents the frequency, and that the frequency changes arbitrarily as time passes by different colors for each user. Since the frequency is not randomly determined for each user and the frequency is arbitrarily determined, the same frequency is used at the same time, resulting in a frequency collision.

Therefore, the throughput [10] shown on the right side of the figure is drastically lowered as the user increases, which is not suitable for multimedia signal transmission requiring a constant speed at all times.

1 (b) shows an orthogonal frequency hopping scheme according to the present invention.

Since all users are time-synchronized and use different frequency assignments, there is no collision of frequency during transmission period, so there is no degradation of transmission quality.

In addition, as the number of users increases (the number of users is limited to the number of frequencies used for frequency hopping), a constant throughput [11] is always provided, so that multimedia signals can be transmitted in real time.

2 is a view illustrating a change in received signal strength due to fading phenomenon.

In the figure, the horizontal axis represents time and the vertical axis represents the strength of the received signal. In the 2.4 GHz band, the distance between the transceiver is 7m and the receiver strength is fixed in dBm over time with the transmitter and receiver fixed.

As can be seen from the figure, even though the transceiver is fixed, the variation in reception intensity is more than 20 dBm, so it is difficult to maintain the transmission quality in a general method, so a diversity technique should be used.

3 is a structural diagram of a data transmission cycle according to an exemplary embodiment of the present invention.

One cycle [30] is divided into a synchronous control section [31] and a user section [32]. The synchronous control section consists of one frame, and all equipments have the same structure regardless of the application field. And for equipment management.

In order to maintain the synchronization of the transmission signal between the equipment to maintain the same cycle length regardless of the application field, the user interval within the cycle is divided into various frame structures according to the application field will be described in detail again in FIG.

Each cycle consists of 'M' dogs and forms a supercycle [33]. The '0' th cycle is used by the group master. It assigns the sequence number of each cycle to the equipment in the group. To transmit information necessary for network synchronization. Synchronous control frame is divided into the equipment used in cycle unit, but the user section of each cycle does not distinguish the equipment used, so multiple equipments can transmit by using the orthogonal leap at the same time and will be described in detail with reference to FIGS. 6 and 8. do.

4 is an orthogonal frequency hopping allocation method according to an embodiment of the present invention.

Among the frequencies available for use [40], an optimal frequency with good reception is selected and filled in the frequency table [41]. In this example, 16 frequencies were selected from 79 frequencies and filled into the frequency table. The frequency table has addresses from '0' to '15' and stores one frequency value for each address.

In frequency table '0', the fourth frequency is stored as Frq (4) among 79 frequencies, and in address '1', the seventh frequency is stored as Frq (7). In this way, Frq (79), that is, the 79th frequency, is stored at address '15'.

The hopping sequence generator 42 randomly outputs one of the values from '0' to '15' by a predetermined algorithm every cycle. In this example, '7' is output in the t-th cycle and '3' is output in the (t + 1) th cycle.

The group master device with offset '0' uses the value output from the hopping sequence generator as the address of the frequency table as it is, so that the address of the random address F _add (0, t) value '7' output at the time 't' is used. The 38th frequency Frq (38) is used for the user period of the cycle. In the same way, the 18th frequency Frq (18) addressed to the random address F _add (0, t + 1) value '3' output at the time 't + 1' is used for the user section of the cycle.

Random address of 't' time of equipment with offset '3' in the frequency table of the figure F _add (3, t) = F _add (0, t) +3 and save it as 10+ address as 7 + 3 = 10 The 65th frequency Frq 65 is selected as the frequency used. In the same way, when the offset of each device is determined, the corresponding random address is generated and the frequency value stored in the random address is used as the frequency of the corresponding cycle.

The lower part of the figure shows the frequency usage history [43] of each device at the t th cycle. The group master uses the frequency stored by address '7' with the offset '0', and device 1 with the offset '3' uses the frequency stored by address '10' and device 2 with the offset '6' Device 3 using the frequency stored by address '13' and offset '10' uses the frequency stored by address '1' so that all devices use different frequencies at the same time, causing frequency conflicts between users. I never do that.

In the same way, the frequency usage history [44] used in the (t + 1) th cycle uses the frequencies stored in the frequency table addresses 3, 6, 9, and 13, respectively, so that each equipment in the cycle Frequency hopping randomly, but devices always use different frequencies to enable orthogonal hopping without frequency collisions.

5 is a cycle structure diagram of the equipment making an orthogonal leap according to an embodiment of the present invention.

All the equipments have the same cycle length and the synchronization control section within the cycle is composed of one synchronization control frame of the same standard. Through this synchronization control frame, the devices in all groups are synchronized in cycle units.

However, since the user section within the cycle must satisfy various requirements according to the user's application field, it has various user frame structures according to the use.

Figure (a) shows an example in which a user section consists of one frame.

Figure (b) shows an example in which the user section consists of two frames.

Figure (c) shows an example of user frames consisting of three frames.

Figure (d) shows an example of user frames consisting of four frames.

Figure (e) shows an example of four frames with uneven user intervals.

Since each frame can be assigned a frequency individually and have individual synchronization capabilities,

As shown in Fig. (F), a lock time [50] is required for a predetermined time required by the frequency synthesizer to stabilize the converted frequency when converting frequency values, and a preamble for maintaining frame synchronization and transmission quality is added. A synchronization area (Preamble) 51 for data transmission, a data area 52 for transmitting multimedia information, and a dummy area 53 for protecting data to be transmitted are allocated.

When only time diversity is used without using frequency diversity, a stabilization area is not required as shown in Fig. (G), and only a synchronization area (preamble), a data area, and a dummy area are allocated. At this time, the operation method of the stabilization area, the synchronization area and the finishing area applies an existing known technology.

The structure of the non-uniform frame shown in Fig. (E) is to process the remaining part as a frame when the edge is generated in the process of matching the block of the multimedia source data with the length of the user frame. The first three frames can be used for multimedia data transfer, while the remaining four frames can be used for spare or special data transfer.

6 is a diagram illustrating a frequency and time diversity frame structure according to an embodiment of the present invention.

It is assumed that F _add (0, t) = 1 [60] and F _add (0, t + 1) = 7 [61] are created by default in the jump sequence generator.

The Group Master uses three Offset '0' '5' '10' using three Frequency Diversity, and the Equipment 1 and Equipment 2 use three Frequency Diversity, respectively, '1' '6' ' Use Offset of 11 'and Offset of' 2 '' 7 '' 12 '. Equipment 3 uses only time diversity, so the frame is divided into three, but only one frequency is used, so the offset is only '3'. Finally, since equipment 4, equipment 5, and equipment 6 do not use diversity, one offset '4', '8', and '9' are used.

In the figure of FIG. 6, since each frame of the user interval uses the frequency stored in the address of the base frequency table address value of the corresponding cycle plus the offset allocated to each frame, only the address value of the frequency table is shown in the figure.

As such, when the address of the frequency table is different, the frequency used is also different. As shown in FIG. 6, it can be seen that frequency collision does not occur at the same time while performing frequency and time diversity.

7 is a block diagram of equipment manufactured according to an embodiment of the present invention.

In storing the excellent frequency values in the frequency table [71], it stores the frequency table values transmitted from the group master or, if the equipment itself is the group master, the propagation strength and the surroundings of all frequencies that can be used as the frequency sounding device [70]. After checking the noise, the frequencies with good condition are selected and stored in the frequency table [71] so that all equipment in the same group maintains the same frequency table.

When the hopping sequence generator 72 randomly outputs the initial frequency table address every cycle, the offset adder 73 adds the offset value allocated to each frame to use the final frequency table address.

The frequency value stored in the address generated by the offset adder is output and sent to the RF module [74] to use as the frequency of the frame.

8 is a group full frame structure diagram according to an embodiment of the present invention.

In this example, it is assumed that 16 frequencies are used and that all equipment uses frequency diversity 3 in one cycle.

Since the group master also uses frequency diversity 3, three offsets are assigned to '0', '5', and '10'. All other equipments require three offsets, but they have the same frame structure as the group master, so three offsets can be used even if only one offset is assigned to each equipment.

For example, in case of assigning Offset '1' to Device 1, Device 1 can use three offsets '1' '6' '11' by adding 1 expression to Groupmaster Offset. By assigning Offset '2' to Device 2 in the same way, three Offsets can be used: '2' '7' and '12'.

In this way, if 16 frequencies are stored and used in the frequency table, even if all the equipments use three frequency diversity, all 16 devices can make orthogonal leap without any frequency collision between each other.

As shown in Figure 8, the horizontal axis represents the frequency value of each device, and you can see that the frequency jumps randomly. However, if you look at the frequency usage of each device on the vertical axis of the same time zone, it can be seen that no single frequency exists.

Each device is synchronized in cycle unit, and the first part of the cycle is composed of synchronous control frame, which is rotated by device, and transmits information using synchronous control frame in its own cycle.

Since the synchronous control frame is not all users transmit radio waves like the user frame, when one device transmits a signal, all other devices are in a reception state.

However, as in the case of equipment 9 and equipment 13, it is possible to exchange information only between two devices in a point-to-point manner by using a synchronization control frame using different frequencies that do not overlap each other.

The present invention as described above,

Even when the users are crowded and the user interference is severe, the orthogonal frequency hopping technique by maintaining the network unit of cycle unit prevents frequency collision between users and there is no time delay caused by the synchronization process. Signal transmission is possible,

Even when the fading phenomenon is severe, all users are synchronized on a cycle-by-cycle basis, and user intervals can freely divide frames by use, allowing frequency and time diversity while maintaining the orthogonal frequency hopping technique, thereby preventing degradation of transmission quality during transmission. Can do it,

By adjusting the length of the user frame with the block of the multimedia source, the error occurred during the transmission process can be controlled in units of blocks so that the user can not detect the damage of the multimedia signal. There is this.

Claims (4)

In the use of orthogonal frequency hopping to prevent frequency collisions between multiple transmission devices when transmitting wireless digital multimedia signals, The process of unifying the transmission method with 'cycle' of the same length regardless of the application field to match the time synchronization between users, 'Cycle' is divided into 'Synchronous Control Section' and 'User Section' so that the Synchronous Control Section is the same length and format in which all equipments are unified, and the User Section is a process that users can freely change according to the application field. The process by which the group master selects frequencies in good condition to create a 'frequency table' and propagates the 'frequency table' to all the devices in the group through the 'synchronous control section'; Gathering multiple cycles to create a 'supercycle', the first cycle of the supercycle is used by the groupmaster, assigning the rest of the cycles to the equipment in the group and the 'offset' value used, Generating an address of a frequency table every cycle by adding an offset value to a value generated by a jump sequence generation algorithm; Through the process of reading the frequency value stored in the frequency table using the generated address and using it as the transmission frequency during the user section of the cycle, Multiple equipment maintains synchronization with each other as frequency hopping in cycle unit, separates synchronization section and user section, maintains the entire network using a unified synchronization section, and even if several devices transmit simultaneously in user section Because the frequency used does not occur because the frequency is different, the transmission quality of the multimedia signal is excellent, and because the pre-synchronization is made in advance, the synchronization time at the beginning of transmission is reduced, so the initial transmission delay time is short. Spaced Orthogonal Leap Technique. The method of claim 1, wherein in order to prevent the transmission signal from being broken due to fading due to multipath, Creating a user frame by dividing the user intervals in the cycle by the number needed for diversity, In order to signal-process each user frame independently, a lock time for a predetermined time required by the frequency synthesizer to stabilize the converted frequency when converting a frequency value for each user frame and a time synchronization of the frame Assigning a synchronization area (Preamble) for storing predetermined preamble information, an information area for transmitting a multimedia signal, and a dummy area for protecting the end of data to be transmitted; By giving different offsets to the created user frames and changing the transmission frequency, frequency diversity is achieved along with time diversity. In addition to maintaining orthogonal synchronization with other devices to prevent frequency collisions, it also maintains synchronization between users even when a transmission signal is damaged at a certain time or frequency. Programmable Frequency Change Frame Allocation Technique, characterized by restoring transmission quality. The method according to claim 1 or 2, in order to maintain excellent transmission quality even when data transmitted in a poor transmission environment is broken, Adjusting the size of the signal processing block of the multimedia signal to be transmitted within the size of the user frame generated in claim 2, Transmitting a multimedia signal using a plurality of user frames using the orthogonal leap defined in claim 1 and the diversity defined in claim 2; Determining a state of a multimedia signal contained in a frame by using a preamble of the received user frame; Restoring a multimedia signal by selecting a normal frame among user frames received as a result of the determination; Even when the entire received multimedia signal cycle is broken, through copying the demodulated multimedia signal block in the previous cycle to replace the broken block, Even though the orthogonal leap and diversity technique are used, even if an error occurs in a transmission signal of a certain section due to a poor transmission environment, the error that affects only the section and does not spread to another section uses the signal of the previous section. Frame-based source data processing technique that prevents the user from detecting a broken signal. A frequency sounding device for selecting a frequency having excellent transmission quality using the technique of claim 1 and 2. A frequency table that stores the selected frequencies by assigning addresses A jump sequence generator for randomly generating a temporary address of a frequency table; "Orthogonal hopping frequency generator" consisting of an offset adder that adds an offset to the generated random signal and creates the final address of a frequency table that can be assigned an orthogonal frequency for each device.

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