HYBRID TIME SLOT SCHEDULING METHOD FOR WIRELESS NETWORK

Abstract

The present disclosure selects a node generating a periodic time slot request in a network to construct a set of periodic time slot request generation nodes, and constructs a time slot request cycle set; selects a node generating an aperiodic time slot request in the network to construct a set of aperiodic time slot request generation nodes, and constructs a time set of the aperiodic time slot request generation nodes; calculates a time slot contention scheduling parameter of each node in the set of the periodic time slot request generation nodes; and if no aperiodic time slot request arrives, allocates a time slot to each time slot requesting node during periodic time slot scheduling; or if an aperiodic time slot request, namely, a sporadic time slot request, arrives, performs rescheduling through hybrid time slot scheduling based on arrival time of the aperiodic time slot request.

Claims

1. A hybrid time slot scheduling method for a wireless network, comprising the following steps: step 1: selecting a node generating a periodic time slot request in a network to construct a set of periodic time slot request generation nodes, and constructing a time slot request cycle set; step 2: selecting a node generating an aperiodic time slot request in the network to construct a set of aperiodic time slot request generation nodes, and constructing a time set of the aperiodic time slot request generation nodes; step 3: calculating a time slot contention scheduling parameter of each node in the set of the periodic time slot request generation nodes; and step 4: if no aperiodic time slot request arrives, allocating a time slot to each time slot requesting node during periodic time slot scheduling; or step 5: if an aperiodic time slot request, namely, a sporadic time slot request, arrives, performing rescheduling through hybrid time slot scheduling based on arrival time of the aperiodic time slot request.

2. The hybrid time slot scheduling method for a wireless network according to claim 1, wherein the selecting a node generating a periodic time slot request in a network in step 1 specifically comprises: defining, as a periodic time slot request generation node, the node periodically generating a time slot request in the network; the set of the periodic time slot request generation nodes in step 1 is specifically as follows: ${\phi }_k=\left\{N_{0,k},N_{1,k},N_{2,k},.Math.N_{n-1,k}\right\}$ wherein ${\phi }_k$ represents a set of periodic time slot request generation nodes at a k.sup.th time point, N.sub.i,k represents an i.sup.th node in the set of the periodic time slot request generation nodes at the k.sup.th time point, n represents a quantity of the periodic time slot request generation nodes, i E [0, n- 1], k E [1, L], L represents a quantity of time points; and the time slot request cycle set in step 1 is specifically as follows: ${\text{TA}}_{\text{K}}=\left\{{\tau }_{0,\text{k}},{\tau }_{1,\text{k}},{\tau }_{2,\text{k}},.Math.{\tau }_{\text{n-1,k}}\right\}$ wherein TA.sub.k represents a set of periodic time slot requests at the k.sup.th time point, τ.sub.i,k represents a time slot request cycle of an i.sup.th node in the set of the periodic time slot request generation nodes at the k.sup.th time point, n represents the quantity of the periodic time slot request generation nodes, L represents the quantity of time points, i ∈ [0, n-1], and k ∈ [1, L].

3. The hybrid time slot scheduling method for a wireless network according to claim 1, wherein the selecting a node generating an aperiodic time slot request in the network in step 2 specifically comprises: defining, as an aperiodic time slot request generation node, the node generating the aperiodic time slot request in the network, wherein the aperiodic time slot request generated by the aperiodic time slot request generation node is defined as the sporadic time slot request; the set of the aperiodic time slot request generation nodes in step 2 is specifically as follows: ${\delta }_{\text{k}}=\left\{{\text{M}}_{0,\text{k}},{\text{M}}_{1,\text{k}},{\text{M}}_{2,\text{k}},.Math.{\text{M}}_{\text{m-1,k}}\right\}$ wherein δ.sub.k represents a set of aperiodic time slot request generation nodes at a k.sup.th time point, M.sub.j,k represents a j.sup.th node in the set of the aperiodic time slot request generation nodes at the k.sup.th time point, m represents a quantity of the aperiodic time slot request generation nodes, L represents a quantity of time points, and $\text{k}\in \left[1,\text{L}\right],$ and $\text{j}\in \left[0,\text{m}-\text{1}\right];$ the time set of the aperiodic time slot request generation nodes in step 2 is specifically as follows: ${\text{time}}_{\text{k}}=\left\{\left({\text{t}}_{0,\text{k}},{\text{D}}_{0,\text{k}}\right),\left({\text{t}}_{1,\text{k}},{\text{D}}_{1,\text{k}}\right),.Math.,\left({\text{t}}_{\text{m-1,k}},{\text{D}}_{\text{m-1,k}}\right)\right\}$ wherein time.sub.k represents a time set of the aperiodic time slot request generation nodes at the k.sup.th time point, t.sub.j,k represents arrival time of an aperiodic time slot request of a j.sup.th node in the time set of the aperiodic time slot request generation nodes at the k.sup.th time point, D.sub.j,k represents a deadline of the aperiodic time slot request of the j.sup.th node in the time set of the aperiodic time slot request generation nodes at the k.sup.th time point, m represents the quantity of the aperiodic time slot request generation nodes, L represents the quantity of time points, k∈[1, L], and j ∈ [0, m-1]; and a deadline D.sub.j of the time slot request is alternatively represented by a quantity of time slots between the deadline D.sub.j of the time slot request and arrival time t.sub.j of the time slot request after the time slot request arrives.

4. The hybrid time slot scheduling method for a wireless network according to claim 1. wherein the time slot contention scheduling parameter of each node in the set of the periodic time slot request generation nodes in step 3 is specifically calculated according to the following formula: ${\rho }_{i,k}=\frac{BS{N}_{i,k}}{{\displaystyle {.Math.}_{i=0}^{n-1}BS{N}_{i,k}}}*\frac{B{N}_{i,k}}{{\displaystyle {.Math.}_{i=0}^{n-1}B{N}_{i,k}}}$ $\text{K}\in \left[1,\text{L}\right]$ wherein BSN.sub.i,k represents a maximum time slot interval of a backoff of node N.sub.i,k before next time slot allocation, a maximum quantity of steps backed off by each node is 0 at the beginning of time slot allocation, L represents a quantity of time points, and n represents a quantity of the periodic time slot request generation nodes: the backoff means that during time slot allocation for node N.sub.i,k, due to existence of another node, a time slot required by node N.sub.i,k is occupied, resulting in delayed allocation of the time slot required by node N.sub.i,k; BN.sub.i,k represents a total quantity of backoffs of node N.sub.i,k before next time slot allocation; and at the beginning of time slot allocation, a total quantity of backoffs of each node is 0; and a larger value of ρ.sub.i leads to more backoffs of node N.sub.i in time slot contention and more steps backed off; and the time slot contention scheduling parameter ρ.sub.i is calculated and recorded during scheduling.

5. The hybrid time slot scheduling method for a wireless network according to claim 1, wherein the allocating a time slot to each time slot requesting node during periodic time slot scheduling in step 4 is constituted by initial time slot scheduling and subsequent time slot scheduling; during the initial time slot scheduling, time slot scheduling is performed by giving priority to a shortest cycle; the node periodically generating a time slot request in the network is defined as a periodic time slot request generation node, wherein the set of the periodic time slot request generation nodes is specifically as follows: ${\phi }_k=\left\{N_{0,k},N_{1,k},N_{2,k},.Math.N_{n-1,k}\right\}$ wherein ${\phi }_k$ represents a set of periodic time slot request generation nodes at a k.sup.th time point, N.sub.i,k represents an i.sup.th node in the set of the periodic time slot request generation nodes at the k.sup.th time point, n represents a quantity of the periodic time slot request generation nodes, i ∈ [0, n-1], k ∈ [1, L], and L represents a quantity of time points; traversal is performed on $\phi {\text{'}}_k$ by using $\phi {\text{'}}_k,$ wherein nodes in $\phi {\text{'}}_k$ are sorted based on a time slot cycle of each node in ${\phi }_k$ in descending order: ${{\phi }^{\prime }}_k=\left\{{N^{\prime }}_{0,k},{N^{\prime }}_{1,k},{N^{\prime }}_{2,k},.Math.{N^{\prime }}_{n-1,k}\right\}$ wherein the nodes in $\phi {\text{'}}_k$ are sorted in ascending order based on sizes of time slot cycles, specifically: in $\phi {\text{'}}_k,$ a first node, namely, N'.sub.0,k, is a node with a shortest time slot cycle. N'.sub.1,k is a node with a second shortest time slot cycle, N'.sub.2,k is a node with a third shortest time slot cycle, ..., and N'.sub.n-1,k is a node with a longest time slot cycle; and if there are two or more nodes with a same time slot cycle, they are sorted based on their subscript numbers in $\phi {\text{'}}_k,$ and a node with a smaller subscript number is sorted as a node with a shorter time slot cycle; the subsequent time slot scheduling is constituted by subsequent contention-free time slot scheduling and subsequent contention-based time slot scheduling; the subsequent contention-free time slot scheduling comprises: allocating a time slot to each node by cycle because the subsequent contention-free time slot scheduling belongs to periodic scheduling, which specifically comprises: allocating the time slot to each node based on a sorting in $\phi {\text{'}}_k,$ in other words, allocating a time slot to N'.sub.0,k first, then allocating a time slot to N'.sub.1,k, and so on, until time slot requests of all the nodes are satisfied; the subsequent contention-based time slot scheduling comprises: calculating the time slot contention scheduling parameter ρ.sub.i,k of each contention node, and preferentially allocating a time slot to a node with a large value of the time slot contention scheduling parameter ρ.sub.i,k; the time slot contention scheduling parameter of each node in the set of the periodic time slot request generation nodes is specifically calculated according to the following formula: ${\rho }_{i,k}=\frac{BS{N}_{i,k}}{{\displaystyle {.Math.}_{i=0}^{n-1}BS{N}_{i,k}}}*\frac{B{N}_{i,k}}{{\displaystyle {.Math.}_{i=0}^{n-1}B{N}_{i,k}}}$ $\text{K}\in \left[1,\text{L}\right]$ wherein BSN.sub.i,k represents a maximum time slot interval of a backoff of node N.sub.i,k before next time slot allocation, a maximum quantity of steps backed off by each node is 0 at the beginning of time slot allocation. L represents a quantity of time points, and n represents a quantity of the periodic time slot request generation nodes; the backoff means that during time slot allocation for node N.sub.i,.sub.k, due to existence of another node, a time slot required by node N.sub.i,k is occupied, resulting in delayed allocation of the time slot required by node N.sub.i,.sub.k, BN.sub.i,.sub.k represents a total quantity of backoffs of node N.sub.i,.sub.k before next time slot allocation; and at the beginning of time slot allocation, a total quantity of backoffs of each node is 0; a larger value of ρ.sub.i leads to more backoffs of node N.sub.i in time slot contention and more steps backed off; and the time slot contention scheduling parameter ρ.sub.i is calculated and recorded during scheduling; a node with a contention relationship is referred to as a contention node; the time slot contention scheduling parameter ρ.sub.i,k of each contention node is calculated: and then the corresponding contention node is sorted in descending order based on a value of the time slot contention scheduling parameter ρ.sub.i,k: ${\theta }_{\text{k}}=\left\{{\text{C}}_{\text{0,K}}{\text{,C}}_{\text{1,K}}{\text{,C}}_{\text{2,K}}\text{,}\cdot \cdot \cdot {\text{C}}_{\text{m-1,K}}\right\};$ and in θ.sub.k, a time slot contention scheduling parameter α.sub.0 of node C.sub.0,.sub.k is largest, a time slot contention scheduling parameter α.sub.1 of C.sub.1,k is the second largest, and so on; and then, a time slot is allocated to node C.sub.θ,k first, then a time slot is allocated to node C.sub.1,k, and so on, until time slot requests of all nodes in θ.sub.k are satisfied.

6. The hybrid time slot scheduling method for a wireless network according to claim 1, wherein in step 5. to-be-allocated time slot requests comprise the periodic time slot request and the aperiodic time slot request; and the performing rescheduling through hybrid time slot scheduling in step 5 comprises the following sub-steps: step 5.1: scheduling the periodic time slot request according to the periodic scheduling method described in step 4; step 5.2: searching for an available time slot before a deadline of the aperiodic time slot request arrives: and if there is an available time slot, allocating a first available time slot found to the aperiodic time slot request, and ending the scheduling; or if there is no available time slot, performing step 5.3; and step 5.3: returning to step 5.1, and regarding the aperiodic time slot request as a periodic time slot request with a cycle of 0 to perform time slot scheduling until the time slot scheduling is completed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] FIG. 1 shows implementation steps of the present disclosure;

[0057] FIG. 2 is a schematic diagram of a time slot scheduling result of a periodic time slot request;

[0058] FIG. 3 shows an allocation conflict at time slot 16;

[0059] FIG. 4 shows a conflict resolution result determined based on a time slot contention scheduling parameter; and

[0060] FIG. 5 shows a scheduling result of an aperiodic time slot request of node M1.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0061] To make the objectives, technical solutions, and advantages of the present disclosure clearer, the present disclosure is further described below in detail with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present disclosure, but not to limit the present disclosure. That is, the described embodiments are only some rather than all embodiments of the present disclosure. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present disclosure without creative efforts shall fall within the protection scope of the present disclosure.

[0062] A first specific embodiment of the present disclosure provides a hybrid time slot scheduling method for a wireless network. Specific steps are as follows.

[0063] Step 1: Select a node generating a periodic time slot request in a network to construct a set of periodic time slot request generation nodes, and construct a time slot request cycle set.

[0064] The selecting a node generating a periodic time slot request in a network in step 1 specifically includes:

[0065] defining, as a periodic time slot request generation node, the node periodically generating a time slot request in the network.

[0066] The set of the periodic time slot request generation nodes in step 1 is specifically as follows:

${\phi }_k=\left\{N_{0,k},N_{1,k},N_{2,k},.Math.N_{n-1,k}\right\}$

where .sup.φk represents a set of periodic time slot request generation nodes at a k.sup.th time point, N.sub.i,k represents an i.sup.th node in the set of the periodic time slot request generation nodes at the k.sup.th time point, n represents a quantity of the periodic time slot request generation nodes, i∈[0, n-1], k∈[1, L], and L represents a quantity of time points.

[0067] The time slot request cycle set in step 1 is specifically as follows:

${\text{TA}}_{\text{K}}=\left\{{\tau }_{0,\text{k}},{\tau }_{1,\text{k}},{\tau }_{2,\text{k}},.Math.{\tau }_{\text{n-1},\text{k}}\right\}$

where TA.sub.k represents a set of periodic time slot requests at the k.sup.th time point, τ.sub.i,k represents a time slot request cycle of an i.sup.th node in the set of the periodic time slot request generation nodes at the k.sup.th time point, n represents the quantity of the periodic time slot request generation nodes, L represents the quantity of time points, i∈[0, n-1], and k∈[1, L].

[0068] Step 2: Select a node generating an aperiodic time slot request in the network to construct a set of aperiodic time slot request generation nodes, and construct a time set of the aperiodic time slot request generation nodes.

[0069] The selecting a node generating an aperiodic time slot request in the network in step 2 specifically includes:

[0070] defining, as an aperiodic time slot request generation node, the node generating the aperiodic time slot request in the network, where the aperiodic time slot request generated by the aperiodic time slot request generation node is defined as a sporadic time slot request.

[0071] The set of the aperiodic time slot request generation nodes in step 2 is specifically as follows:

${\delta }_{\text{k}}=\left\{{\text{M}}_{0,\text{k}},{\text{M}}_{1,\text{k}},{\text{M}}_{2,\text{k}},.Math.{\text{M}}_{\text{m-1,k}}\right\}$

[0072] where represents a set of aperiodic time slot request generation nodes at the k.sup.th time point, M.sub.j,k represents a j.sup.th node in the set of the aperiodic time slot request generation nodes at the k.sup.th time point, m represents a quantity of the aperiodic time slot request generation nodes, L represents the quantity of time points, [0073] k∈[1, L], and j∈[0, m-1].

[0074] The time set of the aperiodic time slot request generation nodes in step 2 is specifically as follows:

${\text{time}}_{\text{k}}=\left\{\left({\text{t}}_{0,\text{k}},{\text{D}}_{0,\text{k}}\right),\left({\text{t}}_{1,\text{k}},{\text{D}}_{1,\text{k}}\right),.Math.,\left({\text{t}}_{\text{m-}1,\text{k}},{\text{D}}_{\text{m-}1,\text{k}}\right)\right\}$

[0075] where time.sub.k represents a time set of the aperiodic time slot request generation nodes at the k.sup.th time point, t.sub.j,k represents arrival time of an aperiodic time slot request of a j.sup.th node in the time set of the aperiodic time slot request generation nodes at the k.sup.th time point, D.sub.j,k represents a deadline of the aperiodic time slot request of the j.sup.th node in the time set of the aperiodic time slot request generation nodes at the k.sup.th time point, m represents the quantity of the aperiodic time slot request generation nodes, L represents the quantity of time points, k∈[1, L], and j∈[0, m-1]; and [0076] a deadline D.sub.j of the time slot request is alternatively represented by a quantity of time slots between the deadline D.sub.j of the time slot request and arrival time t.sub.j of the time slot request after the time slot request arrives.

[0077] Step 3: Calculate a time slot contention scheduling parameter of each node in the set of the periodic time slot request generation nodes.

[0078] The time slot contention scheduling parameter of each node in the set of the periodic time slot request generation nodes in step 3 is specifically calculated according to the following formula:

${\rho }_{i,k}=\frac{BS{N}_{i,k}}{{\displaystyle {.Math.}_{i=0}^{n-1}BS{N}_{i,k}}}*\frac{B{N}_{i,k}}{{\displaystyle {.Math.}_{i=0}^{n-1}B{N}_{i,k}}}$

$\text{K}\in \left[1,\text{L}\right]$

[0079] where BSN.sub.i,k represents a maximum time slot interval of a backoff of node N.sub.i,k before next time slot allocation, a maximum quantity of steps backed off by each node is 0 at the beginning of time slot allocation, L represents the quantity of time points, and n represents the quantity of the periodic time slot request generation nodes; and the backoff means that during time slot allocation for node N.sub.i,k, due to existence of another node, a time slot required by node N.sub.i,k is occupied, resulting in delayed allocation of the time slot required by node N.sub.i,k; BN.sub.i,k represents a total quantity of backoffs of node N.sub.i,k before next time slot allocation; and at the beginning of time slot allocation, a total quantity of backoffs of each node is 0; and [0080] a larger value of ρ.sub.i leads to more backoffs of node N.sub.i in time slot contention and more steps backed off; and the time slot contention scheduling parameter ρ.sub.i is calculated and recorded during scheduling;

[0081] Step 4: If no aperiodic time slot request arrives, allocate a time slot to each time slot requesting node during periodic time slot scheduling.

[0082] The allocating a time slot to each time slot requesting node during periodic time slot scheduling in step 4 is constituted by initial time slot scheduling and subsequent time slot scheduling.

[0083] During the initial time slot scheduling, time slot scheduling is performed by giving priority to a shortest cycle.

[0084] The node periodically generating a time slot request in the network is defined as a periodic time slot request generation node, where the set of the periodic time slot request generation nodes is specifically as follows:

${\phi }_k=\left\{N_{0,k},N_{1,k},N_{2,k},.Math.N_{n-1,k}\right\}$

[0085] where

${\phi }_k$

represents the set of the periodic time slot request generation nodes at the k.sup.th time point, N.sub.i,k represents the i.sup.th node in the set of the periodic time slot request generation nodes at the k.sup.th time point, n represents the quantity of the periodic time slot request generation nodes, i∈[0, n-1], k∈[1, L], and L represents the quantity of time points;

[0086] Traversal is performed on

${\phi }_k$

by using

$\phi {\text{'}}_k,$

wherein nodes in

$\phi {\text{'}}_k$

are sorted based on a time slot cycle of each node in

${\phi }_k$

in descending order:

${{\phi }^{\prime }}_k=\left\{{N^{\prime }}_{0,k},{N^{\prime }}_{1,k},{N^{\prime }}_{2,k},.Math.{N^{\prime }}_{n-1,k}\right\}$

where the nodes in

$\phi {\text{'}}_k$

are sorted in ascending order based on sizes of time slot cycles, specifically: in

$\phi {\text{'}}_k,$

a first node, namely, N'.sub.0,k, is a node with a shortest time slot cycle, N'.sub.1,k is a node with a second shortest time slot cycle, N'.sub.2,k is a node with a third shortest time slot cycle, ..., and N'.sub.n-1,k is a node with a longest time slot cycle; and if there are two or more nodes with a same time slot cycle, they are sorted based on their subscript numbers in

$\phi {\text{'}}_k,$

and a node with a smaller subscript number is sorted as a node with a shorter time slot cycle.

[0087] For three nodes in Table 1, after they are sorted based on sizes of their cycles, N.sub.0 has a shortest cycle, N.sub.2 has a second shortest cycle, and N.sub.1 has a longest cycle. In this case, a result of time slot scheduling by giving priority to the shortest cycle is shown in FIG. 2.

[0088] The subsequent time slot scheduling is constituted by subsequent contention-free time slot scheduling and subsequent contention-based time slot scheduling.

[0089] The subsequent contention-free time slot scheduling includes: [0090] allocating a time slot to each node by cycle because the subsequent contention-free time slot scheduling belongs to periodic scheduling, which specifically includes: [0091] allocating the time slot to each node based on a sorting in $\phi {\text{'}}_k,$ in other words, allocating a time slot to N'.sub.0,k first, then allocating a time slot to N'.sub.1,k, and so on, until time slot requests of all the nodes are satisfied

[0092] The subsequent contention-based time slot scheduling includes:

[0093] calculating the time slot contention scheduling parameter ρ.sub.i,k of each contention node, and preferentially allocating a time slot to a node with a large value of the time slot contention scheduling parameter ρ.sub.i,k.

[0094] The time slot contention scheduling parameter of each node in the set of the periodic time slot request generation nodes is specifically calculated according to the following formula:

${\rho }_{i,k}=\frac{BS{N}_{i,k}}{{\displaystyle {.Math.}_{i=0}^{n-1}BS{N}_{i,k}}}*\frac{B{N}_{i,k}}{{\displaystyle {.Math.}_{i=0}^{n-1}B{N}_{i,k}}}$

$\text{K}\in \left[\text{1, L}\right]$

[0095] where BSN.sub.i,k represents the maximum time slot interval of the backoff of node N.sub.i,k before next time slot allocation, the maximum quantity of steps backed off by each node is 0 at the beginning of time slot allocation, L represents the quantity of time points, and n represents the quantity of the periodic time slot request generation nodes; and the backoff means that during time slot allocation for node N.sub.i,k, due to the existence of the another node, the time slot required by node N.sub.i,k is occupied, resulting in delayed allocation of the time slot required by node N.sub.i,k; BN.sub.i,k represents the total quantity of backoffs of node N.sub.i,k before next time slot allocation; and at the beginning of time slot allocation, the total quantity of backoffs of each node is 0; and [0096] the larger value of ρ.sub.i leads to more backoffs of node N.sub.i in time slot contention and more steps backed off; and the time slot contention scheduling parameter ρ.sub.i is calculated and recorded during scheduling.

[0097] A node with a contention relationship is referred to as a contention node. The time slot contention scheduling parameter ρ.sub.i,k of each contention node is calculated. Then the corresponding contention node is sorted in descending order based on a value of the time slot contention scheduling parameter ρ.sub.i,k:

${\theta }_{\text{k}}=\left\{{\text{C}}_{0,\text{K}},{\text{C}}_{1,\text{K}},{\text{C}}_{1,\text{K}},.Math.{\text{C}}_{\text{m-1,K}}\right\}$

[0098] In θ.sub.k, a time slot contention scheduling parameter α.sub.0 of node C.sub.0,k is largest, a time slot contention scheduling parameter α.sub.1 of C.sub.1,k is the second largest, and so on. Then, a time slot is allocated to node C.sub.0,k first, then a time slot is allocated to node C.sub.1,k, and so on, until time slot requests of all nodes in θ.sub.k are satisfied.

[0099] Step 5: If an aperiodic time slot request, namely, the sporadic time slot request, arrives, perform rescheduling through hybrid time slot scheduling based on arrival time of the aperiodic time slot request.

[0100] In step 5, to-be-allocated time slot requests include the periodic time slot request and the aperiodic time slot request.

[0101] The performing rescheduling through hybrid time slot scheduling in step 5 includes the following sub-steps:

[0102] Step 5.1: Schedule the periodic time slot request according to the periodic scheduling method described in step 4.

[0103] Step 5.2: Search for an available time slot before a deadline of the aperiodic time slot request arrives; and if there is an available time slot, allocate a first available time slot found to the aperiodic time slot request, and end the scheduling; or if there is no available time slot, perform step 5.3.

[0104] Step 5.3: Return to step 5.1, and regard the aperiodic time slot request as a periodic time slot request with a cycle of 0 to perform time slot scheduling until the time slot scheduling is completed.

[0105] A second specific embodiment of the present disclosure provides a hybrid time slot scheduling method for a wireless network. Specific steps are as follows.

[0106] Step 1: Define a periodic time slot request.

[0107] Node N.sub.i in a network periodically generates a time slot request with a cycle of τ.sub.i. Therefore, for n nodes connected to the network, the following node set φ is available:

$\phi =\left\{N_0,N_{1,}{N}_2,.Math.N_{n-1}\right\}$

[0108] For a network with three nodes, each of the three nodes periodically generates a periodic time slot request, and correspondingly, the following set is available:

$\phi =\left\{N_0,N_1,N_2\right\}$

[0109] A time slot request cycle of each node is shown in Table 1.

TABLE-US-00001 Time slot request cycles of the three nodes Node Time slot request cycle N.sub.0 τ.sub.0 = 4 N.sub.1 τ.sub.1 = 7 N.sub.2 τ.sub.2 = 5

[0110] Step 2: Define an aperiodic time slot request.

[0111] Node M.sub.j in the network generates the aperiodic time slot request. This kind of aperiodic time slot request, also known as a sporadic time slot request, has arrival time t.sub.j and a deadline D.sub.j. Therefore, for m nodes generating aperiodic time slot requests in the network, the following node set δ is available:

$\delta =\left\{{\text{M}}_0,{\text{M}}_1,{\text{M}}_2,.Math.{\text{M}}_{\text{m-1}}\right\}$

[0112] In the above set, t.sub.j is represented by a number of a to-be-allocated time slot when the time slot request arrives; and D.sub.j represents time at which the slot request must be completed, which is alternatively represented by a quantity of time slots between D.sub.j and t.sub.j after the time slot request arrives.

[0113] For a network with two nodes, each of the two nodes the aperiodic time slot request, and correspondingly, the following set is available:

$\delta =\left\{{\text{M}}_0,{\text{M}}_1\right\}$

[0114] In the above set, a time slot request cycle of each node is shown in Table 2.

TABLE-US-00002 Time slot request cycles of the two nodes Node Time slot request cycle M.sub.0 t.sub.0=5, D.sub.0=3 M.sub.1 t.sub.1=3, D.sub.1=2

[0115] Step 3: Determine a time slot contention scheduling parameter.

[0116] When a plurality of nodes initiate time slot requests, time slot scheduling is assisted by using the time slot contention scheduling parameter. For node N.sub.i, the time slot contention scheduling parameter is α.sub.i:

${\alpha }_i=\frac{BS{N}_i}{{\displaystyle {.Math.}_{i=0}^{n-1}BS{N}_i}}*\frac{B{N}_i}{{\displaystyle {.Math.}_{i=0}^{n-1}B{N}_i}}$

where BSN.sub.i represents a maximum time slot interval of a backoff of node N.sub.i before next time slot allocation, and a maximum quantity of steps backed off by each node is 0 at the beginning of time slot allocation.

[0117] The backoff means that during time slot allocation for node N.sub.i, due to existence of another node, a time slot required by node N.sub.i is occupied, resulting in delayed allocation of the time slot required by node N.sub.i; BNi represents a total quantity of backoffs of node N.sub.i before next time slot allocation; and at the beginning of time slot allocation, the total quantity of backoffs of each node is 0.

[0118] A larger value of α.sub.i leads to more backoffs of node N.sub.i in time slot contention and more steps backed off. The time slot contention scheduling parameter α.sub.i is calculated and recorded during scheduling.

[0119] Step 4: Perform periodic time slot scheduling.

[0120] When no aperiodic time slot request arrives, periodic time slot scheduling is adopted. During periodic time slot scheduling, a time slot is allocated to each time slot requesting node, which is divided into two sub-steps: initial time slot scheduling and subsequent time slot scheduling.

[0121] During the initial time slot scheduling, time slot scheduling is performed by giving priority to a shortest cycle.

[0122] For the three nodes in Table 1, after they are sorted based on sizes of their cycles, N.sub.0 has a shortest cycle, N.sub.2 has a second shortest cycle, and N.sub.1 has a longest cycle. In this case, a result of time slot scheduling by giving priority to the shortest cycle is shown in FIG. 2.

[0123] The subsequent time slot scheduling includes subsequent contention-free time slot scheduling and subsequent contention-based time slot scheduling.

[0124] The subsequent contention-free time slot scheduling includes:

[0125] allocating a time slot to each node by cycle because the subsequent contention-free time slot scheduling belongs to periodic scheduling.

[0126] The subsequent contention-based time slot scheduling includes:

[0127] calculating the time slot contention scheduling parameter α.sub.i of each contention node, and preferentially allocating a time slot to a node with a large value of the time slot contention scheduling parameter α.sub.i.

[0128] For each node in Table 1, a conflict occurs in a 17.sup.th slot, namely, time slot 16, as shown in FIG. 3. In this case, rescheduling needs to be performed.

TABLE-US-00003 Parameters of the three nodes Node Time slot request cycle BSN.sub.i BN.sub.i a.sub.i N.sub.0 τ.sub.0 = 4 BSN.sub.0=0 BN.sub.0=0 a.sub.0=0 N.sub.1 τ.sub.1 = 7 BSN.sub.1=2 BN.sub.1=1 a.sub.1=⅓ N.sub.2 τ.sub.2 = 5 BSN.sub.2=1 BN.sub.2=1 a.sub.2=½

[0129] Based on the calculated time slot contention scheduling parameter α.sub.i, a time slot is preferentially allocated to N.sub.2, then a time slot is allocated to N.sub.1, and finally a time slot is allocated to N.sub.0. A scheduling result is shown in FIG. 4.

[0130] Step 5: Perform hybrid time slot scheduling.

[0131] The aperiodic time slot request, namely, the sporadic time slot request, is rescheduled based on the arrival time of the aperiodic time slot request during periodic scheduling. In this case, to-be-allocated time slot requests include the periodic time slot request and the aperiodic time slot request.

[0132] A method for hybrid time slot scheduling includes the following steps:

[0133] Step 5.1: Schedule the periodic time slot request according to the periodic scheduling method described in step 4.

[0134] Step 5.2: Search for an available time slot before a deadline of the aperiodic time slot request arrives; and if there is an available time slot, allocate a first available time slot found to the aperiodic time slot request, and end the scheduling; or if there is no available time slot, perform step 5.3.

[0135] Step 5.3: Return to step 5.1, and regard the aperiodic time slot request as a periodic time slot request with a cycle of 0 to perform time slot scheduling until the time slot scheduling is completed.

[0136] For the nodes N.sub.1, N.sub.2, N.sub.3, M.sub.1 and M.sub.2 in Table 1 and Table 2, according to step 1 above, a result of periodic time slot scheduling is obtained, as shown in FIG. 2; and according to step 2, a time slot request of node M.sub.1 arrives first, and the time slot request can be allocated to slot 2 and slot 3. Based on the scheduling result shown in FIG. 2, slot 3 is available, and the aperiodic time slot request of node M.sub.1 is allocated to slot 3, as shown in FIG. 5. When a time slot request of node M.sub.0 arrives, the time slot request can be allocated to slot 4, slot 5 and slot 6. Based on a scheduling result shown in FIG. 5, slot 5 is available, and the aperiodic time slot request of node M.sub.0 is allocated to slot 5.

[0137] The specific embodiments described in the present disclosure are merely illustrative of the spirit of the present disclosure. A person skilled in the art can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, but it may not depart from the spirit of the present disclosure or the scope defined by the appended claims.