CN101610094A

CN101610094A - Channel selecting method and communication system

Info

Publication number: CN101610094A
Application number: CNA2008101269679A
Authority: CN
Inventors: 刘培; 邹卫霞; 陈凌君; 邱晶
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2008-06-20
Filing date: 2008-06-20
Publication date: 2009-12-23
Anticipated expiration: 2028-06-20
Also published as: CN101610094B

Abstract

The embodiment of the invention discloses a kind of channel selecting method and communication system.Described channel selecting method comprises: the interference level that obtains the working sub-band of each logic channel; The size of the interference level of the working sub-band of more described each logic channel; Select the little logic channel of the interference level of described working sub-band as the logic channel that sends the new beacon period of creating.Described communication system comprises: acquiring unit is used to obtain the interference level of the working sub-band of each logic channel; Processing unit is used for the size of the described interference level that more described acquiring unit obtains; Selected cell is used for the comparative result according to described processing unit, selects the little logic channel of the interference level of working sub-band as the logic channel that sends the new beacon period of creating.Embodiment of the invention technical scheme can reduce the interference between the equipment of adjacent piconets, improves systematic function.

Description

Channel selection method and communication system

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a channel selection method and a communication system.

Background

Ultra Wideband (UWB), as a new generation wireless communication technology, is a key technology for implementing Wireless Personal Area Network (WPAN) multimedia transmission. There are two main ways of UWB technology today: multi-band orthogonal frequency division multiplexing (MB-OFDM) and direct-sequence code division multiple access (DS-CDMA). The MB-OFDM based WiMedia UWB (Wireless multimedia ultra Wide band) platform is taken as the first commercial UWB standard in the world, and the ECMA-368 standard and the ECMA-369 standard are generated at present. China is also currently customizing its own UWB standard.

For the MB-OFDM-UWB technique, Time-Frequency Code TFC (Time-Frequency Code) codes are used to distinguish logical channels, 14 sub-bands are divided into 5 groups, each group includes three or two Frequency bands, and 30 logical channels are totally divided by two types of Time-Frequency codes, i.e., Time-Frequency Interleaving (TFI) codes and Fixed-Frequency Interleaving (FFI) codes. The time-frequency code is a frequency hopping technology, a piconet is a basic structural unit of a Wireless Personal Area Network (WPAN), and if the time-frequency code adopted by a certain piconet is 123123, it means that the 1 st OFDM symbol is transmitted in a frequency band 1, the 2 nd OFDM symbol is transmitted in a frequency band 2, the 3 rd OFDM symbol is transmitted in a frequency band 3, and the 4 th OFDM symbol is transmitted in a frequency band 1. In the ECMA-368 standard, a distributed medium access control mac (medium access control) protocol is used. Each device announces its presence by sending its beacon and knows its presence and actions by monitoring its beacons. In this standard, a superframe is used to coordinate operations between devices. The superframe is 65.536ms long and is divided into 256 medium access slots MAS (media access slots), each MAS being 256 μ s. A superframe consists of two parts: a Beacon Period (BP), and a Data Transmission Period (DTP). At the BP, management and control information is exchanged via beacon frames sent by each device, which ensures sequential access to the wireless medium.

In the prior art, each device may initiate its own BP, with its own beacon Period Start time bpst (beacon Period Start time) and BP length (determined by the number of devices in its range, with an upper limit). To avoid having multiple BPs overlapped by neighboring devices, when a new device is powered up, it scans for beacon frames at least one superframe period long before it transmits any frames. When scanning in a superframe period and detecting no beacon frame head, a new BP is needed to be created, the beacon frame head is detected additionally, when the frame check sequence FCS (frame check sequence) of the beacon frame has no error, an attempt is made to join a piconet, and if all piconets can not join, a new BP is created.

When a device wants to create a new BP, a logical channel is selected according to predefined logical channel priorities, and the new BP is transmitted on the selected logical channel. The predefined logical channel priorities are seen in table 1.

Table 1: logical channel selection priority

As shown in table 1, if the mobile device is battery powered and has limited power consumption, the logical channel has the highest priority for TFI, that is, logical channel 7, and a new BP is preferentially selected to be transmitted on logical channel 7.

During the research and practice of the prior art, the inventor finds that the prior art has the following problems:

the reason why a new BP needs to be built in the device is mainly two reasons: (1) no other piconets are in operation within the device reception range; (2) there is an active piconet within the reception range of the device, but the device cannot access it because there are not enough resources. For the first reason, the absence of other MB-OFDM devices (piconet devices) in the reception range does not mean that the device will not be disturbed by other MB-OFDM devices out of range while operating; for the second reason, there must be interference from other MB-OFDM devices. Therefore, in the prior art, simply selecting logical channels according to priority may cause interference between devices of adjacent piconets to be large, which may affect system performance.

Disclosure of Invention

The technical problem to be solved by the embodiments of the present invention is to provide a channel selection method and a communication system, which can reduce interference between devices of adjacent piconets and improve system performance.

In order to solve the technical problem, the embodiment provided by the invention is realized by the following technical scheme:

the embodiment of the invention provides a channel selection method, which comprises the following steps: obtaining interference levels of working sub-bands of each logic channel; comparing the interference level of the working sub-band of each logic channel; and selecting the logic channel with low interference level of the working sub-band as the logic channel for sending the newly created beacon period.

An embodiment of the present invention provides a communication system, including: the acquisition unit is used for acquiring the interference level of the working sub-band of each logic channel; the processing unit is used for comparing the interference level acquired by the acquisition unit; and the selection unit is used for selecting the logic channel with the small interference level of the working sub-band as the logic channel for sending the newly created beacon period according to the comparison result of the processing unit.

It can be seen from the above technical solutions that, in the technical solution of the embodiments of the present invention, a logical channel is selected, specifically, by obtaining an interference level of a working subband of each logical channel, comparing the interference levels of the working subbands of each logical channel, and then according to a comparison result, selecting a logical channel with a small interference level of the working subband as a logical channel for sending a newly created beacon period, the defect caused by simply selecting a logical channel according to priority in the prior art can be overcome, interference between devices of adjacent piconets is reduced, and system performance is improved.

Drawings

FIG. 1 is a flow chart of a channel selection method according to an embodiment of the present invention;

FIG. 2 is a flow chart of a second channel selection method according to an embodiment of the present invention;

FIG. 3 is a flowchart detailing the steps 202 of the method of the present invention;

FIG. 4 is a flow chart of a three-channel selection method according to an embodiment of the present invention;

FIG. 5 is a comparison graph of bit error rates under the CM1 channel model for the two solutions of the present invention and the prior art;

FIG. 6 is a graph comparing throughput under the CM1 channel model for two schemes according to the present invention and the prior art;

FIG. 7 is a comparison graph of bit error rates under the CM2 channel model for the two solutions of the present invention and the prior art;

FIG. 8 is a graph comparing throughput under the CM2 channel model for two schemes according to the present invention and the prior art;

FIG. 9 is a comparison graph of bit error rates under the CM3 channel model for the two solutions of the present invention and the prior art;

FIG. 10 is a graph comparing throughput under the CM3 channel model for two schemes according to the present invention and the prior art;

FIG. 11 is a comparison graph of bit error rates under the CM4 channel model for the two solutions of the present invention and the prior art;

FIG. 12 is a graph comparing throughput under the CM4 channel model for both embodiments of the present invention and prior art schemes;

fig. 13 is a schematic structural diagram of a communication system according to an embodiment of the present invention.

Detailed Description

Embodiments of the present invention provide a channel selection method, which can reduce interference between devices of adjacent piconets and improve system performance.

The technical scheme of the embodiment of the invention mainly selects the logic channel with small interference level as the logic channel for sending the newly created beacon period BP by comparing the interference levels of the working sub-bands of all the logic channels, thereby reducing the interference between the devices of the adjacent piconets.

Referring to fig. 1, a flow chart of a channel selection method according to an embodiment of the present invention includes the steps of:

step 101, obtaining interference levels of working sub-bands of each logic channel;

the obtaining of the interference level of the working subband of each logical channel specifically includes:

and within the set times, detecting the interference level of the working sub-band of each logic channel according to the frequency hopping period to obtain a detection result. The frequency hopping period is 18 OFDM symbol times, and the number of logical channels is 7; or, the frequency hopping period is 24 OFDM symbol times, and the number of logical channels is 12.

102, comparing the interference level of the working sub-band of each logic channel;

specifically, the interference levels of the working sub-bands of each logic channel are logically calculated, and the comparison is performed according to the calculation results to obtain the arrangement sequence of the interference levels of the working sub-bands of each logic channel.

And 103, selecting the logic channel with the small interference level of the working sub-band as the logic channel for sending the newly created beacon period BP.

In the first embodiment, by selecting the logical channel through the above steps, interference between devices of adjacent piconets can be reduced, and system performance can be improved.

The following description will first be made with reference to the ECMA-368 standard for logical channel selection.

Please refer to fig. 2, which is a flowchart illustrating a second channel selection method according to an embodiment of the present invention, including the steps of:

step 201, detecting the interference level of the working sub-band of each logic channel according to the frequency hopping period, and acquiring a detection result;

when a device determines to create a new BP, first, the interference level of the working subband of each logical channel is detected, and in this embodiment, the detection method of the matched filter is used for the detection of the interference level. Considering the hopping pattern of the logical channel, the detection is in units of one OFDM symbol time, and the detection order is as follows: 123123213213312312 (the pattern is the frequency hopping pattern of the logical channel), that is, the working subband number 1 is detected in the first symbol time, the working subband number 2 is detected in the second symbol time, and so on, one detection needs to detect one frequency hopping period. That is, the interference level in one OFDM symbol time is detected in the operating subband of each logical channel in one hopping period according to the hopping pattern of the logical channel. Under the ECMA-368 standard, the hopping period is 18 OFDM symbol times. The same test is performed multiple times in view of timing issues. In this embodiment, considering the timing sequence, the two OFDM symbols before and after include the same or different conditions, and therefore, the operations are performed 4 times in sequence, and may be performed continuously or at intervals, and in order to make the result of each detection as uncorrelated as possible in time, the detection may be performed once in each MAS time.

Step 202, using the detection result as input, performing logical operation through a certain evaluation algorithm, and selecting a logical channel according to the operation result;

in the comparison of the logical channels, the interference level of the working sub-band of the logical channel is the minimum, and when the evaluation algorithm is used for logical operation of one logical channel, the interference level in 6 OFDM symbol times of the logical channel is the minimum.

Step 203, according to the obtained selection result, transmitting a new BP on the selected logical channel.

Step 202 is described in detail below.

The embodiment of the invention uses a gray level correlation analysis method as an evaluation algorithm, and particularly, the interference level in each OFDM symbol time of a logic channel frequency hopping period is used as an index, and 7 used logic channels are used as alternative schemes, namely, each logic channel corresponds to one scheme, so that the logic channel selection problem when equipment initiates a new BP is converted into a typical multi-index decision problem, and a multi-index decision model is established.

Furthermore, the problem of time sequence is considered in the design process of the logic channel selection strategy, and the static selection strategy is popularized to dynamic multi-index judgment, so that the comprehensive performance of each scheme is reflected to the maximum extent, and the judgment accuracy is improved.

Referring to fig. 3, a flowchart of a second step 202 according to an embodiment of the present invention includes the steps of:

301. obtaining an evaluation matrix according to the input interference level and the frequency hopping pattern of the logic channel;

after the interference level of the working sub-band of each logical channel is detected and obtained through step 201, the detection result forms a matrix:

wherein c is more than or equal to 1 and less than or equal to 3 to represent frequency point number, j is more than or equal to 1 and less than or equal to 6 to represent jth OFDM symbol in one frequency hopping period, t is more than or equal to 1 and less than or equal to 4 to represent result of t detection, thus g_cj ^tThe interference level on the c sub-band in the jth OFDM symbol time in the t detection is obtained. Then, according to the matrix G^tAnd combining the hopping patterns of the logical channels to obtain G^tMatrix A as a result of the t-th test^tMatrix A^tThe evaluation matrix is used as an evaluation matrix of the interference level received by each logic channel in each OFDM symbol time in the t-th detection, and specifically includes the following steps:

wherein, i is more than or equal to 1 and less than or equal to 7 to represent the serial number of the alternative logical channel, j is more than or equal to 1 and less than or equal to 6 to represent the jth OFDM symbol in a frequency hopping period, t is more than or equal to 1 and less than or equal to 4 to represent the result of the tth detection, therefore, a_ij ^tThat is, in the t-th detection, if the i-th logical channel is used, the interference level received in the j-th OFDM symbol time is large. Since four tests were performed, four different evaluation matrices could be obtained, which were used as input matrices for the following algorithm.

Step 302, carrying out standardization processing on the evaluation matrix;

since the interference level is a cost-type indicator, i.e., smaller and better, the matrix A is given the formula (1)^tAnd carrying out normalization processing.

Formula (1)

The normalized decision matrix thus obtained is as follows:

303, calculating the weight among indexes in the normalized decision matrix according to the normalized decision matrix;

and calculating the weight between each index in the normalized decision matrix, namely calculating the weight of each numerical value in the matrix. In the multi-index judgment, the method for determining the index weight mainly comprises a subjective weighting method and an objective weighting method. In order to avoid the influence of artificial subjective factors brought by a subjective weighting method, the embodiment of the invention adopts an objective weighting method and determines the weight of the evaluation index by an entropy method according to an information entropy theory in decision analysis.

In the embodiment of the invention, the information entropy is adopted

The information is a measure of the degree of system disorder, and the absolute values of the two are equal and the signs are opposite. In multi-target judgment, the larger the change degree of the attribute value of a certain index is, the smaller the information entropy is, the larger the information quantity provided by the index is, and the larger the weight of the index is; conversely, the smaller the change degree of the attribute value of an index is, the larger the information entropy is, the smaller the information quantity provided by the index is, and the smaller the weight of the index is. Therefore, the weight of each index can be calculated by using the information entropy according to the variation degree of the attribute value of each index.

The calculation process is as follows:

1) calculating the entropy value of the j index;

2) defining a difference coefficient;

for the jth index, the smaller the difference of the attribute values is, the smaller e is_j ^tThe larger; when the index values are all equal to each other,

e_{j}^{t} = e_{\max}^{t} = 1,

at this time, the attribute values have no effect on the comparison of the schemes; e when the index value difference of each scheme is larger_j ^tThe smaller the indicator, the greater the contribution to the solution. Thus, the coefficient of variability is defined:

3) and determining the index weight.

Since there is no preference for metrics, the jth metric weight is:

step 304, calculating to obtain local optimal decision reference vectors and gray associated vectors of local worst decision reference vectors of 7 schemes according to the normalized decision matrix and the index weight;

in the design process of the logic selection strategy based on gray level correlation, firstly, a good reference scheme, a poor reference scheme, a feasible scheme and a correlation coefficient and a correlation degree of the good scheme and the feasible scheme to the poor scheme are defined, and the purpose is to use the good reference scheme and the poor reference scheme as a standard for measuring other feasible schemes to balance the good and the poor of each scheme, so that the problem that the decision is difficult to make when the correlation coefficient is very poor under the parameters under the condition of only considering the optimal reference vector can be solved to a certain extent.

According to the normalized decision matrix, the following definitions are made:

definition 1: vector quantity

Is a time sequence T_tThe local optimal decision reference vector.

Definition 2: vector quantity

Is a time sequence T_tThe local worst decision reference vector.

Due to the contradiction between decision targets of multiple targets, there are generally:

<math><mrow> <msubsup> <mi>Q</mi> <mi>min</mi> <mi>t</mi> </msubsup> <mo>&NotEqual;</mo> <msubsup> <mi>b</mi> <mi>ij</mi> <mi>t</mi> </msubsup> <mo>,</mo> <mi>j</mi> <mo>=</mo> <mn>1,2</mn> <mo>,</mo> <mo>·</mo> <mo>·</mo> <mo>·</mo> <mo>,</mo> <mn>6</mn> </mrow></math>

or

<math><mrow> <msubsup> <mi>Q</mi> <mi>max</mi> <mi>t</mi> </msubsup> <mo>&NotEqual;</mo> <msubsup> <mi>b</mi> <mi>ij</mi> <mi>t</mi> </msubsup> <mo>,</mo> <mi>j</mi> <mo>=</mo> <mn>1,2</mn> <mo>,</mo> <mo>·</mo> <mo>·</mo> <mo>·</mo> <mo>,</mo> <mn>6</mn> <mo>.</mo> </mrow></math>

Calculating T_iThe grey correlation degree of the normalized decision matrix and the local optimal decision reference vector under the time sequence is as follows:

where ρ is a resolution coefficient, ρ ∈ [0, 1], and ρ is generally 0.5.

From 7 x 6 f_ij ^tConstructing a grey correlation judgment matrix F^tComprises the following steps:

t can be calculated by combining the index weight and the grey correlation judgment matrix_iThe gray correlation of the effect of timing scheme i (i ═ 1, 2, …, 7) with its locally optimal decision reference vector is:

the grey relevance vector of all 7 schemes to the locally optimal decision reference vector is then: (χ_i ^t)^T，i＝1，2，…，7

Similarly, T can be calculated_iThe effect of timing scheme i (i ═ 1, 2, …, 7) is associated with its local worst decision reference vector in gray by_i ^t(i ═ 1, 2, …, 7), then the gray association vector for all 7 schemes with the local worst decision reference vector is:

(ψ_i ^t)^T，i＝1，2，…，7。

305, calculating a global optimal decision vector and a global worst decision vector according to the gray relevance vector of the local optimal decision reference vector and the gray relevance vector of the local worst decision reference vector;

and synthesizing gray relevance vectors of local optimal decision reference vectors of 7 schemes in 4 time sequences to obtain an overall optimal relevance matrix:

taking the matrix as an algorithm input again, and obtaining the association effect of the scheme i (i is 1, 2, …, 7) and the overall ideal optimal gray association degree χ through the loop calculation of the steps 301 and 303_i(i ═ 1, 2, …, 7), and the overall optimal decision vector is further found to be (χ ═ R ═ g₁，χ₂，…，χ₇)^T。

Similarly, the overall worst incidence matrix can be obtained:

thus, the overall worst decision vector is found: c ═ psi₁，ψ₂，…，ψ₇)^T。

And step 306, obtaining a sequencing vector of the decision scheme according to the overall optimal decision vector and the overall worst decision vector.

According to the overall optimal decision vector and the overall worst decision vector, the ordering vector of the decision scheme can be obtained as P ═ (P)₁，p₂，…，p₇)^TWherein 0 is not more than p_iLess than or equal to 1. Scheme i toProbability of expectation p_iSubject to the preferred embodiment, with the desired value 1-p_iSubject to the inferior scheme. Then it is possible to determine which scheme, i.e. which logical channel, is optimal, based on the ordering vector.

Further, considering that the final goal of the algorithm is to make some solutions closer to the good solution and closer to the bad solution, and thus make other solutions closer to the good solution and closer to the bad solution, this is equivalent to minimizing the expectation that the decision-making solution is neither dependent on the good solution nor dependent on the bad solution, by which various alternatives can be distinguished more clearly, avoiding ambiguous decision dilemma. Therefore, an objective function f (x) can be provided according to a classical least square method, and a comprehensive optimal decision model is established:

for the convenience of solving, the formula is inversely transformed to obtain the product

To solve the optimal solution vector P ═ P (P) of the system₁，p₂，…，p_n)^TScheme i with expected probability p_iThe degree of association from the preferred embodiment is maximized, so

Can obtain the product

Obviously, this time p_iThe larger the calculation result is, the closer the scheme i is to the overall optimal decision vector and the farther away the overall worst decision vector is.

According to the calculation result, the scheme ordering vector P ═ (P) can be re-determined₁，p₂，…，p_n)^T，p_iArranged from big to small, the selection can be more accurateThe scheme is selected, namely the logical channel is selected more accurately.

It should be noted that, in the above steps, the normalization processing performed on the evaluation matrix in step 302 is for example to facilitate subsequent calculation, and may not be performed. In addition, the gray level correlation analysis method is also only an example of the evaluation algorithm, and the principle is similar as long as the interference level can be compared by using other logic operations so as to more conveniently compare the interference levels of the detected working subbands of the logic channels and select the logic channel with a small interference level.

It can be found that, in the second technical solution of the embodiment, under the ECMA-368 standard, by using a gray level correlation analysis method as an evaluation algorithm, the interference levels of the working sub-bands of each logic channel can be accurately compared, so that a logic channel with a small interference level can be selected to transmit a newly-created BP, thereby reducing interference between devices of adjacent piconets and improving system performance.

The second embodiment introduces the selection of the logical channel under the ECMA-368 standard, and the technical scheme of the second embodiment of the invention is also applicable to the UWB standard proposed in china.

Please refer to fig. 4, which is a flowchart illustrating a three-channel selection method according to an embodiment of the present invention, including the steps of:

step 401, detecting the interference level of the working sub-band of each logic channel according to the frequency hopping period, and obtaining the detection result;

when a device determines to create a new BP, first, the interference level of the working subband of each logical channel is detected, and in this embodiment, the detection method of the matched filter is used for the detection of the interference level. Considering the hopping pattern of logical channel hopping, the detection is in units of one OFDM symbol time, and the detection order at the first carrier receiver is: 345634653546356436453654 (the pattern is the hopping pattern of the logical channels); the detection order at the second carrier receiver is: 789107810979810791087108971098. that is, at the first carrier receiver, the working subband number 3 is detected for the first symbol time and the working subband number 4 is detected for the second symbol time; at the second carrier receiver, the working subband number 7 is detected in the first symbol time, the working subband number 8 is detected in the second symbol time, and so on, one detection needs to detect one frequency hopping period. That is, the interference level in one OFDM symbol time is detected in the operating subband of each logical channel in one hopping period according to the hopping pattern of the logical channel. Under the China UWB standard, the frequency hopping period is 24 OFDM symbol times. The same test is performed multiple times in view of timing issues. In this embodiment, considering the timing sequence, the two OFDM symbols before and after include the same or different conditions, and therefore, the operations are performed 4 times in sequence, and may be performed continuously or at intervals, and in order to make the result of each detection as uncorrelated as possible in time, the detection may be performed once in each MAS time.

Step 402, using the detection result as input, performing logical operation through a certain evaluation algorithm, and selecting a logical channel according to the operation result;

in the comparison of the logical channels, the interference level of the working sub-band of the logical channel is the minimum, and when the evaluation algorithm is used for logical operation of one logical channel, the interference level in 4 OFDM symbol times of the logical channel is the minimum.

Step 403, according to the obtained selection result, transmitting a new BP on the selected logical channel.

For step 402, a gray level correlation analysis method is also used as an evaluation algorithm, and specifically, the interference level in each OFDM symbol time of a logic channel frequency hopping period of the chinese UWB standard is used as an index, and 12 used logic channels are used as alternative schemes, that is, each logic channel corresponds to one scheme, so that a logic channel selection problem when a device initiates a new BP is converted into a typical multi-index decision problem, and a multi-index decision model is established.

As for the specific process of step 402, the following steps are included:

step 501, obtaining an evaluation matrix according to the input interference level and the frequency hopping pattern of the logic channel;

502, carrying out standardization processing on the evaluation matrix;

step 503, calculating the weight between each index in the normalized decision matrix by the normalized decision matrix;

step 504, calculating to obtain gray associated vectors of the local optimal decision reference vectors and the local worst decision reference vectors of the 12 schemes according to the normalized decision matrix and the index weight;

and 505, calculating the gray relevance vector of the local optimal decision reference vector and the gray relevance vector of the local worst decision reference vector to obtain an overall optimal decision vector and an overall worst decision vector.

Step 506, obtaining a sequencing vector of the decision scheme according to the overall optimal decision vector and the overall worst decision vector.

The above steps are similar to the specific steps in step 202 in example one, and are not repeated here.

It can be found that in the third technical solution of the embodiment, under the chinese UWB standard, by using a gray level correlation analysis method as an evaluation algorithm, the interference levels of the working sub-bands of each logic channel can be accurately compared, so that a logic channel with a small interference level can be selected to transmit a newly created BP, thereby reducing interference between devices of adjacent piconets and improving system performance.

In order to better embody the beneficial effects of the technical solutions of the embodiments of the present invention and the prior art, the technical solutions of the embodiments of the present invention and the prior art are subjected to simulation tests.

The test environment is as follows: assuming that a 20m x 20m area has been operated by 3 piconets, each operating with a radius of 10m, the logical channels of operation are random but not identical, and the devices requiring the newly created BP are outside the range of 3 piconets.

The superframe structure of ECMA-368 is simplified by considering only a Distributed Reservation Protocol DR P (Distributed Reservation Protocol) part, the transmitting and receiving nodes are not changed within each MAS of the piconet, and the transmitting and receiving nodes are changed once per MAS, considering the worst case of 100% operation. The transmit power of each piconet device is up-limited to-41.3 dBm/Mhz. In addition, only the case when the throughput is 160Mbps is considered.

The simulation results are shown in fig. 5-12 for the four channel (CM 1-CM 4) models provided by IEEE.

FIG. 5 is a comparison graph of bit error rates under the CM1 channel model for the two solutions of the present invention and the prior art; FIG. 7 is a comparison graph of bit error rates under the CM2 channel model for the two solutions of the present invention and the prior art; fig. 9 is a comparison graph of bit error rates under the CM3 channel model for the two solutions of the present invention and the prior art; fig. 11 is a comparison graph of the error rate of the CM4 channel model according to the embodiment of the present invention and the two solutions of the prior art. In these four figures, the upper curve corresponds to the prior art solution and the lower curve corresponds to the embodiment of the invention. It can be found that the bit error rate is low in the scheme of the embodiment of the invention.

FIG. 6 is a graph comparing throughput under the CM1 channel model for two schemes according to the present invention and the prior art; FIG. 8 is a graph comparing throughput under the CM2 channel model for two schemes according to the present invention and the prior art; FIG. 10 is a graph comparing throughput under the CM3 channel model for two schemes according to the present invention and the prior art; fig. 12 is a graph comparing throughput under the CM4 channel model for the two schemes of the present invention and the prior art. In these four figures, the lower curve corresponds to the prior art solution and the upper curve corresponds to the embodiment of the invention. It can be found that the system throughput of the embodiment of the invention is high.

In summary, according to the simulation results, the technical scheme of the embodiment of the invention has a lower error rate and higher throughput than the prior art scheme under various channel models.

It should be noted that, since the multiband OFDM UWB technology is based on the UWB scheme proposed by the OFDM technology, for some communication systems using the OFDM technology, such as 4G systems, the technical solution of the embodiment of the present invention can be used when channel selection and cell handover are involved, and the principle is similar.

It will be understood by those skilled in the art that all or part of the steps in the method for implementing the above embodiments may be implemented by hardware that is instructed to implement by a program, and the program may be stored in a computer-readable storage medium, which may be a read-only memory, a magnetic or optical disk, and the like.

The foregoing describes a channel selection method in detail according to an embodiment of the present invention, and accordingly, an embodiment of the present invention provides a communication system.

Please refer to fig. 13, which is a schematic diagram of a communication system according to an embodiment of the present invention.

As shown in fig. 13, the communication system includes: acquisition unit 131, processing unit 132, and selection unit 133.

An obtaining unit 131 is configured to obtain an interference level of the working subband of each logical channel.

A processing unit 132, configured to compare the magnitude of the interference level acquired by the acquiring unit 131.

A selecting unit 133, configured to select, according to the comparison result of the processing unit 132, a logical channel with a small interference level of the working subband as a logical channel for transmitting the newly created beacon period BP.

The processing unit 132 of the communication system further comprises: an arithmetic processing unit 1321 and a comparing unit 1322.

An operation processing unit 1321 configured to perform a logical operation on the interference level acquired by the acquisition unit 131.

A comparing unit 1322, configured to perform comparison according to the logical operation result of the operation processing unit 1321, so as to obtain the arrangement order of the interference levels acquired by the acquiring unit 131.

The arithmetic processing unit 1321 further includes: a setting unit 13211, a weighting unit 13212, a first associating unit 13213, a second associating unit 13214.

A setting unit 13211, configured to obtain a first matrix according to the interference level of each logical channel acquired by the acquiring unit 131 and the frequency hopping pattern of each logical channel.

A weighting unit 13212 configured to configure weights for the values in the first matrix. The weight of the evaluation index, i.e. the value in the first matrix, can be determined by entropy method according to the information entropy theory in the decision analysis.

A first associating unit 13213, configured to determine, according to the first matrix and the weight, gray association degree vectors of the interference levels of the logical channels and the local optimal decision reference vectors and the local worst decision reference vectors, respectively. The communication system uses a gray level correlation analysis method as an evaluation algorithm, so that a relevant gray level correlation degree vector is calculated according to a correlation principle of the algorithm.

A second associating unit 13214, configured to synthesize the gray association degree vector of each local optimal decision reference vector and the gray association degree vector of each local worst decision reference vector to perform operation, so as to obtain an overall optimal decision vector and an overall worst decision vector.

The comparing unit 1322 obtains the ordering vector of each logical channel according to the overall optimal decision vector and the overall worst decision vector obtained by the second associating unit 13214. Then it is possible to determine which scheme, i.e. which logical channel, is optimal, based on the ordering vector.

The arithmetic processing unit 1321 further includes: a normalization processing unit 13215.

A normalization processing unit 13215, configured to perform normalization processing on the first matrix obtained by the setting unit 13211; the weight unit 13212 configures weights for the normalized values in the first matrix. The first associating unit 13213 determines a gray relevance vector according to the normalized first matrix and the weight.

The processing unit 132 of the communication system further comprises: an optimization unit 1323.

An optimizing unit 1323, configured to perform an operation on the ranking vector obtained by the comparing unit 1322 according to a least square method, and re-determine a ranking vector according to a result of the operation.

The acquisition unit 131 of the communication system further includes: detection section 1311, and reception section 1312.

A detecting unit 1311, configured to detect, according to the frequency hopping pattern of each logical channel, an interference level in an orthogonal frequency division multiplexing symbol time in a frequency hopping period in a working subband of each logical channel, and obtain a detection result. The same detection is performed multiple times by the detection unit 1311 in view of timing issues. In this embodiment, considering the timing sequence, the two OFDM symbols before and after include the same or different conditions, so the detection unit 1311 performs 4 detections successively. A receiving unit 1312, configured to receive the detection result of the detecting unit 1311.

The hopping period when the detecting unit 1311 detects is 18 orthogonal frequency division multiplexing symbol times, the number of logical channels is 7, and this case is applicable to the ECMA-368 standard; or, the frequency hopping period is 24 orthogonal frequency division multiplexing symbol times, the number of logical channels is 12, and the situation is applicable to the UWB standard proposed in china.

In summary, the technical solution of the embodiment of the present invention selects the logical channels, specifically, by obtaining the interference levels of the working subbands of the logical channels, comparing the interference levels of the working subbands of the logical channels, and then according to the comparison result, selecting the logical channel with the small interference level of the working subband as the logical channel for sending the newly created beacon period BP, the defect caused by simply selecting the logical channel according to the priority in the prior art can be overcome, the interference between the devices of the adjacent piconets can be reduced, and the system performance can be improved.

Furthermore, the technical scheme of the embodiment of the invention is that a gray level correlation analysis method is used as an evaluation algorithm, and the interference level of the working sub-band of each logic channel is compared through the operation of the algorithm, so that the comparison is more accurate, and the selection is more accurate.

Furthermore, the technical scheme of the embodiment of the invention can be suitable for the ECMA-368 standard and the UWB standard proposed by China, and is flexible to apply.

In the embodiment of the invention, only the frequency hopping period is 18 OFDM symbol times, and the number of logical channels is 7; alternatively, the two cases of 24 OFDM symbol times for the frequency hopping period and 12 ″ for the logical channel number are described as examples, it is easy to conceive that the channel selection method and the communication system disclosed in the embodiments of the present invention are also applicable when the frequency hopping period and the logical channel number take other values.

The above detailed description is provided for a channel selection method and a communication system according to the embodiments of the present invention, and the principles and embodiments of the present invention are described herein by applying specific examples, and the description of the above embodiments is only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

Claims

1. A method for channel selection, comprising:

obtaining interference levels of working sub-bands of each logic channel;

comparing the interference level of the working sub-band of each logic channel;

and selecting the logic channel with low interference level of the working sub-band as the logic channel for sending the newly created beacon period.

2. The channel selection method of claim 1, wherein:

the comparing the interference level of the working sub-band of each logic channel specifically comprises:

and carrying out logical operation on the interference levels of the working sub-bands of each logical channel, and comparing according to the operation result to obtain the arrangement sequence of the interference levels of the working sub-bands of each logical channel.

3. The channel selection method of claim 2, wherein:

the logic operation is performed on the interference levels of the working sub-bands of each logic channel, and the comparison is performed according to the operation result to obtain the arrangement sequence of the interference levels of the working sub-bands of each logic channel, which specifically comprises:

obtaining a first matrix according to the interference level of the working sub-band of each logic channel and the frequency hopping pattern of the logic channel;

configuring weights for the values in the first matrix;

determining the interference level of the working sub-band of each logic channel and the gray relevance degree vector of each local optimal decision reference vector and each local worst decision reference vector respectively according to the first matrix and the weight;

integrating the gray relevance vector of each local optimal decision reference vector and the gray relevance vector of each local worst decision reference vector to perform operation to obtain an overall optimal decision vector and an overall worst decision vector;

and obtaining the sequencing vector of each logic channel according to the overall optimal decision vector and the overall worst decision vector.

4. The channel selection method of claim 3, wherein:

the obtaining the first matrix according to the interference level of the working sub-band of each logic channel and the frequency hopping pattern of the logic channel further comprises:

and normalizing the first matrix, and then entering a step of configuring weight and a step of determining grey correlation degree vectors.

5. The channel selection method of claim 3, wherein:

after the obtaining of the ordering vector of each logical channel, the method further includes:

and operating the sequencing vector according to a least square method, and re-determining the sequencing vector according to an operation result.

6. The channel selection method according to any one of claims 1 to 5, characterized by:

and detecting the interference level in the orthogonal frequency division multiplexing symbol time in the working sub-band of each logic channel in the frequency hopping period according to the frequency hopping pattern of the logic channel to obtain a detection result.

7. The channel selection method of claim 6, wherein:

and detecting the interference level in the orthogonal frequency division multiplexing symbol time in the working sub-band of each logic channel in the frequency hopping period according to the frequency hopping pattern of the logic channel, and executing the step of obtaining the detection result for multiple times.

8. The channel selection method of claim 6, wherein:

the frequency hopping period is 18 orthogonal frequency division multiplexing symbol times, and the number of logical channels is 7; or,

the frequency hopping period is 24 orthogonal frequency division multiplexing symbol times, and the number of logical channels is 12.

9. A communication system, comprising:

the acquisition unit is used for acquiring the interference level of the working sub-band of each logic channel;

the processing unit is used for comparing the interference level acquired by the acquisition unit;

and the selection unit is used for selecting the logic channel with the small interference level of the working sub-band as the logic channel for sending the newly created beacon period according to the comparison result of the processing unit.

10. The communication system of claim 9, wherein the processing unit further comprises:

an arithmetic processing unit configured to perform a logical operation on the interference level acquired by the acquisition unit;

and the comparison unit is used for comparing according to the logical operation result of the operation processing unit to obtain the arrangement sequence of the interference levels acquired by the acquisition unit.

11. The communication system according to claim 10, wherein the arithmetic processing unit further comprises:

a setting unit, configured to obtain a first matrix according to the interference level of each logical channel obtained by the obtaining unit and the frequency hopping pattern of each logical channel;

a weighting unit configured to configure weights for the values in the first matrix;

a first correlation unit, configured to determine, according to the first matrix and the weight, gray correlation vectors between the interference levels of the logic channels and the local optimal decision reference vectors and between the interference levels of the logic channels and the local worst decision reference vectors;

the second association unit is used for integrating the gray association degree vector of each local optimal decision reference vector and the gray association degree vector of each local worst decision reference vector to perform operation so as to obtain an overall optimal decision vector and an overall worst decision vector;

and the comparison unit obtains the sequencing vector of each logic channel according to the overall optimal decision vector and the overall worst decision vector obtained by the second association unit.

12. The communication system according to claim 11, wherein the arithmetic processing unit further comprises:

the normalization processing unit is used for performing normalization processing on the first matrix obtained by the setting unit; the weight unit is used for configuring weights for the numerical values in the first matrix after normalization processing;

the first correlation unit determines a grey correlation degree vector according to the first matrix after normalization processing and the weight.

13. The communication system of claim 11, wherein the processing unit further comprises:

and the optimization unit is used for calculating the sequencing vector obtained by the comparison unit according to a least square method and re-determining the sequencing vector according to the calculation result.

14. The communication system according to claim 9, wherein the obtaining unit further comprises:

and the detection unit is used for detecting the interference level in the orthogonal frequency division multiplexing symbol time in the working sub-band of each logic channel in the frequency hopping period according to the frequency hopping pattern of each logic channel to obtain a detection result.