RELAYING NODE, TIME DIVISION DUPLEX COMMUNICATION SYSTEM AND
COMMUNICATION METHOD
FIELD OF THE INVENTION
[0001] The present invention generally relates to the field of wireless communication, and
in particular to a time division duplex communication system, a communication method
therein and a relay node.
BACKGROUND OF THE INVENTION
[0002] With the fast development of wireless multimedia services, users have increasing
demands for data communication capability and transmission quality. However, since there
are many dead spaces formed due to influence of factors such as barriers and shadows in the
complex wireless environment, it is difficult for a user to obtain continuous communication
service with high speed and high quality. In order to solve this problem, a relay node is used
in a wireless system to relay wireless communication signals between a base station and a
mobile station, so as to improve system throughput and user data rate.
[0003] Figure 1 illustrates a schematic view of a wireless communication system. As shown
in Figure 1, the wireless communication system includes a base station, a relay node and a
mobile station. The mobile stations are divided into those served by a relay node, namely the
mobile station 2, and those served by a base station, namely the mobile station l.The link
between a base station and a relay node is referred to as a relay link, as indicated by the solid
arrows in Figure 1. The link between a relay node and a mobile station or between a base
station and a mobile station is referred to as an access link, as indicated by the dotted arrows
in Figure 1. A base station sends data to a relay node via a relay link at a certain point of time,,
and at a certain point of time that follows, the relay node sends the data to a mobile station via
an access link.
[0004] Hereinafter, a frame structure employed in the wireless communication is described
by taking a LTE (Long Term Evolution) TDD (Time Division Duplexing) wireless
communication system as an example. Each frame in the frame structure of the LTE TDD
wireless communication system is of the length of 10ms and includes 10 sub-frames of 1ms
length each. Depending on the different ratios of uplink sub-frames to downlink sub-frames in
a frame, there are totally 7 sub-frame configurations defined in the LTE TDD wireless
communication system, as shown in the following tablel.
Table 1: uplink and downlink sub-frame configuration in the LTE TDD communication
system
[0005] In the table 1, U represents an uplink sub-frame, D represents a downlink sub-frame,
and S represents a special sub-frame. In an S sub-frame, the first few OFDM (Orthogonal
Frequency Division Multiplexing) symbols are used for the downlink data sending while the
subsequent few OFDM symbols are used for the uplink and downlink switching and the
uplink access signal sending. In order to facilitate the expression, the special sub-frame and
the downlink sub-frame are collectively referred to as downlink sub-frame. The uplink
sub-frame U is used for signal transmission from the mobile station to the relay node or from
the mobile station to the base station, or for signal transmission from the relay node to the
base station. The downlink sub-frame D and the special sub-frame S are used for signal
transmission from the base station to the mobile station or from the relay node to the mobile
station, or for signal transmission from the base station to the relay node.
[0006] After receiving data sent by the base station or the relay node, the mobile station is
required to send a decoding response signal ACK/NACK to the base station or the relay node,
where ACK represents a correct decoding signal and NACK represents a mistaken decoding
signal. It is stipulated in the existing LTE TDD standard that the time interval between data
receiving by a device and ACK/NACK feedback by the device should be greater than or equal
to 3ms, namely as long as three sub-frames, and ACK/NACK feedback locations are fixedly
set for 7 sub-frame configurations, as shown in Figure 2 (a), Figure 2 (b) and Figure 2 (c),
which respectively show schematic views of sub-frame configurations 1, 3 and 6 in an LTE
TDD wireless communication system. As shown in Figure 2 (a), according to the sub-frame
configuration 1, for example, the mobile station is required to feed back ACK/NACK in the
seventh sub-frame after receiving data in the 0th sub-frame and/or the first sub-frame, and for
example the base station is required to feed back ACK/NACK in the sixth sub-frame after
receiving data in the second sub-frame.
[0007] In the case where the relay node is taken into account, the feedback scheme shown
in Figure 2 may have problems, since some of the uplink sub-frames must be set to be uplink
relay link sub-frame in which a relay node sends a signal to a base station, and some of the
downlink sub-frames must be set to be downlink relay link sub-frame in which a relay node
sends a signal to a mobile station.
[0008] ACK/NACK, which the mobile station generates after receiving data, should be sent
in the corresponding fixed uplink sub-frames. If those uplink sub-frames are used as the
uplink relay link sub-frame, the relay node may be unable to receive ACK/NACK from the
mobile station since the relay node is in a sending state in the uplink relay link, i.e. there is
collision between ACK/NACK and data. Figure 3 is taken as an example to illustrate how this
collision occurs. In Figure 3, the sub-frame #2 is set to be an uplink relay link sub-frame, and
the sub-frame #9 is set to be a downlink relay link sub-frame. The data signals sent by the
relay node in the fifth sub-frame and the sixth sub-frame correspond to ACK/NACK fed back
by the mobile station to the relay node in the second sub-frame. However, the relay node may
be unable to receive ACK/NACK fed back by the mobile station served by the relay node,
since at this point of time the sub-frame #2 is already used as an uplink relay link sub-frame,
i.e. the relay node is in a sending state. That is, the collision between ACK/NACK and data
sending occurs.
SUMMARY OF THE INVENTION
[0009] It is necessary to provide a scheme which is able to avoid the above mentioned
collision between ACK/NACK and data.
[0010] The present invention provides a communication method in a time division duplex
communication system. The communication system includes a base station, a mobile station
and a relay node, the relay node being not in a receiving state and a sending state concurrently.
The communication method includes: receiving, by the relay node, a first signal from the base
station in a predetermined downlink sub-frame of a frame; and sending, by the relay node, a
second signal to the base station in a predetermined uplink sub-frame of a frame; wherein the
first signal is a response signal to the second signal or the second signal is a response signal to
the first signal.
[0011] According to one aspect of the present invention, there is provided a relay node used
for a time division duplex communication system, the communication system including a
base station, a mobile station and a relay node. The relay node includes a transceiver which is
not in a receiving state and a sending state concurrently and the transceiver is configured to:
receive a first signal from the base station in a predetermined downlink sub-frame of a frame;
and send a second signal to the base station in a predetermined uplink sub-frame of a frame;
wherein the first signal is a response signal to the second signal or the second signal is a
response signal to the first signal,
[0012] According to another aspect of the present invention, there is provided a time
division duplex communication system including a base station, a mobile station, and the
above mentioned relay node.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The present invention may be better understood by referring to the detailed
description in conjunction with the accompanying drawings hereinafter. The accompanying
drawings together with the following detailed description are included in the present
description and form a part of the description, so as to be used for further illustrating the
preferable embodiments of the present invention and explaining the principle and advantages
of the present invention, wherein
[0014] Figure 1 shows a schematic view of a wireless communication system;
[0015] Figure 2 (a), Figure 2 (b) and Figure 2 (c) respectively show schematic views of
sub-frame configurations 1, 3 and 6 as well as ACK/NACK feedback schemes in an LTE
TDD wireless communication system;
[0016] Figure 3 shows a schematic view of collision between ACK/NACK and data in the
prior art;
[0017] Figure 4 shows a flow chart of a communication method in a time division duplex
communication system according to one embodiment of the present invention;
[0018] Figure 5 shows a schematic view of a first ACK/NACK feedback scheme of the
sub-frame configuration 1;
[0019] Figure 6 shows a schematic view of a second ACK/NACK feedback scheme of the
sub-frame configuration 1;
[0020] Figure 7 shows a schematic view of a third ACK/NACK feedback scheme of the
sub-frame configuration 1;
[0021] Figure 8 shows a schematic view of a fourth ACK/NACK feedback scheme of the
sub-frame configuration 1;
[0022] Figure 9 shows a schematic view of a first ACK/NACK feedback scheme of a
sub-frame configuration 3;
[0023] Figure 10 shows a schematic view of a second ACK/NACK feedback scheme of the
sub-frame configuration 3;
[0024] Figure 11 shows a schematic view of ACK/NACK feedback scheme of a sub-frame
configuration 6;
[0025] Figure 12 shows a structural view of a relay node according to an embodiment of the
present invention; and
[0026] Figure 13 shows a structural view of a time division duplex communication system
according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0027] Hereinafter, embodiments of the present invention will be described by referring to
the accompanying drawings. It should be noted that representations and descriptions of the
components and processes which are unrelated to the present invention and already know by
the skilled in the art are omitted in the accompanying drawings and this description for the
purpose of conciseness.
[0028] In an LTE TDD wireless communication system, a relay node may not in a receiving
state and a sending state concurrently. Therefore, in a downlink relay link, the relay node is in
a receiving state, and thus may not send any signal to a mobile station served by this relay
node; and in an uplink relay link, the relay node is in a sending state, and thus may not receive
any signal which is sent by the mobile station to this relay node. Therefore, in order to utilize
the relay node more effectively, generally one or more sub-frames of one 10ms frame are
configured to be relay link sub-frames used for communication in a relay link, and the other
sub-frames are configured to be access link sub-frames used for communication in an access
link.
[0029] In order to avoid the occurrence of the collision problem mentioned above, in the
embodiments of the present invention there is provided a scheme to pair the uplink relay link
sub-frame with the downlink relay link sub-frame.
[0030] Figure 4 shows a flow chart of a communication method in a time division duplex
communication system according to one embodiment of the present invention.
[0031] In the step S402, the relay node receives a first signal from the base station in a
predetermined downlink sub-frame of a frame.
[0032] In the step S404, the relay node sends a second signal to the base station in a
predetermined uplink sub-frame of a frame. Herein, the first signal is a response signal to the
second signal or the second signal is a response signal to the first signal.
[0033] It should be noted that the predetermined downlink sub-frame in which the relay
node receives the first signal and the predetermined uplink sub-frame in which the relay node
sends the second signal may be not in the same frame.
[0034] It can be seen that, in the steps S402 and S404, the predetermined downlink
sub-frame is a sub-frame predetermined to be used as the downlink relay link and the
predetermined uplink sub-frame is a sub-frame predetermined to be used as the uplink relay
link. The above mentioned response signal may be an ACK/NACK feedback signal for a data
signal. That is to say, the first signal may be a data signal and the second signal may be a
decoding response signal for the first signal, namely the ACK/NACK feedback signal; or the
second signal may be a data signal and the first signal may be the ACK/NACK feedback
signal for the second signal.
[0035] In the above mentioned method, by pairing a downlink relay link sub-frame with a
uplink relay link sub-frame, these two sub-frames are respectively used for transmission of a
data signal and a response signal to the data signal between the relay node and the base station.
That is to say, if the relay node receives a data signal from the base station in a downlink relay
sub-frame, the relay node sends to the base station a response signal to the data signal in a
paired uplink sub-frame; and if the relay node sends a data signal to the base station in an
uplink sub-frame, the relay node receives from the base station a response signal to the data
signal in a paired downlink relay sub-frame. The sub-frames rather than the relay link
sub-frames are access link sub-frame. Since the downlink relay link sub-frame and the uplink
relay link sub-frame are already paired, the mobile station is not able to perform, in the uplink
relay link sub-frame, feedback for a data signal sent by the relay node to the mobile station in
the downlink access link sub-frame. Thus the collision is avoided. There may be one pair or a
plurality of pairs of the above mentioned paired downlink relay link sub-frame and uplink
relay link sub-frame.
[0036] Hereinafter, the ACK/NACK feedback schemes may be described in detail by taking
an LTE TDD wireless communication system as an example.
[0037] In an LTE TDD wireless communication system, in a 10ms frame, a broadcast
signaling, an addressing signaling and a synchronization signaling are transmitted fixedly in
the 0th sub-frame, the first sub-frame, the fifth sub-frame and the sixth sub-frame, i.e. the
mobile station receives system information from the base station or the relay node in these
four sub-frames. Therefore, the 0th sub-frame, the first sub-frame, the fifth sub-frame and the
sixth sub-frame may only be used as downlink access link sub-frames other than relay link
sub-frames. As described above, since the Oth sub-frame, the first sub-frame, the fifth
sub-frame and the sixth sub-frame cannot be used as downlink relay link sub-frames, the Oth
sub-frame, the first sub-frame, the fifth sub-frame, the sixth sub-frame and other downlink
access link sub-frames can only be used by the base station and the relay node to send
respectively a signal to the mobile stations they respectively serve for.
[0038] Moreover, it is stipulated in the existing LTE TDD standard that the time interval
between data receiving by a device and ACK/NACK feedback by the device should be greater
than or equal to 3ms, namely as long as three sub-frames.
[0039] Figure 5 shows a schematic view of a first ACK/NACK feedback scheme of a
sub-frame configuration 1.
[0040] As shown in Figure 5, according to the sub-frame configuration 1 of LTE TDD,
among the Oth to the ninth sub-frames of each frame, the second, third, seventh and eighth
sub-frames are uplink sub-frames, and the other sub-frames are downlink sub-frames.
Moreover, the relay node receives a first signal from the base station in the fourth sub-frame,
and the relay node sends a second signal to the base station in the eighth sub-frame. The first
signal is a response signal to the second signal or the second signal is a response signal to the
first signal. It can be seen that the fourth sub-frame is paired with the eighth sub-frame in this
scheme.
[0041] Specifically, the fourth sub-frame is a downlink relay link sub-frame, and the relay
node is in a receiving state in this sub-frame and for example receives a data signal from the
base station. The eighth sub-frame is an uplink relay link sub-frame, and the relay node is in a
sending state in this sub-frame and for example feeds back to the base station a decoding
response signal ACK/NACK to the data signal. In the case where the fourth sub-frame is used
as a downlink relay link sub-frame, the fourth sub-frame cannot be used as a downlink access
link sub-frame, and the mobile station does not feed back ACK/NACK to the relay node in
the eighth sub-frame which is at an ACK/NACK feedback position corresponding to the
fourth sub-frame. Therefore, the relay node may send ACK/NACK to the base station in the
eighth sub-frame. Thus the collision is avoided that the relay node has to receive a signal
while sending a signal.
[0042] Figure 6 shows a schematic view of a second ACK/NACK feedback scheme of the
sub-frame configuration 1;
[0043] As shown in Figure 6, according to the sub-frame configuration t of LTE TDD,
among the 0th to the ninth sub-frames of each frame, the second, third, seventh and eighth
sub-frames are uplink sub-frames, and the other sub-frames are downlink sub-frames.
Moreover, the relay node receives a first signal from the base station in the ninth sub-frame,
and the relay node sends a second signal to the base station in the third sub-frame. It can be
seen that the ninth sub-frame is paired with the third sub-frame in this scheme.
[0044] Specifically, the ninth sub-frame is a downlink relay link sub-frame, and the relay
node is in a receiving state in this sub-frame and for example receives a data signal from the
base station. The third sub-frame is an uplink relay link sub-frame, and the relay node is in a
sending state in this sub-frame and for example feeds back to the base station a decoding
response signal ACK/NACK to the data signal. In the case where the ninth sub-frame is used
as a downlink relay link sub-frame, the ninth sub-frame cannot be used as a downlink access
link sub-frame, and the mobile station does not feed back ACK/NACK to the relay node in
the third sub-frame which is at an ACK/NACK feedback position corresponding to the ninth
sub-frame. Therefore, the relay node may send ACK/NACK to the base station in the third
sub-frame. Thus the collision is avoided that the relay node has to receive a signal while
sending a signal.
[0045] Figure 7 shows a schematic view of a third ACK/NACK feedback scheme of the
sub-frame configuration 1.
[0046] As shown in Figure 7, according to the sub-frame configuration 1 of LTE TDD,
among the 0th to the ninth sub-frames of each frame, the second, third, seventh and eighth
sub-frames are uplink sub-frames, and the other sub-frames are downlink sub-frames.
Moreover, the relay node receives a first signal from the base station in the ninth sub-frame,
and the relay node sends a second signal to the base station in the third sub-frame; the relay
node receives a third signal from the base station in the fourth sub-frame, and the relay node
sends a fourth signal to the base station in the eighth sub-frame. The third signal is a response
signal to the fourth signal or the fourth signal is a response signal to the third signal. It can be
seen that, in this scheme, the fourth sub-frame is paired with the eighth sub-frame, and the
ninth sub-frame is paired with the third sub-frame.
[0047] Specifically, the ninth sub-frame is a downlink relay link sub-frame, and the relay
node is in a receiving state in this sub-frame and for example receives a data signal from the
base station. The third sub-frame is an uplink relay link sub-frame, and the relay node is in a
sending state in this sub-frame and for example feeds back to the base station a decoding
response signal ACK/NACK to the data signal. In the case where the ninth sub-frame is used
as a downlink relay link sub-frame, the ninth sub-frame cannot be used as a downlink access
link sub-frame, and the mobile station does not feed back ACK/NACK to the relay node in
the third sub-frame which is at an ACK/NACK feedback position corresponding to the nintfr
sub-frame. Therefore, the relay node may send ACK/NACK to the base station in the third
sub-frame. Thus the collision is avoided that the relay node has to receive a signal while
sending a signal.
[0048] Similarly, the mobile station may not send a signal to the relay node while the relay
node is sending a signal to the base station in the eighth sub-frame.
[0049] Figure 8 shows a schematic view of a fourth ACK/NACK feedback scheme of the
sub-frame configuration 1.
[0050] As shown in Figure 8, according to the sub-frame configuration 1 of LTE TDD,
among the 0th to the ninth sub-frames of each frame, the second, third, seventh and eighth
sub-frames are uplink sub-frames, and the other sub-frames are downlink sub-frames.
Moreover, the relay node receives a fifth signal from the base station in the fourth sub-frame,
the relay node receives a sixth signal from the base station in the ninth sub-frame, and the
relay node sends a response signal to the fifth signal and the sixth signal to the base station in
the third sub-frame. The fifth signal and the sixth signal may be data signals.
[0051] Specifically, the ninth and fourth sub-frames are downlink relay link sub-frames, and
the relay node is in a receiving state in these sub-frames and for example receives a data
signal from the base station. Moreover, the relay node also receives a data signal from the
base station in the ninth sub-frame. The third sub-frame is an uplink relay link sub-frame, and
the relay node is in a sending state in this sub-frame and for example feeds back to the base
station a decoding response signal ACK/NACK to the data signals received in the fourth and
ninth sub-frames. In the case where the ninth sub-frame is used as a downlink relay link
sub-frame, the ninth sub-frame cannot be used as a downlink access link sub-frame, and the
mobile station does not feed back ACK/NACK to the relay node in the third sub-frame which
is at an ACK/NACK feedback position corresponding to the ninth sub-frame. Therefore, the
relay node may send ACK/NACK to the base station in the third sub-frame. Thus the collision
is avoided that the relay node has to receive a signal while sending a signal.
[0052] Similarly, for a data signal received in the fourth sub-frame, the sub-frame time
when the relay node sends ACK/NACK to the base station is the third sub-frame. As
mentioned above, the mobile station does not send a signal to the relay node while the relay
node is sending a signal to the base station. Thus the above mentioned collision is avoided.
[0053] In another case in Figure 8, the relay node sends a seventh signal to the base station
in the third sub-frame, and the relay node receives from the base station a response signal to
the seventh signal in the ninth sub-frame; the relay node receives an eighth signal from the
base station in the fourth sub-frame, and the relay node sends to the base station a response
signal to the eighth signal in the third sub-frame. Herein, the seventh signal and the eighth
signal may be data signals.
[0054] Similarly, the mobile station does not send a signal to the relay node while the relay
node is sending a signal to the base station in the eighth sub-frame.
[0055] It can be seen that, in Figure 8, the ninth sub-frame is paired with the third
sub-frame, but the fourth sub-frame is not paired. In Figure 8, for a data signal sent by the
mobile station to the relay node in the eighth frame, the relay node should feed back
ACK/NACK in the fourth sub-frame. However, the fourth sub-frame is used as a downlink
relay link sub-frame. Therefore, there may be another kind of collision. This kind of collision
may be avoided by utilizing the following solution. In the fourth frame, the relay node is
firstly in a sending state, and feeds back ACK/NACK to the mobile station; and then the relay
node switches from the sending state into a receiving state and becomes a downlink sub-frame.
Specifically, in LTE TDD, the fourth sub-frame is used as an MBSFN (Multicast Broadcast
Single Frequency Network) sub-frame. In the first one or two OFDM (Orthogonal Frequency
Division Multiplexing) symbols of this sub-frame, the base station and the relay node sent
respectively control and reference signals (may including ACK/NACK feedback signals) to
their corresponding mobile stations. The subsequent OFDM symbols in this sub-frame are
used for uplink relay link. In order to achieve this object, the fourth sub-frame of the base
station should be configured to be a special sub-frame. In this special sub-frame, after the first
one or two OFDM symbol periods, the base station immediately switches from the sending
state into the receiving state such that the base station is able to receive a signal from the relay
node. Of course, this scheme requires the base station to switch from the receiving state back
into the sending state before the next sub-frame arrives. It should be noted that there should
be two OFDM symbols reserved respectively for the switches from the receiving state into the
sending state and vice versa, so as to avoid interference.
[0056] Figure 9 shows a schematic view of a first ACK/NACK feedback scheme of a
sub-frame configuration 3.
[0057] As shown in Figure 9, according to the sub-frame configuration 3 of LTE TDD,
among the 0th to the ninth sub-frames of each frame, the second, third and fourth sub-frames
are uplink sub-frames, and the other sub-frames are downlink sub-frames. Moreover, the relay
node sends a first signal to the base station in the third sub-frame, and the relay node receives
a second signal from the base station in the seventh or eighth sub-frame. The first signal is a
response signal to the second signal or the second signal is a response signal to the first signal.
It can be seen that the third sub-frame is paired with the seventh/eighth sub-frame in this
scheme.
[0058] Specifically, the third sub-frame is an uplink relay link sub-frame, and the relay node
is in a sending state in this sub-frame and for example sends a data signal to the base station.
The seventh or eighth sub-frame is a downlink relay link sub-frame, and the relay node is in a
receiving state in this sub-frame and for example receives a decoding response signal
ACK/NACK to the data signal from the base station. In the case where the seventh or eighth
sub-frame is used as a downlink relay link sub-frame, the seventh or eighth sub-frame cannot
be used as a downlink access link sub-frame, and the mobile station does not feed back
ACK/NACK to the relay node in the third sub-frame which is at an ACK/NACK feedback
position corresponding to the seventh or eighth sub-frame. Therefore, the relay node may send
a data signal to the base station in the third sub-frame. Thus the collision is avoided that the
relay node has to receive a signal while sending a signal.
[0059] In another case in Figure 9, the relay node receives a ninth signal from the base
station in the seventh sub-frame, and the relay node receives a tenth signal from the base
station in the eighth sub-frame; the relay node sends a response signal to the ninth signal and
to the tenth signal to the base station in the third sub-frame. Herein, the ninth signal and the
tenth signal may be data signals.
[0060] Specifically, considering the asymmetry between the uplink and downlink signal
transmission (for example, the amount of data in the downlink direction is usually larger than
that in the uplink direction), therefore herein the seventh and eighth sub-frames are used as
downlink relay link sub-frames, and the relay node is in the receiving state in these two
sub-frames and for example receives a data signal from the base station; the third sub-frame is
used as uplink relay link sub-frame, and the relay node is in the sending state in this
sub-frame and for example sends to the base station a decoding response signal ACK/NACK
to the data signals received in the seventh and eighth sub-frames. In the case where the
seventh and eighth sub-frames are used as downlink relay link sub-frames, the seventh and
eighth sub-frames cannot be used as downlink access link sub-frames, and the mobile station
does not feed back ACK/NACK to the relay node in the third sub-frame which is at an
ACK/NACK feedback position corresponding to the seventh and eighth sub-frames.
Therefore, the relay node may send ACK/NACK to the base station in the third sub-frame.
Thus the collision is avoided that the relay node has to receive a signal while sending a signal.
[0061] Figure 10 shows a schematic view of a second ACK/NACK feedback scheme of the
sub-frame configuration 3.
[0062] As shown in Figure 10, according to the sub-frame configuration 3 of LTE TDD,
among the 0th to the ninth sub-frames of each frame, the second, third and fourth sub-frames
are uplink sub-frames, and the other sub-frames are downlink sub-frames. Moreover, the relay
node receives a first signal from the base station in the ninth sub-frame, and the relay node
sends a second signal to the base station in the third sub-frame. The first signal is a response
signal to the second signal or the second signal is a response signal to the first signal. It can be
seen that the ninth sub-frame is paired with the third sub-frame in this scheme.
[0063] Specifically, the ninth sub-frame is a downlink relay link sub-frame, and the relay
node is in a receiving state in this sub-frame and for example receives a data signal from the
base station. The third sub-frame is an uplink relay link sub-frame, and the relay node is in a
sending state in this sub-frame and for example sends a decoding response signal
ACK/NACK to the data signal to the base station. In the case where the ninth sub-frame is
used as a downlink relay link sub-frame, the ninth sub-frame cannot be used as a downlink
access link sub-frame, and the mobile station does not feed back ACK/NACK to the relay
node in the third sub-frame which is at an ACK/NACK feedback position corresponding to
the ninth sub-frame. Therefore, the relay node may send ACK/NACK to the base station in
the third sub-frame. Thus the collision is avoided that the relay node has to receive a signal
while sending a signal.
[0064] Figure 11 shows a seventh schematic view of a predetermined downlink sub-frame
and a predetermined uplink sub-frame acquired according to a sub-frame configuration 6.
[0065] As shown in Figure 11, according to the sub-frame configuration 6 of LTE TDD,
among the 0th to the ninth sub-frames of each frame, the second, third, fourth, seventh and
eighth sub-frames are uplink sub-frames, and the other sub-frames are downlink sub-frames.
Moreover, the relay node sends a first signal to the base station in the fourth sub-frame, and
the relay node receives a second signal from the base station in the ninth sub-frame. The first
signal is a response signal to the second signal or the second signal is a response signal to the
first signal. It can be seen that the ninth sub-frame is paired with the fourth sub-frame in this
scheme.
[0066] Specifically, the fourth sub-frame is an uplink relay link sub-frame, and the relay
node is in a sending state in this sub-frame and for example sends a data signal to the base
station. The ninth sub-frame is a downlink relay link sub-frame, and the relay node is in a
receiving state in this sub-frame and for example receives a decoding response signal
ACK/NACK to the data signal from the base station. In the case where the ninth sub-frame is
used as a downlink relay link sub-frame, the ninth sub-frame cannot be used as a downlink
access link sub-frame, and the mobile station does not send a signal to the relay node in the
fourth sub-frame which is at an ACK/NACK feedback position corresponding to the ninth
sub-frame. Therefore, the relay node may send a data signal to the base station in the fourth
sub-frame. Thus the collision is avoided that the relay node has to receive a signal while
sending a signal.
[0067] Figure 12 shows a structural view of a relay node according to an embodiment of the
present invention.
[0068] The relay node 1200 provided by the embodiment is used in a time division duplex
communication system, for example in an LTE TDD system. Therefore, the LTE TDD system
includes a base station, a mobile station and the relay node 1200. The relay node 1200
includes a transceiver 1202. The transceiver 1202 is not in a receiving state and a sending
state concurrently, and the transceiver 1202 is configured to: receive a first signal from the
base station in a predetermined downlink sub-frame of a frame; and send a second signal to
the base station in a predetermined uplink sub-frame of a frame; wherein the first signal is a
response signal to the second signal or the second signal is a response signal to the first signal.
[0069] The transceiver 1202 of the relay node 1200 may also be configured to perform a
flow shown in any one of the above mentioned Figures 5-11, which will not be described in
detail herein.
[0070] Figure 13 shows a structural view of a time division duplex communication system
according to an embodiment of the present invention.
[0071] The time division duplex communication system 1300 provided by the embodiment
includes a base station 1302, a mobile station 1306 and a relay node 1304 provided by the
above mentioned embodiment.
[0072] The time division duplex communication system 1300 may be an LTE TDD system.
[0073] In order to make the relay node 1304 receive and send a signal respectively in a
predetermined downlink sub-frame and a predetermined uplink sub-frame, the base station
1302 is configured to notify the relay node 1304 of the predetermined downlink sub-frame
and the predetermined uplink sub-frame at the beginning of a communication. The base
station 1302 may be configured to notify different relay nodes 1304 of the same
predetermined downlink sub-frames and predetermined uplink sub-frames at the beginning of
the communication, and the base station 1302 may also be configured to notify different relay
nodes 1304 of different predetermined downlink sub-frames and predetermined uplink
sub-frames at the beginning of the communication.
[0074] It should be noted that, in Figures 5-11, as for the shown relay link sub-frame, it
only means that the communication between the relay node and the base station may utilize
this sub-frame position, and it does not mean that the communication between the relay node
and the mobile station and the communication between the base station and the mobile station
cannot utilize this sub-frame position. In one embodiment, the communication between the
base station and the mobile station may also utilize this sub-frame position. In another
embodiment, the communication between the relay node and the mobile station may also
utilize this sub-frame position. In the case where the communication between the relay node
and the mobile station or the communication between the base station and the mobile station
utilizes this sub-frame position, the feedback position for ACK/NACK in the prior art (for
example as shown in Figure 2) may be utilized.
[0075] In the foregoing paragraphs, the embodiments of the present invention are described
by taking an LTE TDD wireless communication system as an example. However, it should be
understood that the embodiments of the present invention are not limited to those and may
also be applied to similar TDD wireless communication systems.
[0076] It needs to be pointed out that it is obvious that each of the components or steps in
the devices and methods of the present invention may be decomposed and/or recombined.
These decomposition and/or recombination should be regarded as equivalent schemes of the
present invention. Moreover, the steps carrying out the series of processes mentioned above
may be performed naturally in order of time as described. However, the steps do not
necessarily be performed according to the time sequence. Some of the steps may be carried
out in parallel or independently from each other.
[0077] Although the present invention and its advantages have been described in detail, it
should be understood that various changes, replacements, variations may be made without
departing from the spirit and scope of the present invention defined by the appending claims.
Moreover, the terms " comprise", "include" or any other variations thereof intend to cover
non-exclusive "include", so that the procedure, method, article or means including a series of
elements not only include those elements, but also include other elements that are not
specifically listed, or also include inherent elements of this procedure, method, article or
means.
[0078] Although the embodiments of the present invention are described in detail in
conjunction with the accompanying drawings in the foregoing, it should be appreciated that
the above mentioned embodiments are only for illustration of the present invention and do not
limit the present invention. For the skilled in the art, various modifications and changes may
be made to the above mentioned implementations without departing from the scope of the
present invention. Therefore, the scope of the present invention is only defined by the
appending claims and their equivalent meanings.
We Claim:
1. A communication method in a time division duplex communication system, the
communication system comprising a base station, a mobile station and a relay node, the relay
node being not in a receiving state and a sending state concurrently, wherein the
communication method comprises:
receiving, by the relay node, a first signal from the base station in a predetermined
downlink sub-frame of a frame; and
sending, by the relay node, a second signal to the base station in a predetermined uplink
sub-frame of a frame;
wherein the first signal is a response signal to the second signal or the second signal is a
response signal to the first signal.
2. The method according to claim 1, wherein each frame comprises 10 sub-frames from the
0th sub-frame to the ninth sub-frame, the second, the third, the seventh and the eighth
sub-frames are uplink sub-frames and the other sub-frames are downlink sub-frames, and
the relay node receives the first signal from the base station in the fourth sub-frame, and
the relay node sends the second signal to the base station in the eighth sub-frame; or
the relay node receives the first signal from the base station in the ninth sub-frame, and
the relay node sends the second signal to the base station in the third sub-frame.
3. The method according to claim 1, wherein each frame comprises 10 sub-frames from the
0th sub-frame to the ninth sub-frame, the second, the third, the seventh and the eighth
sub-frames are uplink sub-frames, the other sub-frames are downlink sub-frames, and
the relay node receives the first signal from the base station in the ninth sub-frame, the
relay node sends the second signal to the base station in the third sub-frame; and, the relay
node receives a third signal from the base station in the fourth sub-frame, and the relay node
sends a fourth signal to the base station in the eighth sub-frame, the third signal being a
response signal to the fourth signal or the fourth signal being a response signal to the third
4. The method according to claim 1, wherein each frame comprises 10 sub-frames from the
0th sub-frame to the ninth sub-frame, the second, the third, the seventh and the eighth
sub-frames are uplink sub-frames, the other sub-frames are downlink sub-frames, and
the relay node receives a fifth signal from the base station in the fourth sub-frame, the
relay node receives a sixth signal from the base station in the ninth sub-frame; and, the relay
node sends a response signal to the fifth signal and the sixth signal to the base station in the
third sub-frame.
5. The method according to claim 1, wherein each frame comprises 10 sub-frames from the
0th sub-frame to the ninth sub-frame, the second, the third, the seventh and the eighth
sub-frames are uplink sub-frames, the other sub-frames are downlink sub-frames, and
the relay node sends the seventh signal to the base station in the third sub-frame, the
relay node receives a response signal to the seventh signal from the base station in the ninth
sub-frame, the relay node receives a eighth signal from the base station in the fourth
sub-frame, and the relay node sends a response signal to the eighth signal to the base station
in the third sub-frame.
6. The method according to claim 1, wherein each frame comprises 10 sub-frames from the
0th sub-frame to the ninth sub-frame, the second, the third and the fourth sub-frames are
uplink sub-frames, the other sub-frames are downlink sub-frames, and
the relay node sends the first signal to the base station in the third sub-frame, the relay
node receives the second signal from the base station in the seventh or the eighth sub-frame;
or
the relay node receives the first signal from the base station in the ninth sub-frame, the
relay node sends the second signal to the base station in the third sub-frame.
7. The method according to claim 1, wherein each frame comprises 10 sub-frames from the
0th sub-frame to the ninth sub-frame, the second, the third and the fourth sub-frames are
uplink sub-frames, the other sub-frames are downlink sub-frames, and
the relay node receives a ninth signal from the base station in the seventh sub-frame, the
relay node receives a tenth signal from the base station in the eighth sub-frame, and the relay
node sends a response signal to the ninth signal and the tenth signal to the base station in the
third sub-frame.
8. The method according to claim 1, wherein each frame comprises 10 sub-frames from the
0th sub-frame to the ninth sub-frame, where the second, the third, the fourth, the seventh and
the eighth sub-frames are uplink sub-frames, the other sub-frames are downlink sub-frames,
and
the relay node sends the first signal to the base station in the fourth sub-frame, the relay
node receives the second signal from the base station in the ninth sub-frame.
9. A relay node, used in a time division duplex communication system, the communication
system comprising a base station, a mobile station and a relay node, the relay node
comprising a transceiver which is not in a receiving state and a sending state concurrently,
wherein the transceiver is configured to:
receive a first signal from the base station in a predetermined downlink sub-frame of a
frame; and
send a second signal to the base station in a predetermined uplink sub-frame of a frame;
wherein the first signal is a response signal to the second signal or the second signal is a
response signal to the first signal.
10. The relay node according to claim 9, wherein each frame comprises 10 sub-frames from
the 0th sub-frame to the ninth sub-frame, the second, the third, the seventh and the eighth
sub-frames are uplink sub-frames and the other sub-frames are downlink sub-frames, and
the transceiver is configured to receive the first signal from the base station in the fourth
sub-frame and to send the second signal to the base station in the eighth sub-frame; or
the transceiver is configured to receive the first signal from the base station in the ninth
sub-frame and to send the second signal to the base station in the third sub-frame.
11. The relay node according to claim 9, wherein each frame comprises 10 sub-frames from
the 0th sub-frame to the ninth sub-frame, the second, the third, the seventh and the eighth
sub-frames are uplink sub-frames, the other sub-frames are downlink sub-frames, and
the transceiver is configured to receive the first signal from the base station in the ninth
sub-frame and to send the second signal to the base station in the third sub-frame; and the
transceiver is configured to receive a third signal from the base station in the fourth sub-frame
and to send a fourth signal to the base station in the eighth sub-frame, wherein the third signal
is a response signal to the fourth signal or the fourth signal is a response signal to the third
signal.
12. The relay node according to claim 9, wherein each frame comprises 10 sub-frames from
the 0th sub-frame to the ninth sub-frame, the second, the third, the seventh and the eighth
sub-frames are uplink sub-frames, the other sub-frames are downlink sub-frames, and
the transceiver is configured to receive a fifth signal from the base station in the fourth
sub-frame, to receive a sixth signal from the base station in the ninth sub-frame, and to send a
response signal to the fifth signal and the sixth signal to the base station in the third
sub-frame.
13. The relay node according to claim 9, wherein each frame comprises 10 sub-frames from
the 0th sub-frame to the ninth sub-frame, the second, the third, the seventh and the eighth
sub-frames are uplink sub-frames, the other sub-frames are downlink sub-frames, and
the transceiver is configured to send a seventh signal to the base station in the third
sub-frame, to receive a response signal to the seventh signal from the base station in the ninth
sub-frame, to receive an eighth signal from the base station in the fourth sub-frame and to
send a response signal to the eighth signal to the base station in the third sub-frame.
14. The relay node according to claim 9, wherein each frame comprises 10 sub-frames from
the 0th sub-frame to the ninth sub-frame, the second, the third and the fourth sub-frames are
uplink sub-frames, the other sub-frames are downlink sub-frames, and
the transceiver is configured to send the first signal to the base station in the third
sub-frame and to receive the second signal from the base station in the seventh or the eighth
sub-frame; or
the transceiver is configured to receive the first signal from the base station in the ninth
sub-frame and to send the second signal to the base station in the third sub-frame.
15. The relay node according to claim 9, wherein each frame comprises 10 sub-frames from
the 0th sub-frame to the ninth sub-frame, the second, the third and the fourth sub-frames are
uplink sub-frames, the other sub-frames are downlink sub-frames, and
the transceiver is configured to receive a ninth signal from the base station in the seventh
sub-frame, to receive a tenth signal from the base station in the eighth sub-frame and to send a
response signal to the ninth and the tenth signal to the base station in the third sub-frame.
16. The relay node according to claim 9, wherein each frame comprises 10 sub-frames from
the 0th sub-frame to the ninth sub-frame, where the second, the third, the fourth, the seventh
and the eighth sub-frames are uplink sub-frames, the other sub-frames are downlink
sub-frames, and
the transceiver is configured to send the first signal to the base station in the fourth
sub-frame and to receive the second signal from the base station in the ninth sub-frame.
17. A time division duplex communication system, comprising a base station, a mobile
station, and a relay node according to any one of claims 9-16.
18. The time division duplex communication system according to claim 17, wherein the
base station is configured to notify the relay node of the predetermined uplink sub-frame and
the predetermined downlink sub-frame at the beginning of a communication.
19. The time division duplex communication system according to claim 18, wherein the
base station is configured to notify different relay nodes of different predetermined uplink
sub-frames and predetermined downlink sub-frames at the beginning of the communication.

A relay node, time division duplex communication system and communication method are
disclosed. The communication system comprises a base station, mobile stations and the relay
node. The relay node will not be in receiving and transmitting state synchronously. The
communication method comprises that the relay node receives a first signal from the base
station in a predetermined downlink subframe of a frame and transmits a second signal to the
base station in a predetermined uplink subframe of the frame, wherein the first signal is a
response signal for the second signal or the second signal is a response signal for the first signal.