KR101040889B1 - Wireless systems in heterogeneous networks and method thereof - Google Patents

Abstract

A wireless communication system in a heterogeneous network includes a synchronization unit for synchronizing frequencies according to a frequency reference signal received through a CPC, and a cooperative communication unit for cooperative communication with a first RAT within the CPC coverage according to the synchronization.

CPC, RAT, Cooperative Communications, Frequency, Time

Description

Wireless systems in heterogeneous networks and method

One embodiment of the present invention relates to a technique for cooperation and interworking between different wireless communication systems in a heterogeneous network.

The present invention is derived from a study conducted as part of the IT source technology development project of the Ministry of Knowledge Economy and the Ministry of Information and Communication Research and Development. [Task management number: 2008-F-001-01, Task name: Environmental adaptation of wireless communication method of mobile communication Type autonomous control technology].

With the development of wireless communication technology, the current wireless communication system is a mixture of cellular-based second generation and third generation mobile communication systems and short-range wireless communication systems such as WLAN, but there is no cooperation between them. However, redundant investments and the efficient use of limited spectrum resources were not possible.

In order to overcome this recently, in a heterogeneous network environment in which different specifications are mixed, an intelligent communication technology that can improve frequency utilization efficiency for a ubiquitous communication environment for users and a maximum return on investment for an operator is provided. Research is ongoing.

Among these, the standardization study on Cognitive Radio System (CRS) centering on ITU-R is a contribution to the cooperative communication between different Radio Access Technology (RAT) using Cognitive-supporting Pilot Channel (CPC). Proposed. In addition, European Patent EP 1802152A1 is a patented technology for a specific method for the operation of the CPC, it has proposed a method for allowing the user terminal to access the optimal RAT by providing information about the various RAT through the CPC.

Since the existing CRS using the CPC provides only the frequency band and the RAT information, when the user terminal changes the RAT according to the region and the service, the Software Defined Radio (SDR) based user terminal may access the frequency and time in order to access each RAT. It doesn't really help you stay motivated.

Meanwhile, according to the European patent EP1845743A1, diversity gain can be obtained by receiving signals from two or more base stations to improve performance when the user terminal is located at the edge of a cell. In this case, since the arrival time of the signal from each base station has a great effect on the performance when combining the signals at the user terminal, even in an asynchronous system such as W-CDMA, time synchronization is required for the multi-RAT transmit diversity gain. However, the existing CPC method does not consider this situation.

According to an embodiment of the present invention, a frequency synchronization time that may occur when a plurality of RATs are connected by having a center frequency signal so that each RAT or a user terminal may easily synchronize frequency synchronization in addition to the existing CPC information commonly received by different RATs. In addition, the present invention provides a wireless communication system and method in heterogeneous networks to prevent an increase in the number of channels and to maximize the effects of operating multiple RATs such as multi-RAT diversity by receiving common time information of each RAT and a user terminal. It aims to do it.

An embodiment of the present invention is a heterogeneous network capable of synchronizing frequencies according to a frequency reference signal received through a CPC, and cooperatively communicating with a first RAT within the CPC coverage according to the synchronization, thereby synchronizing frequencies of a user terminal. An object of the present invention is to provide a wireless communication system and method.

An embodiment of the present invention is a heterogeneous network capable of synchronizing the time of the user terminal by synchronizing the time according to the time reference signal received through the CPC and cooperatively communicating with the first RAT within the CPC coverage according to the synchronization. An object of the present invention is to provide a wireless communication system and method.

An embodiment of the present invention selects the first RAT capable of optimal cooperative communication based on the CPC information received through the CPC, transmits an access grant signal to the selected first RAT, and sends the transmitted access grant signal. An object of the present invention is to provide a wireless communication system and method in a heterogeneous network capable of receiving a first RAT signal from the first RAT in response to the first RAT signal, and cooperatively communicating with the first RAT signal according to the first RAT signal.

According to an embodiment of the present invention, when the user terminal is moved, the second RAT located in a region different from the first RAT may be selected based on the CPC information received through the CPC, and cooperative communication with the selected second RAT may be performed. It is an object of the present invention to provide a wireless communication system and method in heterogeneous networks.

One embodiment of the present invention is multi-RAT simultaneous access, multi-RAT sequential access, multi-RAT diversity, multi-RAT multiplexing, frequency band conversion communication, distributed band communication, user terminal communication, inter-RAT communication, Relay communication, Mesh It is an object of the present invention to provide a wireless communication system and method in a heterogeneous network for cooperative communication using any one of a network communication, a self-organizing network, and an ad hoc communication.

An embodiment of the present invention synchronizes frequencies according to a frequency reference signal received through a CPC, synchronizes time according to a time reference signal received through the CPC, and user terminals within the CPC coverage according to the synchronization. It is an object of the present invention to provide a wireless communication system and method in a heterogeneous network capable of synchronizing the time or frequency of the RAT by cooperative communication.

An embodiment of the present invention transmits a frequency reference signal to a user terminal and a RAT in CPC coverage, synchronizes the frequency of the user terminal and the RAT, and transmits a time reference signal to the user terminal and the RAT to the user terminal. It is an object of the present invention to provide a wireless communication system and method in a heterogeneous network for synchronizing the time between the RAT and the cooperative communication with the synchronized user terminal.

In a heterogeneous wireless communication system according to an embodiment of the present invention, a synchronization unit for synchronizing frequencies according to a frequency reference signal received through a CPC, and cooperative communication with a first RAT in the CPC coverage according to the synchronization It includes a cooperative communication unit.

Wireless communication system in heterogeneous network according to an embodiment of the present invention is a synchronization unit for synchronizing the frequency of the user terminal and the RAT, according to the frequency reference signal transmitted to the user terminal and the RAT in the CPC coverage, and the synchronized And a cooperative communication unit for controlling cooperative communication between a user terminal and the RAT.

In a wireless communication method in a heterogeneous network according to an embodiment of the present invention, receiving a frequency reference signal through a CPC, synchronizing a frequency according to the received frequency reference signal, and the CPC coverage according to the synchronization Cooperatively communicating with a first RAT in the network.

According to an embodiment of the present invention, in a heterogeneous wireless network in which various RATs centered on CPC exist, when a user terminal communicates by changing RATs according to a service and a wireless channel environment, or simultaneously connects the RATs, the performance is improved. In addition, by providing time and frequency as a reference, the synchronization time can be shortened and the performance can be improved.

According to an embodiment of the present invention, the frequency of the user terminal may be synchronized by synchronizing frequencies according to the frequency reference signal received through the CPC and cooperatively communicating with the first RAT within the CPC coverage according to the synchronization. .

According to an embodiment of the present invention, the time of the user terminal may be synchronized by synchronizing the time according to the time reference signal received through the CPC and cooperatively communicating with the first RAT within the CPC coverage according to the synchronization. .

According to an embodiment of the present invention, based on the CPC information received through the CPC, selecting the first RAT capable of optimal cooperative communication, and transmits a connection permission signal to the selected first RAT, the transmitted connection A first RAT signal may be received from the first RAT in response to the permission signal, and cooperative communication with the first RAT may be performed according to the first RAT signal.

According to an embodiment of the present invention, when the user terminal is moved, the second RAT located in a region different from the first RAT is selected based on the CPC information received through the CPC, and the cooperative communication with the selected second RAT is performed. can do.

According to an embodiment of the present invention, multi-RAT simultaneous access, multi-RAT sequential access, multi-RAT diversity, multi-RAT multiplexing, frequency band conversion communication, distributed band communication, inter-user communication, inter-RAT communication, relay communication , Cooperative communication can be performed using any one of mesh network communication, self-organizing network, and ad hoc communication.

According to an embodiment of the present invention, the frequency is synchronized according to the frequency reference signal received through the CPC, the time is synchronized according to the time reference signal received through the CPC, the CPC coverage according to the synchronization By cooperative communication with the user terminal within, it is possible to synchronize the time or frequency of the RAT.

According to an embodiment of the present invention, by transmitting a frequency reference signal to the user terminal and the RAT in the CPC coverage, to synchronize the frequency of the user terminal and the RAT, and to transmit the time reference signal to the user terminal and the RAT By synchronizing the time of the user terminal and the RAT, it is possible to control the cooperative communication between the synchronized user terminal and the RAT.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings and accompanying drawings, but the present invention is not limited to or limited by the embodiments.

1 is a diagram illustrating a connection relationship of a wireless communication system in a heterogeneous network according to an embodiment of the present invention.

As shown, the Cognitive-supporting Pilot Channel (CPC) has the widest coverage in an environment where one or more Radio Access Technologies (RATs) exist. The CPC includes a frequency band, a location, a specification, etc. of the RATs included in the CPC coverage, so that UEs in the CPC coverage may select an optimal RAT in consideration of service and wireless channel environment. Send information to the user terminal.

The user terminal may be provided with a service by selecting a first RAT (RAT A) capable of most optimal wireless communication using the CPC information. To this end, the user terminal should be able to access different RATs simultaneously or sequentially. In order to access the RAT, the user terminal must first synchronize frequency synchronization. However, since each of the RATs and the user terminal uses an oscillator generating different reference frequencies, performance may be degraded due to frequency deviation when simultaneous reception is performed at different RATs.

In order to prevent this, an independent frequency synchronization circuit (PLL) must be provided so that each RAT and frequency synchronization can be matched with each other. However, if different RATs are synchronized with one common frequency reference signal, RF implementation cost can be reduced because only one frequency synchronization circuit can be used even if a plurality of RF circuits are used.

Alternatively, if the digital RF technology using the band pass sampling theory capable of simultaneous reception in a user terminal is applied, there is an advantage in that multiple bands can be simultaneously received with one frequency synchronization circuit and an RF circuit. In other words, if the reference frequencies between the RATs are different from each other, the frequency acquisition can be performed again each time the RAT is changed, so that a performance degradation due to time delay is expected. However, if the frequency synchronization is matched between the RATs, the user terminal can save time since the frequency synchronization can be performed immediately through the frequency tracking process without the frequency acquisition process whenever the RAT is changed.

On the other hand, when using the downlink reception method using the spatial diversity through different RAT, the signals sent from each RAT should be able to reach the user terminal at the same time with a certain time standard. If the time difference between received signals is too great, it is difficult to obtain diversity gain at the receiver. To solve this, there must be a kind of time reference signal that can synchronize time at the network end between different RATs, which is disadvantageous in terms of system specification compatibility and time delay. If the time reference signal is transmitted through a common CPC channel, the portion to be considered at the network end may be much reduced. On the contrary, if the time criteria are not met even when a plurality of RATs receive a signal from one UE, it is difficult to recover the signals received by the plurality of RATs at the network side.

In addition, it can be noted that there may be various performance degradations when time synchronization and frequency synchronization are not matched between different RATs. To compensate for this, as shown in FIG. 2, one CPC or several CPCs can receive a certain reference signal and use it for frequency and time synchronization. The reference signal may be a GPS signal, or other method may be used to allow various RATs to have a common time and frequency.

2 is a diagram illustrating a connection relationship of a wireless communication system in a heterogeneous network according to another embodiment of the present invention.

As shown, the user terminal or the plurality of RATs may cooperatively communicate by synchronizing time according to a time reference signal received from a CPC or a reference signal generator. If some RATs cannot meet the time criteria due to backward compatibility, the user terminal may synchronize time with the RATs. Alternatively, the RATs may synchronize time with the user terminal. Likewise, in the frequency domain, the user terminal or the plurality of RATs may cooperatively communicate by synchronizing frequencies according to a frequency reference signal received through a CPC or a reference signal generator.

Such a user terminal and each of the RATs should have a separate circuit capable of synchronizing with a time reference signal or a frequency reference signal received from a reference signal generator. The implementation scheme may be different in each situation. For example, the user terminal may have a plurality of RF circuits capable of simultaneously receiving CPC information, a RAT signal, a frequency reference signal, and a time reference signal, or may use a method capable of simultaneous reception such as digital RF.

Hereinafter, an embodiment of the present invention will be described with reference to FIG. 3 when a wireless communication system in a heterogeneous network is a user terminal .

3 is a diagram illustrating a configuration of a wireless communication system in a heterogeneous network according to an embodiment of the present invention.

As shown, the wireless communication system 300 in a heterogeneous network includes a synchronization unit 320 for synchronizing frequencies according to a frequency reference signal received through a CPC, and a first RAT in the CPC coverage according to the synchronization. It may be configured to include a cooperative communication unit 330 for cooperative communication.

The RF circuits 310 to 310 -N may receive CPC information, a RAT signal, a frequency reference signal, and a time reference signal through the CPC. According to an implementation manner, the wireless communication system 300 may include a plurality of RF circuits 310 to 310 -N to simultaneously receive the CPC information, the RAT signal, the frequency reference signal, and the time reference signal. have. Although illustrated in the drawings as an RF circuit, a method capable of simultaneous reception such as digital RF may be used according to an implementation method.

The synchronizer 320 may synchronize time according to the time reference signal received through the CPC. That is, the synchronization unit 320 receives the frequency reference signal generated from the reference signal generator through the CPC to synchronize the frequency, and receives the time reference signal generated from the reference signal generator through the CPC to time. Can be synchronized.

The cooperative communication unit 330 may receive the CPC information through the CPC, and select the first RAT capable of optimal cooperative communication based on the CPC information. As described above, the CPC information may include any one of a frequency band, a location, and a specification for RATs within the CPC coverage. The cooperative communication unit 330 may cooperatively communicate with the first RAT by transmitting a connection permission signal to the selected first RAT and receiving a first RAT signal from the first RAT in response to the transmitted connection permission signal. have.

In one embodiment of the present invention, as the user terminal moves in position, the cooperative communication RAT may be changed, so that the cooperative communication unit 330 may perform optimal cooperative communication based on the CPC information received through the CPC. A second RAT located in a region different from the first RAT may be selected, and cooperative communication with the selected second RAT may be performed. For example, the cooperative communication unit 330 selects a RAT capable of currently optimal cooperative communication as the second RAT instead of the first RAT based on the CPC information, and transmits an access grant signal to the selected second RAT. Thus, a second RAT signal can be received from the second RAT, and cooperative communication with the second RAT is possible.

In one embodiment of the present invention, the cooperative communication unit 330 is multi-RAT simultaneous access, multi-RAT sequential access, multi-RAT diversity, multi-RAT multiplexing, frequency band conversion communication, distributed band communication, inter-user communication, RAT Cooperative communication can be performed using any one of inter-communication, relay communication, mesh network communication, self-organizing network, and ad hoc communication.

4 illustrates a graph associated with a time reference signal or a frequency reference signal according to an embodiment of the present invention.

As shown, a wireless communication system in a heterogeneous network may perform cooperative communication by synchronizing time according to a time reference signal received from a CPC or a reference signal generator. Alternatively, in the frequency domain, a wireless communication system in a heterogeneous network may cooperatively communicate by synchronizing frequency according to a frequency reference signal received through the CPC or the reference signal generator.

Hereinafter, another embodiment of the present invention will be described with reference to FIG. 5 when a wireless communication system in a heterogeneous network is a RAT .

5 is a diagram illustrating a configuration of a wireless communication system in a heterogeneous network according to another embodiment of the present invention.

As shown, the wireless communication system 500 in a heterogeneous network cooperates with a synchronization unit 510 for synchronizing frequencies according to a frequency reference signal received through a CPC, and a user terminal in the CPC coverage according to the synchronization. It may be configured to include a cooperative communication unit 520 to communicate.

That is, the synchronization unit 510 may synchronize time according to the time reference signal received through the CPC. The frequency reference signal and the time reference signal may be generated from a reference signal generator, transferred to the CPC, and the CPC may be transmitted to the RAT. Accordingly, the plurality of RATs may synchronize frequency and time through the frequency reference signal and the time reference signal.

The cooperative communication unit 520 may receive a connection permission signal from the user terminal and transmit a first RAT signal according to the received connection permission signal to the user terminal, thereby cooperatively communicating with the user terminal.

According to another embodiment of the present invention, when the wireless communication system in a heterogeneous network is a CPC, the wireless communication system in the heterogeneous network transmits a frequency reference signal to a user terminal and a RAT within the CPC coverage, so that the user terminal and the By synchronizing the frequency of the RAT, and transmitting a time reference signal to the user terminal and the RAT to synchronize the time of the user terminal and the RAT, it is possible to control the cooperative communication with the synchronized user terminal.

In addition, embodiments of the present invention include computer-readable media containing program instructions for performing various computer-implemented operations. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like.

While specific embodiments of the present invention have been described so far, various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims and the claims.

1 is a diagram illustrating a connection relationship of a wireless communication system in a heterogeneous network according to an embodiment of the present invention.

2 is a diagram illustrating a connection relationship of a wireless communication system in a heterogeneous network according to another embodiment of the present invention.

3 is a diagram illustrating a configuration of a wireless communication system in a heterogeneous network according to an embodiment of the present invention.

4 illustrates a graph associated with a time reference signal or a frequency reference signal according to an embodiment of the present invention.

5 is a diagram illustrating a configuration of a wireless communication system in a heterogeneous network according to another embodiment of the present invention.

<Explanation of symbols for main parts of the drawings>

300: wireless communication system in heterogeneous networks

310 RF circuit

320: synchronization unit

330: cooperative communication department

Claims (10)

A synchronization unit for synchronizing frequencies according to a frequency reference signal received through a Cognitive-supporting Pilot Channel (CPC); And Cooperative communication unit for communicating with a first RAT whose frequency is synchronized within the CPC coverage where one or more Radio Access Technologies (RATs) exist Wireless communication system in a heterogeneous network comprising a. The method of claim 1, The synchronization unit, And synchronizing time according to a time reference signal received through the CPC. The method of claim 1, The cooperative communication unit, Receive CPC information including any one of a frequency band, a location, and a specification for one or more RATs included in the CPC coverage through the CPC, and based on the CPC information among the one or more RATs; Select a RAT, transmit a connection grant signal to the selected first RAT, receive a first RAT signal from the first RAT in response to the transmitted connection grant signal, and according to the received first RAT signal, A wireless communication system in a heterogeneous network in communication with the first RAT. delete The method of claim 1, The cooperative communication unit, In response to the movement of the location of the wireless communication system, the CPC receives CPC information including any one of a frequency band, a location, and a specification for one or more RATs included in the CPC coverage, and the one or more RATs. Selecting a second RAT located in a region different from the first RAT based on the CPC information, and communicating with the selected second RAT. The method of claim 1, The cooperative communication unit, And communicate with the frequency synchronized user terminal within the CPC coverage. The method of claim 1, The cooperative communication unit, Multi-RAT simultaneous access, multi-RAT sequential access, multi-RAT diversity, multi-RAT multiplexing, frequency band conversion communication, distributed band communication, inter-user communication, inter-RAT communication, relay communication, mesh network communication, self-organizing network And communicating with the first RAT using any one of, and Ad Hoc communication. Transmitting a frequency reference signal to a user terminal and a RAT included in Cognitive-supporting Pilot Channel (CPC) coverage in which one or more Radio Access Technologies (RATs) exist, and according to the transmitted frequency reference signal, the user terminal and the RAT Synchronizing unit for synchronizing the frequency between; And The cooperative communication unit for controlling the user terminal and the RAT with the frequency is synchronized with each other Wireless communication system in a heterogeneous network comprising a. The method of claim 8, The synchronization unit, And transmitting a time reference signal to the user terminal and the RAT, and synchronizing a time between the user terminal and the RAT according to the transmitted time reference signal. Receiving a frequency reference signal through a Cognitive-supporting Pilot Channel (CPC); Synchronizing a frequency according to the received frequency reference signal; And Communicating within a CPC coverage where one or more Radio Access Technologies (RATs) exist, the frequency-synchronized first RAT Including, wireless communication method in a heterogeneous network.

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