Adaptive transmitting method based on CDD mode and user equipment

Abstract

The present invention relates to the technical field of wireless communications, and specifically discloses an adaptive transmission method and user equipment for a CDD mode in a V2X communication technology, where the user equipment comprises an antenna module at least comprising a first antenna and a second antenna. The method comprises the following steps: user equipment acquires SNR values of two antennas, responds to the difference of the SNR values of the antennas, adaptively adjusts the transmitting power of the antennas according to a preset transmitting power allocation table, and realizes the comprehensive advantage characteristics of CDD and TxD modes even if only hardware supporting the CDD mode exists, thereby achieving the purpose of increasing the antenna gain in a specific scene.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, and more particularly to an adaptive transmitting method for single CDD mode under V2X communication technology and a user equipment. BACKGROUND

[0002] V2X (Vehicle-to-Everything) as a new generation of communication technology, realizes the coordinated perception and interconnection of V (vehicle) and any information interaction object X (mainly including people, vehicles, road infrastructure, cloud platforms or networks, etc.). V2X communication builds a mobile Internet environment perception and information interaction system through vehicle-to-vehicle (Vehicle-to-Vehicle, V2V), vehicle-to-infrastructure (Vehicle-to-Infrastructure, V2I), vehicle-to-pedestrian (Vehicle-to-Pedestrian, V2P), and vehicle-to-network or cloud platform (Vehicle-to-Network, V2N), thereby building a data environment that meets the intelligent traffic perception and interconnection characteristics, and realizing the wide information interconnection and collaborative control of people, machines and things in the ITS system.

[0003] V2X technology has broad application prospects. Not only has 3GPP organization given a detailed evolution scheme, but also a complete industry chain has been formed from chip, software to module and testing. In particular, the domestic policy and industrial environment have formed a good synergy for the development of V2X.

[0004] Although C-V2X has not been widely deployed in actual road sections, most countries have set up special road sections for experimental research in order to study and verify this technology.

[0005] At present, there are various transmitting modes in the mainstream antenna transmitting and receiving scheme of the user equipment UE supporting C-V2X communication technology, including CDD, TxD, Hybrid TxD, etc. According to the existing test data, whether in actual field test or in simulation test, in most scenarios (including but not limited to different environmental conditions in laboratory and field: rural, suburban, urban; line of sight and non-line of sight, etc.), CDD (Cyclic delay diversity) mode has excellent performance in the dimensions of signal coverage distance / BLER and gain / antenna imbalance. Therefore, CDD mode, as the preferred technology of the scheme and the first choice of various mainstream automobile manufacturers, is also an official standard evolution technology of 3GPP, because of its excellent performance in laboratory simulation test and most scenarios in field test.

[0006] However, CDD is not perfect in all scenarios. Experiments show that in some specific scenarios, the performance of the effective detection distance and the associated bit error rate of the CDD mode is inferior to that of the TxD mode, such as in the line-of-sight, low-speed, and suburban scenarios. Therefore, in view of the defects of the CDD mode in these aspects, the present application develops some new features to make up for the defects without affecting the original characteristics of the CDD mode.

[0007] The present application is a new technical strategy based on the original technical solution of CDD, which does not involve changes in hardware, retains the advantages of the CDD mode itself, and absorbs and realizes the characteristics of other modes such as the TxD mode, so as to achieve the purpose of performance improvement and defect compensation at a minimum cost. SUMMARY

[0008] The present application specifically relates to a self-adaptive transmission method and a user equipment for the CDD mode in the field of V2X communication technology.

[0009] For example, in some embodiments, a self-adaptive transmission method based on the CDD mode is disclosed, which comprises the following steps: the UE detects the SNR of the signals received by the first and second antennas, and determines the ratio 1 / N of the SNRs of the first and second antennas; when the value of N is 1, the UE cyclically executes the step of allocating the same transmission power to the first and second antennas; and when the value of N is not 1, the UE calls a preset transmission power allocation table according to the antenna power ratio of 1 / N, and executes the step of allocating the corresponding transmission power to the first and second antennas.

[0010] In some embodiments, the unbalance degree N of the first and second antennas can be used as a condition for subsequent power control, that is, the difference N of the received signal strengths of the first and second antennas is obtained.

[0011] In some embodiments, the period of the antenna SNR detection performed by the UE is 5ms.

[0012] In some embodiments, the UE obtains the actual antenna gain G1 after executing step two. Further, the allocation of the antenna power is adjusted within the range interval of 1 / (N+M) to 1 / (N-M), and N>M, to obtain the antenna gain G2.

[0013] In some embodiments, when the two antenna gain values G1 and G2 are different, the UE selects the power allocation scheme corresponding to the larger value of G1 and G2.

[0014] In some embodiments, in the preset power table, higher transmission power is allocated to the antenna with a higher SNR value.

[0015] In some embodiments, the UE allocates all the power to the antenna with a higher SNR value.

[0016] In some implementations, the UE updates the configuration file via commands to adjust the antenna power allocation.

[0017] In some implementations, the UE dynamically allocates transmit power to the first and second antennas by enabling DPS mode.

[0018] The present invention also provides a user equipment that supports a single CDD mode and can execute the method of any one of the present invention, wherein its antenna module includes at least: a first signal propagation link consisting of an IFFT module, a first CP module, a first PA module and a first antenna, and a second signal propagation link consisting of an IFFT module, a CDD module, a second CP module, a second PA module and a second antenna.

[0019] Beneficial effects of the embodiments of the present invention:

[0020] According to the scheme disclosed in this invention, it is possible to implement a system that originally only supports a single CDD mode on hardware, such as an antenna module, user equipment, or system. Without changing the hardware, the fundamental transmission mode still follows the CDD mode. Based on this hardware, features of other transmission modes, particularly TxD, are further incorporated. That is, without requiring hardware support, this invention can still integrate the characteristics of other transmission modes, such as TxD, in addition to the features of the CDD mode. Since data has shown that the TxD transmission mode can provide better antenna gain in certain scenarios, combining the characteristics of both transmission modes can achieve comprehensive optimization of transmission performance, compensate for the shortcomings of the CDD mode in specific scenarios, comprehensively improve signal coverage, and provide diverse transmission strategies in diverse V2X scenarios, thereby achieving the goal of performance improvement.

[0021] It should be understood that the content described in this section is not intended to identify key or important features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. For example, the "apparatus" and "user equipment" mentioned above include, but are not limited to, terminal devices capable of network communication such as mobile phones, data cards, and automotive electronics, and may also be the smallest circuit unit or module that implements the function. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0022] Other details and advantages of the invention will become apparent from the detailed description provided below. It should be understood that the following drawings are merely illustrative and should not be considered as limiting the invention. A detailed description will be given below with reference to the drawings, in which:

[0023] Figure 1This is a schematic diagram of an embodiment of an antenna module circuit that fully supports CDD, TxD and other modes in the prior art;

[0024] Figure 2 This is a schematic diagram of an embodiment of the antenna module circuit that only supports CDD mode in this invention;

[0025] Figure 3 This is a statistical diagram illustrating the bit error rate and coverage distance of the CDD and TxD modes referenced in this invention in a suburban scenario;

[0026] Figure 4 This is a flowchart illustrating an embodiment of the method of the present invention;

[0027] Figure 5 This is a schematic diagram of a set of data set in the preset transmit power allocation table of the present invention based on the SNR comparison value;

[0028] Figure 6 This is a schematic diagram of a set of data set in the preset transmit power allocation table of the present invention based on the imbalance.

[0029] Figure 7 This is a schematic diagram of a set of data set for adjusting the transmit power using the DPS mode in this invention. Detailed Implementation

[0030] To make the technical problems, technical solutions, and beneficial effects of this invention clearer and more understandable, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0031] Furthermore, to better illustrate this disclosure, numerous specific details are set forth in the following detailed description. Those skilled in the art will understand that this disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of this disclosure.

[0032] like Figure 1The diagram shows an existing C-V2X antenna transmit diversity design, presenting a fully functional design that can fully support multiple transmit modes at the hardware level. For example, with a DPDT switch, it can achieve different transmit characteristics. For instance, when only the first signal propagation link is enabled (without a CDD module) and the link has dual transmit antennas Ant 0 and Ant 1, the device does not support CDD (Cyclic Delay Diversity) mode but can support TxD (Antenna Switch Diversity) mode. However, when both the first and second signal propagation links are enabled simultaneously, and both transmit antennas are present, hybrid TxD can be supported, meaning the user equipment can switch between CDD and TxD modes.

[0033] As introduced in the background section, the CDD mode's superior performance in most scenarios has made it the mainstream solution. However, based on existing test data, it can be observed that while the CDD mode does have advantages in most scenarios, it is not perfect. The CDD mode also has shortcomings in certain single scenarios, requiring the use of the hybrid TxD mode to compensate for these shortcomings. This involves the support for hybrid modes. Figure 1 The complete hardware circuitry in the system needs to rely on or enable the hybrid TxD mode to compensate for the shortcomings of the CDD transmission mode in certain scenarios in order to take advantage of both CDD and TxD transmission modes. However, the obvious problem is that in the hybrid TxD mode, it is necessary to switch between the two modes constantly, which brings a considerable switching burden and resource consumption to the user equipment.

[0034] like Figure 2 The diagram shows the design scheme of the antenna module of the present invention, which includes at least a first and a second signal propagation link, and corresponding to a first and a second antenna.

[0035] At least one IFFT module is provided on the first signal propagation link S1a to implement OFDM (Orthogonal Frequency Division Multiplexing) modulation of the signal;

[0036] The first CP module, the cyclic prefix module, copies the signal at the end of the OFDM signal to form a cyclic structure, ensuring that the OFDM signal with time delay has an integer multiple of the period.

[0037] The first PA module, also known as the radio frequency signal amplifier PA0, is used to amplify the radio frequency signal from the front-end circuit and feed it to the first antenna Ant0 at the back end.

[0038] The first antenna, Ant 0, is used to transmit and receive radio frequency signals.

[0039] At least one CDD module is connected to the back end of the same IFFT module on the second signal propagation link S2a. Specifically, CDD is a transmit diversity mechanism that applies a different phase delay (cyclic phase delay) to each OFDM subcarrier. It is used for spatial multiplexing to increase diversity between two spatial paths.

[0040] The second CP module, the cyclic prefix module, copies the signal at the end of the OFDM signal to form a cyclic structure, ensuring that the OFDM signal with time delay has an integer multiple of the period.

[0041] The second PA module, namely the radio frequency signal amplifier PA1, is used to amplify the radio frequency signal of the front-end circuit and feed it to the back-end second antenna Ant 1;

[0042] The second antenna, Ant 1, is used to transmit and receive radio frequency signals.

[0043] It is evident that, compared to Figure 1 The present invention provides a complete circuit design scheme, in which the DPDT switch module is eliminated in the hardware design scheme.

[0044] This invention represents a further creative improvement upon the single CDD mode, retaining the advantages of the CDD mode while incorporating features of the TxD mode. Its working principle and advantages are reflected in the following aspects: At the hardware level, it simplifies circuit design by eliminating the DPDT switch, thus removing the burden of switching between CDD and TxD modes, while still retaining the advantages of both the original CDD and TxD modes, overcoming their shortcomings in certain single scenarios. Methodologically, it achieves its objectives by introducing a power control mechanism (a combination of performance optimization and power-saving mechanisms). The method of this invention will be explained in detail in the following description of the embodiments.

[0045] like Figure 3 The figure shows the shortcomings of CDD mode compared to TxD mode in certain specific scenarios, based on publicly available test data. The comparison data between CDD and TxD modes in the figure reveals that in a single scenario, such as line-of-sight, low-speed, or suburban scenarios, the effective detection range and associated bit error rate curves of CDD mode are inferior to those of TxD mode. Under the same bit error rate conditions, such as 10% BLER, the effective detection range of CDD mode is nearly 100m less than that of TxD. At the same bit error rate of 10%, the effective detection range of CDD is 950m, while that of TxD can be extended to 1050m, meaning that the effective detection range of CDD mode is only 90% of that of TxD mode.

[0046] Based on test data from CDD and TxD modes under Gaussian additive white noise channel conditions, the better the balance between the transmitting antennas, the more significant the gain advantage of the TxD mode. When the antenna imbalance is close to 0 dB, the TxD mode achieves a higher gain performance than the CDD mode, reaching 5 dB, which clearly improves the effective coverage distance. Conversely, for CDD mode, the higher the antenna imbalance, the higher the gain. Therefore, the method in this embodiment of the invention needs to create antenna imbalance to compensate for the insufficient or missing gain in the CDD mode.

[0047] like Figure 4 The illustration shows one embodiment of the method of the present invention. It should be understood that the description in this paragraph and the disclosure in Figure 4 are only a preferred embodiment of the method of the present invention.

[0048] In step one, by default, the UE allocates the same transmit power to both antennas, that is... Figure 2 With the support of the disclosed hardware circuitry, the two antennas transmit signals externally using the same transmit power in CDD mode.

[0049] For different antennas, the SNR performance of CDD mode varies in specific scenarios, resulting in poor signal coverage in specific scenarios, as described in the background section.

[0050] Therefore, in step two, the UE enables SNR detection for both antennas. Under existing technology, after the antennas receive a signal, demodulation is performed at the modem to detect the signal-to-noise ratio (SNR). In this embodiment, the SNR detection period is set to 5ms, but it is understood that other values ​​can also be used to set the detection period.

[0051] In step three, the UE obtains the SNR values ​​of the two antennas, namely SNR0 and SNR1, and the ratio of the two is 1 / N.

[0052] If the SNR values ​​of the two antennas are equal, it means that no adjustment is needed using this method. The UE will still operate by equally distributing the transmit power to the two antennas.

[0053] If the SNR values ​​of the two antennas are not equal, that is, if there is a difference in the signal-to-noise ratio of the antennas, then it is considered that the UE needs to intervene in order to compensate for the poor signal coverage.

[0054] In step 4, for the case where the SNR values of the two antennas are not equal, the transmission powers of the two antennas need to be adjusted correspondingly according to the subsequent steps. The final adjustment result is to make the overall antenna gain as high as possible after adjusting the transmission powers of the two antennas, thereby improving the coverage rate. Specifically, if the ratio of the SNRs of the two antennas is 1 / N, then the transmission power ratio of the corresponding antennas is also considered to be 1 / N. Further assume that the imbalance of the two antennas is N, that is, the intensity difference between the two corresponding antennas is N. After obtaining the imbalance of the two antennas, the antenna power corresponding to the imbalance can be adapted based on this data, thereby changing the transmission power of the antenna. At this time, the actual antenna gain obtained is G1.

[0055] On this basis, considering the pursuit of the best antenna gain effect, even if the transmission power of the antenna has been adjusted according to the above method, it is still possible to further adjust the transmission powers of the two antennas within a certain range by the correction factor M, where M < N, in step 5. The suggestion here is to adjust within the dynamic range of 1 / (N + M) to 1 / (N - M), and obtain the antenna gain value G2 at this time.

[0056] In step 6, compare the two antenna gain values G1 and G2, and preferably select the case with the larger antenna gain value.

[0057] Therefore, in the final step, select the adjustment method corresponding to the larger antenna gain value to adjust the transmission powers of the two antennas.

[0058] When the G2 value is larger, adopt the power adjustment scheme corresponding to G2.

[0059] When the G1 value is larger, adopt the power adjustment scheme corresponding to G1.

[0060] Among them, the preset setting, that is, the preset transmission power distribution table is as Figures 5-7 shown.

[0061] Specific examples are as follows:

[0062] When the UE detects the SNR and gets N = 10, then,

[0063] It is considered that the power ratio of the first and second antennas is 1:10, that is, the imbalance of the two antennas is 10 db. Query and call the preset power distribution table for the preset configuration of 10 db imbalance, and TX0 = 20 dbm, TX1 = 10 dbm.

[0064] Suppose the total antenna gain G1 = 3 dBi obtained at this time

[0065] If the adjustment factor, assume M = 3, then,

[0066] The first and second antennas are adjusted on this basis to obtain higher antenna gain, and the adjustment range is (1:13 - 1:7). Similarly, query and call the preset power distribution table for the preset configuration in this interval to obtain the new antenna gain, and compare to obtain the maximum antenna gain and record it as G2.

[0067] Specifically, when the power ratio is 1:12, assume that the obtained gain at this time is G2 = 5 dbi, and it is the maximum gain in this interval. At this time, TX0 = 20 dbm and TX1 = 8 dbm.

[0068] At this time, G2 > G1, so the power distribution scheme corresponding to G2, TX0 = 20 dbm and TX1 = 8 dbm, is the optimal choice.

[0069] If the first and second antennas are adjusted on this basis to obtain the antenna gain, and the adjustment range is (1:13 - 1:7). Similarly, query and call the preset power distribution table for the preset configuration in this interval to obtain the new antenna gain, and compare to obtain the maximum antenna gain and record it as G2.

[0070] Specifically, when the power ratio is 1:12, assume that the obtained gain at this time is G2 = 2 dbi, and it is the maximum gain in this interval. At this time, TX0 = 20 dbm and TX = 8 dbm.

[0071] At this time, G2 < G1, so the power distribution scheme corresponding to G1, TX0 = 20 dbm and TX1 = 10 dbm, is the optimal choice.

[0072] It should be understood that the above examples are for explaining the operation mode of this method in actual applications, and the data does not represent the measurement values and method execution results in the real scenario.

[0073] And as Figures 5-7 shown, it corresponds to an example diagram of the preset transmit power distribution table. It should be understood that the preset transmit power distribution table can be constructed in quite a number of data situations, and the example diagram given is only a partial data interception.

[0074] The corresponding Chinese explanations of the relevant terms in this application document are as follows:

[0075] CDD: Cyclic Delay Diversity Technology

[0076] TxD: Transmit Diversity Switching Technology

[0077] CP: Cyclic Prefix Technology

[0078] DPDT: Double Pole Double Throw Switch

[0079] SNR: Signal-to-Noise Ratio

[0080] AWGN: Additive White Gaussian Noise

[0081] It should be noted that the above descriptions of hardware, methods, and even user equipment are merely examples and not intended to limit the invention. In other embodiments of the invention, the method may have more, fewer, or different steps, and the order, inclusion, and functional relationships between the steps may differ from those described and illustrated. For example, multiple steps may typically be combined into a single step, or a single step may be split into multiple steps. For those skilled in the art, variations in the order of the steps are also within the scope of protection of this invention without inventive effort.

[0082] The technical solution of the present invention, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor or microcontroller to execute all or part of the steps of the methods described in the various embodiments of the present invention.

[0083] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware associated with program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments.

[0084] While the present invention has been disclosed above with reference to preferred embodiments, it is not limited thereto. Any modifications and alterations made by those skilled in the art without departing from the spirit and scope of the invention should be included within the scope of protection of the invention. Therefore, the scope of protection of the invention should be determined by the scope defined in the claims.

Claims

1. A method for adaptive transmission based on CDD mode, characterized in that, Comprising: UE detects SNR of signals received by first and second antennas, determines a ratio of SNRs of first and second antennas as 1 / N; In response to N being 1, UE performs step one of assigning same transmit power to first and second antennas; In response to N not being 1, UE invokes a preset transmit power allocation table according to antenna power ratio of 1 / N, and performs step two of assigning corresponding transmit power to first and second antennas.

2. The method of claim 1, wherein, Conditions for UE to perform step two include setting unbalance degree of first and second antennas as N, i.e. UE obtains a difference of N of received signal strengths of first and second antennas.

3. The method of claim 2, wherein, Period of UE performing antenna SNR detection is 5ms.

4. The method of claim 2, wherein, After UE performs step two, UE obtains actual antenna gain G1, further adjusts antenna power allocation within a range interval of 1 / (N+M) to 1 / (N-M), and N>M, to obtain adjusted antenna gain G2.

5. The method of claim 4, wherein, In response to different antenna gain values, UE selects a power allocation scheme corresponding to a larger value of G1 and G2.

6. The method of claim 2, wherein, In the preset transmit power allocation table, higher transmit power is allocated to antennas with higher SNR values.

7. The method of claim 6, wherein, UE allocates all power to antennas with higher SNR values.

8. The method of any one of claims 1-7, wherein, UE updates configuration files by means of commands to adjust antenna power allocation.

9. The method according to any one of claims 1-7, wherein, UE performs dynamic allocation of transmit power to first and second antennas by enabling DPS mode.

10. A user equipment supporting single CDD mode, which can perform any one of methods 1-7; The user equipment has an antenna module, which at least includes: There are a first signal propagation link composed of IFFT module, first CP module, first PA module and first antenna, and a second signal propagation link composed of IFFT module, CDD module, second CP module, second PA module and second antenna.

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