CN107635237B - Control channel establishment method in cognitive radio network based on jump stay strategy - Google Patents
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Abstract
The invention discloses a control channel establishing method in a cognitive radio network based on a jump stay strategy, which solves the redundancy problem existing in the existing control channel establishing method by shortening the cycle length of a frequency jump sequence of a single-transceiver unauthorized user and minimizing the maximum time required by establishing a control channel among multiple-transceiver unauthorized users. The method comprises the following specific steps: removing single-transceiver unlicensed user frequency hopping sequence redundancy: the method for generating the frequency hopping sequence by the single-transceiver unauthorized user is set so as to shorten the length of the frequency hopping sequence period of the single-transceiver unauthorized user; removing multi-transceiver unlicensed user frequency hopping sequence redundancy: the number of hopping transceivers and dwell transceivers for a multi-transceiver unlicensed user is determined by minimizing the maximum time required for control channel establishment between the multi-transceiver unlicensed users.
Description
Technical Field
The invention relates to a control channel establishing method in a cognitive radio network based on a jump stay strategy, belonging to the technical field of radio networks.
Background
With the proliferation of wireless devices and applications, communications over unlicensed spectrum become very congested. At the same time, the licensed spectrum is not fully utilized. In order to improve spectrum utilization efficiency and solve the problem of communication congestion in an unlicensed frequency band, cognitive radio networks have been developed. In a cognitive radio network, an unauthorized user can dynamically use a licensed spectrum for communication without interfering with the normal communication of the authorized user. Since usage of licensed spectrum by authorized users is dynamic and mobility of unauthorized users, the available licensed spectrum is time-varying for unauthorized users. Furthermore, cognitive radio networks are typically heterogeneous. Thus, an unauthorized user may have different available licensed spectrum and different numbers of transceivers.
Cognitive radio networks are divided into licensed and unlicensed networks. The authorized network comprises authorized users and authorized base stations. Unlicensed networks can be further divided into infrastructure-based unlicensed networks and infrastructure-less unlicensed networks. An infrastructure unlicensed network is composed of unlicensed base stations and unlicensed users. Infrastructure-less unlicensed networks are composed of unlicensed users. The infrastructure-free unauthorized network does not require infrastructure expense and thus has a wide application prospect. Clocks between unauthorized users in infrastructure-less unauthorized networks are typically asynchronous, i.e., time-shifted.
Since in a cognitive radio network, the licensed frequency bands available to an unlicensed user may be different and dynamically changing. Therefore, if an unauthorized user wants to communicate with its target unauthorized user, they must first access the same authorized spectrum at the same time to exchange control information for establishing a communication link, which is the control channel establishment procedure. The frequency hopping sequence technique is a representative technique for realizing the establishment of the control channel. The main idea of the frequency hopping sequence is that each unauthorized user generates its own frequency hopping sequence according to its frequency hopping sequence generation method, and then accesses its available authorized channel at each time slot according to its generated frequency hopping sequence until meeting at the same time with its target unauthorized user on the same channel. Control channel setup time is typically used to measure the performance of the control channel setup method. The control channel establishment time is the time taken by a pair of unauthorized users to establish a control channel, and is characterized by a time slot taken by the unauthorized users starting the control channel establishment process to complete the control channel establishment. Since the licensed spectrum that may be used by an unlicensed user is typically assumed to be constant during control channel setup. Therefore, it is desirable to provide a control channel establishing method that enables an unauthorized user to quickly establish a control channel with its target unauthorized user.
The jump stay strategy can well solve the problem of establishing a control channel between unauthorized users in the heterogeneous cognitive radio network. The main idea is that the hopping dwell strategy generates the spectrum hopping sequence in cycles and the spectrum hopping sequence per cycle contains two modes, namely a hopping mode and a dwell mode. In the hopping mode, the unauthorized user accesses different available channels continuously, and the channel index of the access channel is determined by the initial channel index and the step size. In stay mode, an unauthorized user stays on one and the same channel, and the stay channel changes once per cycle.
The related research literature for the control channel establishment method in the cognitive radio network based on the jump stay strategy at present is as follows:
the Jump strategy was first proposed by Zhiyong Lin et al in 2011 "IEEE INFOCOM" in Jump-Stay Based Channel-hosting Algorithm with guarded Rendezvous for Cognitive Radio Networks ". The jump dwell strategy generates a frequency jump sequence in cycles, which are divided into internal cycles and external cycles. The internal period consists of two modes, namely a skip mode and a stay mode. The outer period is composed of a plurality of inner periods. The hop step size changes once per inner period and the initial channel index changes once per outer period. The hop dwell strategy can ensure that the control channel between unauthorized users is established for a limited time.
An article "Enhanced Jump-Stay Rendezvous Algorithms for Cognitive Radio Networks" published by Zhiyong Lin et al in IEEE COMMUNICATIONS LETTERS 2013 to further shorten the time required to establish a control channel. The jump stopping strategy is improved, and an enhanced jump stopping strategy is provided. In the enhanced jump stay strategy, only one period is provided, the jump step is always constant, and the initial channel index changes once every period. The enhanced hop-dwell strategy reduces the time required to establish a control channel between unauthorized users compared to the hop-dwell strategy.
A parallel sequence method based ON a jump stay strategy is proposed by Lu Yu et al in 2015, which is published in IEEE TRANSACTIONS MOBILE COMPUTING, in the article of Multiple Radios for Fast render in Cognitive Radio Networks. In the parallel sequence method, an unauthorized user is equipped with a plurality of transceivers, which can be classified into a hopping transceiver and a staying transceiver. The number of the staying transceivers is 1, and the rest transceivers are all hopping transceivers. The dwell transceiver stays on the same available channel for one period, with the dwell channel changing once per period. The hopping transceiver accesses different available channels over a period without interruption. Because the unauthorized user is provided with a plurality of transceivers in the parallel sequence method, the unauthorized user can access a plurality of available channels in the same time slot to try to establish the control channel, thereby shortening the cycle length of the frequency hopping sequence and further shortening the time required for establishing the control channel. However, in the parallel sequence method, an unauthorized user needs to be equipped with at least two transceivers. If only one transceiver is installed in an unauthorized user, the parallel sequence method cannot guarantee that a control channel between unauthorized users can be established within a limited time. Therefore, the parallel sequence method is not applicable to the heterogeneous cognitive radio network.
An Adjustable Multi-transceiver method was proposed by Lu Yu et al in 2015, IEEE GLOBECOM, in "Adjustable Redezvous in Multi-Radio coherent Radio Networks". In the adjustable transceiver approach, the number of parked transceivers is variable. Furthermore, the adjustable transceiver method uses only the available channel set of the unauthorized user in generating the frequency hopping sequence. Therefore, the cycle length of the frequency hopping sequence can be further shortened, and the time required for establishing the control channel can be reduced. However, the scalable multi-transceiver approach is also not applicable to heterogeneous cognitive radio networks, since an unauthorized user needs to install at least two transceivers.
An article "Energy-Efficient Channel hosting Protocol for Cognitive Radio Networks" published by Aohan Li et al in "IEEE GLOBECOM" of 2017 proposes a control Channel establishment method based on a jump stay strategy, and solves the problem that the existing control Channel establishment method cannot be applied to a heterogeneous Cognitive Radio network. This approach includes two strategies, a multi-transceiver frequency hopping sequence strategy and a single-transceiver frequency hopping sequence strategy. The unauthorized user selects one strategy to generate the frequency hopping sequence according to the number of transceivers. If the unauthorized user is equipped with a transceiver, selecting a single transceiver frequency hopping sequence strategy; otherwise, a multi-transceiver frequency hopping sequence is selected. However, the period length of the frequency hopping sequence generated by this method is lengthy. Although this approach solves the problem of control channel establishment in heterogeneous cognitive radio networks, the time required for control channel establishment is not well improved.
Disclosure of Invention
The invention aims to solve the problem of the cycle length redundancy of a frequency hopping sequence generated by a control channel establishing method in the existing heterogeneous cognitive radio network. The invention provides a control channel establishing method in a cognitive radio network based on a jump stay strategy, which can effectively reduce the cycle length of a frequency jump sequence and further reduce the time required by establishing the control channel in a heterogeneous cognitive radio network.
The technical scheme of the invention is as follows:
a control channel establishing method in a cognitive radio network based on a jump stay strategy comprises the following steps:
step 1, removing the frequency hopping sequence redundancy of the single transceiver unauthorized user: the method for generating the frequency hopping sequence by the single-transceiver unauthorized user is set so as to shorten the length of the frequency hopping sequence period of the single-transceiver unauthorized user;
In the method for establishing a control channel of a heterogeneous cognitive radio network based on a jump stay strategy, the method for setting an unauthorized user of a single transceiver to generate a frequency jump sequence specifically comprises the following steps:
step 1, setting the cycle length of a frequency hopping sequence of a single transceiver unauthorized user: setting the cycle length of the stay mode 2 as P, and setting the cycle length of the frequency hopping sequence as 4P, wherein P is the minimum prime number which is not less than the number of the authorized channels;
and 3, setting a generation mode of a staying channel of the staying mode 2: the dwell channel index for dwell mode 2 is generated as follows:
in the method for establishing a control channel of a heterogeneous cognitive radio network based on a hop dwell strategy, the specific step of removing the frequency hop sequence redundancy of the unauthorized user of the multi-transceiver is as follows:
step 1, obtaining a maximum control channel establishment time expression among multiple transceiver unauthorized users: the maximum control channel setup time is the time required to set up the control channel in the worst case. In the worst case, the unauthorized user of the multi-transceiver with a longer frequency hopping sequence period precedes its frequency hopping sequence
In a period, the channel accessed by the staying transceiver is unavailable for the target multi-transceiver unauthorized user, wherein miNumber of transceivers, k, for multiple transceiver unauthorized usersiThe number of hopping transceivers for the multi-transceiver unlicensed user, G is the number of commonly available channels between unlicensed users. The expression of the maximum control channel establishment time between the multi-transceiver unauthorized users is as follows:
MTTCCE＝max{wA,wB}×(F(A,B)+2),
wherein,
withe cycle length of the frequency hopping sequence for the unauthorized user i.
and 3, determining the number of the optimal jump transceivers and the optimal stay transceivers of the multi-transceiver unauthorized user according to the objective function and the constraint function.
The invention has the beneficial effects that:
(1) the invention reduces the redundancy of the single-transceiver unauthorized user by shortening the cycle length of the frequency hopping sequence of the single-transceiver unauthorized user, thereby shortening the time required by the single-transceiver unauthorized user to establish a control channel;
(2) the invention determines the format of the hop transceiver of the unauthorized user and the staying transceiver thereof by minimizing the maximum time required by the establishment of the control channel of the unauthorized user of the multi-transceiver, thereby shortening the time required by the unauthorized user of the multi-transceiver to establish the control channel.
Drawings
Fig. 1 is a flowchart of a method for establishing a control channel in a cognitive radio network based on a jump stop strategy according to the present invention.
Fig. 2 is a flow chart of a method for generating a frequency hopping sequence for a single transceiver unauthorized user.
Fig. 3 is a flow chart for removing frequency hopping sequence redundancy of a multi-transceiver unlicensed user.
Fig. 4 is a diagram illustrating establishment of a control channel between a single-transceiver unauthorized user and a multi-transceiver unauthorized user.
Fig. 5 is a diagram illustrating establishment of a control channel between single-transceiver unauthorized users.
Fig. 6 is a diagram illustrating establishment of a control channel between multi-transceiver unlicensed users.
Detailed Description
The following further describes a specific embodiment of the present invention with reference to the drawings and technical solutions.
As shown in fig. 1, the method for establishing a control channel in a cognitive radio network based on a jump stay strategy of the present invention mainly removes redundancy through two steps, which include:
step 1, removing the frequency hopping sequence redundancy of the single transceiver unauthorized user: the method for generating the frequency hopping sequence by the single-transceiver unauthorized user is set so as to shorten the length of the frequency hopping sequence period of the single-transceiver unauthorized user;
As shown in fig. 2, the specific steps of the method for generating the frequency spectrum hopping sequence by the single-transceiver unauthorized user can be summarized as follows:
step 1, setting the cycle length of a frequency hopping sequence of a single transceiver unauthorized user: setting the cycle length of the stay mode 2 as P, and setting the cycle length of the frequency hopping sequence as 4P, wherein P is the minimum prime number which is not less than the number of the authorized channels;
and 3, setting a generation mode of a staying channel of the staying mode 2: the dwell channel index for dwell mode 2 is generated as follows:
as shown in fig. 3, the step of removing the spectrum hopping sequence redundancy of the multi-transceiver unlicensed user includes:
step 1, obtaining a maximum control channel establishment time expression among multiple transceiver unauthorized users;
the MTTCCE is the time required to establish a control channel between multi-transceiver unauthorized users in the worst case. In the worst case, the unauthorized user of the multi-transceiver with a longer frequency hopping sequence period precedes its frequency hopping sequence
In a period where the channel accessed by the staying transceiver is not available to its target multi-transceiver unauthorized user, wiCycle length of frequency hopping sequence, m, for unauthorized user iiNumber of transceivers, k, for multiple transceiver unauthorized usersiThe number of hopping transceivers for the multi-transceiver unlicensed user, G is the number of commonly available channels between unlicensed users.
And 3, determining the number of the optimal jump transceivers and the optimal stay transceivers of the multi-transceiver unauthorized user according to the objective function and the constraint function.
As shown in fig. 4, the frequency hopping sequence is generated by the multi-transceiver unauthorized user according to the control channel establishment method in the cognitive radio network based on the hopping stay policy of the present invention, and the control channel between the multi-transceiver unauthorized users can be established between the stay transceiver of the multi-transceiver unauthorized user having a long frequency hopping sequence period and the transceiver of another multi-transceiver unauthorized user. Since in a heterogeneous cognitive radio network, the licensed spectrum that a multi-transceiver unlicensed user may use may be different. The worst-case time required to establish the control channel is therefore used to characterize the performance of the control channel establishment method. Thus, the expression of the maximum time required for control channel establishment between multi-transceiver unlicensed users is:
MTTCCE＝max{wA,wB}×(F(A,B)+2),
wherein,
as shown in fig. 5, when two unauthorized users are each equipped with a transceiver: when delta is more than or equal to 0*<2P or 3P<δ*<4P, the control channel between the two can be established between the hopping modes of two unauthorized users or between stay mode 1, where δ*δ mod4P, δ being the clock offset between two unauthorized users; when 2P is less than or equal to delta*At ≦ 3P, the control channel between the two unauthorized users may be established between stay mode 2 for one unauthorized user and hop mode for the other unauthorized user. In summary, the control channel establishment method in the cognitive radio network based on the jump stay strategy of the present invention can ensure the establishment of the control channel between the single transceiver unauthorized users on the basis of removing the redundancy.
As shown in fig. 6, when one unauthorized user is equipped with one transceiver and another unauthorized user is equipped with multiple transceivers, the control channel between the two unauthorized users can be established between the stay mode 2 of the single-transceiver unauthorized user and one period of the multiple-transceiver unauthorized user, i.e. the method for establishing the control channel in the cognitive radio network based on the skip stay policy of the present invention can ensure the establishment of the control channel between the single-transceiver unauthorized user and the multiple-transceiver unauthorized user on the basis of removing redundancy.
Claims (1)
1. A control channel establishing method in a cognitive radio network based on a jump stay strategy is characterized by comprising the following steps:
step 1, removing the frequency hopping sequence redundancy of the single transceiver unauthorized user: the method for generating the frequency hopping sequence by the single-transceiver unauthorized user is set so as to shorten the length of the frequency hopping sequence period of the single-transceiver unauthorized user; the method for setting the single transceiver unauthorized user to generate the frequency hopping sequence comprises the following specific steps:
(1) setting the cycle length of the frequency hopping sequence of the single transceiver unauthorized user: setting the cycle length of the stay mode 2 as P, and setting the cycle length of the frequency hopping sequence as 4P, wherein P is the minimum prime number which is not less than the number of the authorized channels;
(2) setting an initial channel index of a hopping pattern: setting an initial channel index generation formula of the hopping pattern as:
wherein ii0The establishment of the control channel is started at [1, | C |)i|]A randomly selected number of (1); i CiI is the available channel number of the unauthorized user i; t is tiA local clock that is an unauthorized user i;
(3) setting a generation mode of a stay channel of stay mode 2: the dwell channel index for dwell mode 2 is generated as follows:
step 2, removing the frequency hopping sequence redundancy of the multi-transceiver unauthorized user: determining the number of hopping transceivers and dwell transceivers for a multi-transceiver unlicensed user by minimizing the control channel between the multi-transceiver unlicensed users and establishing the maximum time required; the specific steps for removing the frequency hopping sequence redundancy of the multi-transceiver unauthorized user are as follows:
(1) obtaining a maximum control channel establishment time expression between multi-transceiver unlicensed users: the maximum control channel establishment time is the time required to establish the control channel under the worst condition; in the worst case, the unauthorized user of the multi-transceiver with a longer frequency hopping sequence period precedes its frequency hopping sequence
In a period, the channel accessed by the staying transceiver is unavailable for the target multi-transceiver unauthorized user, wherein miNumber of transceivers, k, for multiple transceiver unauthorized usersiThe number of the hopping transceivers for the multi-transceiver unauthorized users, G is the number of the public available channels between the unauthorized users; the expression of the maximum control channel establishment time among the multi-transceiver unauthorized users is as follows:
MTTCCE＝max{wA,wB}×(F(A,B)+2)，
wherein,
withe cycle length of the frequency hopping sequence for the unauthorized user i;
(2) establishing an objective function and a constraint function: the objective function is: min (MTTCCE), the constraint function is:
(3) and determining the number of the optimal hop transceivers and the optimal stay transceivers of the multi-transceiver unauthorized user according to the objective function and the constraint function.
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| US20150085817A1 (en) * | 2013-09-25 | 2015-03-26 | Hong Kong Baptist University | Method for achieving rendezvous for cognitive radio networks |
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| US20150085817A1 (en) * | 2013-09-25 | 2015-03-26 | Hong Kong Baptist University | Method for achieving rendezvous for cognitive radio networks |
| CN105763224A (en) * | 2016-04-14 | 2016-07-13 | 电子科技大学 | Distributed asynchronous frequency hopping system frequency hopping sequence generation method |
| CN106788820A (en) * | 2017-01-04 | 2017-05-31 | 河海大学常州校区 | Cognitive radio networks multi-transceiver unauthorized user meets method |
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