KR101915159B1 - Method and apparatus for implementing device-to-device broadcast communication in a wireless communication network - Google Patents

Abstract

The invention provides a method of implementing device-to-device broadcast communication at a user equipment in a wireless communication network, the method comprising the steps of: - removing a first row in a Walsh matrix H ₁ and a first matrix H ₂ Determining a set of transmission patterns comprising all of the rows, the first matrix H ₂ being a Walsh matrix H ₁ multiplied by -1; - determining one row from the set of transmission patterns; And - implementing a device-to-device broadcast in accordance with a transmission pattern corresponding to a determined row, the transmission pattern comprising the steps of: based on each element in the determined row: Sending a broadcast at the same time; - to continuously receive the broadcast when the element is at the second value.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for implementing device-to-device broadcast communication in a wireless communication network,

The present disclosure relates to mobile communication technologies, and more particularly, to a method for implementing device-to-device broadcast communication in a wireless communication network and corresponding user equipment.

Device-to-device (D2D) communication has been introduced as a significant improvement to Long Term Evolution (LTE-Advanced) for cellular networks. Related standardization was performed in the Third-Generation Partnership Project (3GPP) to study both device discovery and direct communication techniques.

For D2D direct communication, broadcast communication in an out-of-coverage scenario is prioritized for a Release 12 time frame. D2D broadcast communication is the most critical task to support VoIP traffic. It is required that the broadcast packet reach as far as possible to the user equipment (UE). In order to increase coverage, narrowband (as low as 2 or 3 RBs) is a reasonable choice for the transmission of broadcast VoIP packets. For large channel bandwidth (50 RBs for 10 MHz bandwidth), we need to broadcast frequency domain multiplexing (FDM) transmissions from multiple UEs to fully utilize the available spectrum resources have. However, it results in half-duplex constraints and in-band emissions that ultimately affect broadcast performance.

With this in mind, the present invention provides a solution for D2D broadcast communication.

According to a first aspect of the invention there is provided a method of implementing device-to-device broadcast communication in a user equipment in a wireless communication network, the method comprising the steps of: - providing a Walsh matrix H ₁ and a first matrix Determining a set of transmission patterns that includes all rows except for a first row in H ₂ , the first matrix H ₂ being a product of a Walsh matrix H ₁ and a -1; - determining one row from the set of transmission patterns; And - implementing a device-to-device broadcast in accordance with a transmission pattern corresponding to the determined row, the transmission pattern comprising the steps of: determining, based on each element in the determined row, Sending a broadcast at a first value; - to continuously receive the broadcast when the element is at the second value.

Advantageously, the transmit pattern set includes Walsh matrix H ₁ and even rows in first matrix H ₂ .

Here, the mechanism for down-selecting appropriate transmission patterns is designed for narrow bands such as 3 MHz and 5 MHz to provide additional advantages. Through this mechanism, transmissions of VoIP packets are spread more uniformly, which helps to achieve time diversity. This mechanism also helps to reduce the overall transmission latency of VoIP packets.

According to a second aspect of the invention there is provided a user equipment implementing a device-to-device broadcast communication in a wireless communication network, the user equipment comprising: a Walsh matrix H ₁ and a first matrix H ₂ A unit for determining a set of transmission patterns that includes all of the rows except for the first row in the first transmission matrix, the first matrix H ₂ being the product of a Walsh matrix H ₁ and -1; A unit for determining a row, the unit configured to determine one row from a set of transmission patterns; And a broadcasting unit configured to implement a device-to-device broadcast in accordance with a transmission pattern corresponding to the determined row, the transmission pattern comprising the following steps based on each element in the determined row: Sending a broadcast when the first value is a first value; - to continuously receive the broadcast when the element is at the second value.

In the present invention, a method for constructing a transmission pattern set is proposed. Here, the total number of transmission patterns is (N-1) * 2. N is the order of the Walsh matrix. This will help reduce collision probability and increase transmission pattern selection in resource allocation. Meanwhile, the transmission pattern according to the present invention still maintains the characteristics of the Walsh based transmission pattern set. By applying the above transmission pattern for D2D broadcast communication, the hard-duplex constraint can be solved and the in-band radiation seen at the receiving UEs can be mitigated.

The individual aspects of the invention will become more apparent from the following description of specific embodiments.

Other features, objects, and advantages of the invention will become more apparent upon review of the following detailed description of non-limiting embodiments taken with reference to the drawings, wherein:
1 illustrates constructing a Walsh matrix-based transmission pattern set according to an embodiment of the present invention;
2 illustrates a set of Walsh matrix-based transmission patterns in accordance with an embodiment of the present invention;
3 illustrates a flowchart of a method for implementing D2D broadcast communication in accordance with an embodiment of the present invention;
Figure 4 illustrates the relationship between two corresponding rows in two matrices in a set of transmit patterns according to an embodiment of the present invention;
5 illustrates a relationship between two arbitrary rows in two matrices in a set of transmit patterns according to an embodiment of the present invention;
6 illustrates a set of Walsh matrix-based transmission patterns in accordance with an embodiment of the present invention;
Figure 7 illustrates a set of Walsh matrix-based transmission patterns in accordance with another embodiment of the present invention;
Figure 8 illustrates a set of Walsh matrix-based transmission patterns in accordance with a further embodiment of the present invention;
9 illustrates a set of Walsh matrix-based transmission patterns in accordance with a further embodiment of the present invention; And
10 illustrates a UE according to an embodiment of the present invention.
In the drawings, the same or similar reference numerals designate the same or corresponding components or features throughout the different views.

First, the design for D2D broadcast communication should consider the following factors:

First, the LTE frame structure is reused to maintain compatibility with legacy cellular communication.

1. In LTE, resources are divided in the time-frequency plane.

2. In LTE, the minimum scheduling (resource allocation) unit is composed of two time-continuous resource blocks in one subframe, referred to as a resource-block (RB) pair. The resource allocation unit for D2D broadcast communication should be a multiple of RB pairs.

For D2D communication, it is required that the broadcast packet reaches the UE as far as possible. In order to increase coverage, narrowband (as low as 2 or 3 RBs) is a reasonable choice for the transmission of broadcast VoIP packets. For large channel bandwidth (50 RBs for 10 MHz bandwidth), we need to broadcast FDM (frequency domain multiplexing) transmissions from multiple UEs to fully exploit the available spectrum resources.

Second, the design should fit into VoIP traffic, the basic traffic type for D2D broadcast communications. VoIP traffic has the following attributes:

VoIP traffic is periodic. The encoder frame length is 20 ms, which means that the speech encoder generates voice packets for each 20 ms. The average length of the talk spurt is 2.5 s.

2. The speech payload per speech frame is 328 bits with header compression.

3. The requirement of end-to-end latency for VoIP traffic is 200 ms. With an inference of processing time, the acceptable transmission delay of a VoIP packet for D2D broadcast communication (unidirectional transmission) is about 160 ms.

1 illustrates the construction of a Walsh matrix-based transmission pattern set according to an embodiment of the present invention. In Figure 1, the order N of the Walsh matrix is set to 8 only for illustration.

As shown in FIG. 1, one Walsh matrix H ₁ is first selected. It has an order of N.

Second, the first matrix H ₂ is obtained as a product of the Walsh matrix H ₁ and -1.

Finally, as shown in FIG. ₂ , the remaining rows in the Walsh matrix H ₁ and the first Walsh matrix H ₂ , except for the first row in each matrix, constitute a transmission pattern set.

Each row in this set of transmission patterns can be used by the UE. Each element in each row may be used to determine whether the UE performs a broadcast transmission or a broadcast reception in one subframe. For example, for element +1, the UE may perform a broadcast transmission, while for element-1, the UE may perform broadcast reception.

3 illustrates a flow chart of a method of implementing D2D broadcast communication in a UE according to an embodiment of the present invention.

As shown in FIG. 3, in step S11, the UE determines a set of transmission patterns including all the rows except for the first row in the Walsh matrix H ₁ and the first matrix H ₂ , where the first matrix H ₂ Is the product of the Walsh matrix H ₁ and -1.

In one embodiment of the invention, the UE and the base station can predefine the corresponding set of transmission patterns and preconfigure it in the UE. When the UE needs to perform broadcast communications, it will use a set of transmission patterns.

Alternatively, the base station can determine a set of transmission patterns and transmit the determined set of transmission patterns to the UE by the first indication message. The UE may determine a set of transmission patterns according to the first indication message. This first indication message may be transmitted, for example, during the scheduling procedure.

Still referring to Fig. 3, in step S12, the UE determines one row from the set of transmission patterns.

This can be implemented by using the following methods:

For example, the UE receives a second indication message from the base station. This second indication message indicates the associated row. Next, the UE determines a row from the transmission pattern set according to the second indication message. Herein, the base station determines, for example, a corresponding row for each UE according to use in a set of transmission patterns, to perform a corresponding broadcast.

Alternatively, the UE itself may determine a row from the set of transmission patterns according to predefined conditions. The predefined conditions include the current usage of each row in the set of transmission patterns; Current interested broadcast from other user equipment; And / or the quality of the current channel. For example, when the UE is very interested in the broadcast of another UE, it may select the appropriate corresponding row to receive the broadcast in the respective subframe. However, when the UE is not interested in the broadcast of another UE, it may select the appropriate corresponding row to transmit the broadcast in the respective subframe.

In step S13, the UE performs a D2D broadcast according to the transmission pattern corresponding to the determined row. As described above, the transmission pattern may include the following procedures based on each element in the determined row: sending a broadcast when the element is at a first value (e.g., +1); - Receive a broadcast when the element has a second value (e.g., -1).

4 illustrates the relationship between two corresponding rows in two matrices in a transmit pattern set according to an embodiment of the present invention. Figure 5 illustrates the relationship between two arbitrary rows in two matrices in a set of transmit patterns according to an embodiment of the present invention.

4 and 5, the attributes of the transmission pattern set will be described below. H (i, :) represents row i in matrix H.

1. For any row in the Walsh matrix H ₁ and the first matrix H ₂ , i. E., H ₁ (i, :) and H ₂ (i, :)) except for the first row, Half is +1, half of elements are -1.

2. It should be noted that the Walsh matrix H ₁ and any two corresponding rows in the first matrix H ₂ (e.g., two third rows denoted in FIG. 4), except for the first row, i. E. _There are N / 2 pairs of {+1, -1} and {-1, +1} for ₁ (i, :) and H ₂ In the present application, since the order of the Walsh matrix is selected as 8 in FIG. 4, there are four pairs of {+1, -1} and four pairs of {-1, +1}.

3. It is assumed that there are two arbitrary rows in the Walsh matrix H ₁ and the first matrix H ₂ , namely H _m (i, :) and H _n (j, :) with i ≠ j ≠ 1, except for the first row , This means that the two rows may come from the same matrix, or they may come from two different matrices. Figure 5 shows four situations: the third and sixth rows in the Walsh matrix H ₁ , the third and sixth rows in the first Walsh matrix H ₂ , the third row in the Walsh matrix H ₁ , and the first Walsh matrix H ₂ , and the sixth row in the Walsh matrix H ₁ and the third row in the first Walsh matrix H ₂ . 5, it is clear that in this situation there are N / 4 pairs of {+1, -1} and N / 4 pairs of {-1, +1}. Since the order of the Walsh matrix in FIG. 5 is selected as 8, there are two pairs of {+1, -1} and two pairs of {-1, +1}.

To improve link level performance, retransmissions of VoIP packets are required and spread in the time domain. The number of potential transmission subframes for a VoIP packet is pre-configured as N. Gaps of sequential potential transmission subframes may also be preconfigured and they may be the same (Np_1 = Np_2 = ... = Np_ (N-1)) or may be different. Based on the elements in either row (except for the first two rows) of both the Walsh matrix H ₁ and the first Walsh matrix H ₂ , the broadcast UE determines whether to transmit / receive in potential transmit subframes .

6 illustrates a set of Walsh matrix-based transmission patterns in accordance with an embodiment of the present invention. UE1 performs the broadcast transmission based on the third row in the Walsh matrix, and H _1, UE2 is assumed to perform a broadcast transmission based on the sixth row in the first Walsh matrix H _2. Based on the features of the two matrices mentioned above, the broadcast has the following attributes:

1. Each broadcast UE transmits a VoIP packet N / 2 times.

2. For any two broadcast UEs using different rows, i. E. Different transmission patterns, UE1 may receive broadcast transmissions from UE2 at least N / 4 times and vice versa, Resolves the duplex constraint.

Herein, if the basis of the two corresponding rows of, i.e., i ≠ 1 is H ₁ (i, :), and H ₂ (i, :) at the transmission pattern is other than the first row, a different matrix, UE1 Can receive broadcast transmissions N / 2 times from UE2, and vice versa.

In the present application, when the transmission pattern is based on two arbitrary rows in two matrices except for the first row, i.e. H _m (i, :) and H _n (j, :) with i ≠ j ≠ 1 , UE1 may receive broadcast transmissions from UE2 N / 4 times, and vice versa.

Here, the number of available transmission patterns is doubled to (N-1) * 2.

7 illustrates a set of Walsh matrix-based transmission patterns in accordance with another embodiment of the present invention. If the transmission patterns are based on two corresponding rows at H ₁ and H ₂ , then all potential transmitting subframes can be occupied for transmission. In the example shown in Figure 7, using the UE1 is the third row of the matrix H ₁ and, UE2 uses the third row of the matrix H _2. UE3 are using the sixth row of the matrix H ₁ and, UE4 is used in the sixth row of the matrix H _2.

By using a set of transmission patterns, multiple transmissions of a VoIP packet are randomized in the time domain, which mitigates the in-band emissions seen by the receiving UEs. Once the row of the Walsh matrix for the transmission pattern is selected, the transmission pattern is fixed. The fixed transmission pattern facilitates packet reception / combination at the receiving UEs. It also reduces signaling overhead when transmission pattern information is conveyed in scheduling assignments prior to data transmission.

For narrower channel bandwidths, such as 3 MHz (15 resource blocks) and 5 MHz (25 resource blocks), it is not necessary to use all the rows of the transmit pattern set. Because of this, for this case, the set of transmission patterns can be further reduced to provide additional gains.

1. Transmissions of VoIP packets are more uniformly spread, which helps to obtain time diversity.

2. DRX (discontinuous reception) is realized and the gap between consecutive transmissions (in terms of sub-frames) needs to be set large enough to ensure sufficient decoding time for VoIP packets. This mechanism helps to reduce the overall transmission latency of VoIP packets.

Figure 9 illustrates a set of Walsh matrix-based transmission patterns in accordance with a further embodiment of the present invention. Herein, UE1 is using the second row of the Walsh matrix H ₁ and, UE2 is used in the fourth row of the first matrix H _2. In the present application, Np_1, Np_3, ... , Np_ (N-1) can be set to 1, which means that there is no gap between two sequential potential transmission subframes.

10 illustrates a UE according to an embodiment of the present invention. As shown in FIG. 10, the UE includes a unit for determining a set of transmission patterns, a unit for determining one row, and a broadcasting unit.

A unit for determining a transmit pattern set is configured to determine a set of transmit patterns that includes all of the rows except for a first row in a Walsh matrix H ₁ and a first matrix H ₂ where the first matrix H ₂ is Walsh It is the product of the matrix H ₁ and -1.

Advantageously, the unit for determining the transmission pattern comprises a pre-configured unit configured to pre-configure the transmission pattern set at the UE.

Alternatively, a unit for determining a transmission pattern may comprise: a first receiving unit configured to receive a first indication message from a base station, the first indication message indicating a set of transmission patterns; And a first determination unit configured to determine a transmission pattern set in accordance with the first indication message.

A unit for determining one row is configured to determine one row from a set of transmission patterns.

Advantageously, the unit for determining one row comprises: a second receiving unit configured to receive a second indication message from a base station, the second indication message indicating a row; And a second determination unit configured to determine a row from the transmission pattern set based on the second indication message.

Alternatively, the unit for determining one row includes a third determination unit configured to determine a row in accordance with a predetermined condition.

Wherein the broadcasting unit is configured to implement a device-to-device broadcast according to a transmission pattern corresponding to a determined row, wherein the transmission pattern is based on each element in the determined row, the following procedures: Sending a broadcast at a first value; - to continuously receive the broadcast when the element is at the second value.

It will be appreciated that the above-described embodiments are merely illustrative, but that the invention will not be limited. Any technical solution that does not depart from the spirit of the invention will fall within the scope of the invention, including that different technical features and methods appearing in different embodiments, methods are used for the sake of convenience.

Claims (14)

A method for implementing device-to-device broadcast communication at a user equipment in a wireless communication network,
Walsh matrix (Walsh matrix) H _1, and determining a transmission pattern set comprising all but the first row in the first matrix, H ₂ - H ₂ is the first matrix of the Walsh matrix H ₁ and -1 Product -;
Determining one row from the set of transmission patterns; And
Implementing a device-to-device broadcast according to a transmission pattern corresponding to the determined row
Wherein the transmission pattern comprises the following steps based on each element in the determined row:
Sending the broadcast when the element is at a first value;
And continuously receiving the broadcast when the element is at a second value. 2. The method of claim 1, wherein determining the transmit pattern set comprises:
Wherein the set of transmission patterns is preconfigured at the user equipment. 2. The method of claim 1, wherein determining the transmit pattern set comprises:
Receiving a first indication message from a base station, the first indication message indicating the set of transmission patterns; And
And determining the transmission pattern set in accordance with the first indication message. 2. The method of claim 1, wherein determining a row from the set of transmission patterns comprises:
Receiving a second indication message from a base station, the second indication message indicating the row; And
And determining the row from the set of transmission patterns based on the second indication message. 2. The method of claim 1, wherein determining a row from the set of transmission patterns comprises:
And determining the row in accordance with a predetermined condition. 6. The method of claim 5, wherein the predetermined conditions are:
i. A current usage state of each row in the transmission pattern set;
ii. Current interested broadcast from other user equipment; And
iii. Quality of current channel
≪ / RTI > 2. The method of claim 1, wherein the set of transmit patterns comprises the Walsh matrix H ₁ and even rows in the first matrix H ₂ . In a wireless communication network, a user equipment implementing device-to-device broadcast communication,
Walsh matrix H ₁ and a unit for determining a transmission pattern set, configured to determine a transmission pattern set comprising all but the first row in the first matrix, H ₂ - the first matrix H ₂ are the Walsh matrix H _A multiplication of ₁ and -1;
A unit configured to determine one row from the set of transmission patterns; And
A broadcast unit configured to implement a device-to-device broadcast in accordance with a transmission pattern corresponding to the determined row;
Wherein the transmission pattern comprises the following steps based on each element in the determined row:
Sending the broadcast when the element is at a first value;
And when the element is at a second value, continuously implementing receiving the broadcast. 9. The apparatus of claim 8, wherein the unit for determining the transmit pattern set comprises:
And a preconfiguration unit configured to preconfigure the transmission pattern set at the user equipment. 9. The apparatus of claim 8, wherein the unit for determining the transmit pattern set comprises:
A first receiving unit configured to receive a first indication message from a base station, the first indication message indicating the set of transmission patterns; And
And a first determination unit configured to determine the transmission pattern set in accordance with the first indication message. 9. The apparatus of claim 8, wherein the unit for determining the one row comprises:
A second receiving unit configured to receive a second indication message from a base station, the second indication message indicating the row; And
And a second determination unit configured to determine the row from the transmission pattern set based on the second indication message. 9. The apparatus of claim 8, wherein the unit for determining the one row comprises:
And a third determination unit configured to determine the row in accordance with a predetermined condition. 13. The method of claim 12, wherein the predetermined conditions are:
i. A current usage state of each row in the transmission pattern set;
ii. Current interested broadcast from other user equipment; And
iii. Quality of current channel
/ RTI > of the user equipment. 9. The user equipment of claim 8, wherein the set of transmit patterns comprises the Walsh matrix H ₁ and even rows in the first matrix H ₂ .

Images