Method and a communication device for clear channel assessment and a vehicle with such a device
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- CONTINENTAL AUTOMOTIVE TECHNOLOGIES GMBH
- Filing Date
- 2024-08-22
- Publication Date
- 2026-07-01
AI Technical Summary
Existing clear channel assessment methods in wireless communication are deterministic and lack flexibility, which can lead to inefficient medium access and potential interference in unlicensed spectra.
A non-deterministic clear channel assessment method that uses a non-decreasing function f(P) to map measured energy levels to a probability range [0,1], combined with a random variable u, to determine channel idle status, introducing uncertainty and adaptability in channel assessment.
The proposed method enhances the flexibility and adaptability of clear channel assessment, reducing the likelihood of interference and improving medium access efficiency, especially in unlicensed spectra.
Smart Images
Figure EP2024073544_06032025_PF_FP_ABST
Abstract
Description
[0001] METHOD AND A COMMUNICATION DEVICE FOR CLEAR CHANNEL ASSESSMENT AND A VEHICLE WITH SUCH A DEVICE
[0002] BACKGROUND
[0003] The invention relates to a computer implemented method and a communication device for a clear channel assessment and a vehicle with such a device.
[0004] In wireless communication, Listen Before Talk (LBT) is a fundamental distributed mechanism for medium access in an unlicensed spectrum. Directional LBT (dLTB) is a generalization applicable to high frequencies where more directional transmissions (e.g., beamforming) is used.
[0005] The principle of LBT is to sense the activity or energy in a frequency channel to determine whether or not the channel is being used or not (busy or idle). This is referred to as a clean channel assessment (CCA). When a channel is idle (= clear), a transmission on that channel can be started without interfering (too much) with another transmission on that channel. When the channel is busy, the transmission is normally halted until the channel is idle again.
[0006] A clear channel assessment may be based on comparing the measured energy or activity with a threshold. A measured energy or activity below the threshold would then indicate the channel being idle. A measured energy or activity above the threshold would then indicate the channel being busy.
[0007] The objective of the invention is to improve the clean channel assessment procedure for wireless communication.
[0008] SUMMARY
[0009] The objective of the invention is met by providing a method according to claim 1 and a communication device according to claim 10.
[0010] According to a first aspect a computer implemented method for a clear channel assessment is provided, comprising the steps of: a) obtaining a non-decreasing function f(P) that maps a measured energy level P on a domain [Pmin, Pmax] to a codomain [0,1 ], wherein Pmin is a minimum measured energy level and Pmax is a maximum measured energy level; b) measuring an energy level in a communication channel; c) determining or calculating f(Pmeas) and generating a value u, wherein u is an random variable; and, d) outputting information indicating that said channel is idle if f(Pmeas) < u; and information indicating said channel is busy when f(Pmeas) > u.
[0011] The function f(P) may be any function that maps a measured energy level P on a domain [Pmin, Pmax] to a codomain [0,1 ], wherein Pmin is a minimum measured energy level and Pmax is a maximum measured energy level.
[0012] In one or more embodiments, the energy level in a channel is the energy in a bandwidth of electro-magnetic frequencies associated with said channel,
[0013] In one or more embodiments, the energy level P is a power (J / s) in a channel or bandwidth, received by a wireless transceiver or receiver. Alternatively a power density (W / Hz) may be determined as energy level P by a wireless transceiver or receiver in a channel or bandwidth. Both are known in the art. Also, an average value (i.e. over a certain bandwidth and / or time period) of said power or said power density may be used.
[0014] In one or more embodiments, Pmax is the maximum energy level measured in a predetermined time period in the relevant channel or bandwidth. Alternatively, Pmax is the maximum energy level that, according to the appropriate standard, may be transmitted in the relevant channel or bandwidth.
[0015] In one or more embodiments, Pmin is the minimum energy level measured in a predetermined time period in the relevant channel or bandwidth. Alternatively, Pmin equals zero.
[0016] The function f(P) may be any function as long as it is a non-decreasing function. It may be continuous or not. It needs to map the domain onto the image as follows: f(P):[Pmin , Pmax] [0,1 ], In one or more embodiments, it can be a linear function, a non-linear function, such as the CDF of a gaussian function centred at any arbitrary point between Pmin and Pmax.
[0017] In one or more embodiments the value of f(P) may be referred to as a probability of P with a value in the range [0,1 ], The value u is a random variable. In one or more embodiments, the value u is a uniform random variable, i.e. u is a random number between 0 and 1 and each value of u has the same probability of being generated. In one or more other embodiments, the value u is a normally distributed random variable.
[0018] Because of the comparison of f(P) with u, the clean channel assessment according to the invention is non-determ inistic. By using function f(P) and u, uncertainty or flexibility is introduced in the clean channel assessment. The selection of the function f(P) will influence the outcome of the clean channel assessment. The selected f(P) may be optimised for a certain communication scenario or access to the communication medium.
[0019] According to one or more embodiment, the method comprises the step of: e) starting a data transmission based on said information.
[0020] When the information indicated that the channel is idle, data transmission may start, for example, with a handshake procedure. On the other hand, when the information indicated that the channel is busy, the data transmission may be postponed, may not start or may be halted until new information is available that indicates that the channel is idle.
[0021] According to one or more embodiment, steps b)-d), and optionally e) after the transmission has ended, are repeated. When the information indicates that the channel is busy, a new clean channel assessment according to the invention may be executed.
[0022] The time period between two clean channel assessment may have a predetermined value or may be variable. For example, the more often a clean channel assessment has resulted in information indicating that the channel is busy, the shorter this time period may be. When the information indicates that the channel is idle, a data transmission may be started. After the transmission of the data, the clean channel assessment may be executed again when more data needs to be transmitted.
[0023] According to one or more embodiments, said function f(P) is defined as: f(P) = (P - Pmin) I (Pmax-Pmin). With this function f(P), the probability that the information indicates that the channel is busy increases linear with the measured energy level Pmeas.
[0024] According to one or more embodiments, said function f(P) is defined as: f(P) = 0 when P<Pa; f(P) = 1 when P>Pb; f(P) = (P-Pa) / (Pb-Pa) when Pa<P<Pb; wherein Pa is a value between Pmin and Pb, and Pb is a value between Pa and Pm ax.
[0025] According to one or more embodiments, step a) comprises selecting a function f(P) from a library comprising one or more non-decreasing functions f(x) that maps x on a domain [Xmin, Xmax] to a codomain [0,1 ], wherein Xmin is a minimum value of x and Xmax is a maximum value of x. It may be advantageous to provide multiple suitable functions, such that quickly an appropriate function may be selected, for example based on the traffic load, movement between sender and receiver, and / or weather conditions.
[0026] According to one or more embodiments, the communication channel operates at one or more wavelengths or a wavelength band in the millimetre band and / or the communication channel operates at a wavelength band (or one or more wavelengths) in an unlicensed spectrum. In the millimetre wavelength (mmW) band electromagnetic waves may have wavelengths from ten to one millimetre.
[0027] According to another aspect of the invention, a computer program is provided, comprising instructions which, when the program is executed by a computer processor, cause the computer processor to carry out the steps of any of the methods as described in this document. Furthermore, a computer-readable medium having stored thereon said computer program is provided.
[0028] According to another aspect of the invention, a communication device is provided comprising:
[0029] - a transceiver arranged for transmitting data on a communication channel and for measuring an energy level in said communication channel; and,
[0030] - a computer processor and a computer-readable medium as described above arranged for carrying out the steps of any of the methods as described in this document, using said transceiver.
[0031] According to one or more embodiments, a vehicle with a communication device as described in this document is provided. The working, advantages and embodiments of the communication device and the vehicle as well as the working, advantages and embodiments of the computer program and computer-readable medium, correspond with the working, advantages and embodiments of the method as described in this document, mutatis mutandis.
[0032] BRIEF DESCRIPTION OF THE DRAWINGS
[0033] For a more complete understanding of the present invention, reference in the following description is made to the accompanying drawings in which:
[0034] Figure 1 illustrates a deterministic clean channel assessment as known in the art;
[0035] Figure 2 illustrates a non-determ inistic clean channel assessment according to one or more embodiments of the invention;
[0036] Figure 3 illustrates a non-determ inistic clean channel assessment according to one or more other embodiments of the invention;
[0037] Figure 4 shows a schematic overview of a method for a clear channel assessment according to one or more embodiments of the invention;
[0038] Figure 5 shows a schematic overview of a vehicle with a communication device to one or more embodiments of the invention.
[0039] DETAILED DESCRIPTION
[0040] Figure 1 illustrates how clean channel assessments are made as known in the art. A energy level P is measured in a communication channel. This Pmeas will be between a minimum energy level Pmin and a maximum energy level Pmax. When the Pmeas is below a threshold energy level T (Pmeas < T), it is concluded that the channel is idle. When the Pmeas is above the threshold energy level T (Pmeas > T), it is concluded that the channel is busy. It may be concluded from figure 1 that the measured energy level determines the outcome of the clear channel assessment.
[0041] Figure 2 illustrates a non-determ inistic clean channel assessment according to one or more embodiments of the invention. In figure 2, a measured energy level Pmeas is mapped on a function f(P), i.e. to each value of Pmeas one value between 0 and 1 is assigned.
[0042] In the example of figure 2, P1 is the currently measured energy level in a certain channel. The value of f(P1 ) can be calculated as 0,75. A value of u may be randomly generated as 0,8. In that case, the channel is considered to be idle or clear. It may be concluded from figure 2, that a clean channel assessment based on a comparison of a function f(P) as defined in this document and a random variable u is non-determ inistic.
[0043] Figure 3 illustrates another example of the function f(P). In this example, the function f(P) is defined as: f(P) = 0 when P<Pa; f(P) = 1 when P>Pb; f(P) = (P-Pa) / (Pb-Pa) when Pa<P<Pb; wherein Pa is a value between Pmin and Pb, and Pb is a value between Pa and Pm ax.
[0044] With this function f(P), the probability that the information indicates that the channel is busy, increases linear with the measured energy level Pmeas between Pa and Pb. It also comprises an interval between Pmin and Pa in which it is certain that the information indicates that the channel is idle. Furthermore, it comprises an interval between Pb and Pmax in which it is certain that the information indicates that the channel is busy.
[0045] It may be understood that the function f(P) may be any non-decreasing function f(P) that maps Pmeas on a domain [Pmin, Pmax] to a codomain [0,1 ], wherein Pmin is a minimum value of Pmeas and Pmax is a maximum value of Pmeas. The function f(P) may be a linear function, a non-linear function, such as the CDF of a gaussian function centred at any arbitrary point between Pmin and Pmax.
[0046] Figure 4 shows a schematic overview of a method 400 for a clear channel assessment according to one or more embodiments of the invention. The method 400 comprises the following steps:
[0047] Step 410: obtaining a non-decreasing function f(P) that maps a measured energy level P on a domain [Pmin, Pmax] to a codomain (0,1 ), wherein Pmin is a minimum measured energy level and Pmax is a maximum measured energy level;
[0048] Step 420: measuring an energy level in a communication channel;
[0049] Step 430: determining or calculating f(Pmeas) and generating a value u, wherein u is a random variable; and, Step 440: outputting information indicating that said channel is idle if f(Pmeas) < u; and information indicating said channel is busy when f(Pmeas) > u.
[0050] In one or more embodiments, the method 400 may further comprise step 450: starting a data transmission based on said information. When the information indicates that the channel is idle, data transmission is started. When the information indicates that the channel is busy, no data is transmitted and the clean channel assessment may be executed again.
[0051] In one or more embodiments, the method 400 may be implemented in a Listen Before Talk (LBT) or a directional LBT (dLTB) procedure.
[0052] As indicated in figure 4, steps 420, 430, 440 (and optionally step 450) may be repeated. For example, when in step 440 the information indicates that the channel is busy. These steps may be repeated until the channel is (indicated as) idle and data transmission is started. Or when in step 450, after the data transmission has ended and more data needs to be transmitted.
[0053] In one or more embodiments, step 410 may comprise step 415: selecting a function f(P) from a library comprising one or more non-decreasing functions f(x) that maps x on a domain [Xmin, Xmax] to a codomain [0,1 ], wherein Xmin is a minimum value of x and Xmax is a maximum value of x.
[0054] In one or more embodiments, the communication channel operates at wavelengths in the millimetre band, for example in one or more bands defined by the 3GPP standards (e.g. Release 17).
[0055] In one or more embodiments the communication channel operates at wavelengths in an unlicensed spectrum. In the unlicensed spectrum, the number of communication devices and how they operate and use the spectrum may be less defined or predetermined as in a licensed spectrum. Therefore, it may be advantageous to deploy a more flexible or non-determ inistic clean channel assessment when transmitting in an unlicensed spectrum.
[0056] Figure 5 shows a schematic overview of a vehicle 500 according to one or more embodiments of the invention with a communication device 510 according to one or more embodiments of the invention. The communication device 510 comprises a transceiver 520 arranged for transmitting data on a communication channel and for measuring an energy level in said communication channel. It further comprises a computer processor 530 and a computer-readable medium 540.
[0057] The computer-readable medium 540 has stored thereon a computer program which comprises instructions which, when the program is executed by computer processor 530 cause the computer processor 530 to carry out the steps of any of the methods for clean channel assessment as described in this document, using the transceiver 520.
[0058] In one or more embodiments, the vehicle 500 may be a car, a motorbike, a van, a truck, a bicycle or a scooter.
[0059] Those of skill will appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Those of skill in the art may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
[0060] The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
[0061] The benefits and advantages that may be provided by the present invention have been described above with regard to specific embodiments. These benefits and advantages, and any elements or limitations that may cause them to occur or to become more pronounced are not to be construed as critical, required, or essential features of any or all of the claims. As used herein, the terms “comprises,” “comprising,” or any other variations thereof, are intended to be interpreted as non-exclusively including the elements or limitations which follow those terms. Accordingly, a system, method, or other embodiment that comprises a set of elements is not limited to only those elements, and may include other elements not expressly listed or inherent to the claimed embodiment.
[0062] While the present invention has been described with reference to particular embodiments, it should be understood that the embodiments are illustrative and that the scope of the invention is not limited to these embodiments. Many variations, modifications, additions and improvements to the embodiments described above are possible. It is contemplated that these variations, modifications, additions and improvements fall within the scope of the invention as detailed within the following claims.
Claims
CLAIMS1 . Computer implemented method for a clear channel assessment, comprising the steps of: a) obtaining a non-decreasing function f(P) that maps a measured energy level P on a domain [Pmin, Pmax] to a codomain (0,1 ), wherein Pmin is a minimum measured energy level and Pmax is a maximum measured energy level; b) measuring an energy level in a communication channel; c) determining f(Pmeas) and generating a value u, wherein u is a random variable; and, d) outputting information indicating that said channel is idle if f(Pmeas) < u; and information indicating said channel is busy when f(Pmeas) > u.
2. Method according to claim 1 , further comprising the step of: e) starting a data transmission based on said information.
3. Method according to claim 1 or 2, wherein steps b)-d), and optionally e) after the transmission has ended, are repeated.
4. Method according to any of claim 1 -3, wherein said function f(P) is defined as: f(P) = (P - Pmin) I (Pmax-Pmin);5. Method according to any of claim 1 -3, wherein said function f(P) is defined as: f(P) = 0 when P<Pa; f(P) = 1 when P>Pb; f(P) = (P-Pa) / (Pb-Pa) when Pa<P<Pb; wherein Pa is a value between Pmin and Pb, and Pb is a value between Pa and Pmax.
6. Method according to any of claims 1 -3, wherein step a) comprises selecting a function f(P) from a library comprising one or more non-decreasing functions f(x) that maps x on a domain [Xmin, Xmax] to a codomain [0,1 ], wherein Xmin is a minimum value of x and Xmax is a maximum value of x.
7. Method according to any of claims 1 -3, wherein the communication channel operates at a wavelength band in the millimetre band and / or thecommunication channel operates at a wavelength band in an unlicensed spectrum.
8. Method according to any of claims 1 -7, wherein said value u is a uniform random variable or a normally distributed random variable.
9. A computer program comprising instructions which, when the program is executed by a computer processor, cause the computer processor to carry out the steps of the method of any of claims 1 -8.
10. A computer-readable medium having stored thereon the computer program of claim 9.
11. Communication device comprising- a transceiver arranged for transmitting data on a communication channel and for measuring an energy level in said communication channel; and,- a computer processor and a computer-readable medium according to claim 9 arranged for carrying out the steps of the method of any of claims 1 -8 using said transceiver.
12. Vehicle with a communication device according to claim 11 .