WO2011065752A2

WO2011065752A2 - Method and system for supporting an interference-free relay between short distance picocells

Info

Publication number: WO2011065752A2
Application number: PCT/KR2010/008365
Authority: WO
Inventors: 류승문; 주완규; 조해영; 최재호
Original assignee: 주식회사 카서
Priority date: 2009-11-24
Filing date: 2010-11-24
Publication date: 2011-06-03
Also published as: WO2011065752A3; WO2011065752A9; KR20110057652A; KR101043303B1

Abstract

The present invention relates to a method and system for supporting an interference-free relay between short distance picocells. The present invention system supports a relay between picocells based on a network cycle including a plurality of control frames and comprises a master device which receives at least one of the plurality of control frames allocated thereto as a synchronous control frame and then transmits the synchronous control frame at an orthogonal hopping frequency; a synchronous relay device which receives the synchronous control frame to remain synchronous with the master device, receives the allocated synchronous control frame out of the plurality of control frames as a relay synchronous control frame and then transmits the relay synchronous control frame at another orthogonal hopping frequency free of interference; and at least one slave device which receives the relay synchronous control frame in a region where the synchronous control frame of the master device has not been received, so as to remain synchronous with the synchronous relay device. Advantages of the present invention are that the relay is supported per se without an additional repeater and there is no collision between signals in the relay.

Description

Method and system for supporting relay without interference between short distance picocells

The present invention relates to a method and a system for supporting relay without interference between short distance picocells, and more particularly, to a method and system capable of supporting a synchronous relay and a payload relay between a short distance picocell without interference.

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 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 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.

The present applicant has proposed a technique for preventing the occurrence of frequency collisions between wireless devices within a short distance in the registered Patent No. 10-0671343 (name of the invention: a high-quality short-range wireless multimedia signal transmission technique used in a mobile terminal). Patent No. 10-0799775 (name of the invention: a wireless network protocol capable of convergence of broadcasting, communication and control in a short distance picocell) has proposed an efficient transmission protocol in a short distance picocell.

According to Korean Patent No. 10-0799775, as shown in FIG. 1, wireless devices belonging to a picocell are classified into a master device and a slave device, and a plurality of slave devices belonging to the coverage of the master device are configured according to a preset protocol. It is disclosed that data is transmitted and received while maintaining synchronization with the master device.

Here, the pico-cell refers to a cell in the near area having a coverage of several tens of meters.

According to the above patent, only the slave device belonging to the picocell based on the master device can perform wireless communication while maintaining synchronization with the master device, and the wireless device outside the picocell area cannot communicate with the master device. .

In some cases, it may be necessary to extend coverage, which does not support such services.

In general, in order to solve the shadow area or to extend the coverage, additional repeaters are provided to satisfy the QoS (Quality of Service) of wireless communication in the corresponding area.

Currently, short-range wireless communication protocols such as WLAN or Bluetooth use independent repeaters to extend coverage, but such repeaters are expensive and inefficient in avoiding interference. That is, conventionally, there is a problem in that a repeater which is expensive and has poor wireless communication quality for expansion of coverage.

In order to solve the problems of the prior art as described above, an object of the present invention is to propose a method and system for supporting interference without short distance between picocells, which enables stable relaying of synchronization signals and data without interference between picocells.

Another object of the present invention is to provide a method and a system for supporting a relay without interference between short distance picocells capable of relaying wireless communication without an expensive relay.

Another object of the present invention is to provide a method and system for supporting relay without interference between short-range picocells having a short delay time in relaying real-time broadcasting and communication.

Still another object of the present invention is to provide a relay support method and system capable of relaying even if a separate device for relay is not added.

In order to achieve the above object, according to a preferred embodiment of the present invention, a system for supporting inter-picocell relay based on a network cycle including a plurality of control frames, the at least one of the plurality of control frames is synchronized A master device which is assigned to a control frame and transmits the synchronous control frame at an orthogonal hopping frequency; Receiving the synchronization control frame to maintain synchronization with the master device, and receives a control frame allocated to the synchronization control frame of the plurality of control frames as a relay synchronization control frame, the relay synchronization control frame at an orthogonal hopping frequency without interference Synchronous relay device for transmitting a; And at least one slave device receiving the relay synchronization control frame in an area where the synchronization control frame of the master device is not received and maintaining synchronization with the synchronization relay device.

According to another aspect of the present invention, a synchronous relay device in a short range wireless communication system based on a network cycle including a plurality of control frames and including a master device and a slave device, the picocell relay is supported, the master device Receiving a synchronization control frame including information for maintaining synchronization from the master device and maintaining synchronization with the master device; And transmitting a relay synchronous control frame by receiving a control frame different from the synchronous control frame among the plurality of control frames, wherein the slave device located in a region where the synchronous control frame of the master device is not received is relayed. A picocell relay support method is provided by receiving a synchronization control frame and maintaining synchronization with the master device, wherein a frequency of the relay synchronization control frame is determined using the information for maintaining synchronization.

According to the present invention, there is an advantage of eliminating the shadow area by extending the wireless coverage by itself without additional expensive repeater.

In addition, according to the present invention, there is an advantage that an expensive signal processing apparatus is not required by supporting relay without generating existing radio feedback or echo.

In addition, according to the present invention, since the synchronous relay and the payload relay are performed using the time and frequency domains of the plurality of synchronous relay devices that do not overlap each other, there is an advantage of avoiding a collision of signals.

1 shows a master-slave structure according to the prior art;

2 is a diagram illustrating a picocell inter-radio relay system according to a preferred embodiment of the present invention.

3 is a diagram illustrating a frame structure in a wireless relay system according to the present invention.

4 illustrates a frame structure of different network cycles in a short range wireless communication protocol according to the present invention.

5 is a diagram illustrating orthogonal allocation in the time and frequency domain of a frame for synchronous relaying in a network cycle and the flow of the relay synchronous control frame in the present invention.

6 is a diagram illustrating a configuration for frequency selection of a synchronous relay device according to the present invention;

7 is a view for explaining the principle that the interference between a plurality of relay paths in accordance with the orthogonal frequency offset when there are a plurality of relay paths in accordance with the present invention.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the drawings, similar reference numerals are used for similar elements.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, the same reference numerals will be used for the same means regardless of the reference numerals in order to facilitate the overall understanding.

2 is a diagram illustrating a picocell inter-radio relay system according to an exemplary embodiment of the present invention.

As shown in FIG. 2, the wireless relay system according to the present invention may include a master device 200, one or more synchronous relay devices 202-n, and one or more slave devices 204-n.

According to the present invention, one wireless device is set as the device as the master device 200 in the near field, and the wireless devices for the synchronous relay and the payload relay receive the synchronous signal with the synchronous relay device 202-n. A wireless device that performs only can be set as the slave device 204-n.

The master device 200 transmits a synchronization signal. At this time, the wireless devices adjacent to the master device 200 and the wireless devices belonging to the coverage of the master device 200 communicate with the master device 200 while maintaining synchronization. Meanwhile, slave devices that do not reach the synchronization signal of the master device 200 receive the synchronization signal from the synchronization relay device 202-n according to the present invention.

As shown in FIG. 2, since the synchronization relay devices 202-n maintain synchronization based on the master device 200, the slave devices receiving the synchronization signal from the synchronization relay device 202-n also master. It is possible to synchronize with the device 200.

Referring to FIG. 3, the short range wireless relay protocol according to the present invention has a basic structure of a network cycle having a length of 256 msec, and one network cycle has 16 cycle structures. Has a length of 16 msec and may include a control frame having a length of 0.88 msec and at least one payload frame having 15.12 msec.

In addition, each frame may include a lock time field, a preamble field, a tag field, a message field, and an end-of-frame information (EoF) field.

Here, the lock time field is a section set for stabilization of frequency synthesis. According to the present invention, since the frequency is converted in units of frames of a cycle, a lock time is required to stabilize the frequency synthesis every frame. The lock time field is preferably 245 ms.

The preamble field is a section for transmitting and receiving a synchronization signal for synchronization acquisition of a frame when transmitting and receiving data wirelessly. The length of the preamble is set in units of 128 μsec. Using a 7-bit scan code, a 128-bit preamble is used by adding '0' to a 127-bit long code using a gold code generator.

The tag field is a portion in which special purpose data allocated to each frame is transmitted and received without applying a group code and a security code. Since the information on the tag is visible to all devices, it can be used for ancillary signals such as a broadcast channel, a distress signal, etc., to clarify the purpose of a frame that is not confirmed only by the preamble. The tag is fixed at 32μsec in length and has a cyclic redundancy check (CRC) function with a length of 16μsec.

The message field is the part where user data is actually loaded and the data is transmitted and received by applying group code and security code. The length of the message field is fixed in the case of a control frame, but in the case of a payload frame, the length may be set in basic units according to the transmission mode in the upper layer. For each frame, a CRC is applied to a tag field and a CRC can be selectively applied to a message field.

The End of Frame Information (EoF) field is the time required for the state transition of the modem and RF at the end of the frame. This frame end information field can be set in units of 1 μsec. This end-of-frame information field follows the next frame. Here, the frame end information field is preferably 42 µsec or more.

4 is a diagram illustrating a frame structure of different network cycles in a short range wireless communication protocol according to the present invention.

As shown in FIG. 4A, when fast synchronization acquisition is required, a network cycle (fast synchronous network cycle) transmits a synchronization signal in every control frame.

That is, in the fast synchronous network cycle, the master device 200 allocates and transmits all 16 control frames as synchronous control frames for maintaining synchronization. In the fast synchronization network cycle, a control frame is defined as a fast synchronization control frame (FSCF).

Meanwhile, as shown in FIG. 4B, two of the 16 control frames used in the normal network cycle are two synchronization control frames (SCFs) of the master device 200, and one is a slave device. Is a request control frame (RCF) that sends request information to a master device in a master device, and one is a master control frame (MCF) that sends control information from a master device to slave devices. Acknowledgment Control Frame (RCF) for Response to Control Frame (RCF), eight are Control Frames for Response to Master Control Frame (MCF) (MACF / FCF), and three are for future use It is a reserved control frame (RFUCF).

The synchronization control frame (SCF) of the master device 200 is used to maintain synchronization and there are two during one normal network cycle. The master device 200 transmits information necessary for synchronization and the slave devices 204-n synchronize with the synchronization control frame (SCF).

According to a preferred embodiment of the present invention, as shown in FIG. 4C, at least one of control frames 9 to 16 of a conventional normal network cycle is referred to as a relay synchronization control frame (RSCF). An assigned relay network cycle is proposed.

Based on the relay network cycle, the one or more synchronous relay devices 202-n include predetermined information in the RSCF and transmit them to other synchronous relay devices or slave devices 204-n when synchronous relay or payload relay is required. .

According to the present invention, the master device 200 receives at least one of a plurality of control frames in a network cycle and transmits a synchronous control frame.

The synchronization control frame of the master device 200 may include a frequency table, hopping information, relay hop count, relay path ID, and the like.

The frequency table may be updated periodically or aperiodically according to the usage environment, and the hopping information is information for determining a frequency to be used by each wireless device 200 to 204 at a specific time.

The relay hop count is decremented by 1 each time a relay is made, and when it reaches 0, no further relay is performed.

The relay path ID is information for uniquely identifying a desired relay path among several relay paths.

Referring to FIG. 2, when a user payload transmission is required from a slave device 204-1 (source node) to three slave devices 204-2 to 204-4, end node, a relay hop count is calculated at the source node. The number of hops to the end node may be set to 3. Since the relay hop count is 0 after the end node is transmitted to the user payload, no further relaying is performed.

On the other hand, prior to relaying the user payload from the source node 204-1 to the end nodes 204-2 to 204-4 as described above, the synchronous relay devices 202-1 and 202-2 are connected from the master device 200. Receives the sync control frame SF0, and transmits the relay sync control frames RSCF and SF1 to the slave devices 204-2 to 204-4 corresponding to the end nodes based on the sync control frame SF0. Through 202-1, synchronization with the master device 200 may be maintained.

According to an exemplary embodiment of the present invention, the synchronous relay device transmits an RSCF using a region in which time and frequency do not overlap each other with the master device 200 and other synchronous relay devices, and the master device ( 200) or collision with or other synchronous relay device.

FIG. 5 is a diagram illustrating orthogonal allocation in a time and frequency domain of a frame for synchronous relay in a network cycle, and flow of a relay synchronous control frame in the present invention.

FIG. 5 illustrates an example in which one master device 200 and first to third synchronous relay devices 202-1 to 202-3 are provided.

5 shows an example in which a plurality of paths exist due to the provision of the plurality of synchronous relay devices 202-1 to 202-3.

As shown in FIG. 5, the master device 200 transmits a synchronous control frame (SCF) 500 at a predetermined frequency.

The first synchronous relay device 202-1 receiving the first control relay 202-1 uses the first frequency offset at a first time allocated to avoid collision and interference with the synchronous control frame 500 of the master device 200. Send frame 502.

The slave device 204-1 receives the first relay synchronization control frame 502, where the first relay synchronization control frame 502 is generated based on the synchronization control frame 500 of the master device 200. As such, the slave device 204-1 is synchronized with the master device 200.

Meanwhile, as shown in the time-frequency axis of FIG. 5, the second synchronous relay device 202-2 that receives the synchronous control frame from the master device 200 has a second relay synchronous with a second frequency offset at the first time. Send control frame 504.

In addition, the third synchronous relay device 202-3 receiving the second relay synchronous control frame 504 transmits the third relay synchronous control frame 506 at a third frequency offset at a first time.

As described above, even when a plurality of synchronous relays are provided so that a synchronous relay is required between a plurality of paths, each synchronous relay device 202-n transmits a relay synchronous control frame in different time and frequency domains. Collision and interference of the wireless signal can be avoided.

In addition, according to the present invention, since some of the plurality of slave devices are allocated to the synchronous relay device to perform synchronous relay and payload relay, the relay service can be performed without any separate equipment such as the access point equipment.

6 is a diagram illustrating a configuration for frequency selection of a synchronous relay device according to the present invention.

As shown in FIG. 6, the synchronous relay device according to the present invention includes an orthogonal frequency offset determiner 600, a hopping sequence generator 602, a first remaining output unit 604, and an adder 606 for frequency selection. And a second remaining output unit 608.

The orthogonal frequency offset determiner 600 according to the present invention determines and outputs an orthogonal frequency offset by combining the hopping information, the relay hop count, and the relay path ID received from the master device 200.

Meanwhile, the hopping sequence generator 602 outputs a random hopping sequence by using a Maximal Pseudo Noise Sequence on a cycle basis, and the output hopping sequence is divided by the size of the frequency table by the first remaining output unit 604. Outputs the value corresponding to the rest. In the present invention, since the frequency table has a size of 16, the first remaining output unit 604 may output one of values of 0 to 15.

The output first residual value is added to the quadrature frequency offset value and the adder 606 and then output to the second remaining output unit 606, and the second remaining output unit 606 outputs the value output from the adder 608. After dividing by the frequency table size, the remainder (second residual value) is output.

An address value (0 to 15) of one of the frequency tables is determined by the second remaining value, and the synchronous relay apparatus uses a frequency corresponding to the address value as a frequency for synchronous relay or payload relay.

The first remaining output unit 604, the adder 606, and the second remaining output unit 608 may be collectively referred to as an address value determining unit in that they are elements that determine an address value of a frequency table.

According to the present invention, a frequency used by each synchronous relay device may be determined differently according to an orthogonal frequency offset.

FIG. 7 is a diagram for explaining a principle that interference between a plurality of relay paths is avoided according to an orthogonal frequency offset when there are multiple relay paths according to the present invention.

Referring to FIG. 7, it is assumed that two paths (relay path A and relay path B) exist in the current picocell. And, it is assumed that one synchronous relay device has two slots (A, B) for transmission and reception.

According to the present invention, since the relay paths A and B have different path IDs, they have different orthogonal frequency offsets, and the plurality of synchronous relay devices A to D belonging to one relay path A may have relay hop counts. Because of the different orthogonal frequency offset also different, which is the same as the plurality of synchronous relay devices (E to F) belonging to the relay path B.

For example, it is assumed that the orthogonal frequency offset is determined by the sum of the path ID and the relay hop count.

In this case, the orthogonal frequency offset may be determined as n + 5 for the synchronous relay device A having the path ID of the relay path A and the relay hop count n. Synchronous relay A transmits payload frame 700 at frequency f _{n + 5} corresponding to orthogonal frequency offset to _{n + 5} .

Since the synchronous relay device B has the same path ID as the synchronous relay device A and 5 and the relay hop count is n−1, the orthogonal frequency offset may be determined as n + 4. Accordingly, a frequency f _{n + 4} different from the synchronous relay device may be determined. The payload frame 702 is transmitted.

Similarly, the synchronous relay device C has an orthogonal frequency offset different from the synchronous relay devices A and B as the relay hop count becomes n-2, thereby transmitting the payload frame 704 at the frequency f _{n + 3} .

On the other hand, when the path ID of the relay path B is set to 1, the synchronous relay device E having the relay hop count of n may have an orthogonal frequency offset set to _{n + 1} and payload at a frequency corresponding to f _{n + 1} . Send frame 710.

Here, the synchronous relay device E has an orthogonal frequency offset difference of +4 when compared to the synchronous relay device A belonging to the relay path A, and thus is different from the frequency f _{n + 5} of the sync relay device A at the same time. By using the frequency f _{n + 1} , frequency collision can be prevented from occurring.

On the other hand, in the relay path B, the synchronous relay device F has a relay hop count of n-1, and when compared with the synchronous relay device E, the synchronous relay device F has an orthogonal frequency offset of n as small as 1, and the payload at a frequency of f _n . Send frame 712.

Similarly, the synchronous relay device G has a relay hop count of n−1, thereby transmitting the payload frame 714 at a frequency of f _n−1 .

In the same manner as described above, transmission of the relay synchronization control frame is also performed.

In the above description, the index of the orthogonal frequency offset is an index of a frequency used by each synchronous relay, but this is for convenience of description, and as illustrated in FIG. 6, a randomly generated hopping sequence and a size of a frequency table. We have already seen that the address value in the frequency table is determined using both and and orthogonal frequency offsets.

As shown in FIG. 7, when there are a plurality of synchronous relay devices and a plurality of paths, each synchronous relay device uses different frequencies in time and frequency domains for each path and for each relay hop count. Because of the allocation, synchronous relay and payload relay are achieved without frequency collision.

Preferred embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art will be able to make various modifications, changes, and additions within the spirit and scope of the present invention. Additions should be considered to be within the scope of the following claims.

Claims

A system for supporting inter-picocell relay based on a network cycle including a plurality of control frames,

A master device receiving at least one of the plurality of control frames as a synchronization control frame and transmitting the synchronization control frame at an orthogonal hopping frequency;

Receiving the synchronization control frame and maintaining synchronization with the master device, and receives a control frame allocated to the synchronization control frame of the plurality of control frames as a relay synchronization control frame, the relay synchronization control frame at an orthogonal hopping frequency without interference Synchronous relay device for transmitting a; And

And at least one slave device receiving the relay synchronization control frame in a region where the synchronization control frame of the master device is not received and maintaining synchronization with the synchronization relay device.
The method of claim 1,

The synchronous relay device includes a plurality of synchronous relay devices, and each of the plurality of synchronous relay devices is assigned a different control frame among the plurality of control frames for transmission of the relay synchronous control frame, and each other at the same time using a preset variable. Picocell relay support system for transmitting the relay synchronization control frame using a different frequency.
The method of claim 2,

The synchronization control frame transmitted by the master device includes at least one of a frequency table, hopping information, a relay hop count, and a path ID, and the plurality of synchronization relay devices may include at least one of the hopping information, the relay hop count, and a path ID. And determining different orthogonal frequency offsets and determining a frequency to transmit the relay sync control frame in the frequency table based on the orthogonal frequency offset.
The method of claim 3,

A plurality of synchronous relay apparatus having the same relay hop count between different paths has a different picocell relay support system having a different orthogonal frequency offset according to each path ID.
The method of claim 3,

And a plurality of synchronous relay devices having different relay hop counts on the same path have different orthogonal frequency offsets according to respective relay hop counts.
The method of claim 3,

The synchronous relay device,

An orthogonal frequency offset determiner for determining the orthogonal frequency offset;

A hopping sequence generator for randomly generating a hopping sequence; And

And an address value determiner configured to determine an address value of the frequency table using the orthogonal frequency offset and the hopping sequence.
The method of claim 6,

The address value determination unit,

A first remainder output unit configured to output a first remainder obtained by dividing the hopping sequence by the size of the frequency table;

An adder for adding the quadrature frequency offset and the output first remainder; And

A second remainder output unit configured to output a second remainder obtained by dividing the added value by the frequency table;

And the second remaining output unit is an address value of the frequency table.
The method of claim 7, wherein

The network cycle is configured by a predetermined number of cycle units, and the address value determination of the frequency table is performed between the picocell relay support system.
In a short range wireless communication system based on a network cycle including a plurality of control frames and including a master device and a slave device, a synchronous relay device supports picocell relaying,

Receiving a synchronization control frame including information for maintaining synchronization from the master device and maintaining synchronization with the master device; And

And transmitting a relay sync control frame by receiving a control frame different from the sync control frame among the plurality of control frames.

The slave device located in an area where the synchronization control frame of the master device is not received maintains synchronization with the master device by receiving the relay synchronization control frame, and the frequency of the relay synchronization control frame provides information for maintaining the synchronization. Picocell relay support method determined using.
The method of claim 9,

The information for maintaining synchronization includes at least one of a frequency table, hopping information, a relay hop count, and a path ID.