阅读说明：本技术 毫米波通信中af中继设备的波束对准方法、中继设备 (Wave beam alignment method of AF (auto-ranging) relay equipment in millimeter wave communication and relay equipment ) 是由 黄联芬 王健铮 杨泽靖 赵毅峰 高志斌 谢新典 胡威 叶明淦 黄鹏飞 杨子 杨波 于 2021-08-23 设计创作，主要内容包括：本发明提供一种毫米波通信中AF中继设备的波束对准方法、中继设备,方法包括：AF中继设备判断接收到的波形信号是否包含SSB；若是,则AF中继设备利用启发式算法进行波束对准。本发明能够在放大转发中继不解调基站广播的同步信号块情况下实现精确地波束对准。(The invention provides a wave beam alignment method of AF (auto-ranging) relay equipment in millimeter wave communication and the relay equipment, wherein the method comprises the following steps: the AF relay equipment judges whether the received waveform signal contains SSB; and if so, the AF relay equipment performs beam alignment by using a heuristic algorithm. The invention can realize accurate beam alignment under the condition that the amplifying and forwarding relay does not demodulate the synchronous signal block broadcasted by the base station.)

1. A wave beam alignment method of AF relay equipment in a millimeter wave communication network is characterized by comprising the following steps:

the AF relay equipment judges whether the received waveform signal contains SSB;

and if so, the AF relay equipment performs beam alignment by using a heuristic algorithm.

2. The method as claimed in claim 1, wherein the method for beam alignment of the AF relay device in the mm-wave communication network, the AF relay device determining whether the received waveform signal contains SSB, further comprises:

and the AF relay equipment initializes the angle of the received wave beam and adopts the wave beam forming technology to fix the angle of the received wave beam.

3. The method as claimed in claim 1, wherein the determining whether the received waveform signal contains SSB by the AF relay device comprises:

the AF relay equipment detects whether the received waveform signal meets periodicity;

if yes, judging whether the waveform signal is a multi-carrier signal;

if yes, judging whether the waveform signal is an OFDM signal;

if yes, judging whether the waveform signal contains SSB.

4. The method of claim 3, wherein the detecting whether the received waveform signal satisfies periodicity by the AF relay device comprises:

the AF relay equipment sets the receiving beam duration T1 to be more than or equal to MT according to the downlink beam scanning period T of the base station, wherein M is more than or equal to 4;

the AF relay equipment divides the received waveform signals into M sections and detects the maximum value and the occurrence time of each section of the waveform signals;

the AF relay equipment calculates the period T2 of each section of waveform signal according to the maximum value and the occurrence moment of each section of waveform signal;

if the period T2 of each section of waveform signal is equal, judging whether the period T2 is matched with the downlink beam scanning period T of the base station, and if so, judging that the received waveform signal meets the periodicity.

5. The method as claimed in claim 3, wherein said determining whether the waveform signal contains SSB comprises:

storing the main synchronization signal sequence to the local AF relay equipment;

and the AF relay equipment performs sliding cross-correlation operation on the receiving sequence of the waveform signal and the main synchronous signal sequence, and if the operation result has an autocorrelation characteristic, the waveform signal is judged to contain SSB.

6. The method as claimed in claim 1, wherein the performing of the beam alignment by the AF relay device using a heuristic algorithm comprises:

initializing simulation annealing algorithm parameters of AF relay equipment, wherein the parameters comprise initial temperature T_SALower limit of temperature T_SA-minInitial receive beam angle (phi)_Initial,θ_Initial) Maximum number of iterations L_IterationAnd receiver sensitivity P₀；

Let f (phi, theta) be P_RelayIn the formula P_RelayPower for the current receive beam angle;

judging whether the maximum iteration number L is reached_Iteration；

If not, the AF relay equipment judges whether P is available or not_Relay>P₀；

If yes, returning to the optimal receiving beam angle, and receiving the waveform signal by the AF relay equipment according to the optimal receiving beam angle;

if not, the formula T is passed_SA＝αT_SAAnd reducing the temperature parameter of the simulated annealing algorithm, wherein the parameter alpha epsilon (0,1) is an attenuation factor, and returning to the AF relay equipment to judge whether the received waveform signal contains the SSB step.

7. An AF relay device, characterized in that, when operating in a millimeter wave communication network, the amplify-and-forward relay device is capable of implementing all the steps performed by the AF relay device in the beam alignment method of the AF relay device in the millimeter wave communication network according to any one of the above claims 1 to 6.

Technical Field

The invention relates to the technical field of millimeter wave relay communication networks, in particular to a beam alignment method of AF (auto-ranging) relay equipment in millimeter wave communication and the AF relay equipment.

Background

Millimeter wave communication has received a great deal of attention from both academic and industrial circles as a popular technology. Compared with a microwave frequency band, the carrier wave of the millimeter wave is shorter in wavelength, higher in frequency and larger in path loss, and the traditional omnidirectional transmission cannot be applied to millimeter wave communication. In order to ensure the communication quality, a large-scale multiple-input multiple-output (Massive MIMO) technology and a Beamforming (Beamforming) technology are adopted in millimeter wave communication to compensate for the propagation loss.

The beam forming is a signal preprocessing technology based on an antenna array, and generates a directional beam by adjusting the weighting coefficient of each array element in the antenna array, so that obvious array gain can be obtained. Therefore, the beamforming technology has great advantages in enlarging the coverage.

However, when there is an obstacle in communication, the beamforming technology still cannot compensate for the large penetration loss, and a relay device needs to be deployed in a link from the source end to the sink end to perform auxiliary communication. In general, the links from the source end to the relay end and the links from the relay end to the sink end are all in line of sight, so that huge penetration loss is avoided.

According to different information processing modes of a relay, the relay is mainly divided into an Amplify and Forward (AF) relay, a decode and forward relay and the like. The AF relay amplifies the received signal directly there by a certain amplification factor and forwards the signal to the sink. The AF relay does not need to demodulate the received signal, has the characteristics of low overhead, low cost and low complexity, and is suitable for a millimeter wave relay communication system.

In Sub 6GHz and traditional low frequency communication systems, a base station periodically broadcasts a synchronization signal omnidirectionally, and an AF relay only needs to receive the signal omnidirectionally and amplify and forward the signal to a user according to a certain proportion without beam alignment. However, in the millimeter wave communication system, the base station side must use a directional beam to transmit signals, and the relay side must also use a directional beam to receive signals, so as to improve the receiving gain and reduce interference. For the AF relay, the direction of the signal transmitted by the base station is unknown, and since the AF relay does not demodulate the signal, it is not possible to accurately obtain whether the received signal contains SSB (synchronization signal and PBCH block are abbreviated, and it is composed of the primary synchronization signal, the secondary synchronization signal, and PBCH), so there is a problem that the beam alignment is difficult.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the art described above. To this end, an object of the present invention is to provide a beam alignment method for an AF relay device in a millimeter wave communication network, which can achieve accurate beam alignment without demodulating a synchronization signal block broadcast by a base station in an amplify-and-forward relay.

The invention aims to provide a beam alignment method of AF relay equipment in a millimeter wave communication network.

A second object of the present invention is to propose an AF relay device.

In order to achieve the above object, an embodiment of a first aspect of the present invention provides a beam alignment method for an AF relay device in a millimeter wave communication network, including the following steps:

the AF relay equipment judges whether the received waveform signal contains SSB;

and if so, the AF relay equipment performs beam alignment by using a heuristic algorithm.

According to the beam alignment method of the AF relay equipment in the millimeter wave communication network, whether the received signals contain the synchronous signal blocks or not is firstly identified, if yes, the optimal receiving beams are searched by using a heuristic algorithm, and beam alignment is achieved. Therefore, the amplifying and forwarding relay can realize accurate beam alignment under the condition of not demodulating the synchronous signal block broadcasted by the base station.

In addition, the beam alignment method for the AF relay device in the millimeter wave communication network according to the above embodiment of the present invention may further have the following additional technical features:

optionally, the AF relay device determines whether the received waveform signal contains an SSB, and before that, the method further includes:

and the AF relay equipment initializes the angle of the received wave beam and adopts the wave beam forming technology to fix the angle of the received wave beam.

Optionally, the determining, by the AF relay device, whether the received waveform signal contains an SSB includes:

the AF relay equipment detects whether the received waveform signal meets periodicity;

if yes, judging whether the waveform signal is a multi-carrier signal;

if yes, judging whether the waveform signal is an OFDM signal;

if yes, judging whether the waveform signal contains SSB.

Optionally, the detecting, by the AF relay device, whether the received waveform signal satisfies periodicity includes:

the AF relay equipment sets the receiving beam duration T1 to be more than or equal to MT according to the downlink beam scanning period T of the base station, wherein M is more than or equal to 4;

the AF relay equipment divides the received waveform signals into M sections and detects the maximum value and the occurrence time of each section of the waveform signals;

the AF relay equipment calculates the period T2 of each section of waveform signal according to the maximum value and the occurrence moment of each section of waveform signal;

if the period T2 of each section of waveform signal is equal, judging whether the period T2 is matched with the downlink beam scanning period T of the base station, and if so, judging that the received waveform signal meets the periodicity.

Optionally, the determining whether the waveform signal contains an SSB includes:

storing the main synchronization signal sequence to the local AF relay equipment;

and the AF relay equipment performs sliding cross-correlation operation on the receiving sequence of the waveform signal and the main synchronous signal sequence, and if the operation result has an autocorrelation characteristic, the waveform signal is judged to contain SSB.

Optionally, the performing, by the AF relay device, beam alignment using a heuristic algorithm includes:

initializing simulation annealing algorithm parameters of AF relay equipment, wherein the parameters comprise initial temperature T_SALower limit of temperature T_SA-minInitial receive beam angle (phi)_Initial,θ_Initial) Maximum number of iterations L_IterationAnd receiver sensitivity P₀；

Let f (phi, theta) be P_RelayIn the formula P_RelayPower for the current receive beam angle;

judging whether the maximum iteration number L is reached_Iteration；

If not, the AF relay equipment judges whether P is available or not_Relay>P₀；

If yes, returning to the optimal receiving beam angle, and receiving the waveform signal by the AF relay equipment according to the optimal receiving beam angle;

if not, the formula T is passed_SA＝αT_SAAnd reducing the temperature parameter of the simulated annealing algorithm, wherein the parameter alpha epsilon (0,1) is an attenuation factor, and returning to the AF relay equipment to judge whether the received waveform signal contains the SSB step.

In order to achieve the above object, a second embodiment of the present invention provides an AF relay device, where the amplify-and-forward relay device is capable of implementing all the steps performed by the AF relay device in the above beam alignment method of an AF relay device in a millimeter wave communication network when operating in the millimeter wave communication network.

According to the AF relay equipment of the embodiment, whether the received signals contain the synchronous signal blocks or not is firstly identified, and if yes, an optimal receiving beam is searched by utilizing a heuristic algorithm so as to achieve beam alignment. Accurate beam alignment can be achieved without demodulating the synchronization signal blocks broadcast by the base station.

Drawings

Fig. 1 is a schematic flowchart of a beam alignment method of an AF relay device in a millimeter wave communication network according to an embodiment of the present invention;

fig. 2 is a schematic flow chart illustrating an identification SSB of the AF relay device in the embodiment of the present invention;

fig. 3 is a schematic flow chart of finding an optimal receiving beam by the AF relay device using a simulated annealing algorithm in the embodiment of the present invention;

fig. 4 is a block diagram of an apparatus structure of an AF relay apparatus according to an embodiment of the present invention;

fig. 5 is a block diagram of an AF relay system according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

The beam alignment method of the amplify-and-forward relay provided by the invention can realize accurate beam alignment under the condition of not demodulating the synchronous signal block broadcasted by the base station, and has the characteristics of low overhead and low cost.

In order to better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

In order to better understand the technical solution, the technical solution will be described in detail with reference to the drawings and the specific embodiments.

Fig. 1 is a schematic flowchart of a beam alignment method of an AF relay device in a millimeter wave communication network according to an embodiment of the present invention.

As shown in fig. 1, a beam alignment method for an AF relay device in a millimeter wave communication network according to an embodiment of the present invention includes the following steps:

s1: and the AF relay equipment initializes the angle of the received wave beam and adopts the wave beam forming technology to fix the angle of the received wave beam.

S2: the AF relay device determines whether the received waveform signal contains SSB, if yes, S3 is executed;

s3: the AF relay device performs beam alignment using a heuristic algorithm.

As a specific embodiment, the step S1 specifically includes:

the scanning period of the downlink beam of the base station is T, and the set A is a set formed by all possible values of the scanning period T of the downlink beam of the base station, namely T belongs to A. In 5G NR, the set a is {5ms,10ms,20ms,40ms,80ms,160ms }.

The AF relay equipment firstly randomly initializes beam angles (phi, theta), wherein the phi and the theta respectively represent a horizontal angle and a vertical angle; and the beam forming technology is adopted to fix the receiving beam direction.

Referring to fig. 2, as an embodiment, the step S2 includes:

s2-1: the AF relay equipment detects whether the received waveform signal meets periodicity;

specifically, first, the AF relay device sets the receive beam duration to T according to the downlink beam scanning period T of the base station₁And in order to ensure that the detected waveform contains 2 or more complete base station downlink beam scanning waveforms, i.e. to ensure the validity of the detection, T is₁The method comprises the following steps: t is₁MT is not less than 4. As a specific example, assume that base station downlink beam scanning is commonWith the period T of 20ms, the AF relay device may optionally set the reception beam duration to T₁Detection was performed for 80 ms. If the longest period of downlink beam scanning of the base station is T ═ 160ms, optionally, the AF relay device may set the receive beam duration to T₁Detection is performed for 640 ms.

Secondly, dividing the received x (t) into M sections by the AF relay equipment, and detecting the maximum value and the occurrence time of each section of waveform signal; then, the AF relay equipment calculates the period T2 of each section of waveform signal according to the maximum value and the occurrence time of each section of waveform signal; if the period T2 of each waveform signal is equal, determining whether the period T2 matches the base station downlink beam scanning period T, that is, determining whether T2 belongs to the set a; if matched, i.e. T₂E, judging that the received waveform signal meets periodicity, and executing a step S2-2; if it isOr x (T) does not satisfy the periodicity (i.e., T2 of each segment of the waveform signal is not equal), the process returns to step S2-1. As a specific example, with T₁Taking 80ms as an example, the millimeter wave AF relay device takes the received signal as T₃The length is 20ms, and the length is divided into 4 sections; detecting the maximum value a of each segment signal_1,iI ∈ {0,1,2,3} and recording the time t at which the maximum value of each segment occurs_1,iI ∈ {0,1,2,3 }; further calculating the parameter k_1,j＝[t_1,j+1+j*T₃]-[t_1,j+(j-1)*T₃]J ∈ {1,2,3 }; if k is_1,1＝k_1,2＝k_1,3Then the received signal is considered to satisfy periodicity; further calculating the period T of the signal x (T)₂＝k_1,1＝k_1,2＝k_1,3And further detecting the period T of the received signal x (T)₂Whether or not to match the base station downlink beam scanning period, i.e. T₂Whether it belongs to set A; if T₂E, executing the step S2-2 if the element belongs to A; if it isOr x (t) does not satisfy the periodicity, return to step S2-1.

In consideration of interference signals possibly existing in the space, the millimeter wave AF relay equipment performs OFDM modulation identification and determines whether the received signals are OFDM signals or not so as to improve the accuracy of SSB detection. The invention uses a scheme for identifying multi-signal and single-carrier signal based on mixed moment, and the scheme makes full use of progressive gaussianity of the multi-signal and can accurately distinguish single-carrier signal from multi-carrier signal. Further, the present invention uses a cyclic prefix based scheme to identify OFDM signals from other multicarrier signals.

S2-2: judging whether the waveform signal is a multi-carrier signal or not;

specifically, on the basis of step 2-1, the AF relay device determines the downlink scanning period T of the base station due to the fixed receiving beam direction₂Then its receive beam duration is 2T₂. Assume that the currently received signal is x₁(t), then receiving signal x₁(t) obtaining a signal x through the RF front-end module, the down converter and the ADC module₁(n) of (a). Then, parameters are definedAs identification parameters for single-carrier signals and multi-carrier signals, where M_2,1、M_6,3Respectively represent signals x₁The mixing moments of orders 2, 1 and 6, 3 of (n) are calculated as follows:

M_2,1＝E[x×x^*]

M_6,3＝E[x³×(x^*)³]

wherein x is^*Representing the conjugate of the signal x.

The parameter p obtained by the multi-carrier signal is only related to the number of the sub-carriers because the multi-carrier signal has progressive gaussianity which is independent of the modulation mode of the sub-carriers₁Parameter p less than single carrier signal₁. Thus, it is possible to vary the parameter p₁Whether the received signal is a multi-carrier signal is judged. Ideally, the parameters found for the multicarrier signalP obtained from single carrier signal₁1. If the signal is a multi-carrier signal, further executing S2-3; if the signal is a single-carrier signal, the process returns to S2-1.

As a specific example, in a millimeter wave actual communication scenario, a set of dynamic threshold values d may be set according to different signal-to-noise ratios₁∈[0.17，0.18]When receiving a signal p₁When d is less than or equal to d, the signal is a multi-carrier signal; when p is₁>When d, the signal is a single carrier signal.

S2-3: judging whether the waveform signal is an OFDM signal;

specifically, the millimeter wave AF relay device calculates the signal x₁(n) correlation, defining received signal correlation valueWherein the parameter M is the signal x₁(n) length. Since the OFDM signal has a cyclic prefix, the received signal correlation value p is obtained when the parameter k is 0 and k is N₂There will be a distinct peak where the parameter N is the effective data length, i.e. the number of sub-carriers comprised by one OFDM symbol, and the parameter p found for the remaining multi-carrier signals₂Then there will only be a distinct peak at k-0. Therefore, on the basis of step 2-2, it can be determined whether the received signal is an OFDM signal; if the signal is an OFDM signal, executing S2-4; if not, the process returns to S2-1.

As a specific example, parameters are definedWherein the parameter a₂Represents p₂Magnitude of the second peak, n₂Is a₂The corresponding number of points. b₂Is n₂The number of points is the average of the amplitudes of several points, and n may be optionally selected₂+2,n₂+1 and find the mean of these two points. Further, the setting parameter d can be set for different signal-to-noise ratios₂∈[0.5,0.7]If c is₂≥d₂The received signal is an OFDM signalContinuing to execute S2-4; otherwise, return to S2-1.

S2-4: and judging whether the waveform signal contains SSB.

The SSB is composed of three parts, namely Primary Synchronization Signals (PSS), Secondary Synchronization Signals (SSS), and a Physical Broadcast Channel (Physical Broadcast Channel). And, the SSB occupies 4 OFDM symbols in the time domain and 240 subcarriers in the frequency domain, specifically, for the PSS signal, it is located in the first OFDM symbol in the time domain, and occupies 56 th to 182 th subcarriers in the frequency domain, and the rest subcarriers are all 0. Further, according to the 5G NR standard, PSS is generated from m sequences in the following way:

x_pss(n)＝1-2x((n+43a)mod 127),0≤n≤127

wherein:

x(i+7)＝(x(i+4)+x(i))mod 2

[x(6) x(5) x(4) x(3) x(2) x(1) x(0)]＝[1 1 1 0 1 1 0]

a ∈ {0,1,2}, and thus there are 3 different PSS sequences.

The millimeter wave AF relay device stores the PSS sequence in the local storage module, which is generated in the manner described above. Millimeter wave AF relay device will receive sequence x₁(n) performing sliding cross-correlation operation with the locally stored PSS sequence, and calculating to obtain p_3,aAnd a is equal to {0,1,2 }. According to the autocorrelation and cross-correlation characteristics of the m-sequence, the autocorrelation value of the PSS is 1, and the cross-correlation value is below 0.2. If p is_3,aIf there is a significant autocorrelation characteristic, it may be determined that there is an SSB signal in the received signal, and S3 is performed; otherwise, returning to the step 2-1.

As a specific example, according to the sequence p_3,aThe difference between the maximum value and the next largest value of (c) can determine whether the signal contains SSB. Setting parametersWherein the parameter a₃Represents p₂Medium maximum value, parameter b₃Represents the sequence p₃Second maximum value of (1), setting parameter d at different signal-to-noise ratios₃∈[0.5，0.7]If c is₃≥d₃Then, it is determined that the SSB is included in the received signal. Otherwise, it is determined that the received signal does not include the SSB.

As an embodiment, the step S3 is described by using a simulated annealing algorithm:

referring to fig. 3, the process of applying the simulated annealing algorithm specifically includes:

s3-1: initializing simulation annealing algorithm parameters of AF relay equipment, wherein the parameters comprise initial temperature T_SALower limit of temperature T_SA-minInitial receive beam angle (phi)_Initial,θ_Initial) Maximum number of iterations L_IterationAnd receiver sensitivity P₀(ii) a This step may also be performed before S1.

S3-2: if it is determined that the SSB signal is included according to the determination result of S2, f (Φ, θ) is made P_RelayIn the formula P_RelayPower for the current receive beam angle; if the SSB signal is not included, setting the reception power corresponding to the reception beam angle to 0, that is, f (Φ, θ) is 0; thus, a function can be defined

S33: judging whether the maximum iteration number L is reached_Iteration；

If not, the AF relay equipment judges whether P is available or not_Relay>P₀；

If yes, returning to the optimal receiving beam angle, and receiving the waveform signal by the AF relay equipment according to the optimal receiving beam angle;

if not, the formula T is passed_SA＝αT_SAThe temperature parameter of the simulated annealing algorithm is decreased, where the parameter α ∈ (0,1) is the decay factor, and S2 is returned.

The invention also provides AF relay equipment, and when the amplifying and forwarding relay equipment works in a millimeter wave communication network, all steps executed by the AF relay equipment in the beam alignment method of the AF relay equipment in the millimeter wave communication network can be realized. The details of the steps are not repeated here, and the details are described above.

Referring to fig. 4, as an embodiment, the amplify-and-forward relay apparatus includes: the device comprises an antenna module, a duplex module, a low-noise amplifier module, a frequency conversion module and a power amplification module. In particular, the amplify-and-forward relay device further includes a control module, which stores information such as a received power value, a PSS sequence, and the like, and is further configured to identify an SSB in a received signal and perform beam alignment by using a simulated annealing algorithm, that is, all steps performed by the AF relay device in the beam alignment method for the AF relay device in the millimeter wave communication network are implemented.

Referring to fig. 5, the present invention further provides a relay system, which includes one or more Base Stations (BSs), the above-mentioned amplify-and-forward relay apparatus, and one or more Users (UEs). Fig. 1 illustrates only one BS and one UE as an example, and obviously, more BSs and UEs may be included.

As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It should be noted that in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

In the description of the present invention, it is to be understood that the terms "first", "second" and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above should not be understood to necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.