CN106162836B

CN106162836B - Wireless communication method

Info

Publication number: CN106162836B
Application number: CN201510134737.7A
Authority: CN
Inventors: 孟艳; 韩锋; 刘建国; 陶涛; 武卓
Original assignee: Alcatel Lucent SAS
Current assignee: Alcatel Lucent SAS
Priority date: 2015-03-26
Filing date: 2015-03-26
Publication date: 2020-03-20
Anticipated expiration: 2035-03-26
Also published as: CN106162836A; WO2016151389A1; TW201642692A

Abstract

A method of activating a slave cell in a base station of an LTE communication system, wherein the slave cell is an unlicensed carrier, the method comprising: the base station carries out idle channel detection on the slave cell and determines whether the slave cell is idle; when the slave cell is idle, the base station transmits a preamble signal on the slave cell, wherein the preamble signal comprises information indicating that the base station activates the slave cell.

Description

Wireless communication method

Technical Field

The present invention relates to the field of communications technologies, and in particular, to the field of wireless communications technologies.

Background

In the field of wireless communication, generally, a traditional deployment method is that a system operates in a licensed band (licenedband), that is, the whole spectrum resource is reserved for the system to use. Typically, LTE communication systems operate using licensed frequency bands.

However, as wireless services further increase, the capacity and frequency band requirements for wireless communication systems also increase. In this case, the licensed band resource of the LTE system is relatively insufficient. Therefore, one of the recent research hotspots in the LTE field is how to utilize the resources of the unlicensed frequency band to offload the high-speed data traffic. This scheme is called as an LTE (Long term evolution) in Unlicensed spectrum (LTE-U) system

For example, in a typical scenario, the LTE system uses the frequency bands of the WiFi system. I.e. the situation where cells of the LTE system and cells of the WiFi system at least partly co-exist in geographical location. In this case, if the LTE system can use the WiFi frequency band to perform traffic offloading at some high-load moments, it is obvious that the performance of the system can be greatly improved, thereby effectively coping with high-load application scenarios.

Obviously, under the coexistence of LTE and WiFi systems, it is the most direct choice to utilize the authorized carrier of LTE system to assist the Access of the unlicensed carrier of WiFi system, so that the Licensed-Assisted Access (LAA) has become a hot spot in the mobile communication field recently.

By utilizing the LAA technology, the existing flow of the LTE system can be furthest used for realizing Carrier Aggregation (CA) scheduling of authorized carriers and unauthorized carriers. However, in order to be compatible with the system of the unlicensed carrier, some new mechanisms need to be introduced, and one of the first problems is how to implement Listen Before Transmission (LBT) of the unlicensed carrier in the LTE-LAA system.

For example, typically, a certain unlicensed carrier is aggregated as a Secondary Cell (Scell for short) of the LTE system and a certain licensed carrier as a Primary Cell (Pcell for short). The base station must determine that the Scell is not occupied by other systems before the Pcell attempts to activate the Scell. Therefore, the base station needs to perform Clear Channel Assessment (CCA) on the Scell to determine that the Channel is Clear, and then perform an operation of activating the Scell. However, when a Load Base Equipment (LBT) based mode is adopted, the Pcell will try to activate the Scell only when there is a Load to send, that is, it is uncertain when the Base station performs CCA, and it is also uncertain whether the Scell is idle at this time. In this case, how the base station notifies its User Equipment (User Equipment, UE for short) that a certain Scell has been activated/deactivated becomes a problem to be solved.

In the present discussion, there are two proposals for this problem. Firstly, the UE blindly decodes a PDCHH or a Cell Reference Signal (CRS for short) on the Scell, and if the PDCCH or CRS can be successfully decoded, it indicates that the Scell has been activated by the base station, and this method does not need to introduce new signaling, but requires the UE to perform an additional blind decoding operation on the Scell, which means a great power consumption, and considering that the use of the unlicensed carrier is sparse, such power consumption causes a great waste of the UE standby time; another method is to explicitly indicate activation of Scell by sending indication signaling on authorized carrier, i.e., Pcell, which has the advantages of saving power, but requiring introduction of new signaling interaction, and more importantly, because the UE does not know when the base station will send the indication signaling, the UE must buffer each subframe data on Scell, so that data transmission on Scell can be correctly processed after receiving the Pcell indication signaling, obviously, the buffer of the UE also causes great waste, and cannot be used as an ideal solution.

Therefore, the aim of the invention is to find a new method for activating Scell; this method needs to enable the base station to effectively notify the UE that a certain Scell has been activated in case of LAA; and avoid wasting power and buffer memory of the UE as much as possible.

Disclosure of Invention

In order to solve the above problems in the prior art, the present invention provides a new method for activating Scell. The base station adds the information indicating activation when sending the preamble signal of the Scell, so that the UE can timely and accurately know that the Scell is activated.

Specifically, according to a first aspect of the present invention, a method for activating a secondary cell in a base station of an LTE communication system is provided, wherein the secondary cell is an unlicensed carrier, and the method includes: the base station carries out idle channel detection on the slave cell and determines whether the slave cell is idle; when the slave cell is idle, the base station transmits a preamble signal on the slave cell, wherein the preamble signal comprises information indicating that the base station activates the slave cell.

Preferably, after the second step, the base station further transmits a first message on the primary cell, wherein the first message is used for notifying a first number of user equipments, and the base station is to communicate with the first number of user equipments on the secondary cell, wherein the first number of user equipments are user equipments scheduled by the base station to communicate on the cell.

More preferably, after the above step, the base station further transmits a second message on the primary cell, wherein the second message is used for notifying the first number of user equipments, and the base station will not communicate with the first number of user equipments on the secondary cell any more.

Preferably, wherein the information instructing the base station to activate the secondary cell comprises an orthogonal sequence related to a cell identity of the base station.

More preferably, the orthogonal sequence related to the cell identity of the base station comprises a primary synchronization signal sequence and/or a secondary synchronization signal sequence of the base station.

According to a second aspect of the present invention, a method for activating a secondary cell in a user equipment of an LTE communication system is provided, wherein the secondary cell is an unlicensed carrier, and the method comprises: the user equipment receives a preamble signal transmitted by a base station on the secondary cell, wherein the preamble signal comprises information indicating that the base station activates the secondary cell.

Preferably, after the above step, the method further includes the step of receiving, by the user equipment, a first message sent by the base station on a primary cell, where the first message is used to notify the user equipment that the base station is to communicate with the user equipment on the secondary cell.

More preferably, after the step, the method further includes the step of receiving, by the user equipment, a second message sent by the base station on the primary cell, where the second message is used to notify the user equipment that the base station will no longer communicate with the user equipment on the secondary cell.

According to a third aspect of the present invention, an apparatus for activating a secondary cell in a base station of an LTE communication system is provided, wherein the secondary cell is an unlicensed carrier, the apparatus comprising: a detection module, configured to perform idle channel detection on the secondary cell by the base station, and determine whether the secondary cell is idle; a preamble sending module, configured to send, by the base station, a preamble signal on the slave cell when the slave cell is idle, where the preamble signal includes information indicating that the base station activates the slave cell.

Preferably, the base station further includes a first sending module, configured to send a first message on the primary cell, where the first message is used to notify a first number of user equipments, and the base station is to communicate with the first number of user equipments on the secondary cell, where the first number of user equipments are user equipments scheduled by the base station to communicate on the cell.

More preferably, the base station further comprises a second sending module, configured to send a second message on the primary cell, where the second message is used for notifying the first number of user equipments that the base station will no longer communicate with the first number of user equipments on the secondary cell.

According to a fourth aspect of the present invention, an apparatus for activating a secondary cell in a user equipment of an LTE communication system is provided, wherein the secondary cell is an unlicensed carrier, and the method includes: a preamble receiving module, configured to receive a preamble signal sent by a base station on the secondary cell, where the preamble signal includes information indicating that the base station activates the secondary cell.

Preferably, the ue further includes a first receiving module, configured to receive a first message sent by the base station on a primary cell, where the first message is used to notify the ue that the base station is to communicate with the ue on the secondary cell.

More preferably, the ue further includes a second receiving module, configured to receive a second message sent by the base station on the primary cell, where the second message is used to notify the ue that the base station will no longer communicate with the ue on the secondary cell.

In the invention, the activated information is indicated by using the existing preamble signal, thereby ensuring that the UE does not need to carry out extra blind decoding operation and saving the electric quantity; by sending the preamble signal before sending the data, the UE is ensured to start to cache the sub-frame on the Scell only after determining that the Scell is activated, thereby saving the cache space; and in the preferred scheme, only the scheduled part of the UE can be notified, thereby reducing the waste of the overall performance of the system and achieving the aim of the invention.

Drawings

Other features, objects and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments thereof, which proceeds with reference to the accompanying drawings.

Fig. 1 shows a flow chart of a method of activating Scell in a base station of an LTE communication system according to the invention;

fig. 2 shows a flow chart of a method of activating Scell in user equipment of an LTE communication system according to the present invention;

fig. 3 shows a block diagram of an apparatus for activating a Scell in a base station of an LTE communication system according to the present invention;

fig. 4 shows a block diagram of a device for activating a Scell in a user equipment of an LTE communication system according to the present invention.

Wherein the same or similar reference numerals indicate the same or similar step features or means/modules.

Detailed Description

In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof. The accompanying drawings illustrate, by way of example, specific embodiments in which the invention may be practiced. The illustrated embodiments are not intended to be exhaustive of all embodiments according to the invention. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

Firstly, according to the application scenario of the present invention, there is an area covered by the LTE communication system, which includes at least one base station and a UE and contacts a licensed carrier between the two, i.e. Pcell. In addition, other unlicensed carriers exist in the area, which may also be used by other LTE or WiFi communication systems.

Since the base station operates in LBE mode, the base station performs CCA or ecca (extendedcca) operation on the unlicensed carrier only at a time when the base station considers it necessary to use the unlicensed carrier for transmission as Scell to confirm whether the unlicensed carrier is idle at this time. However, considering that the CCA/ECCA operation takes a very short time (minimum time about 20 microseconds), it is much less than one LTE subframe. Therefore, the CCA/ECCA operation of the base station may occur in one subframe of the Scell, which means that even if the base station confirms that the Scell is idle in the current subframe, the complete data transmission can only be transmitted in the next subframe. And the current subframe is not finished, so the base station must occupy the rest part of the current subframe in a certain mode, otherwise, in the rest time of the current subframe, if other systems also execute the CCA/ECCA operation, the base station also judges that the Scell is idle and available, and the collision is caused in the next subframe. In order to solve the problem that the base station occupies an unlicensed carrier in the current subframe, a scheme has been proposed in the industry: after confirming that the Scell is available, the base station transmits a preamble signal in the remaining time of the current subframe, so that other devices can sense that the carrier is occupied by a certain system when performing CCA/ECCA operation later. It is further proposed that the preamble signal may also be used for adjusting Automatic Gain Control (AGC) at the receiving end, and for this purpose, the UE may blindly decode the preamble signal on the Scell.

Based on the above scheme, the present invention further provides that information that can indicate that the base station has activated the Scell may be added to the preamble signal, so that when the UE blindly decodes the preamble signal, it can be known that the base station starts data transmission on the Scell in the next subframe. So that the UE can know exactly when to start buffering data on the Scell without buffering every subframe data on the Scell. Meanwhile, the blind decoding operation is originally performed by the UE, so that no new operation is introduced to cause power consumption. Thus, the object of the present invention is achieved.

On this basis, according to one embodiment of the present invention, a method for activating Scell in a base station of an LTE communication system is provided. Specifically, the method comprises the following steps:

firstly, the base station performs CCA/ECCA operation on the Scell to determine whether the Scell is idle.

And secondly, if the result is that the Scell is idle, the base station sends a preamble signal through the Scell, wherein the preamble signal comprises information for activating the Scell.

Preferably, the indication may be performed using an orthogonal sequence related to a Cell identity (Cell ID) of the base station. Typically, a Primary Synchronization Signal (PSS) sequence and/or a Secondary Synchronization Signal (SSS) sequence of the base station may be used for indication.

Furthermore, after the second step, the base station may also send a first message on the Pcell informing those UEs scheduled on the Scell with which the base station will communicate on the Scell. The method has the advantages that only part of the UE is scheduled on the Scell, so that all the UE is not required to cache data on the Scell, and the UE which needs to cache the data of the Scell can be directly indicated on the Pcell through signaling, so that the cache space of other UE is saved.

Further, when the base station is about to deactivate the Scell, the base station may also send a second message on the Pcell informing those UEs scheduled on the Scell that the base station will no longer communicate with them on the Scell. Thus, the UEs know that the data on the Scell does not need to be buffered from the next subframe, thereby releasing the buffer space.

Fig. 1 shows a flow chart of activating Scell according to the above embodiment, including:

s11, the base station carries out idle channel detection on the slave cell and determines whether the slave cell is idle;

s12, when the slave cell is idle, the base station sends a preamble signal on the slave cell, wherein the preamble signal comprises information indicating that the base station activates the slave cell.

Correspondingly, according to another embodiment of the invention, a method for activating the Scell in the UE of the LTE communication system is provided. Specifically, the method comprises the following steps:

the UE receives a preamble signal sent by the base station on the Scell, where the preamble signal includes information indicating that the base station activates the Scell.

Further, the UE receives a first message sent by the base station on the Pcell, where the first message is used to notify the UE that the base station is to communicate with the UE on the Scell.

Preferably, the UE may then receive a second message sent by the base station on the Pcell, the second message informing the UE that the base station will no longer communicate with the UE on the Scell.

Fig. 2 shows a flow chart of activating Scell according to the above embodiment, including:

s21, the user equipment receives a preamble signal sent by a base station on the secondary cell, wherein the preamble signal comprises information indicating that the base station activates the secondary cell.

The following describes the apparatus corresponding to the above method provided by the present invention with reference to the drawings, and the unit/device features thereof are corresponding to the step features in the above method, which will be simplified.

Fig. 3 shows a device 30 for activating Scell in a base station of an LTE communication system according to the present invention, the device comprising:

a detecting module 3001, configured to perform idle channel detection on the secondary cell by the base station, and determine whether the secondary cell is idle;

a preamble transmitting module 3002, configured to transmit, by the base station, a preamble signal on the slave cell when the slave cell is idle, where the preamble signal includes information indicating that the base station activates the slave cell.

Fig. 4 shows an apparatus 40 for activating Scell in a UE of an LTE communication system according to the present invention, the apparatus comprising:

a preamble receiving module 4001, configured to receive a preamble signal sent by a base station on the secondary cell, where the preamble signal includes information indicating that the base station activates the secondary cell.

While embodiments of the present invention have been described above, the present invention is not limited to a particular system, device, and protocol, and various modifications and changes may be made by those skilled in the art within the scope of the appended claims.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art from a study of the specification, the disclosure, the drawings, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. In the present invention, "first" and "second" merely indicate names and do not represent order relationships. In practical applications of the invention, one element may perform the functions of several technical features recited in the claims. Any reference signs in the claims shall not be construed as limiting the scope.

Claims

1. A method of activating a slave cell in a base station of an LTE communication system, wherein the slave cell is an unlicensed carrier, the method comprising:

a. the base station carries out idle channel detection on the slave cell and determines whether the slave cell is idle;

b. when the slave cell is idle, the base station transmits a preamble signal on the slave cell, wherein the preamble signal comprises information indicating that the base station activates the slave cell.

2. The method of claim 1, further comprising, after said step b,

c. the base station transmits a first message on a primary cell, wherein the first message is used for informing a first number of user equipment, the base station is to communicate with the first number of user equipment on the secondary cell, and the first number of user equipment is the user equipment scheduled by the base station to communicate on the secondary cell.

3. The method of claim 2, further comprising, after said step c,

d. the base station transmitting a second message on the primary cell, wherein the second message is for the informing of the first number of user equipments with which the base station will no longer communicate on the secondary cell.

4. The method of claim 1, wherein the information instructing the base station to activate the secondary cell comprises an orthogonal sequence related to a cell identity of the base station.

5. The method of claim 4, wherein the orthogonal sequence related to the cell identity of the base station comprises a primary synchronization signal sequence and/or a secondary synchronization signal sequence of the base station.

6. A method of activating a slave cell in a user equipment of an LTE communication system, wherein the slave cell is an unlicensed carrier, the method comprising:

A. the user equipment receives a preamble signal transmitted by a base station on the secondary cell, wherein the preamble signal comprises information indicating that the base station activates the secondary cell.

7. The method of claim 6, further comprising, after said step A,

B. the user equipment receives a first message sent by the base station on a primary cell, wherein the first message is used for informing the user equipment, and the base station is to communicate with the user equipment on the secondary cell.

8. The method of claim 7, further comprising, after said step B,

C. and the user equipment receives a second message sent by the base station on the primary cell, wherein the second message is used for informing the user equipment that the base station is not communicated with the user equipment on the secondary cell any more.

9. An apparatus for activating a slave cell in a base station of an LTE communication system, wherein the slave cell is an unlicensed carrier, the apparatus comprising:

a detection module, configured to perform idle channel detection on the secondary cell by the base station, and determine whether the secondary cell is idle;

a preamble sending module, configured to send, by the base station, a preamble signal on the slave cell when the slave cell is idle, where the preamble signal includes information indicating that the base station activates the slave cell.

10. The apparatus of claim 9, further comprising,

a first sending module, configured to send a first message on a primary cell by the base station, where the first message is used to notify a first number of user equipments, with which the base station is to communicate on the secondary cell, and the first number of user equipments is user equipments scheduled by the base station to communicate on the secondary cell.

11. The apparatus of claim 10, further comprising,

a second sending module, configured to send a second message on the primary cell by the base station, where the second message is used for notifying the first number of user equipments that the base station will no longer communicate with the first number of user equipments on the secondary cell.

12. An apparatus for activating a slave cell in a user equipment of an LTE communication system, wherein the slave cell is an unlicensed carrier, the apparatus comprising:

a preamble receiving module, configured to receive a preamble signal sent by a base station on the secondary cell, where the preamble signal includes information indicating that the base station activates the secondary cell.

13. The apparatus of claim 12, further comprising,

a first receiving module, configured to receive, by the user equipment, a first message sent by the base station on a primary cell, where the first message is used to notify the user equipment that the base station is to communicate with the user equipment on the secondary cell.

14. The apparatus of claim 13, further comprising,

a second receiving module, configured to receive, by the user equipment, a second message sent by the base station on a primary cell, where the second message is used to notify the user equipment that the base station will no longer communicate with the user equipment on the secondary cell.