WO2014155199A2

WO2014155199A2 - A frequency diversity transmission method for machine-type communication

Info

Publication number: WO2014155199A2
Application number: PCT/IB2014/000575
Authority: WO
Inventors: Yu Chen; Zhang Zhang
Original assignee: Alcatel Lucent
Priority date: 2013-03-27
Filing date: 2014-03-19
Publication date: 2014-10-02
Also published as: TWI531179B; JP2016515773A; WO2014155199A3; CN104079337B; CN104079337A; TW201445918A; JP6118452B2

Abstract

A method for transmitting data to a user equipmentin a base station in a wireless communication system, wherein the user equipment is a machine-type communication device, the method comprising the following steps: mapping, by the base station, data to be transmitted to a first number of frequency resource blocks according to a first rule, wherein the first number is greater than 1; assigning, by the base station, different frequencies to each of the frequency resource blocks; encapsulating, by the base station, each of the frequency resources blocks into different subframes, and then sending them to the user equipment sequentially.

Description

A Frequency Diversity Transmission Method for Machine-Type

Communication

FIELD OF THE INVENTION

The present invention relates to the field of wireless communication technology, and more particularly, to the field of a machine-type communication technology.

BACKGROUND OF THE INVENTION

In recent years, machine-type communication (MTC) has become a hot issue in the field of wireless communication technology. In a recent 3GPP standardization meeting, a new objective was proposed for evolution of the existing MTC technology, which requires improvement of a low-cost MTC device so as to realize 20dB coverage enhancement.

The so-called low-cost MTC device refers to a series of low-complexity and low-power-consumption wireless devices, e.g., a wireless sensor device. Such devices have the following two prominent features which make the above improvement objective very difficult to realize:

First, such devices always work on a very narrow band. Typically, in the existing 3 GPP specification, the operation bandwidth of a MTC device is 1.4MHz or expressed as 6 frequency resource blocks (RBs). Such a narrow frequency band makes it hard to apply many conventional technologies that realize gains to the MTC. Typically, the frequency diversity technology that is commonly used in the field of wireless communication cannot be applied to MTC directly due to the fact that too narrow operation band can not be further partitioned.

Second, it is hard for a low-cost MTC to perform a prompt and accurate channel condition report, because such devices are generally mounted on various kinds of industrial apparatus or inside a building; therefore, the penetration loss of its channel is rather considerable. Further, due to the above reasons, if the frequency diversity cannot be applied, its receiver faces a deep fading.

For the above two reasons, it is desirable to seek a new-type frequency diversity method applicable to low-cost MTC device. Such method must be capable of working on a narrow operation frequency band of a MTC device without significantly increasing signaling overhead; further, it can be implemented in a simple way, so as to retain the inherent advantages of the low-cost MTC device, such as low complexity and low power consumption.

SUMMARY OF THE INVENTION

In order to solve the above problems in the prior art, the present invention provides a new frequency diversity method applicable to a MTC device. The gain effect of a frequency diversity is achieved by mapping the data of a transmission block (TB) to a plurality of bundled RBs, assigning different frequencies to the bundled plurality of RBs, and then encapsulating these RBs in different subframes to transmit in succession; additionally, a simplest scheduling manner may also be implemented by setting a fixed frequency interval.

Specifically, according to a first aspect of the present invention, there is proposed a method for transmitting data to a user equipment in a base station in a wireless communication system, wherein the user equipment is a machine-type communication device, the method comprising the following steps: mapping, by the base station, to-be-transmitted data to a first number of frequency resource blocks according to a first rule, wherein the first number is greater than 1 ; assigning, by the base station, different frequencies to each of the frequency resource blocks; encapsulating, by the base station, each of the frequency resources into different subframes to transmit to the user equipment sequentially.

Preferably, there further comprises: transmitting, by the base station, a first message to the user equipment, the first message being used for notifying the user equipment of time and frequency for transmitting a first of the frequency resource blocks.

Preferably, frequency interval between each of the frequency resource blocks is identical.

More preferably, the identical frequency interval is configured by the base station.

Preferably, the first number is configured by the base station.

Preferably, the first number is 2, 4, or 8.

More preferably, the first message further includes the identical frequency interval.

More preferably, the first message further includes the first number.

Preferably, the first rule includes: mapping all contents of the to-be-transmitted data to each of the frequency resource blocks.

Preferably, the first rule includes: dividing the to-be-transmitted data into the first number of parts, each of the parts is mapped to one of the frequency resource blocks, respectively.

Preferably, each of the frequency resource blocks uses a different hybrid automatic repeat request redundancy version.

Preferably, each of the frequency resource blocks carries a different segment of a same code block, respectively.

According to a second aspect of the present invention, there is proposed a method of receiving data in a user equipment in a wireless communication system, wherein the user equipment is a machine-type communication device, the method comprising the following steps: receiving in succession, by the user equipment, a first number of subframes transmitted from a base station, respectively, with each of the subframes having a frequency resource block encapsulated therein, wherein frequency of each of the frequency resource blocks is different from each other; restoring to-be-received data from frequency resource blocks encapsulated in the first number of subframes.

Preferably, there further comprises: receiving, by the use equipment, a first message transmitted from the base station, the first message being used for notifying the user equipment of time and frequency for transmitting a first of the frequency resource blocks.

More preferably, frequency interval between each of the frequency resource blocks is identical.

More preferably, the first number is configured by the base station. More preferably, the first number is 2, 4, or 8.

More preferably, the first message further includes the first number.

Preferably, when each of the frequency resource blocks carry a code block segment, respectively, there further comprises, after receiving the first number of subframes, restoring all of the to-be-received data from all of the frequency resource blocks encapsulated in the first number of subframes.

According to a third aspect of the present invention, there is proposed an apparatus for transmitting data to a user equipment in a base station in a wireless communication system, wherein the user equipment is a machine-type communication device, the apparatus comprising: a mapping unit for mapping data to be transmitted to a first number of frequency resource blocks according to a first rule, wherein the first number is greater than 1 ; an assigning unit for assigning different frequencies to each of the frequency resource blocks; a transmitting unit for encapsulating each of the frequency resources into different subframes to transmit to the user equipment sequentially.

Preferably, there further comprises: a notifying unit for transmitting a first message to the user equipment, the first message being used for notifying the user equipment of time and frequency for transmitting a first of the frequency resource blocks.

More preferably, frequency interval between each of the frequency resource blocks is identical, and the first message further includes the identical frequency interval and/or the first number.

According to a fourth aspect of the present invention, there is proposed an apparatus for receiving data in a user equipment in a wireless communication system, wherein the user equipment is a machine-type communication device, the apparatus comprising: a first receiving unit for receiving in succession a first number of subframes transmitted from a base station, respectively, with each of the subframes having a frequency resource block encapsulated therein, wherein frequency of each of the frequency resource blocks is different from each other; a restoring unit for restoring to-be-received data from frequency resource blocks encapsulated in the first number of subframes.

Preferably, there further comprises: a second receiving unit for receiving a first message transmitted from the base station, the first message being used for notifying the user equipment of time and frequency for transmitting a first of the frequency resource blocks.

In the present invention, the total bandwidth of a system can be sufficiently utilized to perform frequency diversity without increasing the operation bandwidth of a MTC device by mapping data of one TB to a plurality of RBs of different frequencies, and then transmitting with a plurality of subframes, such that each MTC device obtains a frequency diversity gain. Meanwhile, by setting a fixed frequency interval, system scheduling becomes extremely simple. Only with one signaling, the above plurality of transmissions may be scheduled, and the scheduling can be performed even in a persistent mode. Therefore, the signaling overheads are very small. Besides, the present invention only increases slightly occupation of the MTC device buffer; therefore, its complexity and cost for implementation are very low.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Through reading the following detailed depiction on the non-limiting embodiments with reference to the accompanying drawings, the other features, objectives, and advantages of the present invention will become more apparent.

Fig. 1 shows a time-frequency domain distribution diagram of the frequency resource blocks according to the present invention;

Fig. 2 illustrates a flowchart of a method for transmitting data according to the present invention;

Fig. 3 illustrates a flowchart of a method for receiving data according to the present invention;

Fig. 4 illustrates a block diagram of a transmitting apparatus according to the present invention;

Fig. 5 illustrates a block diagram of a receiving apparatus according to the present invention,

wherein, like or similar reference numerals indicate like or similar step features or means/modules.

DETAILED DESCRIPTION OF THE INVENTION The following detailed description of the preferred embodiments will refer to the accompanying drawings that form a part of the present invention. The accompanying drawings exemplarily show some particular embodiments capable of implementing the present invention. The exemplary embodiments are not intended to exhaust all embodiments according to the present invention. It may be appreciated that without departing from the scope of the present invention, other embodiments may also be used, or structural or logical amendments may be performed to the embodiments of the present invention. Therefore, the following detailed description is not limitative, and the scope of the present invention is defined by the appending claims.

In the current 3 GPP specification, the operation bandwidth of each low-cost MTC device is only 1.4MHz; therefore, it would be rather difficult to realize frequency diversity directly within this bandwidth range. On the other hand, from the perspective of a cell including one base station and a plurality of low-cost MTC devices, the bandwidth of the whole system still suffices to meet the requirements of applying the frequency diversity technology. Therefore, the present invention innovatively proposes a scheduling method based on bundling of a plurality of RBs, to conveniently obtain a frequency diversity gain on a low-cost MTC device.

Fig. 1 illustrates a time-frequency domain distribution diagram for RB bundling according to one specific embodiment of the present invention. It is seen from this figure that the base station maps data of one TB to four different RBs, and then assigns a different frequency to each of the RBs. It should be pointed out here that it does not affect implementation of the present invention how many RBs one TB is mapped to, and the frequency diversity can be implemented as long as the number of RBs is more than one. Typically, one TB may be mapped to 2, 4, or 8 RBs. The more the number of RBs is, the higher is the gain achieved, and correspondingly, the higher is the overhead for corresponding implementation. Hereinafter, for the convenience of depiction, an example of mapping to 4 RBs will be taken. It is further seen from this figure that each of the RBs is encapsulated into a subframe with a bandwidth of 1.4MHz, respectively, and then transmitted to a target MTC device in succession. The key lies in that each of the RBs, or each of the transmitted subframes, uses a different frequency.

It is seen from the above process that for transmitting/ receiving each of the RBs/ subframes, it still only uses a 1.4MHz bandwidth; but from the perspective of the overall transmission/ reception of one TB, it is implemented by using 4 different 1.4MHz bandwidths, i.e., the frequency diversity transmission for an individual MTC device is realized at the TB level. Therefore, the key improvement of the present invention lies in dividing one transmission into a plurality of dundled transmissions, with the frequency used in each bundled transmission different from each other; therefore, for an individual MTC device, a considerable frequency diversity gain may be achieved by receiving a plurality of times of transmission results at different frequencies.

Different rules may be adopted when the base station performs the TB-RB mapping. For example, all data of one TB may be repetitively mapped to a plurality of RBs, i.e., each RB contains the same data, and all data of the same TB are repetitively transmitted at different frequencies; or the data of one TB may be divided into a plurality of parts, and each of the parts is mapped to one RB, respectively, i.e., data of the same TB are transmitted by segments at different frequencies. For example, in the above embodiment, the data of one TB may be divided into 4 parts that are mapped to 4 RBs, respectively; then each of the RBs is assigned with a different frequency and transmitted to the target MTC device, respectively.

One advantage of the transmission method according to the present invention is the ability of a very flexible scheduling. For example, the parameter of mapping one TB to how many RBs may be configured by the base station, so as to adapt to different traffic types or channel conditions; or the parameter may be predefined in the system, and the advantage of pre-defining lies in that the base station and the MTC device may know the parameter without signaling interaction.

Besides, in order to further simplify the signaling overhead of scheduling, a preferred solution is setting a fixed offset between the frequencies of respective RBs. In this way, only with the parameter of frequency offset, the frequency variation between multiple times of bundled transmission can be depicted. Likewise, the parameter may also be configured by the base station or predefined.

Therefore, in a most simplified case, i.e., the number of TB mapping is predefined and the frequency offset is also fixed and predefined, the base station only needs to schedule transmission of the first RB, i.e., it is only required that the base station notify the MTC device of the time and frequency of transmission of the first RB via a first signaling message, then the MTC device would know the subsequent transmit frequency and transmit times based on the predefined parameters, then perform a corresponding reception operation, thereby restoring the TB transmitted by the base station. On the other hand, when the number of TB mapping and the frequency offset are configured by the base station, the two parameters and the scheduling information of the first RB may also be transmitted together to the MTC device via the first signaling message described above, so as to complete scheduling of multiple times of bundled transmission through one signaling message.

Besides, as a preferred solution, upon transmission, the base station can also use a different HARQ redundancy version (RV) for each RB, such that each transmission of the multiple times of bundled transmissions may be repeated individually.

Another preferred solution is to make each RB carry one segment of a same code block, respectively, i.e., all bundled RBs are jointly encoded; in this way, further encoding/ decoding gain may be obtained.

Correspondingly, according to the present invention, at the receiving end, the MTC device receives in succession a plurality of bundled RBs transmitted by the base station at a plurality of different frequencies based on the persistent schedule configuration or the abovementioned first message, and then restores the data of the TB transmitted by the base station. Depending on the condition of the transmitting end, the MTC device may decode each time after receiving a RB to obtain partial data of the TB and then combine them; or in the case of joint encoding at the transmitting end, the MTC device performs joint decoding to restore all data of the TB after receiving all RBs.

Fig. 2 shows a method of transmitting data to a user equipment in a base station in a wireless communication system according to the above specific embodiment, wherein the user equipment is a machine-type communication device, the method comprising the following steps:

S21 : the base station maps to-be-transmitted data to a first number of frequency resource blocks according to a first rule, wherein the first number is greater than 1 ;

522. the base station assigns a different frequency to each of the frequency resource blocks;

523. the base station encapsulates each of the frequency resource blocks into a different subframe to transmit to the user equipment in succession.

Fig. 3 shows a method of receiving data in a user equipment in a wireless communication system according to the above specific embodiment, wherein the user equipment is a machine-type communication device, the method comprising the following steps:

S31 : the user equipment receives in succession a first number of subframes transmitted from the base station, respectively, with each of the subframes having a frequency resource block encapsulated therein, wherein each of the frequency resource blocks is different from one another;

S32. restoring to-be-received data from the frequency resource blocks encapsulated in the first number of subframes.

Hereinafter, apparatuses corresponding to the above methods, as provided by the present invention, will be introduced with reference to block diagrams. In light of the fact that the unit/module features have a correspondence relationship with the method features in the above methods, their depictions will be brief.

Fig. 4 illustrates a block diagram of an apparatus S40 for transmitting data to a user equipment in a base station in a wireless communication system, wherein the user equipment is a machine-type communication device, the apparatus s40 comprising:

a mapping unit 4001 for mapping to-be-transmitted data to a first number of frequency resource blocks according to a first rule, wherein the first number is greater than 1 ;

an assigning unit 4002 for assigning a different frequency to each of the frequency resource blocks;

a transmitting unit 4003 for encapsulating each of the frequency resource blocks into a different subframe to transmit to the user equipment in succession.

Fig. 5 illustrates a block diagram of an apparatus S50 for receiving data in a user equipment in a wireless communication system, wherein the user equipment is a machine-type communication device, the apparatus S50 comprising:

a first receiving unit 501 for receiving in succession a first number of subframes transmitted from the base station, respectively, with each of the subframes having a frequency resource block encapsulated therein, wherein each of the frequency resource blocks is different from one another;

a restoring unit 5002 for restoring to-be-received data from the frequency resource blocks encapsulated in the first number of subframes.

The above has described the embodiments of the present invention. However, the present invention is not limited to a specific system, apparatus, or a specific protocol. Those skilled in the art may make various variations or modifications within the scope of the appended claims.

A person of normal skill in the art may understand and implement other variations of the disclosed embodiments through studying the description, the disclosed content, the drawings, and the appended claims. In the claims, the wording "comprise" does not exclude other elements and steps, and the wording "a" or "an" does not exclude plurality. In the present invention, "first" and "second" merely indicate a name, instead of representing a sequential relationship. In actual applications of the present invention, a spare part may perform the functions of a plurality of technical features as recited in the claims. Any reference sign in the claims should not be understood as a limitation to the scope.

Claims

What is claimed is

1. A method of transmitting data to a user equipmentin a base station in a wireless communication system, wherein the user equipment is a machine-type communication device, the method comprising the following steps:

b. mapping, by the base station, to-be-transmitted data to a first number of frequency resource blocks according to a first rule, wherein the first number is greater than 1 ;

c. assigning, by the base station, a different frequency to each of the frequency resource blocks;

d. encapsulating, by the base station, each of the frequency resource blocks into a different subframe to transmit to the user equipment in succession.

2. The method according to claim 1 , wherein there further comprises before said step b:

a. transmitting, by the base station, a first message to the user equipment, the first message being used for notifying the user equipment of time and frequency for transmitting a first of the frequency resource blocks.

3. The method according to claim 2, wherein in said step c, frequency interval between each of the frequency resource blocks is identical.

4. The method according to claim 3, wherein the identical frequency interval is configured by the base station.

5. The method according to claim 2, wherein in said step b, the first number is configured by the base station.

6. The method according to claim 2, wherein in said step b, the first number is 2, 4, or 8.

7. The method according to claim 4, wherein the first message further includes the identical frequency interval.

8. The method according to claim 5, wherein the first message further includes the first number.

9. The method according to claim 1 , wherein the first rule in said step b includes:

mapping all contents of the to-be-transmitted data to each of the frequency resource blocks.

10. The method according to claim 1 , wherein the first rule in the step b includes:

dividing the to-be-transmitted data into the first number of parts, each of the parts being mapped to one of the frequency resource blocks, respectively.

1 1. The method according to Claim 1 , wherein each of the frequency resource blocks uses a different hybrid automatic repeat request redundancy version.

12. The method according to claim 1 , wherein each of the frequency resource blocks carries a different segment of a same code block, respectively.

13. A method of receiving data in a user equipment in a wireless communication system, wherein the user equipment is a machine-type communication device, the method comprising the following steps:

B. receiving in succession, by the user equipment, a first number of subframes transmitted from the base station, respectively, with each of the subframes having a frequency resource block encapsulated therein, wherein each of the frequency resource blocks is different from one another;

C. restoring to-be-received data from the frequency resource blocks encapsulated in the first number of subframes.

14. The method according to claim 13, wherein there further comprises before the step B :

A. receiving, by the use equipment, a first message transmitted from the base station, the first message being used for notifying the user equipment of time and frequency for transmitting a first of the frequency resource blocks.

15. The method according to claim 14, wherein in said step B, frequency interval between each of the frequency resource blocks is identical.

16. The method according to claim 15, wherein the identical frequency interval is configured by the base station.

17. The method according to claim 14, wherein in said step B, the first number is configured by the base station.

18. The method according to claim 14, wherein in said step B, the first number is 2, 4, or 8.

19. The method according to claim 16, wherein the first message further includes the identical frequency interval.

20. The method according to claim 17, wherein the first message further includes the first number.

21. The method according to claim 13, wherein each of the frequency resource blocks carries a code block segment, respectively, and the step C further comprises after receiving the first number of subframes, restoring all of the to-be-received data from all of the frequency resource blocks encapsulated in the first number of subframes.

22. An apparatus for transmitting data to a user equipment in a base station in a wireless communication system, wherein the user equipment is a machine-type communication device, the apparatus comprising:

a mapping unit for mapping to-be-transmitted data to a first number of frequency resource blocks according to a first rule, wherein the first number is greater than 1 ;

an assigning unit for assigning a different frequency to each of the frequency resource blocks;

a transmitting unit for encapsulating each of the frequency resource blocks into a different subframe to transmit to the user equipment in succession.

23. The apparatus according to claim 22, further comprising:

a notifying unit for transmitting a first message to the user equipment, the first message being used for notifying the user equipment of time and frequency for transmitting a first of the frequency resource blocks.

24. The apparatus according to claim 23, wherein frequency interval between each of the frequency resource blocks is identical, and the first message further includes the identical frequency interval and/or the first number.

25. An apparatus for receiving data in a user equipment in a wireless communication system, wherein the user equipment is a machine-type communication device, the apparatus comprising:

a first receiving unit for receiving in succession a first number of subframes transmitted from the base station, respectively, with each of the subframes having a frequency resource block encapsulated therein, wherein frequency of each of the frequency resource blocks is different from one another;

a restoring unit for restoring to-be-received data from the frequency resource blocks encapsulated in the first number of subframes.

26. The apparatus according to claim 25, further comprising:

a second receiving unit for receiving a first message transmitted from the base station, the first message being used for notifying the user equipment of time and frequency for transmitting a first of the frequency resource blocks.

27. The apparatus according to claim 26, wherein frequency interval between each of the frequency resource blocks is identical, and the first message further includes the identical frequency interval and/or the first number.