CN108649995B - A Cognitive Radio Blind Rendezvous Method Based on Available Channel Sets - Google Patents

Abstract

The present invention provides a cognitive radio blind rendezvous method based on an available channel set, which includes that a pair of cognitive users U _i and U _j to be rendezvous randomly select one channel s _i and s _j from their respective idle channel sets; Generate seed sequences D _i and D _j according to s _i and s _j and the channel-based seed generation method; generate respective frequency hopping sequences Z _i and Z _j by D _i and D _j according to the random frequency hopping sequence generation method; cognitive user The frequency hopping communication is performed according to the frequency hopping sequence until the rendezvous is completed. The present invention can realize the rendezvous only by the available channel set, which improves the efficiency of the rendezvous, and the frequency hopping sequence ensures fast and stable rendezvous between cognitive users, and is more flexible.

Description

Cognitive radio blind convergence method based on available channel set

Technical Field

The invention belongs to the field of communication, and relates to a cognitive radio blind rendezvous method, in particular to a cognitive radio blind rendezvous method based on an available channel set.

Background

With the rapid development of wireless communication technology, the number of wireless devices and the amount of communication data have been increasing explosively in recent years, which makes the problem of scarcity of wireless spectrum resources increasingly prominent. In addition, a great deal of research shows that the traditional spectrum resource fixed allocation technology causes low utilization rate of a great amount of spectrum resources. In order to improve the spectrum utilization rate and relieve the spectrum resource demand pressure, cognitive radio is a widely paid attention as an intelligent wireless technology for realizing dynamic spectrum resource allocation.

To implement the cognitive radio technology, a communication link between cognitive users is established first. Since the cognitive users belong to unauthorized users, it is difficult for the cognitive users to establish a connection with each other under the condition that no dedicated common control channel is allocated, and the cognitive users need to search for communication target users thereof in a frequency hopping manner on the authorized channel to establish a communication link. Such a communication link establishment problem without dedicated control channel conditions is called the blind rendezvous problem (blindezvous).

In order to effectively solve the blind rendezvous problem of the cognitive user, a breakthrough needs to be made in the blind rendezvous solution, wherein the key point is to design a frequency hopping sequence generation algorithm which is based on an available channel set, does not need role playing, uses additional requirements such as user ID and the like and has good performance guarantee, and the problem which is solved and the realized aim of the invention are achieved.

Disclosure of Invention

In order to solve the above problems, the present invention provides a cognitive radio blind rendezvous method based on a set of available channels, comprising

A pair of cognitive users U to be converged_iAnd U_jRandomly selecting 1 channel s from respective sets of idle channels_iAnd s_j；

According to s_iAnd s_jAnd a corresponding seed sequence D is generated by a seed generation method based on the channel_iAnd D_j；

From D_iAnd D_jRespective frequency hopping sequences Z are generated according to a random frequency hopping sequence generation method_iAnd Z_j；

The cognitive user follows the frequency hopping sequence Z_iAnd Z_jFrequency hopping communications are conducted until rendezvous is complete.

In an embodiment of the present invention, the seed generation method includes: determining the total number M of the selectable channels and the number s of the current selected channel of each cognitive user_iAnd the minimum binary digit number of M

Defining a seed component A_iO, I, wherein A_iNumbering the channels s_iCorresponding L-bit binary number, O ═<0，0，..，0>1×L，I＝<1，1，..，1>1×L。

According to A_i，O，I，s_iConstruction of seed D_i。

In the embodiment of the present invention, further, the seed D_i＝<A_i，O，I，A_i，O，I，s_i>1×(6L+1)。

In the embodiment of the invention, the method for generating the random frequency hopping sequence comprises the step of sequentially constructing the frequency hopping basic sequence Z according to the values of the seed components^(k)Where k is the seed component index.

In an embodiment of the present invention, the value of the seed component is 0, 1 or s_i。

In this embodiment of the present invention, further, when the value of the seed component is 0, the frequency hopping basic sequence Z is^(k)From a random sequence X₀In turn and a random sequence Y₀Is composed of interlaced corresponding elements of (1), wherein X₀、Y₀Randomly selecting any permutation of p elements from m available channel numbers, wherein m is the number of channels available for the cognitive user, and p is the minimum prime number not less than m, namely:

Z^(k)＝<X₀[1]，Y₁[1]，X₁[2]，Y₁[2]，...，...，X₀[p]，Y₀[p]>1×2_p

in this embodiment of the present invention, further, when the value of the seed component is 1, the frequency hopping basic sequence Z is^(k)From a random sequence X₁In turn and a random sequence Y₁Is composed of interlaced elements of (a), wherein X₁For randomly selecting an arrangement of p elements from m available channel numbers, Y₁Randomly selecting a permutation of p +1 elements from m available channel numbers, wherein m is the number of channels available for the cognitive user, and p is the minimum prime number not less than m, namely:

Z^(k)＝<X₁[1]，Y₁[1]，X₁[2]，Y₁[2]，...，...，X₁[p]，Y₁[p-1]，..，X₁[p]，Y₁[p-1]，..，X₁[p]，Y₁[p-2]，..，X₁[p]，Y₁[p-3]，..，X₁[p]，Y₁[p-(p-1)]，X₁[1]，Y₁[2]，X₁[2]，Y₁[3]，..，X₁[p]，Y₁[p+1]>1×2p(p+1)。

in the embodiment of the invention, the cognitive user U_iAnd U_jAnd performing convergence according to the channel numbers in the sequence corresponding to the current time slot, and if the convergence is successful, stopping frequency hopping and starting to transmit data by the cognitive user.

The invention has the beneficial effects that:

1. high efficiency: according to the invention, the cognitive users only need to realize blind convergence according to the available channel set information and do not need the global information of all channels, so that the algorithm efficiency is improved, and the fast and stable convergence among the cognitive users is ensured.

2. Flexibility: additional information about the cognitive user is not needed, such as defining the cognitive user as a transmitter or a receiver, or knowing the ID of the cognitive user in advance, so that the method can be flexibly applied to various cognitive wireless networks.

Drawings

Fig. 1 shows a complete hopping sequence of user 1 in a two-dimensional table in embodiment 1 of the present invention;

fig. 2 is a complete frequency hopping sequence of the user 2 presented in a two-dimensional table form in embodiment 1 of the present invention;

FIG. 3 is a schematic diagram showing convergence of user 1 and user 2 in embodiment 1 of the present invention;

FIG. 4 is a graph of simulation results of maximum rendezvous time for an embodiment of the invention;

FIG. 5 is a graph of simulation results of average rendezvous time for an embodiment of the invention.

Detailed Description

A cognitive radio blind rendezvous method based on an available channel set comprises a pair of cognitive users U to be rendezvoused_iAnd U_jRandomly selecting 1 channel s from respective sets of idle channels_iAnd s_j(ii) a According to s_iAnd s_jAnd generating a seed sequence D based on the channel seed generation method_iAnd D_j(ii) a From D_iAnd D_jRespective frequency hopping sequences Z are generated according to a random frequency hopping sequence generation method_iAnd Z_j(ii) a Cognitive user U_iAnd U_jAccording to said frequency hopping sequence Z_iAnd Z_jFrequency hopping communications are conducted until rendezvous is complete.

The method comprises the following specific steps:

it is known that: total number of channels M, cognitive user set

N is the total number of the cognitive users; idle channel concentrated station

Wherein C is_kRepresents the k-th cognitive user U_kCorresponding to a set of idle channels. Arbitrary user U_iAnd user U_j(j ≠ i) is a pair of users that are to rendezvous the communication.

The method comprises the following steps: user U_iAt C_iTo select 1 channel s_iUser U_jAt C_jTo select 1 channel s_j。

Step two: user U_iAnd user U_jAccording to channel s respectively_iAnd s_jAnd a channel-based seed generation algorithm for generating a seed D_iAnd D_j。

Step three: user U_iAnd user U_jAccording to seed D respectively_iAnd D_jAnd a hopping sequence generation algorithm generates a hopping sequence Z_iAnd Z_j。

Step four: user U_iAnd user U_jRespectively adopt Z_iAnd Z_jAnd carrying out frequency hopping communication until rendezvous is completed.

The seed generation method comprises the following steps:

step A1: initialization, for arbitrarily assigned user U_iGiven the set of channels C available to the user_iAnd the selected channel number s_iThe total number of channels M, can represent the minimum binary digit number of M channels

Step A2: definition of seed component, definition A_iNumbering the channels s_iCorresponding L bit binary number O＝<0，0，..，0>1×L，I＝<1，1，..，1>1×L。

Step A3: seed production, seed D_i＝<A_i，O，I，A_i，O，I，s_i>1×(6L+1)。

The frequency hopping sequence generation method comprises the following steps:

the known conditions are: any given user U_iSeed D of_iAnd (3) initializing: k is 1;

step B1: if k ≦ 6L, perform step B2, otherwise, perform step B3.

Step B2: if D is_i[k]Step B4 is executed when the value is 0; otherwise, step B5 is performed.

Step B3: frequency hopping sequence Z^(k)＝<s_i>And then, the process is ended.

Step B4: initialization of X₀＝<0，0，..，0>1×p，Y₀＝<0，0，..，0>1×p，m＝|C_iL is user U_iP is the smallest prime number not less than m.

Step B41: x₀[1：m]＝Select(C_i，m)；

// is X₀The first m elements of (A) are C_iA random arrangement of available channels, where and hereinafter elements refer to the number of channels;

Y₀[1：m]＝Select(C_i，m)；

// is Y₀The first m elements of (A) are C_iRandom arrangement of available channels

Step B42: if p is>m，X₀[m+1：p]＝Select(C_i，p-m)；

// is X₀Each of the m +1 th to p-th elements of (A) is at C_iRandomly selecting the number of one channel from available channels;

Y₀[m+1：p]＝Select(C_i，p-m)；

// is Y₀Each of the m +1 th to p-th elements of (A) is at C_iRandomly selecting the number of one channel from available channels;

step B43: frequency hopping sequence Z^(k)＝<X₀[1]，Y₁[1]，X₁[2]，Y₁[2]，...，...，X₀[p]，Y₀[p]>1×2p；

Step B44: k is k +1, and the step B1 is returned;

step B5: initialization of X₁＝<0，0，..，0>1×p，Y₀＝<0，0，..，0>1×(p+1)，m＝|C_iL is user U_iP is the smallest prime number not less than m.

Step B51: x₁[1：m]＝Select(C_i，m)；

// is X₁The first m elements of (A) are C_iA random permutation of available channels;

Y₁[1：m]＝Select(C_i，m)；

// is Y₁The first m elements of (A) are C_iA random permutation of available channels;

step B52: if p is>m，X₁[m+1：p]＝Select(C_i，p-m)；

// is X₁Each of the m +1 th to p-th elements of (A) is at C_iRandomly selecting the number of one channel from the channels;

Y₁[m+1：p+1]＝Select(C_i，p+1-m)；

// is Y₁Each of the m +1 th to p +1 th elements of (A) is at C_iRandomly selecting the number of one channel from the channels;

step B53: frequency hopping sequence:

Z^(k)＝<X₁[1]，Y₁[1]，X₁[2]，Y₁[2]，...，...，X₁[p]，Y₁[p-1]，..，X₁[p]，Y₁[p-1]，..，X₁[p]，Y₁[p-2]，..，X₁[p]，Y₁[p-3]，..，X₁[p]，Y₁[p-(p-1)]，X₁[1]，Y₁[2]，X₁[2]，Y₁[3]，..，X₁[p]，Y₁[p+1]>1×2p(p+1)；

step B54: k equals k +1, and the process returns to step B1.

The frequency hopping method comprises the following steps:

initialization: t is 1;

step C1: if the cognitive user does not rendezvous, sequentially executing the steps C2 to C5;

step C2: k ═ ((t-1) mod (6L +1)) + 1;

step C3:

step C4: cognitive user attempting on channel Z^(k)[n]Upper convergence; // Z^(k)[n]Denotes z^(k)The nth element of (1);

step C5: if the convergence is successful, the cognitive user stops frequency hopping and starts to transmit data; otherwise, go to step C6;

step C6: and returning to the step C1 when t is t + 1.

Example 1

Assuming the full set of channels as C ═ C₁，c₂，c₃I.e. there are a total of M-3 channels. Considering two cognitive users, suppose the available channel sets for user 1 and user 2 are C, respectively₁＝{c₁，c₂And C₂＝{c₂，c₃Channel 2 is their only common available channel. Suppose s is selected by user 1 in the initial stage₁S selected by user 2 as 1₂＝2。

1) Note that M ═ 3, s₁And s₂Are respectively the binary representation sequences of<0，1>And<1，0>. According to the seed generation algorithm, the user 1 and the user 2 respectively generate seeds D₁And D₂The following were used:

D₁＝<0，1，0，0，1，1，0，1，0，0，1，1，s₁>1×13，

D₂＝<1，0，0，0，1，1，1，0，0，0，1，1，s₂>1×13。

2) generating a frequency hopping basic sequence

User 1: c₁＝{c₁，c₂The number m of available channels is 2, and the minimum prime number p not less than m is 2;

when k is 1, D₁[1]Assuming that X is generated through the operations of steps B41 and B42 as 0₀＝<1，2>1×p，Y₀＝<2，1>1 × p, then the corresponding basic sequence of frequency hopping Z⁽¹⁾＝<X₀[1]，Y₁[1]，X₁[2]，Y₁[2]，...，...，X₀[p]，Y₀[p]>1×2p＝<1，2，2，1>. When k is 2, D₁[2]Assuming that X is generated through the operations of steps B41 and B42 as 1₁＝<2，1>1×p，

Y₁＝<1，2，1>1 × (p +1), then the corresponding hopping basic sequence:

Z⁽²⁾＝<X₁[1]，Y₁[1]，X₁[2]，Y₁[2]，...，...，X₁[p]，Y₁[p-1]，..，X₁[p]，Y₁[p-1]，..，X₁[p]，Y₁[p-2]，..，X₁[p]，Y₁[p-3]，..，X₁[p]，Y₁[p-(p-1)]，X₁[1]，Y₁[2]，X₁[2]，Y₁[3]，..，X₁[p]，Y₁[p+1]>1×2p(p+1)

＝<2，1，1，2，2，1，1，1，2，2，1，1>。

for simplicity, for k 3, 4, …, 12, if D₁[k]Assuming that 0, the generated base sequence Z is assumed^(k)) And Z⁽¹⁾Same (note D)₁[1]0); if D is₁[k]Assuming that 1, the generated base sequence Z is assumed^(k)And Z⁽²⁾Same (note D)₁[2]＝1)。

When k is 13, Z⁽¹³⁾＝<s₁>＝<1>。

And (4) a user 2: c₂＝{c₂，c₃And when k is equal to 2, selecting the minimum prime number p which is not less than m as 21，D₂[1]Assuming that X is generated through the operations of steps B41 and B42 as 1₁＝<2，3>1×p，Y₁＝<3，2，3>1 x (p +1), the corresponding basic sequence of frequency hopping becomes<2，3，3，2，2，3，3，3，2，2，3，3>。

When k is 2, D₂[2]Assuming that X is generated through the operations of steps B41 and B42 as 0₀＝<3，2>1×p，Y₀＝<2，3>1 × p, then the corresponding basic sequence of frequency hopping Z⁽²⁾＝<X₀[1]，Y₁[1]，X₁[2]，Y₁[2]，...，...，X₀[p]，Y₀[p]>1×2p＝<3，2，2，3>。

For simplicity, for k 3, 4, …, 12, if D₂[k]Assuming that 0, the generated base sequence Z is assumed^(k)And Z⁽²⁾Same (note D)₂[2]0); if D is₂[k]Assuming that 1, the generated base sequence Z is assumed^(k)) And Z⁽¹⁾Same (note D)₂[1]＝1)。

When k is 13, Z⁽¹³⁾＝<s₂>＝<2>。

3) Performing a frequency hopping sequence attempting to rendezvous

And the user 1 and the user 2 continuously try to rendezvous according to the frequency hopping algorithm execution flow by utilizing respective frequency hopping sequences until rendezvous is successful. The frequency hopping sequence of user 1 can be presented in the form of a two-dimensional table, see in particular fig. 1; similarly, the frequency hopping sequence for user 2 can be presented by fig. 2.

User 1 and user 2 can guarantee that rendezvous is achieved in a limited time, regardless of their slot offsets. For example, assuming that user 1 starts executing its hopping sequence 7 slots after user 2 has executed it (slot offset 7), the algorithm theory ensures that user 1 and user 2 achieve rendezvous on their common available channel 2 after 33 slots, as shown in fig. 3. Note that, user 1 and user 2 may achieve rendezvous in a shorter time, for example, in this embodiment, user 1 and user 2 may access channel 2 simultaneously to achieve rendezvous after 5 time slots, but this is not guaranteed by the algorithm theory, but is relevant to the specific example.

As shown in fig. 3, the frequency hopping sequences of fig. 1 and 2 are performed, with user 1 and user 2 guaranteed rendezvous within a limited time.

Simulation experiment results

Simulation experiments were performed at matlab7.11, and representative CSAC, MMC, EJS and SSB were selected for comparison. For convenience, the process proposed by the present invention is named ZOS. In the simulation experiment, M is set to 100, that is, the full set of channels C includes 100 channels; randomly picking a part of channels from C to form an available channel set of each user, wherein each user has theta multiplied by M (0 ≦ theta ≦ 1) available channels on average, and the parameter theta is set to be changed from 0.1 to 0.5 in the simulation experiment; in addition, the number of commonly available channels between two users is set to 6. The results of the simulation experiments are given in fig. 4 and 5, where fig. 4 gives the results in terms of Maximum rendezvous time (Maximum TTR) and fig. 5 gives the results in terms of Average rendezvous time (Average TTR), each of which is statistically obtained based on 5000 independent runs. It can be seen that the rendezvous method proposed by the present invention outperforms the existing blind channel rendezvous method in terms of performance.

The above is only an embodiment of the present invention, and the total number of selectable channels, the channel number, and the sequence number of the frequency hopping start timeslot of the cognitive user in the embodiment are only examples, and the protection scope of the present invention is not limited thereby; any alterations and modifications that would be obvious to those skilled in the art without departing from the spirit of the invention are intended to be included within the scope of the invention.

Claims (3)

1. A method for cognitive radio blind rendezvous based on a set of available channels, comprising:

a pair of cognitive users U to be converged_iAnd U_jRandomly selecting 1 channel s from respective sets of idle channels_iAnd s_j；

According to said channel s_i、s_jChannel-based seed generation methodSeed sequence D_iAnd D_j；

From D_iAnd D_jRespective frequency hopping sequences Z are generated according to a random frequency hopping sequence generation method_iAnd Z_j；

Cognitive user U_iAnd U_jAccording to said frequency hopping sequence Z_iAnd Z_jCarrying out frequency hopping communication until convergence is completed;

the seed generation method comprises the following steps:

determining the total number M of potential available channels and the number s of the current selected channel of each cognitive user_iAnd the minimum binary digit L of M, i.e.

Defining a seed component A_iO, I, wherein A_iNumbering the channels s_iCorresponding L-bit binary number, O ═<0，0，...，0>_1×L，I＝<1，1，...，1>_1×L；

According to A_i，O，I，s_iConstruction of seed D_i；

The method for generating the random frequency hopping sequence comprises the steps of sequentially constructing a frequency hopping basic sequence Z according to the value of the seed component^(k)Wherein k is a seed component subscript;

the value of the seed component is 0, 1 or s_i；

When the value of the seed component is 0, the frequency hopping basic sequence Z^(k)From a random sequence X₀In turn and a random sequence Y₀Is composed of interlaced corresponding elements of (1), wherein X₀、Y₀Randomly selecting any permutation of p elements from m available channel numbers, wherein m is the number of channels available for the cognitive user, and p is the minimum prime number not less than m, namely:

Z^(k)＝<X₀[1]，Y₀[1]，X₀[2]，Y₀[2]，...，...，X₀[p]，Y₀[p]>_1×2p。

2. the method of claim 1, wherein the seed D is a member of the set of available channels_i＝<A_i，O，I，A_i，O，I，s_i>_1×(6L+1)。

3. The cognitive radio blind rendezvous method based on the set of available channels according to claim 1,

the cognitive user U_iAnd U_jAnd performing convergence according to the channel numbers in the sequence corresponding to the current time slot, and if the convergence is successful, stopping frequency hopping and starting to transmit data by the cognitive user.

Images