CN106304375B

CN106304375B - Wireless communication method

Info

Publication number: CN106304375B
Application number: CN201510281912.5A
Authority: CN
Inventors: 刘建国; 韩锋; 孟艳; 陶涛; 谷俊嵘; 武卓; 王钧
Original assignee: Nokia Shanghai Bell Co Ltd
Current assignee: Nokia Shanghai Bell Co Ltd
Priority date: 2015-05-28
Filing date: 2015-05-28
Publication date: 2019-12-13
Anticipated expiration: 2035-05-28
Also published as: CN106304375A

Abstract

A method for determining a free channel sensing threshold value in user equipment of an LTE communication system, wherein the free channel is an unlicensed carrier channel, and the method comprises the following steps: the user equipment receives a first message sent from a base station, wherein the first message contains a first adjusting value used for adjusting the threshold value; and the user equipment determines the threshold value according to the first adjusting value and the maximum transmitting power of the user equipment.

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 (licensed band), that is, the entire spectrum resource is reserved for the system. 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.

Typically, before a User Equipment (UE) tries to transmit data on a certain unlicensed carrier Channel, it must first determine that the Channel is not occupied by other devices, and therefore, Clear Channel Association (CCA) operation must be performed to determine whether the Channel is currently idle by measuring the current transmit power level of the Channel. Specifically, whether the UE can occupy the channel is determined by comparing the measured transmit power level with a CCA threshold (CCAthreshold, abbreviated as CCA TL) of the UE, and obviously, whether the UE can occupy the channel is closely related to a setting value of CCA TL of the UE. Considering the difference in the transmission power of different devices, the existing technical specifications specify the setting value for CCA TL as follows:

For the device with the emission Power equal to or more than 23dBm Effective omnidirectional radiation Power (EIRP), the CCA TL value is set as the lower limit value of the system, namely-73 dBm/MHz;

For devices with transmit power below 23dBm EIRP, the CCA TL value is determined by the following equation (1):

TL＝-73dBm/MHz+(23dBm-P_H)/(1MHz) (1)

Wherein P is_HRepresents the most of the UEA large transmission power.

Obviously, the method considers the equipment with smaller compensation transmitting power, avoids the occurrence of high-power equipment obtaining higher access opportunity, and ensures the fairness of channel access. Is successful in existing WiFi systems.

however, the situation is different when considering the scenario of LTE-LAA. Firstly, the WiFi system mainly considers data services, while the LTE system can carry multiple services, the requirements of the same UE for channel performance are actually different when carrying different services, and determining the CCA TL value only according to the transmission power inevitably results in that channels available under some services are not available for other services, thereby resulting in wrong channel occupation. More importantly, the channel occupation of the WiFi system is full bandwidth, and for the LTE system of frequency division multiplexing, the UE may only use a partial frequency band of the unlicensed carrier channel, and the measurement of CCA operation performed by the UE is the aggregate value of the transmission powers of all devices on the entire frequency band, so that the actual channel occupation situation cannot be accurately reflected as a result. Thirdly, each node in the WiFi system is equal, while the LTE system has a requirement for scheduling access opportunities of each UE separately because of centralized control of the base station.

It is therefore an object of the present invention to find a new method of determining the value of CCA TL; the method needs to enable the UE to meet different service requirements when performing CCA operation under the condition of LTE-LAA; and the system is compatible with frequency division multiplexing, and can meet the requirement of centralized scheduling of a base station.

Disclosure of Invention

To solve the above problems in the prior art, the present invention proposes a new method for determining the CCA TL value. The method for sending the TL adjustment value to the UE by the base station ensures that the base station can control the CCA operation of the UE according to the actual situation.

Specifically, according to a first aspect of the present invention, a method for determining an idle channel sensing threshold in a user equipment of an LTE communication system is provided, where the idle channel is an unlicensed carrier channel, and the method includes: the user equipment receives a first message sent from a base station, wherein the first message contains a first adjusting value used for adjusting the threshold value; and the user equipment determines the threshold value according to the first adjusting value and the maximum transmitting power of the user equipment.

preferably, the second step further includes determining the threshold value according to the bandwidth of the idle channel sensing operation.

More preferably, the second step further comprises determining the threshold value according to the following formula:

TL＝max(TL_min，min(TL_max，-73dBM+(23dBm-P_H)+10×log₁₀B+Δ_TL))

wherein TL represents the threshold value, TL_minRepresents the lower limit of the threshold value, TL_maxRepresents the upper limit of said threshold value, P_HRepresents the maximum transmission power of the user equipment, B represents the bandwidth of the idle channel sensing operation, Delta_TLrepresenting the first adjustment value.

More preferably, the bandwidth of the idle channel sensing operation is the bandwidth of the unlicensed carrier channel.

More preferably, the bandwidth of the idle channel sensing operation is the bandwidth allocated to the user equipment by the base station.

More preferably, the first message and the second message are radio resource control messages.

more preferably, the first message and the second message are layer 1 messages.

According to a second aspect of the present invention, a method for assisting a user equipment in determining a free channel sensing threshold in a base station of an LTE communication system is provided, where the free channel is an unlicensed carrier channel, and the method includes: the base station determines a first adjustment value for adjusting the threshold value; and the base station sends a first message to the user equipment, wherein the first message comprises the first adjustment value.

Preferably, the first step further includes the base station determining the first adjustment value according to the following rule: when the access opportunity of the user equipment needs to be improved, increasing the first adjusting value; and when the link performance of the user equipment needs to be improved, reducing the first adjustment value.

Preferably, after the second step, the base station further sends a second message to the user equipment, where the second message includes the bandwidth of the idle channel sensing operation.

More preferably, the first message and the second message are layer 1 messages.

according to a third aspect of the present invention, an apparatus for determining a clear channel sensing threshold in a user equipment of an LTE communication system is provided, where the clear channel is an unlicensed carrier channel, and the apparatus includes: a receiving module, configured to receive a first message sent from a base station by the user equipment, where the first message includes a first adjustment value used to adjust the threshold value; a determining module, configured to determine, by the user equipment, the threshold according to the first adjustment value and the maximum transmission power of the user equipment.

According to a fourth aspect of the present invention, an apparatus for assisting a user equipment in determining a free channel sensing threshold in a base station of an LTE communication system is provided, where the free channel is an unlicensed carrier channel, and the apparatus includes: a determining module, configured to determine, by the base station, a first adjustment value for adjusting the threshold value; a sending module, configured to send, by the base station, a first message to the user equipment, where the first message includes the first adjustment value.

in the invention, the base station sends the TL adjustment value to the UE, so that the base station can adjust the CCA operation of the UE according to the actual requirement, can be set differently according to the business situation and can also be used for adjusting the access probability, and the practical situation of the frequency division multiplexing system is met by introducing the frequency range of the CCA operation into the CCA TL value calculation method, thereby 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 determining a clear channel sensing threshold in a user equipment of an LTE communication system according to the invention;

Fig. 2 shows a flow chart of a method for assisting a user equipment in determining a clear channel perception threshold in a base station of an LTE communication system according to the invention;

fig. 3 shows a block diagram of an apparatus for determining a clear channel sensing threshold in a user equipment of an LTE communication system according to the present invention;

fig. 4 shows a block diagram of an apparatus for assisting a user equipment in determining a clear channel perception threshold in a base station 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.

First, 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. In addition, other unlicensed carriers exist in the area, which may also be used by other LTE or WiFi communication systems.

When the base station considers that the UE needs to use the unlicensed carrier channel for transmission, the UE may perform CCA operation on the unlicensed carrier channel to confirm whether the unlicensed carrier channel is free for use at this time. The result of the CCA operation is to determine whether the channel is clear by comparing the measured transmit power value with the CCA TL value. Therefore, firstly, the UE needs to determine the CCA TL value used for this CCA operation, and according to the method of the present invention, the determination of the CCA TL value needs to be adjusted according to the indication of the base station, in addition to considering the maximum transmission power of the UE, typically the maximum transmission power of the UE in a burst transmission, according to the method of the prior art, which is hereinafter referred to as a first adjustment value. And after receiving the first message, the UE acquires the first adjustment value and determines the CCA TL value of the CCA operation according to the maximum transmission power of the UE. The above is the basic solution of the present invention. Through the first adjustment value determined by the base station, the base station can realize various control modes and meet the requirements of various services and scheduling, thereby achieving the aim of the invention.

Based on the above scheme, the present invention further provides that a concept of bandwidth may be introduced in the CCA operation, that is, the bandwidth for CCA operation may also be considered in the method for determining the CCA TL value, so that a more accurate channel sensing result may be obtained in a frequency division multiplexing system, thereby avoiding breaking fairness of channel access under the condition of LTE-FDD system access.

On this basis, according to one embodiment of the present invention, a method of determining a CCA TL value is presented. Specifically, the threshold value is determined according to the following formula (2):

TL＝max(TL_min，min(TL_max，-73dBM+(23dBm-P_H)+10×log₁₀B+Δ_TL)) (2)

Wherein,TL represents the threshold value, TL_minrepresents the lower limit of the threshold value, TL_maxThe value of the upper/lower limit may be predetermined by the system, or configured by a base station through radio resource Control (RRC for short) signaling, so as to limit the determined threshold within a reasonable range. P_Hrepresents the maximum transmit power of the UE, B represents the bandwidth of the CCA operation, Δ_TLRepresenting the first adjustment value.

Further, B in equation (2), the value of the bandwidth over which the CCA operates, may be determined in several ways.

For example, the value of B may be the bandwidth of the unlicensed carrier channel, that is, the CCA operation is performed on the entire channel frequency band, which is closest to the prior art and may be applied to a time division multiplexing system.

For another example, the value of B may be a bandwidth allocated to the UE by the base station through the resource allocation message, which is typically applied to a frequency division multiplexing system, so that the UE can perform channel sensing on the bandwidth to be used, thereby obtaining the most accurate result.

the value of B may also be explicitly indicated to the UE by the base station through a second message, which is mainly to give a specific bandwidth range for the purpose of flexible scheduling by the base station, so as to implement various centralized control functions at the base station side.

Without loss of generality, the first message and the second message in the above embodiments may be RRC signaling messages or layer 1(layer 1) messages.

Fig. 1 shows a flow chart for determining a CCA TL value according to the above embodiment, including:

S11, the user equipment receives a first message sent from a base station, wherein the first message comprises a first adjusting value used for adjusting the threshold value;

And S12, the user equipment determines the threshold value according to the first adjustment value and the maximum transmission power of the user equipment.

correspondingly, according to another embodiment of the invention, a method for assisting in determining a CCA TL value in a base station of an LTE communication system is provided. Specifically, the method comprises the following steps:

The base station determines the first adjustment value mentioned above and sends the first adjustment value to the UE through a first message.

Further, the base station should determine the first adjustment value according to the following principle:

1. and if the probability of accessing the unlicensed carrier channel by the UE needs to be improved, increasing the first adjustment value. It can be seen from formula (2) that the CCATL value of the UE is increased at this time, that is, the UE is allowed to access the channel even when the transmission power in the channel is measured to be high, so that the access delay performance of the UE is improved to meet the requirement of real-time service.

2. The first adjustment value is decreased if needed to improve the link performance of the UE. It can be seen from the formula (2) that the CCA TL value of the UE is reduced at this time, that is, the UE is required to perform channel sensing in a larger range, so as to ensure that the channel is also unoccupied in the larger range, further avoiding co-channel interference, and thus improving link performance. In addition, other devices may also be provided with more access opportunities.

Similarly, the base station may then send a second message to the UE to inform of the specific value range of the CCA operation bandwidth B.

Also without loss of generality, the first message and the second message in the above embodiments may be RRC signaling messages or layer 1(layer 1) messages.

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

S21, the base station determines a first adjusting value for adjusting the threshold value;

S22, the base station sends a first message to the user equipment, wherein the first message comprises the first adjusting value.

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 an apparatus 30 for determining a clear channel sensing threshold in a UE of an LTE communication system according to the present invention, the apparatus comprising:

A receiving module 3001, configured to receive, by the user equipment, a first message sent from a base station, where the first message includes a first adjustment value used to adjust the threshold value;

A determining module 3002, configured to determine, by the user equipment, the threshold according to the first adjustment value and the maximum transmission power of the user equipment.

Fig. 4 shows an apparatus 40 for assisting a UE in determining a clear channel perception threshold in a base station of an LTE communication system according to the present invention, the apparatus comprising:

A determining module 4001, configured to determine, by the base station, a first adjustment value for adjusting the threshold value;

A sending module 4002, configured to send, by the base station, a first message to the user equipment, where the first message includes the first adjustment value.

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 for determining a free channel sensing threshold value in user equipment of an LTE communication system, wherein the free channel is an unlicensed carrier channel, and the method comprises the following steps:

a. The user equipment receives a first message sent from a base station, wherein the first message contains a first adjusting value used for adjusting the threshold value;

b. and the user equipment determines the threshold value according to the first adjusting value, the maximum transmitting power of the user equipment and the bandwidth of the idle channel sensing operation.

2. The method of claim 1, wherein step b further comprises determining the threshold value according to the following formula:

TL＝max(TL_min，min(TL_max，-73dBM+(23dBm-P_H)+10×log₁₀B+Δ_TL))

3. the method of claim 1, wherein a bandwidth of the clear channel sensing operation is a bandwidth of the unlicensed carrier channel.

4. The method of claim 1, wherein a bandwidth of the clear channel aware operation is a bandwidth allocated to the user equipment by the base station.

5. The method of claim 1, wherein a bandwidth of the clear channel aware operation is determined by the base station and signaled to the user equipment via a second message.

6. The method of claim 5, wherein the first message and the second message are radio resource control messages.

7. The method of claim 5, wherein the first message and the second message are layer 1 messages.

8. A method for assisting user equipment in determining a free channel perception threshold value in a base station of an LTE communication system, wherein the free channel is an unlicensed carrier channel, and the method comprises the following steps:

A. the base station determines a first adjustment value for adjusting the threshold value;

B. the base station sends a first message to the user equipment, wherein the first message comprises the first adjustment value;

C. And the base station sends a second message to the user equipment, wherein the second message contains the bandwidth of the idle channel sensing operation.

9. The method of claim 8, wherein in the step a, the base station determines the first adjustment value according to the following rule:

When the access opportunity of the user equipment needs to be improved, increasing the first adjusting value;

And when the link performance of the user equipment needs to be improved, reducing the first adjustment value.

10. The method of claim 8, wherein the first message and the second message are radio resource control messages.

11. The method of claim 8, wherein the first message and the second message are layer 1 messages.

12. an apparatus for determining a clear channel sensing threshold in a user equipment of an LTE communication system, wherein the clear channel is an unlicensed carrier channel, the apparatus comprising:

A receiving module, configured to receive a first message sent from a base station by the user equipment, where the first message includes a first adjustment value used to adjust the threshold value;

a determining module, configured to determine, by the user equipment, the threshold according to the first adjustment value, the maximum transmission power of the user equipment, and the bandwidth of the idle channel sensing operation.

13. an apparatus for assisting a user equipment in determining a clear channel perception threshold in a base station of an LTE communication system, wherein the clear channel is an unlicensed carrier channel, the apparatus comprising:

A determining module, configured to determine, by the base station, a first adjustment value for adjusting the threshold value;

A sending module, configured to send, by the base station, a first message and a second message to the user equipment, where the first message includes the first adjustment value, and the second message includes a bandwidth of the idle channel sensing operation.