Apparatus and method for operating resources in communication system

A method for operating resources by a base station in a communication system is provided. The method includes transmitting at least one beam to at least one terminal, receiving strength information of the at least one beam from the at least one terminal, determining at least one of resources which are not used for communication between the at least one terminal and the base station, and resources, whose interference to communication between the base station and the at least one terminal is less than or equal to a predetermined threshold, based on the strength information of the at least one beam, and allocating the determined resources as resources for communication which is performed between terminals without the base station.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit under 35 U.S.C. §119(a) of a Korean patent application filed on Jul. 2, 2012 in the Korean Intellectual Property Office and assigned Serial No. 10-2012-0071767, the entire disclosure of which is hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to an apparatus and method for operating resources in a communication system. More particularly, the present disclosure relates to an apparatus and method for operating resources to increase the efficiency of transmission and reception in a communication system.

BACKGROUND

In line with the exponential increase in the average amount of data used by mobile users, there is an increasing user demand for higher data rates. Methods capable of providing a high data rate may be roughly classified into a method of performing communication using a wider frequency band and a method of increasing the frequency usage efficiency. The latter method has a lot of difficulty in providing a higher average data rate since it is hard to further increase the frequency usage efficiency through the technology improvements as the currently available communication technologies have already provided the frequency usage efficiency close to its theoretical limit. Therefore, an efficient way to increase the data rate is to provide data services over a wider frequency band.

In order to provide data services over a wide frequency band, available frequency bands need to be considered, and millimeter-wave bands of 30 GHz or higher are commonly used, because the bands of 1 GHz or higher, capable of broadband communication, are limited. In these high frequency bands, unlike in the 2 GHz band used by the cellular systems according to the related art, the signal attenuation may significantly increase with the increase in the distance, causing a significant reduction in service coverage of a base station.

SUMMARY

Aspects of the present disclosure are to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present disclosure is to provide an apparatus and method for operating resources to increase the efficiency of transmission and reception in a communication system.

Another aspect of the present disclosure is to provide an apparatus and method for operating resources to allow terminals to communicate with each other without a base station in a communication system.

Another aspect of the present disclosure is to provide an apparatus and method for operating resources to allow a base station to efficiently transmit resource allocation information to a terminal in a communication system.

In accordance with an aspect of the present disclosure, a method for operating resources by a base station in a communication system is provided. The method includes transmitting at least one beam to at least one terminal, receiving strength information of the at least one beam from the at least one terminal, determining at least one resource which is not used for communication between the at least one terminal and the base station, and resources, whose interference to communication between the base station and the at least one terminal is less than or equal to a predetermined threshold, based on the strength information of the at least one beam, and allocating the determined resources as resources for communication which is performed between terminals without the base station.

In accordance with another aspect of the present disclosure, a method for operating resources by a terminal in a communication system is provided. The method includes receiving at least one beam from a base station, measuring a strength of the at least one beam, transmitting information about the strength of the at least one beam to the base station, and receiving, from the base station, at least one resource which is not used for communication between at least one terminal and the base station and resources whose interference to communication between the base station and the at least one terminal is less than or equal to a predetermined threshold, wherein the at least one resource is determined and allocated by the base station based on the information about the strength of the at least one beam.

In accordance with another aspect of the present disclosure, an apparatus for operating resources by a base station in a communication system is provided. The apparatus includes a transmitter configured to transmit at least one beam to at least one terminal, a receiver configured to receive strength information of the at least one beam from the at least one terminal, and a controller configured to determine at least one resource which is not used for communication between the at least one terminal and the base station, and resources, whose interference to communication between the base station and the at least one terminal is less than or equal to a predetermined threshold, based on the strength information of the at least one beam, and to allocate the determined resources as resources for communication which is performed between terminals without the base station.

In accordance with another aspect of the present disclosure, an apparatus for operating resources by a terminal in a communication system is provided. The apparatus includes a receiver configured to receive at least one beam from a base station, a transmitter configured to measure a strength of the at least one beam, and to transmit information about the strength of the at least one beam to the base station, and a controller configured to receive, from the base station, at least one resource which is not used for communication between at least one terminal and the base station and resources whose interference to communication between the base station and the at least one terminal is less than or equal to a predetermined threshold, and to control communication with another terminal using the received resources, wherein the at least one resource is determined and allocated by the base station based on the information about the strength of the at least one beam.

DETAILED DESCRIPTION

FIG. 1illustrates a terminal and a base station providing beamforming using array antennas in a communication system according to an embodiment of the present disclosure.

Referring toFIG. 1, the base station110may transmit data in each cell by switching a direction of a DownLink (DL) Transmit (Tx) beam using a plurality of array antennas Array0 and Array1, and the terminal130may receive data by switching a direction of a Receive (Rx) beam.

When using the beam forming technique, the base station110and the terminal130provide data services by selecting directions of the Tx and Rx beams showing the optimal channel environment among the directions of the Tx and Rx beams. The same technique may be applied not only to a DL channel carrying data from the base station110to the terminal130, but also to an UpLink (UL) channel carrying data from the terminal130to the base station110.

Assuming that the number of directions of the Tx beams in which the base station110can transmit data is N, and the number of directions of the Rx beams in which the terminal130can receive data is M, in order to select the optimal DL Tx/Rx directions, the base station110transmits a predetermined signal in each of N available Tx directions at least M times, and the terminal130receives each of the N Tx beams using M Rx beams. In this way, the base station110may transmit a specific reference signal at least N×M times, and the terminal130may receive the reference signal N×M times, measure received strengths of the received signals, and determine the direction showing the highest measured strength among the N×M measured strengths as the optimal Tx/Rx beam direction.

The process in which the base station110transmits a signal in all of the base station110's available Tx directions at least once will be referred to as ‘beam sweeping’, and the process in which the terminal130selects the optimal Tx/Rx beam direction will referred to as ‘beam selection’. This optimal DL Tx/Rx beam selection process may be applied in the same way even to a UL Tx/Rx process for transmitting data from the terminal130to the base station110.

FIGS. 2 and 3illustrate a base station that transmits signals through Tx beams having a specific beam width in performing communication using a beamforming technique in a communication system according to an embodiment of the present disclosure.

Referring toFIG. 2, the base station110is installed in the location of a specific height201and has a predetermined beam width205. The beam width205of the base station110may be defined for each of the elevation angle and the azimuth. In the example given inFIG. 2, a Tx beam of the base station110is transmitted in a direction corresponding to a specific elevation angle203.

FIG. 3shows the number of Tx beams transmittable by the base station110, on the assumption that in the example where the base station110is installed as inFIG. 2, the base station110has an installation height of 35 m and transmits Tx beams having a beam width of 5° for each of the elevation angle and the azimuth in one sector having an angle of 30° and coverage of 200 m. As illustrated inFIG. 3, one sector having an angle of 30° and coverage of 200 m may be configured using 96 Tx beams having a beam width of 5° for each of the elevation angle and the azimuth.

The Tx beams transmitted by the base station110are spread in the form of fan (or sector) when there is no obstacle. However, in the example ofFIG. 3, each of the Tx beams will be assumed to arrive at the ground in the form of rectangle for convenience purpose only, and the rectangles represent 96 areas in which the Tx beams having specific azimuth and elevation angle have arrived at the ground. The 96 Tx beams are transmitted to farther areas as the elevation angle is greater, and as the TX beams are transmitted farther by the base station110, their transmission distances are longer and they are received in wider areas.

A ratio written in each rectangle represents a ratio of an Rx area of a Tx beam that is transmitted to a specific location to the size of all of the 96 areas. As illustrated inFIG. 3, it can be understood that even for a Tx beam having the same elevation angle and azimuth, a Tx beam transmitted to the boundary area of the base station110is received in a wider area, compared to a Tx beam that is transmitted to an area close to the center of the base station110. InFIG. 3where the base station is assumed to have the height of 35 m and the coverage of 200 m, the largest Rx area may be a maximum of 480 times the size of the smallest Rx area.

If the base station110uses Tx beams having a narrow elevation angle and azimuth, a large number of Tx beams and Rx areas may exist. For example, when transmitting a DL synchronization channel and broadcast control channels by beam sweeping using narrow Tx beams, the base station110needs to repeatedly transmit the Tx beams in all of the narrow Tx beam directions one or more times, for a total of 96 times or more. The number of transmissions needed to transmit a DL synchronization channel and broadcast control channels by beam sweeping is proportional to the number of Tx beams existing in the coverage of the base station110, so a way to reduce the Tx overhead of the DL synchronization channel and broadcast control channels in the base station110is to support the entire coverage of the base station110with a fewer number of Tx beams. To this end, a beam width of each Tx beam should be widened. However, as the beam width increases, the beamforming effects are lower, and if the beam width becomes narrower to increase the beamforming effects, the number of Tx beams required to support the entire coverage of the base station110becomes larger, causing an increase in the overhead required to transmit the broadcast-type channels.

A way to address this issue is to design a beam width used to transmit broadcast channels to be different from a beam width used to transmit user data. For example, a Tx beam having a beam width of 30° may be used as a Tx beam for transmitting broadcast channels in a sector of 60°, and a Tx beam having a beam width of 10° may be used as a Tx beam for transmitting user data. In the method of using a plurality of different beam widths, a Tx beam having a wide beam width will be referred to as a wide beam or a coarse beam, while a Tx beam having a narrow beam width will be referred to as a narrow beam or a fine beam.

FIG. 4illustrates how a base station schedules terminals located in different locations using different fine beams in a communication system according to an embodiment of the present disclosure.

Referring toFIG. 4, according to an embodiment of the present disclosure, when scheduling a plurality of terminals, the base station400may identify the time, space, and frequency resources that are not used in scheduling, or that may not significantly interfere with the scheduled terminals, and use the identified resources for inter-terminal communication or relay communication. The space resources are not limited to the physical space resources, but may include information about a Multiple Input Multiple Output (MIMO) layer which may occur between transceivers of a base station and a terminal, antenna configuration information used in Tx/Rx antennas, and information about different beamformings formed by transceivers. In the case of beamforming, for example, if one or more Tx beams exist in the base station, the Tx beams or their patterns may be regarded as different space resources.

The term ‘relay communication’ as used herein may refer to communication between a base station and a terminal, or communication performed via one or more relay terminals. The term ‘inter-terminal communication’ as used herein may refer to communication that is performed only between terminals without the intervention of a base station. Both the relay communication and the inter-terminal communication will be referred to as ‘local communication’. An operation in which the base station directly transmits data to terminals based on its scheduling will be referred to ‘direct communication’, which is distinguishable from the relay communication and the inter-terminal communication.

Referring toFIG. 4, the base station400is a base station that is installed in the same way as inFIG. 3, and schedules two terminals existing in different locations401and402at a certain time, using two different fine beams. Because the signal attenuation effects are significant in the millimeter-wave bands to which various embodiments of the present disclosure are applied, a signal of a Tx beam transmitted to the area401is received with lower power due to the signal attenuation as it goes far away from the area401, and a signal of a Tx beam transmitted to the area402is also received with lower power due to the signal attenuation as it goes far away from the area402. Accordingly, if the two areas, in which the Tx beams from the base station400are received, are spaced apart enough from each other spatially, interference between the two beams may be suppressed to a low level, making it possible to efficiently reuse the time and frequency resources.

An area (such as an area403), that is quite far from the areas401and402to which the base station400has transmitted the two Tx beams, is a location where the two Tx beams and the time and frequency resources may be reused, since this area is a location where the interference with the two Tx beams transmitted to the areas401and402is limited to a low level. When the base station400schedules terminals at a certain time using beamforming, one or more spatial areas like the area403, in which the interference with terminals, for which direct communication is scheduled, is limited to a low level, may exist in the coverage of the bases station400. Terminals located in this area may perform local communication using the available time and frequency resources of the base station400. The area in which the interference is limited to a low level refers to an area where the interference occurs to be lower than or equal to a predetermined threshold. As for the resources for local communication, all or some of the available time and frequency resources may be reused to minimize the interference to terminals for direct communication.

FIG. 5illustrates how a base station400performs scheduling for direct communication and local communication in a communication system according to another embodiment of the present disclosure.

Referring toFIG. 5, the areas serviced by the base station400may be divided into an area where a terminal #1501and a terminal #2502, for which direct communication is scheduled, are located, and an area503where local communication is available. Local communication may be performed between a terminal #3503-aand a terminal #4503-b, and/or between a terminal #5503-cand a terminal #6503-d, all of which are located in the area503.

Local communication may be performed by reusing all or some of the available frequency resources, including the frequency resource areas scheduled for the terminal #1501and the terminal #2502which perform direct communication. For example, among the frequency areas of a specific time (slot)504scheduled for direct communication, an area505is a resource area scheduled for the terminal #2502and an area507is a resource area scheduled for the terminal #1501. An area506may be used for local communication by preventing or minimizing overlapping with the areas505and507. In other words, in another embodiment of the present disclosure, only selected some of the available frequency resource areas may be reused for local communication to minimize interference with the terminals, for which direct communication is scheduled.

FIG. 6illustrates how a base station schedules direct communication and local communication upon a change in communication environment in a communication system according to an embodiment of the present disclosure.

Referring toFIG. 6, since the base station400adaptively operates resources for direct communication depending on the communication environment, the spatial areas scheduled for local communication and the time and frequency resource areas allocated for local communication may adaptively vary depending on how the base station400schedules direct communication for terminals.

Referring toFIG. 6, a time slot #0601illustrates an example of scheduling direct communication for a terminal #1605and a terminal #2606, and scheduling local communication for areas607and608where local communication is available. A time slot #1602illustrates an example of scheduling direct communication for a terminal #3609and a terminal #4610which are different from the terminals, for which direct communication was scheduled in the time slot #0601, and thus scheduling local communication for areas611and612which are different from the areas607and608where local communication was available in the time slot #0601. A time slot #2603illustrates an example of scheduling direct communication for a terminal #4613and a terminal #5614which are different from the terminals, for which direct communication was scheduled in the time slot #1602, and thus scheduling local communication for a new area615where local communication is available. As such, the space resources used for local communication may dynamically vary in every scheduling time depending on how the base station400schedules direct communication.

In order to find the time, space, and frequency resources which do not cause interference of a predetermined threshold or more to the terminals performing direct communication, the base station400may use at least one of information about the base station400's Tx beam-specific received signal strength (or reception performance) that all terminals in the base station400's cell have measured and reported, information about interference between Tx beams, and information about at least one Tx/Rx beam used to transmit data to terminals performing direct communication. To this end, the base station400transmits a reference signal via each Tx beam in predetermined time and frequency areas. A terminal measures a received Tx beam-specific reference signal and reports information about the signal strength and interference between Tx beams to the base station400. As the received signal strength information for Tx beams and the interference information between Tx beams, an average value measured over all the frequency resources may be reported, or a value measured for each frequency resource may be reported for each frequency resource. The base station400may determine Tx beams scheduled for local communication and information about frequency resources to be operated for local communication, using at least one of information about the base station400's Tx beam-specific received signal strength that terminals have measured and reported, Tx beam-specific interference information, and information about at least one of Tx/Rx beams used to transmit data to terminals performing direct communication.

When the base station400has scheduled a specific terminal using a specific Tx beam, the base station400may determine, as an area where the interference by direct communication is limited, the Tx beam whose signal strength is less than or equal to a predetermined threshold or whose signal strength compared to that of Tx beams used for direct communication is less than or equal to a predetermined threshold, among the base station400's Tx beams except for the specific Tx beam scheduled for direct communication, based on the information about the Tx beam-specific received signal strength measured and reported by the scheduled terminal, thereby operating the determined Tx beam for local communication.

When the base station400has scheduled direct communication for a plurality of terminals, the base station400may determine, as an area where the interference by direct communication is limited, the Tx beam whose signal strength is less than or equal to a predetermined threshold or whose signal strength compared to that of Tx beams used for direct communication is less than or equal to a predetermined threshold, based on any one (for example, the highest signal strength value) of the signal strength values that the scheduled terminals have independently measured and reported for the same Tx beam except for the Tx beams scheduled for direct communication, thereby operating the determined Tx beam for local communication. The base station400may determine, as terminals capable of performing local communication, the terminals that have reported the Tx beam operated for local communication as a Tx beam having the highest signal strength.

The base station400may determine an area where local communication is performed, using information about the base station400's Tx beam-specific received signal strength that the terminal for local communication has reported, in addition to the Tx beam-specific received signal strength information of the terminal performing direct communication. The base station400determines that the interference to an area of a terminal by direct communication is limited, if received signal strength of Tx beams scheduled for direct communication out of the Tx beam-specific received signal strength information reported by terminals for local communication is less than or equal to a predetermined threshold, or if received signal strength of Tx beams scheduled for direct communication compared to the Tx beam having the highest reception performance is less than or equal to a predetermined threshold. The base station400thereby determines, as an area where local communication may be performed, the area where the terminal is located, or the area where the Tx beam is operated, that the terminal has reported as a Tx beam having the highest signal strength.

When operating a specific Tx beam for local communication, the base station400may operate, for local communication, the frequency area that minimizes overlapping of frequency resources with the terminals performing direct communication.

In a case where the base station400has operated local communication for specific Tx beam area and frequency resources, upon receiving related information, the terminals may determine that local communication has been operated for the terminals, if the Tx beam operated by the base station400for local communication has the highest received signal strength. Alternatively, the terminals may compare the received signal strength of the Tx beam operated by the base station400for local communication with the highest received signal strength of the Tx beam, and determine that local communication has been operated for the terminals, if the comparison results fall within a predetermined value.

FIGS. 7A and 7Billustrate a frame structure used to transmit and receive signals in a communication system according to another embodiment of the present disclosure.

Referring toFIG. 7A, one frame has a length of 5 ms, and is comprised of five sub-frames, each of which may be divided into a DL Tx interval710carrying signals from a base station to a terminal, and a UL Tx interval720carrying signals from a terminal to a base station. Some of the DL Tx interval710may be used as a scheduling area740for carrying scheduling information, or may be used as an area730for carrying a DL reference signal.

A base station transmits a reference signal for each of its Tx beams in the reference signal area730more than once. For example, when performing beamforming using 96 Tx beams having a beam width of 5° at the elevation angle and azimuth, the base station transmits a reference signal for each of the 96 Tx beams in the reference signal area730at least once. For example, as illustrated inFIG. 7B, the base station transmits a reference signal for each of the 96 Tx beams in the reference signal area730once in every sub-frame.

A terminal receives each Tx beam-specific reference signal transmitted from the base station in the reference signal area730using one or more Rx beams, measures received signal strength for each Tx/Rx beam pair, and reports the measurements results to the base station.

FIGS. 8A and 8Billustrate an operation in which terminals801and802report their received signal strength to a base station400in a communication system according to another embodiment of the present disclosure.

Referring toFIGS. 8A and 8B, the terminal #1801may report received signal strengths of different reference signals for eight areas including the terminal801's area803up to an area810which is quite distanced from the area803. A terminal #2802may also report received signal strengths of different reference signals for six areas including the terminal802's area811and areas812to816which are respectively further away from the area811. As illustrated inFIGS. 8A and 8B, as received signal strength of a reference signal for a specific area is higher, the area is expressed darker. For the terminal #1801, a reference signal for the area803is received with the highest signal strength, and a reference signal for an area804is received with the second highest signal strength. In this way, in terms of the signal strength at which a reference signal is received, the area804is higher than area805, the area805is higher than an area806, the area806is higher than an area807, the area807is higher than an area808, the area808is higher than an area809, and the area809is higher than the area810. For the terminal #2802, a reference signal for the area811is received with the highest signal strength, and a reference signal for the area816is received with the lowest signal strength.

If the base station400schedules direct communication for the terminal #2802upon receiving reports on received signal strengths of Tx beam-specific reference signals from the terminal #1801and the terminal #2802, the base station400may select a Tx beam whose received signal strength is lower than or equal to a threshold, or whose received signal strength compared to that of a Tx beam used for direct communication is lower than or equal to a threshold, among its Tx beams, received signal strengths for which have been reported by the terminal #2802, thereby operating the selected Tx beam and its associated area, for local communication. For example, the base station400may operate the area815or the area816for local communication, and the terminal #1801that has reported the Tx beam corresponding to the area as the best Tx beam, may be determined as a terminal capable of local communication.

Using the Tx beam-specific received signal strength information reported by the terminal #1801capable of local communication, the base station400determines whether to operate local communication for the associated area. For the Tx beam used for local communication with the terminal #2802, the terminal #1801has reported low received signal strength for the reference signal, and if the received signal strength is lower than or equal to a threshold, or is lower by a threshold than or equal to the highest received signal strength reported by the terminal #1801, the base station400may determine the area803where the terminal #1801is located, as an area where local communication is available.

In a case where the base station400has operated local communication for the area803, upon receiving this information, the terminal #1801may determine that the terminal #1801is a terminal capable of local communication, if the Tx beam corresponding to the area803among the Tx beams of the base station400has the highest received signal strength. Alternatively, the terminal #1801may compare the received signal strength of the Tx beam corresponding to the area803with the highest received signal strength of the Tx beam, and determine that the terminal #1801is a terminal capable of local communication, if the comparison results fall within a predetermined value.

The base station400transmits information about the time, space, and frequency resources operated for local communication to the terminals located in the space resources where local communication is available. To this end, the base station400may form a Tx beam having a beam width corresponding to the space, and transmit scheduling information for the time, space and frequency resources using the formed Tx beam. The scheduling information may be transmitted over a scheduling channel or in a separately defined resource area. The scheduling information may be transmitted to a plurality of terminals in a broadcast or multicast manner, rather than being transmitted to each terminal in a unicast manner.

FIG. 9illustrates an operation in which a base station transmits scheduling information to different terminals using different beam widths in a communication system according to an embodiment of the present disclosure.

Referring toFIG. 9, when scheduling direct communication, the base station400delivers scheduling information to terminals using fine Tx beams. For example, the base station400delivers scheduling information to terminals902,903, and904that perform direct communication with the base station400, using fine Tx beams907,908, and909, respectively. On the other hand, if the base station400delivers scheduling information to terminals905and906that perform local communication with each other, using fine Tx beams one by one, a lot of base station resources may be consumed for the delivery of scheduling information. Therefore, the base station400may deliver scheduling information using one Tx beam910having a beam width corresponding to an area where local communication is available.

The base station400may transmit scheduling information for the time, space, and frequency resources operated for local communication, over a broadcast channel.

The scheduling information for local communication may include information about the time, space, and frequency resources allocated for inter-terminal communication or relay communication. The spatial information may include information about one or more coarse beams or one or more fine beams that the base station400will allocate for local communication.

FIG. 10illustrates a frame structure designed to transmit scheduling information for time, space and frequency resources used for local communication, over a scheduling channel in a communication system according to an embodiment of the present disclosure.

Referring toFIG. 10, a base station400may transmit scheduling information for direct communication and local communication in a scheduling area740of each sub-frame. The scheduling area740may be comprised of ten scheduling units, and includes an area1003used to transmit scheduling information for direct communication and an area1004used to transmit scheduling information for local communication.

The scheduling information for direct communication may be transmitted using fine Tx beams, while the scheduling information for local communication may be transmitted using a Tx beam having a beam width corresponding to the area where local communication is available. The scheduling information for local communication may include information about the time, space, and frequency resources allocated for inter-terminal communication or relay communication, and information about one or more different areas1005,1006, and1007in the time and frequency resources. The scheduling information for local communication may also include information about one or more coarse or fine Tx beams allocated for local communication.

Upon receiving the scheduling information for local communication, a terminal may determine whether the terminal is capable of local communication, based on the received scheduling information. The terminal may determine that the terminal is capable of local communication, if the scheduling information for local communication includes a Tx beam measured by the terminal and having the highest received signal strength among the DL Tx beams of the base station400. Alternatively, the terminal may compare the received signal strength of the Tx beam, which is included in scheduling information for local communication, with received signal strength of a Tx beam showing the highest received signal strength among the signals the terminal has received, and may determine that the terminal is capable of local communication, if the comparison results fall within a predetermined value.

In a case where a terminal capable of local communication exchanges local communication data with another terminal in the time, space, and frequency resources operated for local communication, upon receiving scheduling information for local communication from the base station400, the terminal may transmit the received scheduling information to another terminal which has failed to receive the scheduling information from the base station400due to obstacles and the like.

FIG. 11is a flowchart illustrating an operation of a base station400in a communication system according to an embodiment of the present disclosure.

Referring toFIG. 11, the base station400performs scheduling for direct communication on a plurality of terminals using one or more Tx/Rx beams at operation1101. Thereafter, based on information about the Tx beam-specific received signal strength of the base station400, that the terminals in the base station400's cell have reported, the base station400determines an area where local communication is available using Tx/Rx beams whose interference to the Tx/Rx beams used for direct communication is lower than or equal to a predetermined threshold at operation1102. The base station400may determine, as an area where local communication is available, the area corresponding to a Tx beam whose received signal strength is lower than or equal to a predetermined value, if received signal strength of Tx beams of the base station400, that the terminals, for which direct communication is scheduled, have measured and reported, is lower than or equal to a predetermined threshold. Alternatively, the base station400may compare the reported received signal strength with the received signal strength of the Tx beam used for direct communication, and determine, as an area where local communication is available, the area corresponding to a Tx beam whose received signal strength is lower than or equal to a predetermined value, if the comparison results fall within a predetermined value.

After determining the area where local communication is available, the base station400may determine the terminal that is located in the area and is capable of local communication, and may allocate resources for local communication taking into account the interference, by which direct communication may affect local communication if the local communication is allowed.

If there is no area where local communication is available at operation1103, the base station400transmits scheduling information for direct communication and ends the scheduling operation at operation1108. On the other hand, if there is an area where local communication is available at operation1103, the base station400determines a terminal located in the area where local communication is available, using the information about its Tx beam-specific received signal strength that terminals in its cell have reported at operation1104. The base station400may determine that the terminal is capable of local communication, if the terminal reports a Tx beam corresponding to the area where local communication is available, as a Tx beam having the highest received signal strength. Alternatively, the base station400may compare the received signal strength of the Tx beam corresponding to the area where local communication is available, which the terminal has reported, with the highest received signal strength of the Tx beam among the signals transmitted from the base station400, and may determine the terminal as a terminal capable of local communication, if the comparison results fall within a predetermined value.

When the base station400has allowed local communication using the information about the base station400's Tx beam-specific received signal strength that the terminals capable of local communication have reported, the base station400determines interference by which the direct communication may affect local communication at operation1105. The base station400may regard the interference by which direct communication may affect local communication, as an allowable level, if the received signal strength of Tx beams scheduled for direct communication is lower than or equal to a predetermined value in the information about the Tx beam-specific received signal strength that the terminals capable of local communication have reported. Alternatively, if received signal strength of Tx beams scheduled for direct communication is equal to or lower by a predetermined value than the received signal strength of the Tx beam having the highest received signal strength among the signals the terminal receives, the base station400may regard the interference by which direct communication may affect local communication, as an allowable level, even though the terminal performs local communication.

If the interference by which direct communication may affect local communication is not regarded as an allowable level at operation1106, the base station400transmits scheduling information for direct communication to terminals without scheduling for local communication and ends the scheduling operation at operation1108.

On the other hand, if the interference by which direct communication may affect local communication is regarded as an allowable level even though local communication is performed at operation1106, the base station400schedules the time, space, and frequency resources for local communication to the terminals determined to be able to perform local communication at operation1107. The space resources operated for local communication may include all or some of the candidate area where local communication is available. The frequency resources operated for local communication may include frequency resources selected to minimize interference in the frequency area between Tx beams operated for local communication and adjacent Tx beams scheduled for direct communication, or all of the available frequency resources.

The base station400transmits scheduling information for direct communication or local communication over a scheduling channel or a broadcast channel and ends the scheduling operation at operation1108.

FIG. 12is a flowchart illustrating an operation of a terminal in a communication system according to an embodiment of the present disclosure.

Referring toFIG. 12, a terminal in the cell serviced by the base station400measures received signal strength of a Tx beam transmitted from the base station400, and reports the measurement results to the base station400at operation1201. Thereafter, the terminal checks scheduling information in the scheduling area of a sub-frame received from the base station400at operation1202.

The terminal determines if scheduling information for direct communication in the scheduling area is available. If the terminal is scheduled as a terminal performing direct communication at operation1203, the terminal performs direct communication in the scheduled resources at operation1204.

On the other hand, if the terminal is not scheduled as a terminal performing direct communication at operation1203, the terminal determines if scheduling information for local communication in the scheduling area is available. If scheduling information for local communication in the scheduling area is available at operation1205, the terminal determines if the terminal is a terminal capable of local communication. If the terminal is a terminal capable of local communication at operation1206, the terminal performs local communication in the time, space, and frequency resources scheduled for local communication at operation1207.

The terminal may determine whether the terminal is a terminal capable of local communication, based on, for example, the reception of scheduling information for the local communication. The terminal may determine that the terminal if a terminal for local communication, if the Tx beam measured by the terminal and having the highest received signal strength among the DL Tx beams of the base station400is included in the scheduling information for local communication, or if the received signal strength of the Tx beam for local communication included in the scheduling information for local communication is lower by a predetermined value than the received signal strength of the Tx beam measured by the terminal and showing the optimal reception performance.

FIG. 13illustrates structures of a base station400and a terminal500in a communication system according to another embodiment of the present disclosure.

Referring toFIG. 13, the base station400includes a controller1300, a transceiver1301, and a data storage1302. The terminal500includes a transceiver1304, an encoder1305, a controller1306, and a modulator1307, and may perform the above-described terminal's functions.

In the base station400, the transceiver1301transmits and/or receives signals to/from the terminal500, the data storage1302stores data, and the controller1300controls the overall operation of the base station400such as scheduling direct communication and local communication.

In the terminal500, the transceiver1304transmits and/or receives signals to/from the base station400, the encoder1305encodes received signals, and the modulator1307modulates the encoded signals. The controller1306controls the overall operation of the terminal500such as measuring and reporting received signal strengths of Tx beams of the base station400.

As is apparent from the foregoing description, resources for direct communication between a base station and a terminal, and resources for local communication between terminals without a base station may be efficiently operated in a communication system, contributing to an increase in the efficiency of transmission and reception.