WO2008078968A1

WO2008078968A1 - Method for supporting short latency in mobile communication system and system thereof

Info

Publication number: WO2008078968A1
Application number: PCT/KR2007/006887
Authority: WO
Inventors: Mi-Hyun Lee; Jae-Weon Cho; Hyun-Kyu Yu; Song-Nam Hong
Original assignee: Samsung Electronics Co., Ltd.
Priority date: 2006-12-27
Filing date: 2007-12-27
Publication date: 2008-07-03
Also published as: KR20080063151A

Abstract

Disclosed is method for transmitting downlink signal by base station in mobile communication system. The method includes: indicating, through first zone, first particular zone of second zone of downlink sub-frame by base station; indicating, through first particular zone, information on dedicated channel for transmission or retransmission of data within first particular zone and second particular zone for receiving feedback signal with respect to data; transmitting or retransmitting data through dedicated channel indicated by first particular zone; and receiving feedback signal through second particular zone, wherein each frame includes downlink sub-frame and uplink sub-frame and includes first zone for transmission of frame control information and second zones for transmission of data burst, second zones are located within downlink sub-frame and uplink sub-frame, respectively, and first particular zone and second particular zone are preset in each of downlink sub-frame and uplink sub-frame.

Description

METHOD FOR SUPPORTING SHORT LATENCY IN MOBILE COMMUNICATION SYSTEM AND SYSTEM THEREOF

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a mobile communication system, and more particularly to a method for supporting a short latency in signal transmission/reception in a mobile communication system and a system thereof.

2. Description of the Related Art

Current mobile communication systems are developing in order to provide various services, such as broadcast, multimedia images, multimedia messages, etc. Especially, the fourth generation (4G) mobile communication system is currently being developed targeting providing a data service capable of guaranteeing a data rate of at least 100 Mbps for fast-moving users and a data rate of at least 1 Gbps for slow-moving users, beyond the voice and packet data communication.

Meanwhile, in a mobile communication system, multiple access schemes are considered for efficient use of limited frequency resources. Further, in the mobile communication system, multiplexing schemes discriminating between the two directions, which include an uplink and a downlink, are considered. One of schemes reflecting such multiple access and multiplexing is a Time Division Duplexing Orthogonal Frequency Division Multiple Access (TDD-OFDMA) scheme.

FIGs. IA and IB illustrate a typical TDD-OFDMA frame structure and a TDD-OFDMA frame structure having multiple zones.

First, referring to FIG. IA, the TDD-OFDMA frame includes a downlink sub-frame and an uplink sub-frame, between which a Transmission/reception Time Gap (TTG) and a Reception/transmission Time Gap (RTG) are located. The downlink sub-frame includes a preamble zone for transmitting a preamble signal, and a control information zone. The control information zone includes a Frame Control Header (FCH), a DL-MAP, and a UL-MAP.

Next, referring to FIG. IB, the downlink sub-frame and the uplink sub- frame may include different zones according to the sub-channel configuration schemes. Zone configuration information is included in the first zone after the preamble, that is, in the zone named Partial Usage of Sub-Channels (PUSC). The zone configuration information may be appointed by . using STC_DL_Zone_Switch_IE() or AAS_DL_IE().

In FIGs. IA and IB, zones defined by solid lines correspond to fixed zones, the existence of which is indispensable, and zones defined by broken lines correspond to variable zones, the existence and the size of which are optional according to cell environment and operation.

Meanwhile, in a mobile communication system, a short latency is required for high speed data transmission. However, it cannot be said that all packets require the short latency. For example, a Voice over Internet Protocol (VoIP) packet using Hybrid Automatic Retransmission Request (HARQ) may require the short latency.

According to a transmission scheme in a system in which each frame has a length of 5 msec, 15 msec or more is required from initial data transmission to next data transmission or retransmission thereof. However, in order to achieve high speed real time data transmission, the data transmission or retransmission should be done within 15 msec.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made to solve the above- mentioned problems occurring in the prior art, and the present invention provides a method for high speed data transmission in a mobile communication system.

Also, the present invention provides a frame structure for high speed data transmission in a mobile communication system.

In accordance with an aspect of the present invention, there is provided a method for transmitting a downlink signal by a base station in a mobile communication system, the method including the steps of: indicating, through a first zone, a first particular zone of a second zone of a downlink sub- frame by the base station; indicating, through the first particular zone, information on a dedicated channel for transmission or retransmission of data within the first particular zone and a second particular zone for receiving a feedback signal with respect to the data; transmitting or retransmitting data through the dedicated channel indicated by the first particular zone; and receiving a feedback signal through the second particular zone, wherein each frame includes the downlink sub-frame and an uplink sub-frame and includes the first zone for transmission of frame control information and second zones for transmission of a data burst, the second zones are located within the downlink sub-frame and the uplink sub-frame, respectively, and the first particular zone and the second particular zone are preset in each of the downlink sub-frame and the uplink sub-frame.

In accordance with another aspect of the present invention, there is provided a method for transmitting an uplink signal by a mobile station in a mobile communication system, the method including the steps of: receiving, through a first zone of a current frame, an indication that indicates a first particular zone of a second zone of a downlink sub-frame and a second particular zone of an uplink sub-frame by the mobile station; receiving, through the first particular zone, an indication that contains information on a dedicated channel for transmission or retransmission of data within the second particular zone and indicates a first particular zone of a next frame for receiving a feedback signal with respect to the data; transmitting or retransmitting data through the dedicated channel indicated by the first particular zone; and receiving a feedback signal through the first particular zone of the next frame, wherein each frame includes the downlink sub-frame and the uplink sub-frame and includes the first zone for transmission of frame control information and second zones for transmission of a data burst, the second zones are located within the downlink sub-frame and the uplink sub-frame, respectively, and the first particular zone and the second particular zone are preset in each of the downlink sub-frame and the uplink sub- frame.

In accordance with another aspect of the present invention, there is provided a method for receiving a downlink signal by a mobile station in a mobile communication system, the method including the steps of: receiving, through a first zone, an indication that indicates a first particular zone of a second zone of a downlink sub-frame by the mobile station; receiving, through the first particular zone, an indication that contains information on a dedicated channel for transmission or retransmission of data within the first particular zone and indicates a second particular zone for receiving a feedback signal with respect to the data; receiving or re-receiving data through the dedicated channel indicated by the first particular zone; and transmitting a feedback signal through the second particular zone, wherein each frame includes the downlink sub-frame and an -A-

uplink sub-frame and includes the first zone for transmission of frame control information and second zones for transmission of a data burst, the second zones are located within the downlink sub-frame and the uplink sub-frame, respectively, and the first particular zone and the second particular zone are preset in each of the downlink sub- frame and the uplink sub- frame.

In accordance with another aspect of the present invention, there is provided a method for transmitting an uplink signal by a base station in a mobile communication system, the method including the steps of: indicating, through a first zone of a current frame, a first particular zone of a second zone of a downlink sub-frame and a second particular zone of an uplink sub-frame by the mobile station; indicating, through the first particular zone, information on a dedicated channel for transmission or retransmission of data within the second particular zone and a first particular zone of a next frame for transmitting a feedback signal with respect to the data; receiving or re-receiving data through the dedicated channel indicated by the first particular zone; and transmitting a feedback signal through the first particular zone of the next frame, wherein each frame includes the downlink sub-frame and the uplink sub-frame and includes the first zone for transmission of frame control information and second zones for transmission of a data burst, the second zones are located within the downlink sub-frame and the uplink sub-frame, respectively, and the first particular zone and the second particular zone are preset in each of the downlink sub-frame and the uplink sub-frame.

In accordance with another aspect of the present invention, there is provided a method for signal transmission/reception by a base station in a mobile communication system, the method including the steps of: indicating, through a first particular zone, information on a dedicated channel for transmission or retransmission of data and a second particular zone for receiving a feedback signal with respect to the data; transmitting or retransmitting data through the dedicated channel indicated by the first particular zone; and receiving a feedback signal through the second particular zone, wherein each frame includes a downlink sub-frame and an uplink sub-frame, and the first particular zone and the second particular zone are preset in each of the downlink sub-frame and the uplink sub-frame.

In accordance with another aspect of the present invention, there is provided a method for signal transmission/reception by a mobile station in a mobile communication system, the method including the steps of: receiving, through a first particular zone, an indication that contains information on a dedicated channel for transmission or retransmission of data and indicates a second particular zone for receiving a feedback signal with respect to the data; receiving or re-receiving data through the dedicated channel indicated by the first particular zone; and transmitting a feedback signal through the second particular zone, wherein each frame includes a downlink sub-frame and an uplink sub-frame, and the first particular zone and the second particular zone are preset in each of the downlink sub-frame and the uplink sub-frame.

In accordance with another aspect of the present invention, there is provided a mobile communication system including: a base station for indicating, through a first zone, a first particular zone of a second zone of a downlink sub- frame by the base station, indicating, through the first particular zone, information on a dedicated channel for transmission or retransmission of data within the first particular zone and a second particular zone for receiving a feedback signal with respect to the data, transmitting or retransmitting data through the dedicated channel indicated by the first particular zone, and receiving a feedback signal through the second particular zone; and a mobile station for receiving, through a first zone of a current frame, an indication that indicates a first particular zone of a second zone of a downlink sub-frame and a second particular zone of an uplink sub-frame by the mobile station, receiving, through the first particular zone, an indication that contains information on a dedicated channel for transmission or retransmission of data within the second particular zone and indicates a first particular zone of a next frame for receiving a feedback signal with respect to the data, transmitting or retransmitting data through the dedicated channel indicated by the first particular zone, and receiving a feedback signal through the first particular zone of the next frame, wherein each frame includes the downlink sub- frame and an uplink sub-frame and includes the first zone for transmission of frame control information and second zones for transmission of a data burst, the second zones are located within the downlink sub-frame and the uplink sub-frame, respectively, and each of the downlink sub-frame and the uplink sub-frame includes the first particular zone and the second particular zone.

In accordance with another aspect of the present invention, there is provided a mobile communication system including: a base station for indicating, through a first particular zone, information on a dedicated channel for transmission or retransmission of data and a second particular zone for receiving a feedback signal with respect to the data, transmitting or retransmitting data through the dedicated channel indicated by the first particular zone, and receiving a feedback signal through the second particular zone; and a mobile station for receiving, through a first particular zone, an indication that contains information on the dedicated channel and indicates the second particular zone from the base station, receiving or re-receiving data through the dedicated channel indicated by the first particular zone, and transmitting a feedback signal through the second particular zone, wherein each frame includes a downlink sub-frame and an uplink sub-frame, and the first particular zone and the second particular zone are preset in each of the downlink sub-frame and the uplink sub-frame.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIGs. IA and IB illustrate a typical TDD-OFDMA frame structure and a TDD-OFDMA frame structure having multiple zones;

FIG 2 illustrates a TDD-OFDMA frame structure for supporting a short latency in downlink data transmission proposed by the present invention;

FIGs. 3A and 3B illustrate downlink data transmission/reception supporting a short latency by using a frame structure proposed by the present invention;

FIG. 4 illustrates a TDD-OFDMA frame structure for supporting a short latency in an uplink data transmission proposed by the present invention;

FIGs. 5A and 5B illustrate uplink data transmission/reception supporting a short latency by using a frame structure proposed by the present invention;

FIG. 6 illustrates locations of dedicated channels for supporting downlink short latency according to an embodiment of the present invention;

FIG. 7 is a signal flow diagram illustrating an operation of a mobile station and a base station using a downlink short latency zone according to an embodiment of the present invention;

FIG. 8 illustrates locations of dedicated channels for supporting uplink short latency according to an embodiment of the present invention; FIG. 9 is a signal flow diagram illustrating a signal flow between a mobile station and a base station using an uplink short latency zone according to an embodiment of the present invention; and

FIG. 10 illustrates a frame structure configured by short latency zones according to the present invention.

FIG. 11 is a flow diagram illustrating a process of signal transmission/reception by a mobile station according to an embodiment of the present invention.

FIG. 12 is a flow diagram illustrating a process of signal transmission/reception by a base station according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

The present invention proposes a signal transmission/reception method for supporting a short latency in a mobile communication system and a system thereof. Especially, the present invention proposes a signal transmission/reception scheme for supporting a short latency based on a frame including multiple divided zones. Also, the present invention proposes a new frame structure capable of satisfying the requirement for a short latency while having a compatibility with the existing frame structure and frame length.

A frame according to the present invention includes at least one transmission zone supporting a short latency, that is, a short latency supporting zone. Here, the frame may be a Time Division Duplexing Orthogonal Frequency Division Multiple Access (TDD-OFDMA) frame. The short latency supporting zone according to the present invention may use the following newly defined dedicated zones.

1. Short Latency Zone (SLZ): Zone for transmitting data requiring a short latency. The SLZ exists both in an uplink and in a downlink. The SLZ is first applied to data requiring a short latency, and may then be applied to data other than the data requiring a short latency also in view of the resource use. For operation of the short latency, the channels as follows are defined. Further, one sub-frame can be constituted by only the short latency zone.

2. Short latency Dedicated Control Channel (SLDCCH): Channel for transmitting control information dedicated for the short latency. The SLDCCH includes data burst assignment information and feedback channel assignment information.

3. Short latency Dedicated Data Channel (SLDDCH): Channel for transmitting data dedicated for the short latency.

4. Short latency Dedicated Feedback Channel (SLDFCH): Channel for transmitting a feedback signal of the data dedicated for the short latency.

Hereinafter, a data transmission scheme supporting a short latency will be described for an uplink and a downlink, respectively.

First, in a downlink, a short latency zone is located in a downlink sub- frame, and a dedicated channel for supporting the short latency zone is located in the downlink sub-frame and the uplink sub-frame. A more detailed description will be given below with reference to FIG. 2.

FIG. 2 illustrates a TDD-OFDMA frame structure for supporting a short latency in downlink data transmission proposed by the present invention.

Referring to FIG. 2, the downlink sub-frame includes a short latency zone. For example, reference numeral 200 in the (L-I)* frame corresponds to the short latency zone. The short latency zone 200 provides an SLDDCH and an SLDCCH. The SLDDCH transmits data requiring the short latency. Further, in order to support the short latency, the SLDFCH of the uplink sub-frame of the same frame transmits a feedback for the data transmitted through the SLDDCH. The short latency zone 200 may be configured by a certain zone within the downlink sub-frame as shown in FIG. IB. Further, a zone 210 of FIG. 2 may be configured by a certain burst zone within a certain zone within the uplink sub- frame shown in FIG IB. Further, the zones 200 and 210 of FIG. 2 are appointed to perform fast signal transmission in consideration of data processing delay time.

Hereinafter, the processing delay time that should be considered for appointment of the zones 200 and 210 will be described. The processing delay time necessary for data transmission can be classified into three types of delay time durations. The first type is a delay time duration from acquisition of resource assignment information by a transmitter through encoding of data to before transmission of the data. The second type is a delay time duration from demodulation and decoding of received data by a receiver through encoding of a feedback message (ACK/NACK) based on the existence or absence of a detected error to before transmission of the feedback message. The third type is a delay time duration from reception of the feedback message by the transmitter through acquisition of resource information and encoding of the data to before transmission or retransmission of the data.

In the downlink data transmission, a base station does not consider the first delay time duration and considers only the second delay time duration and the third delay time duration. For example, in the case of applying the HARQ scheme for downlink data transmission with an interval of 0.9 ms, allowable minimum delay time durations have lengths of 0 ms, 1.8 ms, and 0.9 ms, respectively. That is, the first delay time duration has a length of 0 ms, the second delay time duration has a length of 1.8 ms, and the third delay time duration has a length of 0.9 ms.

FIGs. 3A and 3B illustrate downlink data transmission/reception supporting a short latency by using a frame structure proposed by the present invention.

Referring to FIG. 3A, control information such as burst assignment information is provided through a first zone in each frame. Further, the data requiring the short latency are transmitted through short latency zones 300, 310, and 320 located after the first zones. Here, the short latency zone includes an SLDDCH. In the frame structure shown in FIG. 3A, the SLDCCH is located within the first PUSC zone.

When a base station transmits data through an SLDDCH of the short latency zone, a mobile station decodes the received data. If the time taken for the decoding is called a reception processing time, the mobile station feeds back an SLDFCH 305, 315, or 325 to the base station at the time point where the reception processing time terminates, to notify existence or absence of a detected error in the received data.

The base station receives the feedback signal from the mobile station and encodes the data to be transmitted through scheduling. If the time taken for such processing is called a transmission processing time, the base station must transmit or retransmit assignment control information or data to the mobile station at the time point where the transmission processing time terminates. However, it is noted from FIG. 3A that the time point of the termination of the transmission processing time by the base station is already beyond the time interval for transmitting the assignment information, which corresponds to the first zone of the downlink sub-frame at the L^Λ frame. Therefore, the base station transmits the assignment information at a time interval corresponding to the first zone of the downlink sub-frame at the (L+l)^ώ frame. Given that one frame has a length of 5 ms, 10 ms is taken from the first burst assignment information transmission and data transmission or retransmission to the next burst assignment information transmission and data transmission or retransmission.

Meanwhile, in FIG. 3 A, the assignment information includes assignment information of a feedback channel of an uplink sub-frame. Therefore, the feedback channel assignment information of the uplink sub-frame according to the present invention indicates an uplink burst zone in the same frame as that of the short latency zone. In a conventional frame structure, feedback channel assignment information of an uplink sub-frame indicates an uplink burst zone in the next frame.

Next, referring to FIG. 3B, short latency zones 350, 360, and 370 are included in the downlink sub-frames, respectively. Each of the short latency zones includes a corresponding SLDCCH and a corresponding SLDDCH. The mobile station performs feedback according to a pre-promised scheme or a scheme indicated by the SLDCCH. A more detailed description in this regard will be given later with reference to FIG. 6.

When a base station transmits data through an SLDDCH of the short latency zone, a mobile station decodes the received data. Given that the time taken for the processing is called a reception processing time, the mobile station feeds back an SLDFCH 305, 315, or 325 to the base station at the time point where the reception processing time terminates, to notify the existence or absence of a detected error in the received data.

The base station receives the feedback signal from the mobile station and prepares for transmission or retransmission of the data. If the time taken for such processing is called a transmission processing time, the base station must transmit or retransmit assignment control information or data to the mobile station at the time point where the transmission processing time terminates. Here, the frame structure of FIG. 3B is different from that of FIG. 3 A in that the time point of the termination of the transmission processing time by the base station is already beyond the time interval corresponding to the first zone of the downlink sub-frame of the L* frame transmitting the assignment control information, but has not reached the time interval for transmitting the assignment information, which corresponds to the short latency zone 360 of the L^Λ frame. Because of downlink subframe includes at least one zone, which provides control information.

Therefore, the base station can perform transmission or retransmission of assignment information and data through the short latency zone 360 at the L^Λ frame other than at the (L+1)^Λ frame. Therefore, in considering a frame having a length of 5 ms, data transmitted at the (L-I)* frame can be retransmitted at the L^Λ frame. At this time, it takes 5 ms, that is, the retransmission interval is 5 ms.

As described above, data burst assignment at a short latency zone is indicated through the SLDCCH, data transmission or retransmission is performed through the SLDDCH, and feedback is performed through the SLDFCH. In considering the data processing delay time including the data transmission, retransmission, and feedback, the short latency zone should be configured within a frame.

In a TDD frame structure, a short latency zone of a downlink sub-frame can be configured in the following manner. First, use of a WiMAX profile system parameters is assumed. In a WiMAX profile, one OFDM symbol period has a length of 102.9 μ s, a frame length is 5 ms (48 symbols periods including

TTG), and a ratio between the number of OFDM symbols of the downlink sub- frame and the number of OFDM symbols of the uplink sub-frame is 29:18. Further, the UL sub-channel includes three OFDM symbols. The base station must transmit a signal by referring to 1.8 ms, which is the second and third processing delay time and by considering 18 symbols periods.

Based on the conditions described above, one short latency zone in a downlink sub-frame may include nine symbols. This can be expressed by equation (1) below.

HARQ retransmission delay (5 ms) = DL shortened latency zone (9 symbols)

+ reception processing time of MS (18 symbols) + SLDFCH symbol period (3 symbols) + transmission processing time of BS (18 symbols) (1) In equation (1), the short latency zone of the downlink sub-frame may include an SLDCCH and an SLDDCH, and the SLDFCH may be configured by using the entire frequency band or a part of the frequency band of a corresponding symbol period.

Hereinafter, a scheme for supporting a short latency in an uplink will be described.

FIG. 4 illustrates a TDD-OFDMA frame structure for supporting a short latency in an uplink data transmission proposed by the present invention.

Referring to FIG. 4, the uplink sub- frame of the (L-I)* frame includes a short latency zone providing an SLDDCH. The assignment control information and feedback assignment information for the SLDDCH within the short latency zone are indicated in the downlink sub-frame. That is, before the short latency zone in the uplink sub-frame, the downlink sub-frame of the (L-I)* frame provides the SLDCCH indicating the allocation control information for the short latency zone. Further, the feedback of the data transmitted by the SLDDCH is provided by an SLDFCH of the downlink sub-frame of the L^ώ frame. In this case, the SLDCCH and the SLDFCH are configured in the form of OFDMA. The short latency zone may be configured by at least one zone within the uplink sub-frame shown in FIG. IB. FIG. 4 shows that locations of the above- mentioned zones are determined in consideration of the transmission processing time and the reception processing time for the uplink data.

For determination of the zones 400 and 410 in the uplink data transmission, the first delay time duration and the third delay time duration as described above should be taken into consideration. For example, in the case of applying the HARQ scheme for uplink data transmission with an interval of 0.9 ms, allowable minimum delay time durations have lengths of 0.9 ms, 1.8 ms, and 0.9 ms, respectively.

FIGs. 5A and 5B illustrate uplink data transmission/reception supporting a short latency by using a frame structure proposed by the present invention.

Referring to FIG. 5A, an SLDCCH included in the first zone in each frame provides SLDDCH-related assignment information and corresponding SLDFCH assignment information. When a base station transmits assignment information through the SLDCCH to a mobile station, the mobile station decodes the assignment information and then transmits data through an SLDDCH within a short latency zone of the uplink sub-frame. Here, the time taken for this processing is called a transmission processing time.

The base station decodes the received data and then feeds back existence or absence of a detected error through a pre-appointed SLDFCH. Then, the base station retransmits burst assignment information through the SLDCCH so that the mobile station can transmit or retransmit the data. Here, the time taken for such processing is called a reception processing time.

It is noted from FIG. 5 A that the assignment information is transmitted in the first zone, and that the time point of termination of the transmission processing time by the mobile station and the reception processing time by the base station is already beyond the time interval for transmitting the assignment, which corresponds to the first zone of the downlink sub-frame at the L* frame. Therefore, the base station can transmit the feedback and control information at the first zone of the downlink sub-frame at the (L+ 1)* frame. Based on the fact that a frame length is 5 ms in a WiMAX profile, it takes 10 ms from the first burst assignment information transmission and data transmission or retransmission to the next burst assignment information transmission and data transmission or retransmission.

Next, referring to FIG. 5B, the base station transmits assignment information through an SLDCCH zone 550 of the downlink sub-frame of the (L- 1) frame, and the mobile station completes data transmission/reception before the short latency 555 of the uplink sub-frame of the (L-I)* frame. Then, the mobile station transmits data through the short latency zone 555, and the base station receives the data through the short latency zone 555 of the (L- I)* frame. Thereafter, the base station can complete processing of the received data before the SLDCCH/SLDFCH zone 560 of the downlink sub-frame of the L* frame, and then transmit feedback and retransmit assignment information for the transmitted data to the mobile station through the SLDCCH/SLDFCH zone 560 of the downlink sub-frame of the L* frame. Therefore, the mobile station can perform data transmission or retransmission in the short latency zone 565 within the L* frame, after the data transmission at the (L-I)* frame. Therefore, in considering that one frame has a length of 5 ms, it takes 5 ms from the data transmission at the (L-I)* frame by the mobile station to the data transmission or retransmission at the L* frame. That is, in the downlink sub-frame of the (L-I)* frame, the mobile station receives short latency zone information of the uplink and receives burst assignment information at the short latency zone. Thereafter, the mobile station transmits data at a burst location assigned within the uplink short latency zone of the (L-I)* frame, and receives a feedback for the data from the base station through the downlink sub-frame of the L^Λ frame. Thereafter, based on the feedback information, the mobile station transmits or retransmits data at the short latency zone within the uplink sub-frame of the L^Λ frame.

In a TDD frame structure, the short latency zone of the uplink sub-frame can be configured by the following method. As in the downlink, the short latency zone of the uplink sub-frame also employs WiMAX profile system parameters. Further, in the uplink transmission, the first, second, and third delays are based on 1.8 ms and satisfy a HARQ retransmission delay of 5 ms. Further, it is assumed that the downlink control channel is configured based on the unit of one symbol. Further, the transmission is performed within a (29, 18) TDD ratio.

Based on the conditions described above, one short latency zone in an uplink sub-frame may include eleven or less symbol periods. This can be expressed by equation (2) below.

HARQ retransmission delay(5 ms) = transmission processing time of MS (9 symbols)

+ SLDDCH symbol period (11 symbols)

+ reception processing time of BS (27 symbols)

+ (SLDCCH & SLDFCH) symbol period (1 symbol) (2)

As noted from equation (2), the uplink short latency zone is configured in consideration of the data transmission/reception delay time, in order to support the short latency.

FIG. 6 illustrates locations of dedicated channels for supporting downlink short latency according to an embodiment of the present invention.

Referring to FIG. 6, the downlink short latency zone in the downlink sub- frame is indicated by the first PUSC zone 600. The short latency zone may be at least one zone from among the zones of PUSC, FUSC, optional FUSC, AMC, and Tile Usage Sub-Channel (TUSC)/TUSC 2, as shown in FIG. IB. Further, a new sub-channel configuration scheme may be applied to the short latency zone.

Further, the location information of the short latency zone may be provided through predetermined information or broadcast information without using the UL-MAP message. That is, the mobile station may be previously aware of the period providing the short latency zone or can acquire the location of the short latency zone by receiving the broadcast information. Further, the short latency zone includes an SLDCCH and an SLDDCH. Meanwhile, the SLDCCH indicates assignment information of the SLDCCH and the SLDDCH. The assignment information includes locations within the sub-frame, modulation and coding schemes, etc. The feedback of the data transmitted in the short latency zone is rapidly performed, so as to provide a feedback channel for support of the short latency.

FIG. 7 is a signal flow diagram illustrating an operation of a mobile station and a base station using a downlink short latency zone according to an embodiment of the present invention.

Referring to FIG. 7, the base station 700 provides location information of the short latency zone through a DL MAP IE of the first PUSC zone (step 702). Step 702 is omissible based on a location indication method preset in the system. Thereafter, the base station 700 provides SLDCCH location and control information through the SLDCCH in the short latency zone (step 704). Thereafter, the base station 700 transmits data at a location in the SLDDCH appointed by the SLDCCH (step 706).

The mobile station 750 performs reception processing, that is, the mobile station 750 decodes a signal in a burst zone allocated to the mobile station itself by using the control information and the SLDDCH transmitted through the SLDCCH (step 708). Thereafter, the mobile station 750 feeds back a result of the data decoding to the base station 700 through an appointed SLDFCH (step 710).

The base station 700 performs transmission processing, such as scheduling, based on the feedback information received from the mobile station 750 (step 712). According to a result of the processing, the base station 700 performs step 704 or 706. If resource assignment information and control information are added and changed, step 704 is performed. Otherwise, step 706 is performed. That is, the SLDCCH for next data transmission and retransmission may be omitted according to the resource assignment scheme. The interval from step 706 to step 712 corresponds to the latency zone. Further, in order to perform rapid transmission, the location of the short latency zone may be either fixed or variable, after it is once appointed. However, a control message for notifying the existence or absence of a corresponding zone to an existing mobile station and a newly connected mobile station should be transmitted.

FIG. 8 illustrates locations of dedicated channels for supporting uplink short latency according to an embodiment of the present invention.

Referring to FIG. 8, the uplink short latency zone is indicated by the UL MAP IE of the first PUSC zone 900. The short latency zone may be at least one zone from among the zones of PUSC, optional PUSC, and AMC as shown in FIG. IB. Further, a new sub-channel configuration scheme may be applied to the short latency zone. Moreover, information on allocation of the SLDCCH, which provides control information and information on allocation of the SLDDCH in the uplink short latency zone, is appointed so that the SLDCCH is provided in a corresponding zone. Also, the SLDCCH provides feedback channel information for rapid transmission of feedback for the data provided by the short latency zone.

FIG. 9 is a signal flow diagram illustrating a signal flow between a mobile station and a base station using an uplink short latency zone according to an embodiment of the present invention.

Referring to FIG. 9, the base station 900 provides location information of the short latency zone in an UL MAP IE of the first PUSC zone (step 902). Thereafter, the base station 900 provides location and modulation information of the SLDCCH (step 904). Further, the base station 900 provides the SLDCCH at the location (step 906). The SLDCCH includes resource assignment information and data transmission information in the uplink short latency zone and corresponding location information of the downlink SLDFCH.

After the mobile station 950 receives information in steps 902 to 906, the mobile station 950 performs transmission processing including modulation and encoding according to a scheme appointed in the SLDCCH (step 908), and then transmits data at an assigned SLDCCH location (step 910).

The base station 900 decodes the signal received from the mobile station 950 (step 912), and transmits a result of the error detection through an SLDFCH appointed by the SLDCCH (step 914). Further, the base station 900 performs resource allocation by scheduling data transmission of the mobile station 950 based on the result of the error detection. Then, according to the resource allocation scheme, step 904, step 906, or step 910 may be performed next. That is, when the resource allocation information is changed, either step 904 or step 906 may be performed. Step 904 corresponds to a case where the location and modulation information of the SLDCCH appointing the information have been changed, and step 906 where the SLDCCH is provided without change in the location and modulation information of the SLDCCH. At this time, the SLDCCH includes resource allocation information, data transmission information, or feedback assignment information. According to the situation, when none of the three types of information is changed, it is possible to transmit only partial information. Step 910 corresponds to a case in which there is no change not only in the SLDCCH but also in the data transmission information and the resource allocation information. That is, the mobile station transmits or retransmits already-assigned zone and transmission information according to the result of error detection without additional control information.

Referring to FIG. 10, one short latency zone includes nine OFDM symbols. In consideration of a TDD frame in which the ratio between the number of downlink symbols and the number of uplink symbols is 29:18, the downlink sub-frame includes one preamble symbol, three zones, and one mid- amble. Further, each zone of the uplink sub-frame may include three sub-zones. In addition, each of all the above-mentioned zones can be configured to be a short latency zone according to the situation. Further, the mid-amble may be used as a MIMO mid-amble, a Broadcast Channel (BCH), a feedback channel, etc., according to the situation.

Referring to FIG. 10, the short latency zone is provided with multiple interlace configuration according to the frame configuration scheme. Here, the interlace configuration refers to a configuration of interlacing, such as an interlacing between data transmission (retransmission) and reception of feedback to the data transmission (retransmission) and interlacing between data reception (re-reception) and transmission of feedback to the data reception (re-reception).

In the case of the interlace 1 in the downlink data transmission, the first zone is used as the short latency zone, and the base station transmits data in DLl and receives a feedback signal from the mobile station in the first sub-zone of ULl. In the case of the interlace 2, the second zone is used as the short latency zone, and the base station transmits data in DL2 and receives a feedback signal from the mobile station in the first sub-zone of UL2. In the case of the interlace 3, the third zone is used as the short latency zone, and the base station transmits data in DL3 and receives a feedback signal from the mobile station in the third sub-zone of UL2. According to the situation, the base station may provide one to three short latency zones within one frame.

Further, in the case of the interlace 1 in the uplink data transmission, ULl is used as the short latency zone, the base station provides an SLDCCH in DL2 before ULl, receives data in ULl, and then provides an SLDFCH in DL2 of the next frame. In the case of the interlace 2, UL2 is used as the short latency zone, the base station provides an SLDCCH in DL3 before UL2, receives data in UL2, and then provides an SLDFCH in DL3 of the next frame. Each interlace has a retransmission delay of 5 ms.

Further, the TDD transmission ratio and the allowable processing delay time determine the number of short latency zones within one frame. The base station determines, based on the cell situation, whether to provide a short latency zone, and can configure one or more short latency zones, so as to provide data transmission/reception satisfying the short latency to the mobile station. In the case of using a smaller number of short latency zones than the maximum number of supportable short latency zones, the used zones may be configured either to be adjacent to each other or not to be adjacent to each other. Locations of the interlaces in the frame may be changed according to the supporting method. That is, when only few zones are used, shorter latency zones may be used and the locations of the channels may be changed, in comparison with the structure using all supportable short latency zones.

Further, an interlace configuration method in a frame, that is, a location and a size of a short latency zone/channel are determined by an allowable processing delay and TDD transmission ratio.

As described above, the proposed scheme can support short latency while having a compatibility with the frame structure standardized in the WiMAX profile. Further, under the existing frame standard, the data burst transmission zone can be configured with only short latency zones. That is, as noted from FIG. 10, one frame can be configured by one preamble, a plurality of downlink short latency zones, a mid-amble, and a plurality of uplink short latency zones.

Referring to FIG. 11, the mobile station acquires short latency zone information in step 1102 and then proceeds to step 1104. The short latency zone information is periodically broadcasted through a broadcast channel by a base station. In step 1104, the mobile station acquires control information by using the acquired short latency zone information, and then proceeds to step 1106. The control information includes data burst assignment information of a downlink short latency zone or a corresponding uplink short latency zone. The control information is transmitted to the mobile station through an SLDCCH.

In step 1106, the mobile station determines if the current zone corresponds to the downlink short latency zone or the uplink short latency zone. As a result of the determination, the mobile station proceeds to step 1108 when the current frame zone corresponds to the downlink short latency zone, and the mobile station proceeds to step 1114 when the current frame zone corresponds to the uplink short latency zone.

In step 1108, the mobile station receives data based on the data burst assignment information. Then, in step 1110, the mobile station generates a feedback signal indicating if the mobile station has successfully received and decoded the data, and then proceeds to step 1112. Meanwhile, in step 1114, the mobile station generates data to be transmitted to the base station, and then proceeds to step 1112.

In step 1112, the mobile station transmits the generated data or a feedback signal through the uplink short latency zone to the base station.

Referring to FIG. 12, the base station appoints a short latency zone in step 1202, and then proceeds to step 1204. Then, in step 1204, the base station determines if the current frame zone corresponds to the downlink short latency zone or the uplink short latency zone. As a result of the determination, the base station proceeds to step 1206 when the current frame zone corresponds to the downlink short latency zone, and the mobile station proceeds to step 1208 when the current frame zone corresponds to the uplink short latency zone.

In step 1206, the base station transmits control information to the mobile station during the downlink short latency zone, and then proceeds to step 1210. In step 1210, the base station transmits a feedback signal for the data received during or before the downlink short latency zone to the mobile station. Meanwhile, in step 1208, the base station receives data or a feedback signal during the uplink short latency zone.

In a communication system according to the present invention as described above, a sub-frame is divided into a plurality of time zones, one or more of the time zones are used as dedicated short latency zone or zones, and a frame structure using the dedicated zone(s) and dedicated channel(s) is used. Therefore, the present invention can efficiently process data and services requiring a short latency.

While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A method for transmitting a downlink signal by a base station in a mobile communication system, the method comprising the steps of: indicating, through a first zone, a first particular zone of a second zone of a downlink sub-frame by the base station; indicating, through the first particular zone, information on a dedicated channel for transmission or retransmission of data within the first particular zone and a second particular zone for receiving a feedback signal with respect to the data; transmitting or retransmitting data through the dedicated channel indicated by the first particular zone; and receiving a feedback signal through the second particular zone, wherein each frame includes the downlink sub-frame and an uplink sub- frame and includes the first zone for transmission of frame control information and second zones for transmission of a data burst, the second zones are located within the downlink sub-frame and the uplink sub-frame, respectively, and the first particular zone and the second particular zone are preset in each of the downlink sub-frame and the uplink sub-frame.

2. The method of claim 1, wherein a MAP Information Element (IE) message is used in indicating, through the first zone, the first particular zone of the second zone of the downlink sub-frame.

3. The method of claim 2, wherein the MAP IE message includes at least one from among resource assignment mode information, a resource zone for data transmission, feedback channel assignment information, and modulation and coding scheme information.

4. The method of claim 1, wherein the first zone, the second zone, the first particular zone, and the second particular zone are determined by time and frequency resources.

5. The method of claim 1, wherein the first particular zone is determined based on a time duration from reception of resource assignment information through encoding of data to before transmission of the data by the base station, a time duration from demodulation and decoding of received data through encoding of a feedback message (ACK/NACK) based on existence or absence of a detected error to before transmission of the feedback message by the mobile station, and a time duration from reception of the feedback message through execution of scheduling and encoding of the data to before transmission or retransmission of the data by the base station.

6. The method of claim 1, wherein the second particular zone is determined based on time taken for downlink signal reception processing by the mobile station from the first particular zone.

7. A method for transmitting an uplink signal by a mobile station in a mobile communication system, the method comprising the steps of: receiving, through a first zone of a current frame, an indication that indicates a first particular zone of a second zone of a downlink sub-frame and a second particular zone of an uplink sub-frame by the mobile station; receiving, through the first particular zone, an indication that contains information on a dedicated channel for transmission or retransmission of data within the second particular zone and indicates a first particular zone of a next frame for receiving a feedback signal with respect to the data; transmitting or retransmitting data through the dedicated channel indicated by the first particular zone; and receiving a feedback signal through the first particular zone of the next frame, wherein each frame includes the downlink sub-frame and the uplink sub- frame and includes the first zone for transmission of frame control information and second zones for transmission of a data burst, the second zones are located within the downlink sub-frame and the uplink sub-frame, respectively, and the first particular zone and the second particular zone are preset in each of the downlink sub-frame and the uplink sub-frame.

8. The method of claim 7, wherein a MAP Information Element (IE) message is used in indicating, through the first zone, the first particular zone of the second zone of the downlink sub- frame.

9. The method of claim 8, wherein the MAP IE message includes at least one from among resource assignment mode information, a resource zone for data transmission, feedback channel assignment information, and modulation and coding scheme information.

10. The method of claim 7, wherein the first zone, the second zone, the first particular zone, and the second particular zone are determined by time and frequency resources.

11. The method of claim 7, wherein the first particular zone is determined based on a time duration taken while a base station receives an uplink signal from the mobile station and transmits a feedback signal with respect to the uplink signal from an end of the second particular zone of a previous frame.

12. The method of claim 7, wherein the second particular zone is determined based on time taken for transmission of an uplink signal by the mobile station from an end of the first particular zone of the current frame.

13. A method for receiving a downlink signal by a mobile station in a mobile communication system, the method comprising the steps of: receiving, through a first zone, an indication that indicates a first particular zone of a second zone of a downlink sub-frame by the mobile station; receiving, through the first particular zone, an indication that contains information on a dedicated channel for transmission or retransmission of data within the first particular zone and indicates a second particular zone for receiving a feedback signal with respect to the data; receiving or re-receiving data through the dedicated channel indicated by the first particular zone; and transmitting a feedback signal through the second particular zone, wherein each frame includes the downlink sub-frame and an uplink sub- frame and includes the first zone for transmission of frame control information and second zones for transmission of a data burst, the second zones are located within the downlink sub-frame and the uplink sub-frame, respectively, and the first particular zone and the second particular zone are preset in each of the downlink sub-frame and the uplink sub-frame.

14. The method of claim 13, wherein a MAP Information Element (IE) message is used in indicating, through the first zone, the first particular zone of the second zone of the downlink sub-frame.

15. The method of claim 14, wherein the MAP IE message includes at least one from among resource assignment mode information, a resource zone for data transmission, feedback channel assignment information, and modulation and coding scheme information.

16. The method of claim 13, wherein the first zone, the second zone, the first particular zone, and the second particular zone are determined by time and frequency resources.

17. The method of claim 13, wherein the first particular zone is determined based on a time duration for downlink signal reception processing by the mobile station, a time duration for feedback signal transmission by the mobile station, and a time duration for downlink signal transmission processing by the base station.

18. The method of claim 13, wherein the second particular zone is determined based on time taken for downlink signal reception processing by the mobile station from an end of the first particular zone.

19. A method for transmitting an uplink signal by a base station in a mobile communication system, the method comprising the steps of: indicating, through a first zone of a current frame, a first particular zone of a second zone of a downlink sub- frame and a second particular zone of an uplink sub-frame by the mobile station; indicating, through the first particular zone, information on a dedicated channel for transmission or retransmission of data within the second particular zone and a first particular zone of a next frame for transmitting a feedback signal with respect to the data; receiving or re-receiving data through the dedicated channel indicated by the first particular zone; and transmitting a feedback signal through the first particular zone of the next frame, wherein each frame includes the downlink sub-frame and the uplink sub- frame and includes the first zone for transmission of frame control information and second zones for transmission of a data burst, the second zones are located within the downlink sub-frame and the uplink sub-frame, respectively, and the first particular zone and the second particular zone are preset in each of the downlink sub-frame and the uplink sub-frame.

20. The method of claim 19, wherein a MAP Information Element (IE) message is used in indicating, through the first zone, the first particular zone of the second zone of the downlink sub- frame.

21. The method of claim 20, wherein the MAP IE message includes at least one from among resource assignment mode information, a resource zone for data transmission, feedback channel assignment information, and modulation and coding scheme information.

22. The method of claim 19, wherein the first zone, the second zone, the first particular zone, and the second particular zone are determined by time and frequency resources.

23. The method of claim 19, wherein the first particular zone is determined based on a time duration taken while a base station receives an uplink signal from the mobile station and transmits a feedback signal with respect to the uplink signal from an end of the second particular zone of a previous frame.

24. The method of claim 19, wherein the second particular zone is determined based on time taken for transmission of an uplink signal by the mobile station from an end of the first particular zone of the current frame.

25. A method for signal transmission/reception by a base station in a mobile communication system, the method comprising the steps of: indicating, through a first particular zone, information on a dedicated channel for transmission or retransmission of data and a second particular zone for receiving a feedback signal with respect to the data; transmitting or retransmitting data through the dedicated channel indicated by the first particular zone; and receiving a feedback signal through the second particular zone, wherein each frame includes a downlink sub-frame and an uplink sub- frame, and the first particular zone and the second particular zone are preset in each of the downlink sub- frame and the uplink sub- frame.

26. The method of claim 25, wherein the first particular zone and the second particular zone are determined by time and frequency resources.

27. The method of claim 25, wherein the first particular zone is determined based on a time duration taken while a base station receives an uplink signal from the mobile station and transmits a feedback signal with respect to the uplink signal from an end of the second particular zone of a previous frame.

28. The method of claim 25, wherein the second particular zone is determined based on time taken for transmission of an uplink signal by the mobile station from an end of the first particular zone of the current frame.

29. A method for signal transmission/reception by a mobile station in a mobile communication system, the method comprising the steps of: receiving, through a first particular zone, an indication that contains information on a dedicated channel for transmission or retransmission of data and indicates a second particular zone for receiving a feedback signal with respect to the data; receiving or re-receiving data through the dedicated channel indicated by the first particular zone; and transmitting a feedback signal through the second particular zone, wherein each frame includes a downlink sub-frame and an uplink sub- frame, and the first particular zone and the second particular zone are preset in each of the downlink sub- frame and the uplink sub- frame.

30. The method of claim 29, wherein the first particular zone and the second particular zone are determined by time and frequency resources.

31. A mobile communication system comprising: a base station for indicating, through a first zone, a first particular zone of a second zone of a downlink sub-frame by the base station, indicating, through the first particular zone, information on a dedicated channel for transmission or retransmission of data within the first particular zone and a second particular zone for receiving a feedback signal with respect to the data, transmitting or retransmitting data through the dedicated channel indicated by the first particular zone, and receiving a feedback signal through the second particular zone; and a mobile station for receiving, through a first zone of a current frame, an indication that indicates a first particular zone of a second zone of a downlink sub-frame and a second particular zone of an uplink sub-frame by the mobile station, receiving, through the first particular zone, an indication that contains information on a dedicated channel for transmission or retransmission of data within the second particular zone and indicates a first particular zone of a next frame for receiving a feedback signal with respect to the data, transmitting or retransmitting data through the dedicated channel indicated by the first particular zone, and receiving a feedback signal through the first particular zone of the next frame, wherein each frame includes the downlink sub-frame and an uplink sub- frame and includes the first zone for transmission of frame control information and second zones for transmission of a data burst, the second zones are located within the downlink sub-frame and the uplink sub-frame, respectively, and each of the downlink sub-frame and the uplink sub-frame includes the first particular zone and the second particular zone.

32. The mobile communication system of claim 31, wherein the base station uses a MAP Information Element (IE) message in indicating, through the first zone, the first particular zone of the second zone of the downlink sub- frame.

33. The mobile communication system of claim 32, wherein the MAP IE message includes at least one from among resource assignment mode information, a resource zone for data transmission, feedback channel assignment information, and modulation and coding scheme information.

34. The mobile communication system of claim 31, wherein the first zone, the second zone, the first particular zone, and the second particular zone are determined by time and frequency resources.

35. The mobile communication system of claim 31, wherein the first particular zone is determined based on a time duration from reception of resource assignment information through encoding of data to before transmission of the data by the base station, a time duration from demodulation and decoding of received data through encoding of a feedback message (ACK/NACK) based on existence or absence of a detected error to before transmission of the feedback message by the mobile station, and a time duration from reception of the feedback message through execution of scheduling and encoding of the data to before transmission or retransmission of the data by the base station.

36. The mobile communication system of claim 31, wherein the second particular zone is determined based on time taken for downlink signal reception processing by the mobile station from the first particular zone.

37. A mobile communication system comprising: a base station for indicating, through a first particular zone, information on a dedicated channel for transmission or retransmission of data and a second particular zone for receiving a feedback signal with respect to the data, transmitting or retransmitting data through the dedicated channel indicated by the first particular zone, and receiving a feedback signal through the second particular zone; and a mobile station for receiving, through a first particular zone, an indication that contains information on the dedicated channel and indicates the second particular zone from the base station, receiving or re-receiving data through the dedicated channel indicated by the first particular zone, and transmitting a feedback signal through the second particular zone, wherein each frame includes a downlink sub-frame and an uplink sub- frame, and the first particular zone and the second particular zone are preset in each of the downlink sub-frame and the uplink sub-frame.