WO2014077673A1 - System and method for frequency channel allocation in a wireless communication network - Google Patents

System and method for frequency channel allocation in a wireless communication network Download PDF

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Publication number
WO2014077673A1
WO2014077673A1 PCT/MY2013/000198 MY2013000198W WO2014077673A1 WO 2014077673 A1 WO2014077673 A1 WO 2014077673A1 MY 2013000198 W MY2013000198 W MY 2013000198W WO 2014077673 A1 WO2014077673 A1 WO 2014077673A1
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Prior art keywords
wireless node
neighboring
wireless
node
nodes
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PCT/MY2013/000198
Other languages
French (fr)
Inventor
Reza Khoshdelniat
Mohammad TAHIR
Hafizal BIN MOHAMMA@DIN
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Mimos Berhad
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Publication of WO2014077673A1 publication Critical patent/WO2014077673A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/02—Power saving arrangements
    • H04W52/0209—Power saving arrangements in terminal devices
    • H04W52/0212—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is master and terminal is slave
    • H04W52/0216—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is master and terminal is slave using a pre-established activity schedule, e.g. traffic indication frame
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/02—Power saving arrangements
    • H04W52/0209—Power saving arrangements in terminal devices
    • H04W52/0212—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is master and terminal is slave
    • H04W52/0219—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is master and terminal is slave where the power saving management affects multiple terminals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/50—Allocation or scheduling criteria for wireless resources
    • H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
    • H04W72/541—Allocation or scheduling criteria for wireless resources based on quality criteria using the level of interference
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H04L1/1607—Details of the supervisory signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/044—Wireless resource allocation based on the type of the allocated resource
    • H04W72/0446—Resources in time domain, e.g. slots or frames
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/044—Wireless resource allocation based on the type of the allocated resource
    • H04W72/0453—Resources in frequency domain, e.g. a carrier in FDMA
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/18—Self-organising networks, e.g. ad-hoc networks or sensor networks
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Definitions

  • the present invention relates to a wireless communication network. More particularly, relates to a channel allocation method for use in a wireless comraunication network to avoid interference and collision of data transmission occurred ;among wireless nodes in the communication network.
  • Typical multi-hop wireless networks such as a wireless mesh network, in which wireless nodes, due to the limited number of channel frequency, generally communicate with one another using a shared frequency channel. This eventually will deteriorate the network performance, especially when more than one nodes within a neighborhood trying to transmit data on the same frequency channel. Under such a circumstance, these transmitting nodes may collide and corrupt at each other and consequently leading to data packet loss. Re-transmission of such missing packets is therefore required. However, such re-transmission process often causes higher energy consumption of the nodes as well as poor network throughput efficiency. Accordingly, various systems and methods have thus been proposed to avoid interference and collision during data transmission over a wireless network.
  • U.S.Patent Application 2010/0118812 (Al) has provided a method of allocating multi-channel to each of the wireless nodes within a network to avoid transmission's interference among the wireless media.
  • This multi-channel allocation method teaches defining a number of logical channels based on the number of nodes within a communication range and thereafter, allocating the resultant number of logical channels to each of the wireless in such a manner that the allocated channel do not overlap with each other for data exchange between the nodes within an interference range.
  • a method for enabling a wireless node to communicate with each of its neighboring wireless-nodes in a- wireless communication network based on a communication link that is in the form of frequency channel and which is substantially free from interference and collision is disclosed.
  • the above mentioned method comprising the steps of: allocating by the wireless node, each of its neighboring wireless nodes a specific frequency channel, wherein the frequency channel is specifically assigned from either one time slot of the wireless node and to be allocated to a corresponding receiving time slot of one of its neighboring wireless nodes; synchronizing the frequency channel allocations between the wireless node and each of its neighboring wireless nodes so as to ensure if each of the time slots of the wireless node overlap with its corresponding receiving time slots of one of its neighboring wireless nodes at which the frequency channel has been specifically allocated; optimizing sleep time of the wireless nodes by identifying and determining non-overlapping time slots of each of the time-synchronized wireless nodes; and facilitating channel shifting for the wireless nodes based on the optimized time slots and the frequency channels that have been specifically allocated at each of the time slots of the wireless node.
  • the frequency channel allocation method further comprising: generating a neighbor node set of the wireless node, wherein the neighbor node set includes information such as the number of the wireless nodes that are discovered within a predetermined transmission range of the wireless node and identity of each of the discovered neighboring wireless nodes, prior to the-step of allocating a specific frequency channel to each of its neighboring wireless nodes.
  • the present invention discloses a wireless communication network having one or more wireless nodes configured to communicate and exchange data wirelessly with at least one of its neighboring wireless node within a predetermined transmission range, wherein each of the wireless nodes comprising: a Tx/Rx antenna enables the wireless node to receive and transmit data within the wireless communication network; a neighbor node discovery module, coupled with the Tx Rx antenna, for generating a neighbor node set of the wireless node; a channel allocation module for initiating the wireless node to assign each of its neighboring wireless nodes recorded in the neighbor node set a specific frequency channel, wherein the frequency channel is specifically assigned from either one time slot of the wireless node and to be allocated to a corresponding receiving time slot of one of its neighboring nodes; a channel allocation synchronization module for allowing the wireless node to be time- synchronized with each of its neighboring wireless nodes and thereby to ensure no neighboring wireless node will be using the same frequency channel to communicate with one another; and a time division optimization module for identifying
  • Figure 1 is a simplified flow chart illustrating a multi-channel allocation method in accordance with an embodiment of the present invention
  • Figure 2 is an exemplary embodiment of the present invention where each of the wireless nodes in a communication network has assigned a specific frequency channel to each of its neighboring nodes;
  • Figure 3 illustrates time division synchronization of a plurality of wireless nodes that are located within a transmission range in a wireless communication network
  • Figure 4 illustrates the resultant overlapping time slots between the wireless nodes from the time division synchronization operation as shown in Figure 3;
  • Figure 5 illustrates unscheduled transmission time slots (e.g. shadowed block) that are identified in the time division unit of each of the wireless nodes for efficient energy utilization and excellent communication network efficiency;
  • Figure 6 is a repetition pattern of the well-defined time division unit of each of the wireless nodes as illustrated in Figure 5 for the respective wireless nodes to follow for subsequent data transmission and/or reception processes;
  • Figure 7 is a flow chart illustrating a method for frequency channel allocation in a wireless communication network according to one exemplary embodiment of the present invention, in detail;
  • Figure 8 is a block diagram of a wireless node being adapted to improve the network performance of a wireless communication network.
  • FIG. 1 is a simplified flowchart illustrating how multi-channel allocation method of one embodiment of the present operates so that interference and collision of data transmission among wireless nodes in a particular wireless communication network can be substantially avoided.
  • such channel- allocation method includes five sequential steps: (i) generating a neighbor node set of each of the wireless nodes in the network, in step S10; (ii) allocating frequency channel by each of the wireless nodes to its neighboring wireless nodes, in step Sll, (iii) synchronizing the frequency channel allocations between each of the wireless nodes and its neighboring wireless nodes in order to ensure overlapping time slot between the wireless nodes for communication, in step S12, (iv) performing time division optimization by identifying and calculating non- overlapping time slot of each of the frequency channel allocations, in step S13; and thereafter, (v) facilitating channel shifting for each wireless node based on the optimized time slots and the frequency channels allocated at each time slot, in step S14.
  • FIG. 2 exemplifies an embodiment of the present invention.
  • Each of the wireless nodes (10) in a communication network (100) allocates a specific frequency channel (15) to each of its neighboring wireless nodes (10) to avoid any potential signal interference among the neighboring wireless nodes (10) during data transmission. It is to be noted that, before allocation of multiple frequency channels (15) for data communication between wireless nodes (10) in the wireless communication network (100), a neighbor node set being associated with each of the wireless nodes (10) must be determined and generated. Any neighbor discovery mechanisms available in the art may be used.
  • each of the wireless nodes (10) respectively, records in its local memory the identification information of each accessible wireless node (10) that is found in its vicinity, suitably, within its transmission range for data communication. The number of its neighboring wireless nodes (10) is also recorded.
  • each of the wireless nodes (10) is initiated to communicate with each of its neighboring wireless nodes through a specific frequency channel (15).
  • the frequency channel (15) may include any available communication link in the art. It is to be understood that multiple frequency channels (15) will be assigned from a wireless node (10) for communication with each of its neighboring wireless nodes (10). Each of the multiple frequency channels (15) is used for a specific transmission and/or delivery of data packets between a wireless node (10) and one of its neighboring wireless nodes (10). Remaining neighboring wireless nodes (10) are therefore not allowed to communicate with this particular wireless node (10) using the same frequency channel (15). With such, signal interference during data transmission between a wireless node (10) and its neighboring wireless nodes (10) can be effectively avoided.
  • each of the multiple frequency channels (15) be specifically assigned and allocated from each of the wireless nodes (10) to each of its neighboring wireless nodes (10)
  • each of these wireless nodes (10) divides its time division unit (20) into several equal-size time slots (25), as illustrated in Figure 3.
  • the resultant time slots (25) will be specifically used and assigned with one of the frequency channels (15) that are associated with the particular wireless node (10).
  • These frequency channels (15) will also be allocated to a specific neighboring node of the particular wireless node (10).
  • the number of time slots (25) of the time division unit (20) within a wireless node (10) is dependant upon the number of neighboring nodes that such a particular wireless node (10) has.Tt is also to be noted that, each time slot (25) has been configured so that each of which can be exclusively used for broadcasting and/or receiving a message by the wireless node (10) from a particular time slot (25) of its neighboring nodes
  • each of those wireless nodes (10) is programmed to be synchronized in time with each of their neighboring wireless nodes (10). This is to ensure that each of those wireless nodes (10) has its assigned time slots (25) be overlapping with a corresponding time slot (25) of its neighboring wireless nodes through a specific frequency channel (15).
  • a particular wireless node (10) will therefore be able to transmit data to each of its neighboring nodes at a specific time slot (25), and each of its neighboring nodes will be receiving data in those time slots (25) that is exclusively assigned thereto.
  • Heavy communication workloads, and more suitably slot collision that often results from more than one wireless node (10) that is trying to transmit and/or receive data in the same time slot (25), could thus be substantially avoided.
  • each wireless node (10) has to verify if its time slots (25) overlap with a corresponding receiving time slot (25) of the neighboring wireless nodes that is specifically allocated thereto.
  • wireless node Nl having a time slot T17 and time slot T15 will be activated to respectively broadcast a message to its corresponding receiving nodes within its predetermined transmission range.
  • Corresponding receiving node, for example, wireless node N2 will overlap its time slot T17, suitably which has been allocated to the wireless node Nl, with the time slot T17 of the wireless node Nl.
  • the wireless node N2 is therefore able to receive the broadcasted message from the wireless node Nl at the time slot T17.
  • message that is broadcasted from the wireless node Nl at the time slot T15 will not be delivered to one of its neighboring wireless nodes, particularly the wireless node N4 that has been previously allocated thereto.
  • the time slot T15 of the wireless node Nl does not overlap with any of the time slots of the receiving wireless node N4.
  • the receiving wireless node N4 may be initiated to check if it has any unallocated time slots.
  • this receiving wireless node N4 may re-arrange the position of its unallocated time slot T15, as shown in the illustrated embodiment, and thereby causing such a time slot to be overlapped with the time-slot T15 of the wireless node Nl, for communication.
  • each of the wireless nodes (10) in the wireless communication network (100) may include a utilization table where the information of the time slots (25) that have been allocated to its neighboring wireless nodes (10) for data packet transmission, the information of the time slots (25) at which the neighboring wireless nodes (10) receive the data packet, and the information of multiple frequency channels (15) that are allocated by the wireless node (10) at a specific time slot (25) to its neighboring wireless nodes (10), are recorded.
  • Each of the wireless nodes (10) may incrementally forward such a utilization table to its neighboring wireless nodes (25) to reflect changes on allocation of frequency channels (15) and time slots (25) by itself.
  • the neighboring wireless nodes (10) may then update their utilization table and rearrange their time slots (25) accordingly so that conflicting assignments of time slots (25) among the wireless nodes (10) could be avoided.
  • time slots (25) that are inactive, particularly, those have not been scheduled by the wireless node (10) for data transmission and/or reception have to be determined.
  • the wireless nodes (10) will be switched into a sleep mode for energy conservation.
  • the unscheduled transmission time slots (25b) can be determined by identifying non-overlapping time slot region in each of the well-synchronized wireless nodes (10).
  • such unscheduled time slots (25b) can be calculated by differential value between the time slot (25) of an initiating wireless node (10) and its corresponding time slot (25) of a receiving wireless node (10) that is allocated to the initiating wireless node (10) after time division synchronization.
  • those overlapping time slot region between the well-synchronized wireless nodes (10) are scheduled time slots (25a).
  • the identified arrangement of the scheduled time slots (25a) and the unscheduled time slots (25b) of a time division unit (20) within a wireless node (10) will be repeatedly used for data packet transmission and/or reception.
  • a repetition pattern of the time division unit (20) of each wireless node (10), wherein its time slots (25) have optimized and allocated with a specific frequency channel (15) is illustrated in Figure 6.
  • FIG. 7 is a flow chart illustrating a method for frequency channel allocation in a wireless communication network (100) according to one exemplary embodiment of the present invention, in detail.
  • the frequency channel allocation method is initiated followed by triggering each of the wireless nodes (10) in the particular communication network (100) to perform neighbor discovery.
  • the wireless nodes (10) generate a neighbor node set in which the number of its neighboring wireless nodes (10) and the identification information of each of the neighboring wireless nodes (10) are recorded.
  • step SI 01 each of the wireless nodes (10) equally divides its predetermined time division unit (20) by the number of its neighboring wireless nodes (10) identified during the neighbor discovery process in step S100.
  • each of the wireless nodes (10) verifies if all of its neighboring wireless nodes (10) have a frequency channel (15) allocated thereto for communication with the wireless node (10).
  • this particular wireless node (10) selects a frequency channel (15) that has not been allocated to any of its neighboring node in step S104.
  • the wireless node (10) Prior to allocating such a selected unallocated frequency channel (15) to the neighboring wireless node (10), the wireless node (10) broadcasts a Channel Selection Message containing the identification information of the selected unallocated frequency channel (15) to all of its neighboring wireless nodes (10) in step S105.
  • the neighboring nodes (10) upon receipt of the Channel Selection Message in step S106, checks whether such a selected unallocated frequency channel (15) is in use by any of its neighboring wireless nodes (10) or not, in step S107. When there is a neighboring wireless node (10) verified using the selected frequency channel (15) in step S108, this particular neighboring wireless node (10) replies the wireless node (10) with a Channel Selection Used Message in step SI09.
  • this particular wireless node (10) selects another frequency channel (15) in the step SI10, and thereafter, as stated in step SI06, this particular wireless node (10) broadcasts a respective Channel Selection Message to all of its neighboring wireless nodes (10) to check for the availability of this selected frequency channel (15) before allocation.
  • the wireless node (10) assumes that none of its neighboring wireless nodes (10) is using the selected frequency channel (15).
  • the particular wireless node (10) therefore sends a Channel Request Message to its neighboring wireless node (10) in step SI12, requesting the neighboring wireless node (10) to record the selected frequency channel (15) as provided in the Channel Request message for communication there between, in step S113.
  • the neighboring wireless node (10) then rearranges its time slots (25) and set an unallocated time slot (25) with the selected frequency channel (15) in step SI14. Thereafter, the neighboring wireless node (10) sends a Channel Reply Acknowledgment Message to the wireless node (10) to acknowledge receipt of the Channel Request Message in step S115.
  • the wireless node (10) Upon receipt of the Acknowledgement Message from the neighboring wireless node (10), the wireless node (10) allocates the selected frequency channel (15) to the neighboring wireless node (10), in step S116, for establishing a communication path there between. In the meanwhile, this wireless node (10) records such a channel frequency allocation into one of its unallocated time slot (25). Steps S102 - SI16 will be repeatedly performed until each of the neighboring wireless nodes (10) of the particular wireless node (10) has been allocated with a specific frequency channel (15) for communication with the wireless node (10).
  • the particular wireless node (10) when a neighboring wireless node (10) is identified having a frequency channel (15) allocated thereto in step SI17, the particular wireless node (10) further determines if all of its neighboring wireless nodes (10) have been allocated with a specific frequency channel (15) in step S118. In the event when there is still a neighboring wireless node (10) identified having no frequency channel (15) allocated thereto, the wireless node (10) is triggered to send an Allocate Channel Message to one of its neighboring wireless node (10) in step S119.
  • the neighboring wireless nodes (10) Once the neighboring wireless nodes (10) has received the Allocate Channel Message, it starts allocating its frequency channels (15) to their neighboring nodes in step S120, and in the meantime, the neighbor discovery in step SlOO is initiated and the subsequent steps S101-S120 will be performed accordingly so as to ensure that all of the wireless nodes (10) in the particular communication network (100) have allocated a specific frequency channel (15) to each of their neighboring wireless nodes (10). After ensuring that the wireless nodes (10) and their neighboring wireless nodes
  • step S121 time division synchronization is then initiated, in step S121.
  • Each of the wireless nodes (10) is synchronized in time with each of its neighboring wireless nodes (10) and at the same time, the wireless nodes (10) verifies if there are any of its neighboring wireless nodes (10) that have not been synchronized in step S122.
  • the respective wireless node (10) is triggered to send this unsynchronized neighboring wireless node (10) a Synchronization Message, in step S124.
  • the Synchronization Message includes information such as the number of time slots (25) of the respective wireless node (10) and the identity of the allocated time slot (25) by this respective wireless node (10) to the neighboring wireless node (10).
  • the unsynchronized neighboring wireless node (10) Upon receipt of the Synchronization Message, the unsynchronized neighboring wireless node (10) verifies if there is any corresponding time slot (15) overlaps with the time slot (15) allocated by the respective wireless node (10), in step S125. In the event when this unsynchronized neighboring wireless node (10) has verified that there is a time slot (25) assigned by the wireless node (10) does not overlap with a corresponding time slot of the neighboring wireless node (10) in step S126, this neighboring wireless node (10) checks whether there is an unallocated overlapping of time slots (25) between itself and the wireless node (10) in subsequent step S127.
  • the receiving neighboring wireless node (10) rearranges its time division unit (20) and thereafter informs the initiating wireless node (10) of its number of time slots (25) and which time slot (25) it has allocated to the corresponding time slot (15) of the initiating wireless node (10), by sending a Acknowledgement Message, in step S129.
  • the neighboring wireless node is initiated to inform the wireless node (10) of its number of time slots (25) and the suggested unallocated time slot (25), in step S131.
  • the wireless node (10) then rearranges its unallocated time slots (25) based on the message received from the neighboring wireless node (10), and thereby assigns a suitable unallocated time slots (25) to be overlapping with the suggested unallocated time slot (25) of the neighboring wireless node (10) for communication, via a specific frequency channel (15) that has been allocated there between, in step S132.
  • the wireless node (10) updates its neighboring nodes by generating a new Synchronization Message when there are any changes on the channel allocation and time division.
  • the Synchronization Message includes information such as the number of time slot (25) the initiating wireless node (10) has and allocation details of each of the time slots (25) to its neighboring wireless node (10).
  • the neighboring node (10) then verifies if the time slot (25) allocated for the wireless node (10) is overlapping with the received time slot (25), in step S134.
  • step S121-S134 The above-mentioned time division synchronization process from step S121-S134 will be repeatedly carried out until each of frequency channel (15) assigned from a wireless node (10) at a specific time slot (15) has been allocated to a corresponding time slot (15) of its neighboring nodes.
  • wireless node (10) informs the wireless node (10) of the number of time slots (25) it has as well as the identity of the allocated time slot (25) by sending an Acknowledgement Message in step S136 (10) has recorded the time slots (25) allocated by them to its neighboring wireless node (10) as performed from step S121-S136, the wireless nodes (10) including their neighboring nodes identify the overlapping time slot regions and the non-overlapping time slot regions between their synchronized wireless nodes (10), in step S137.
  • the non-overlapping time slot regions will be considered as unscheduled transmission time slots (25a).
  • the unscheduled transmission time slots cause the wireless node (10) to switch into a sleep mode.
  • the overlapping time slot regions will be considered as scheduled time slots in which the wireless node (10) is scheduled to actively take part in data packet transmission and/or reception.
  • the resultant time division unit (20) of each of the wireless nodes (10) from S100-S137, in which each of its time slots (25) are optimized and each has a specific frequency channel (15) allocated thereto, will be repeatedly used by its respective wireless node (10) for subsequent data transmission in the particular communication network (100).
  • FIG 8 is a block diagram of a wireless node (10) adapted for use in a wireless communication network (100) so that collision- free data transmission between each of its neighboring wireless nodes in the particular network can be established.
  • the wireless node (10) including its neighboring node each has a Tx/Rx antenna (45) that can be used to communicate wirelessly with other devices or other wireless nodes (10) within a predetermined transmission range.
  • Each of the wireless nodes (10) further includes a neighbor node discovery module, a channel allocation module (30), a channel allocation synchronization module (35), a time division optimization module (not shown) and a modulation and coding module (40).
  • the neighbor node discovery module coupled with the Tx/Rx antenna (45) of the wireless node (10) to allow a particular wireless node (10) to generate its neighbor node set by determining and identifying which wireless nodes (10) are in communication with it within a predetermined transmission range.
  • the channel allocation module (30) configured to initiate a particular wireless node (10) to assign a specific frequency channel (15) to each of its neighboring nodes after its neighbor node set has generated.
  • the channel allocation synchronization module (35) allows the particular wireless node (10) to be time-synchronized with each of its neighboring wireless nodes (10) and thereby to ensure no neighboring wireless node (10) will be using the same frequency channel (15) to communicate with one another.
  • the particular wireless node (10) After time division synchronization, the particular wireless node (10) will be triggered by the time division optimization module to identify unscheduled transmission time slots (25a) of the particular wireless node (10) so that this particular wireless node (10) can optimize its utilization of time slots (25) and minimize energy consumption during data transmission.

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  • Computer Networks & Wireless Communication (AREA)
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  • Mobile Radio Communication Systems (AREA)

Abstract

The present invention relates to a method of managing allocation of multiple frequency channels (15) in conjunctions with time slots (25) by each of the wireless node (10) so that each of these wireless nodes (10) can communicate with each of its neighboring wireless nodes (10) based on a specific frequency channel (15) that has been allocated there between at a specifically assigned time slot (25), and thereby prevents the other neighboring wireless nodes (10) from any potential interference during the transmission.

Description

SYSTEM AND METHOD FOR FREQUENCY CHANNEL ALLOCATION IN A WIRELESS COMMUNICATION NETWORK
FIELD OF INVENTION
The present invention relates to a wireless communication network. More particularly, relates to a channel allocation method for use in a wireless comraunication network to avoid interference and collision of data transmission occurred ;among wireless nodes in the communication network.
BACKGROUND
Typical multi-hop wireless networks, such as a wireless mesh network, in which wireless nodes, due to the limited number of channel frequency, generally communicate with one another using a shared frequency channel. This eventually will deteriorate the network performance, especially when more than one nodes within a neighborhood trying to transmit data on the same frequency channel. Under such a circumstance, these transmitting nodes may collide and corrupt at each other and consequently leading to data packet loss. Re-transmission of such missing packets is therefore required. However, such re-transmission process often causes higher energy consumption of the nodes as well as poor network throughput efficiency. Accordingly, various systems and methods have thus been proposed to avoid interference and collision during data transmission over a wireless network. Most of them suggest assignment of non-overlapped frequency channel by which nodes are not allowed to transmit their data packet at the same time. For example, U.S.Patent Application 2010/0118812 (Al) has provided a method of allocating multi-channel to each of the wireless nodes within a network to avoid transmission's interference among the wireless media. This multi-channel allocation method teaches defining a number of logical channels based on the number of nodes within a communication range and thereafter, allocating the resultant number of logical channels to each of the wireless in such a manner that the allocated channel do not overlap with each other for data exchange between the nodes within an interference range.
SUMMARY In one aspect of the present invention, a method for enabling a wireless node to communicate with each of its neighboring wireless-nodes in a- wireless communication network based on a communication link that is in the form of frequency channel and which is substantially free from interference and collision is disclosed. The above mentioned method comprising the steps of: allocating by the wireless node, each of its neighboring wireless nodes a specific frequency channel, wherein the frequency channel is specifically assigned from either one time slot of the wireless node and to be allocated to a corresponding receiving time slot of one of its neighboring wireless nodes; synchronizing the frequency channel allocations between the wireless node and each of its neighboring wireless nodes so as to ensure if each of the time slots of the wireless node overlap with its corresponding receiving time slots of one of its neighboring wireless nodes at which the frequency channel has been specifically allocated; optimizing sleep time of the wireless nodes by identifying and determining non-overlapping time slots of each of the time-synchronized wireless nodes; and facilitating channel shifting for the wireless nodes based on the optimized time slots and the frequency channels that have been specifically allocated at each of the time slots of the wireless node.
In accordance with one embodiment, the frequency channel allocation method further comprising: generating a neighbor node set of the wireless node, wherein the neighbor node set includes information such as the number of the wireless nodes that are discovered within a predetermined transmission range of the wireless node and identity of each of the discovered neighboring wireless nodes, prior to the-step of allocating a specific frequency channel to each of its neighboring wireless nodes.
In another aspect, the present invention discloses a wireless communication network having one or more wireless nodes configured to communicate and exchange data wirelessly with at least one of its neighboring wireless node within a predetermined transmission range, wherein each of the wireless nodes comprising: a Tx/Rx antenna enables the wireless node to receive and transmit data within the wireless communication network; a neighbor node discovery module, coupled with the Tx Rx antenna, for generating a neighbor node set of the wireless node; a channel allocation module for initiating the wireless node to assign each of its neighboring wireless nodes recorded in the neighbor node set a specific frequency channel, wherein the frequency channel is specifically assigned from either one time slot of the wireless node and to be allocated to a corresponding receiving time slot of one of its neighboring nodes; a channel allocation synchronization module for allowing the wireless node to be time- synchronized with each of its neighboring wireless nodes and thereby to ensure no neighboring wireless node will be using the same frequency channel to communicate with one another; and a time division optimization module for identifying unscheduled transmission time slots, and thereby maximizing sleep time of the wireless node for efficient energy conservation. BRIEF DESCRIPTION OF THE DRAWINGS
Other objects, features, and advantages of the invention will be apparent from the following description when read with reference to the accompanying drawings. In the drawings, wherein like reference numerals denote corresponding parts throughout the several views: Figure 1 is a simplified flow chart illustrating a multi-channel allocation method in accordance with an embodiment of the present invention;
Figure 2 is an exemplary embodiment of the present invention where each of the wireless nodes in a communication network has assigned a specific frequency channel to each of its neighboring nodes;
Figure 3 illustrates time division synchronization of a plurality of wireless nodes that are located within a transmission range in a wireless communication network;
Figure 4 illustrates the resultant overlapping time slots between the wireless nodes from the time division synchronization operation as shown in Figure 3; Figure 5 illustrates unscheduled transmission time slots (e.g. shadowed block) that are identified in the time division unit of each of the wireless nodes for efficient energy utilization and excellent communication network efficiency;
Figure 6 is a repetition pattern of the well-defined time division unit of each of the wireless nodes as illustrated in Figure 5 for the respective wireless nodes to follow for subsequent data transmission and/or reception processes; Figure 7 is a flow chart illustrating a method for frequency channel allocation in a wireless communication network according to one exemplary embodiment of the present invention, in detail; and Figure 8 is a block diagram of a wireless node being adapted to improve the network performance of a wireless communication network.
DETAILED DESCRIPTION The present invention will now be described in detail with reference to the accompanying in drawings.
Figure 1 is a simplified flowchart illustrating how multi-channel allocation method of one embodiment of the present operates so that interference and collision of data transmission among wireless nodes in a particular wireless communication network can be substantially avoided. As depicted, such channel- allocation method includes five sequential steps: (i) generating a neighbor node set of each of the wireless nodes in the network, in step S10; (ii) allocating frequency channel by each of the wireless nodes to its neighboring wireless nodes, in step Sll, (iii) synchronizing the frequency channel allocations between each of the wireless nodes and its neighboring wireless nodes in order to ensure overlapping time slot between the wireless nodes for communication, in step S12, (iv) performing time division optimization by identifying and calculating non- overlapping time slot of each of the frequency channel allocations, in step S13; and thereafter, (v) facilitating channel shifting for each wireless node based on the optimized time slots and the frequency channels allocated at each time slot, in step S14.
Figure 2 exemplifies an embodiment of the present invention. Each of the wireless nodes (10) in a communication network (100) allocates a specific frequency channel (15) to each of its neighboring wireless nodes (10) to avoid any potential signal interference among the neighboring wireless nodes (10) during data transmission. It is to be noted that, before allocation of multiple frequency channels (15) for data communication between wireless nodes (10) in the wireless communication network (100), a neighbor node set being associated with each of the wireless nodes (10) must be determined and generated. Any neighbor discovery mechanisms available in the art may be used. During operation, each of the wireless nodes (10), respectively, records in its local memory the identification information of each accessible wireless node (10) that is found in its vicinity, suitably, within its transmission range for data communication. The number of its neighboring wireless nodes (10) is also recorded.
Thereafter, each of the wireless nodes (10) is initiated to communicate with each of its neighboring wireless nodes through a specific frequency channel (15). The frequency channel (15) may include any available communication link in the art. It is to be understood that multiple frequency channels (15) will be assigned from a wireless node (10) for communication with each of its neighboring wireless nodes (10). Each of the multiple frequency channels (15) is used for a specific transmission and/or delivery of data packets between a wireless node (10) and one of its neighboring wireless nodes (10). Remaining neighboring wireless nodes (10) are therefore not allowed to communicate with this particular wireless node (10) using the same frequency channel (15). With such, signal interference during data transmission between a wireless node (10) and its neighboring wireless nodes (10) can be effectively avoided.
Further, it is to be noted that, in order to enable each of the multiple frequency channels (15) be specifically assigned and allocated from each of the wireless nodes (10) to each of its neighboring wireless nodes (10), each of these wireless nodes (10) divides its time division unit (20) into several equal-size time slots (25), as illustrated in Figure 3. The resultant time slots (25) will be specifically used and assigned with one of the frequency channels (15) that are associated with the particular wireless node (10). These frequency channels (15) will also be allocated to a specific neighboring node of the particular wireless node (10). The number of time slots (25) of the time division unit (20) within a wireless node (10) is dependant upon the number of neighboring nodes that such a particular wireless node (10) has.Tt is also to be noted that, each time slot (25) has been configured so that each of which can be exclusively used for broadcasting and/or receiving a message by the wireless node (10) from a particular time slot (25) of its neighboring nodes
Still referring to Figure 3, upon all of the wireless nodes (10) in the particular communication network (100) have allocated a specific frequency channel (15) to each of their neighboring wireless nodes (10), each of those wireless nodes (10) is programmed to be synchronized in time with each of their neighboring wireless nodes (10). This is to ensure that each of those wireless nodes (10) has its assigned time slots (25) be overlapping with a corresponding time slot (25) of its neighboring wireless nodes through a specific frequency channel (15). By this way, a particular wireless node (10) will therefore be able to transmit data to each of its neighboring nodes at a specific time slot (25), and each of its neighboring nodes will be receiving data in those time slots (25) that is exclusively assigned thereto. Heavy communication workloads, and more suitably slot collision that often results from more than one wireless node (10) that is trying to transmit and/or receive data in the same time slot (25), could thus be substantially avoided.
In one embodiment, in order to ensure communication between the wireless nodes (10), each wireless node (10) has to verify if its time slots (25) overlap with a corresponding receiving time slot (25) of the neighboring wireless nodes that is specifically allocated thereto. For example, as shown in Figure 4, wireless node Nl having a time slot T17 and time slot T15 will be activated to respectively broadcast a message to its corresponding receiving nodes within its predetermined transmission range. Corresponding receiving node, for example, wireless node N2, will overlap its time slot T17, suitably which has been allocated to the wireless node Nl, with the time slot T17 of the wireless node Nl. With such overlapping time slots, the wireless node N2 is therefore able to receive the broadcasted message from the wireless node Nl at the time slot T17. On the other hands, message that is broadcasted from the wireless node Nl at the time slot, T15 will not be delivered to one of its neighboring wireless nodes, particularly the wireless node N4 that has been previously allocated thereto. This is mainly because wireless node Nl are time synchronized with the wireless node N4. Equally, the time slot T15 of the wireless node Nl does not overlap with any of the time slots of the receiving wireless node N4. To enable communication between these two wireless nodes, Nl and N4, the receiving wireless node N4 may be initiated to check if it has any unallocated time slots. Upon an unallocated time slot is identified, this receiving wireless node N4 may re-arrange the position of its unallocated time slot T15, as shown in the illustrated embodiment, and thereby causing such a time slot to be overlapped with the time-slot T15 of the wireless node Nl, for communication.
In one embodiment, each of the wireless nodes (10) in the wireless communication network (100) may include a utilization table where the information of the time slots (25) that have been allocated to its neighboring wireless nodes (10) for data packet transmission, the information of the time slots (25) at which the neighboring wireless nodes (10) receive the data packet, and the information of multiple frequency channels (15) that are allocated by the wireless node (10) at a specific time slot (25) to its neighboring wireless nodes (10), are recorded. Each of the wireless nodes (10) may incrementally forward such a utilization table to its neighboring wireless nodes (25) to reflect changes on allocation of frequency channels (15) and time slots (25) by itself. The neighboring wireless nodes (10) may then update their utilization table and rearrange their time slots (25) accordingly so that conflicting assignments of time slots (25) among the wireless nodes (10) could be avoided.
Further to the embodiment, in order to allow efficient energy utilization in each wireless node (10), time slots (25) that are inactive, particularly, those have not been scheduled by the wireless node (10) for data transmission and/or reception, have to be determined. As will be noted, with the use of such unscheduled transmission time slots, the wireless nodes (10) will be switched into a sleep mode for energy conservation. In accordance with one illustrated embodiment in Figure 5, the unscheduled transmission time slots (25b) can be determined by identifying non-overlapping time slot region in each of the well-synchronized wireless nodes (10). More suitably, such unscheduled time slots (25b) can be calculated by differential value between the time slot (25) of an initiating wireless node (10) and its corresponding time slot (25) of a receiving wireless node (10) that is allocated to the initiating wireless node (10) after time division synchronization. As will be apparent . to one skilled in the art, those overlapping time slot region between the well-synchronized wireless nodes (10) are scheduled time slots (25a). As will be noted, the identified arrangement of the scheduled time slots (25a) and the unscheduled time slots (25b) of a time division unit (20) within a wireless node (10) will be repeatedly used for data packet transmission and/or reception. A repetition pattern of the time division unit (20) of each wireless node (10), wherein its time slots (25) have optimized and allocated with a specific frequency channel (15) is illustrated in Figure 6.
Figure 7 is a flow chart illustrating a method for frequency channel allocation in a wireless communication network (100) according to one exemplary embodiment of the present invention, in detail. As shown in Figure 7, in step S100, the frequency channel allocation method is initiated followed by triggering each of the wireless nodes (10) in the particular communication network (100) to perform neighbor discovery. The wireless nodes (10) generate a neighbor node set in which the number of its neighboring wireless nodes (10) and the identification information of each of the neighboring wireless nodes (10) are recorded. Subsequently, in step SI 01, each of the wireless nodes (10) equally divides its predetermined time division unit (20) by the number of its neighboring wireless nodes (10) identified during the neighbor discovery process in step S100.
Thereafter, in step S102, each of the wireless nodes (10) verifies if all of its neighboring wireless nodes (10) have a frequency channel (15) allocated thereto for communication with the wireless node (10). When a neighboring wireless node (10) is identified in step S103 that it does not have a frequency channel (15) allocated thereto, this particular wireless node (10) selects a frequency channel (15) that has not been allocated to any of its neighboring node in step S104. Prior to allocating such a selected unallocated frequency channel (15) to the neighboring wireless node (10), the wireless node (10) broadcasts a Channel Selection Message containing the identification information of the selected unallocated frequency channel (15) to all of its neighboring wireless nodes (10) in step S105. The neighboring nodes (10), upon receipt of the Channel Selection Message in step S106, checks whether such a selected unallocated frequency channel (15) is in use by any of its neighboring wireless nodes (10) or not, in step S107. When there is a neighboring wireless node (10) verified using the selected frequency channel (15) in step S108, this particular neighboring wireless node (10) replies the wireless node (10) with a Channel Selection Used Message in step SI09. After being informed that the selected frequency channel (15) is in use, this particular wireless node (10) selects another frequency channel (15) in the step SI10, and thereafter, as stated in step SI06, this particular wireless node (10) broadcasts a respective Channel Selection Message to all of its neighboring wireless nodes (10) to check for the availability of this selected frequency channel (15) before allocation. When there is no reply from any of its neighboring wireless nodes (10) regarding the broadcasted Channel Selection message in step Sill, the wireless node (10) assumes that none of its neighboring wireless nodes (10) is using the selected frequency channel (15). The particular wireless node (10) therefore sends a Channel Request Message to its neighboring wireless node (10) in step SI12, requesting the neighboring wireless node (10) to record the selected frequency channel (15) as provided in the Channel Request message for communication there between, in step S113. The neighboring wireless node (10) then rearranges its time slots (25) and set an unallocated time slot (25) with the selected frequency channel (15) in step SI14. Thereafter, the neighboring wireless node (10) sends a Channel Reply Acknowledgment Message to the wireless node (10) to acknowledge receipt of the Channel Request Message in step S115. Upon receipt of the Acknowledgement Message from the neighboring wireless node (10), the wireless node (10) allocates the selected frequency channel (15) to the neighboring wireless node (10), in step S116, for establishing a communication path there between. In the meanwhile, this wireless node (10) records such a channel frequency allocation into one of its unallocated time slot (25). Steps S102 - SI16 will be repeatedly performed until each of the neighboring wireless nodes (10) of the particular wireless node (10) has been allocated with a specific frequency channel (15) for communication with the wireless node (10).
In one embodiment, when a neighboring wireless node (10) is identified having a frequency channel (15) allocated thereto in step SI17, the particular wireless node (10) further determines if all of its neighboring wireless nodes (10) have been allocated with a specific frequency channel (15) in step S118. In the event when there is still a neighboring wireless node (10) identified having no frequency channel (15) allocated thereto, the wireless node (10) is triggered to send an Allocate Channel Message to one of its neighboring wireless node (10) in step S119. Once the neighboring wireless nodes (10) has received the Allocate Channel Message, it starts allocating its frequency channels (15) to their neighboring nodes in step S120, and in the meantime, the neighbor discovery in step SlOO is initiated and the subsequent steps S101-S120 will be performed accordingly so as to ensure that all of the wireless nodes (10) in the particular communication network (100) have allocated a specific frequency channel (15) to each of their neighboring wireless nodes (10). After ensuring that the wireless nodes (10) and their neighboring wireless nodes
(10) have a specific frequency channel (15) that is allocated there between, time division synchronization is then initiated, in step S121. Each of the wireless nodes (10) is synchronized in time with each of its neighboring wireless nodes (10) and at the same time, the wireless nodes (10) verifies if there are any of its neighboring wireless nodes (10) that have not been synchronized in step S122. When an unsynchronized neighboring node is found in step S123, the respective wireless node (10) is triggered to send this unsynchronized neighboring wireless node (10) a Synchronization Message, in step S124. The Synchronization Message includes information such as the number of time slots (25) of the respective wireless node (10) and the identity of the allocated time slot (25) by this respective wireless node (10) to the neighboring wireless node (10).
Upon receipt of the Synchronization Message, the unsynchronized neighboring wireless node (10) verifies if there is any corresponding time slot (15) overlaps with the time slot (15) allocated by the respective wireless node (10), in step S125. In the event when this unsynchronized neighboring wireless node (10) has verified that there is a time slot (25) assigned by the wireless node (10) does not overlap with a corresponding time slot of the neighboring wireless node (10) in step S126, this neighboring wireless node (10) checks whether there is an unallocated overlapping of time slots (25) between itself and the wireless node (10) in subsequent step S127.
When the time slot (25) of the wireless node (10) has found to be overlapping with an unallocated time slot (25) of the neighboring wireless node (10) in step S128, the receiving neighboring wireless node (10) rearranges its time division unit (20) and thereafter informs the initiating wireless node (10) of its number of time slots (25) and which time slot (25) it has allocated to the corresponding time slot (15) of the initiating wireless node (10), by sending a Acknowledgement Message, in step S129.
On the contrary, when the frequency channel (15) assigned by the wireless node (10) has not been allocated to any of the time slots (25) of the neighboring wireless node (10) in step S130, the neighboring wireless node is initiated to inform the wireless node (10) of its number of time slots (25) and the suggested unallocated time slot (25), in step S131. The wireless node (10) then rearranges its unallocated time slots (25) based on the message received from the neighboring wireless node (10), and thereby assigns a suitable unallocated time slots (25) to be overlapping with the suggested unallocated time slot (25) of the neighboring wireless node (10) for communication, via a specific frequency channel (15) that has been allocated there between, in step S132.
Thereafter, in step S133, the wireless node (10) updates its neighboring nodes by generating a new Synchronization Message when there are any changes on the channel allocation and time division. The Synchronization Message includes information such as the number of time slot (25) the initiating wireless node (10) has and allocation details of each of the time slots (25) to its neighboring wireless node (10). The neighboring node (10) then verifies if the time slot (25) allocated for the wireless node (10) is overlapping with the received time slot (25), in step S134. The above-mentioned time division synchronization process from step S121-S134 will be repeatedly carried out until each of frequency channel (15) assigned from a wireless node (10) at a specific time slot (15) has been allocated to a corresponding time slot (15) of its neighboring nodes.
Further, in the event when this unsynchronized neighboring wireless node (10) has verified that the time slot (25) assigned by the wireless node (10) overlaps with a corresponding time slot (25) of the neighboring node in step S135 wireless node (10) informs the wireless node (10) of the number of time slots (25) it has as well as the identity of the allocated time slot (25) by sending an Acknowledgement Message in step S136 (10) has recorded the time slots (25) allocated by them to its neighboring wireless node (10) as performed from step S121-S136, the wireless nodes (10) including their neighboring nodes identify the overlapping time slot regions and the non-overlapping time slot regions between their synchronized wireless nodes (10), in step S137. The non-overlapping time slot regions will be considered as unscheduled transmission time slots (25a). The unscheduled transmission time slots cause the wireless node (10) to switch into a sleep mode. The overlapping time slot regions, however, will be considered as scheduled time slots in which the wireless node (10) is scheduled to actively take part in data packet transmission and/or reception. The resultant time division unit (20) of each of the wireless nodes (10) from S100-S137, in which each of its time slots (25) are optimized and each has a specific frequency channel (15) allocated thereto, will be repeatedly used by its respective wireless node (10) for subsequent data transmission in the particular communication network (100).
Figure 8 is a block diagram of a wireless node (10) adapted for use in a wireless communication network (100) so that collision- free data transmission between each of its neighboring wireless nodes in the particular network can be established. As shown, the wireless node (10) including its neighboring node, each has a Tx/Rx antenna (45) that can be used to communicate wirelessly with other devices or other wireless nodes (10) within a predetermined transmission range. Each of the wireless nodes (10) further includes a neighbor node discovery module, a channel allocation module (30), a channel allocation synchronization module (35), a time division optimization module (not shown) and a modulation and coding module (40).
In accordance with the preferred embodiment, the neighbor node discovery module coupled with the Tx/Rx antenna (45) of the wireless node (10) to allow a particular wireless node (10) to generate its neighbor node set by determining and identifying which wireless nodes (10) are in communication with it within a predetermined transmission range. The channel allocation module (30) configured to initiate a particular wireless node (10) to assign a specific frequency channel (15) to each of its neighboring nodes after its neighbor node set has generated. The channel allocation synchronization module (35) allows the particular wireless node (10) to be time-synchronized with each of its neighboring wireless nodes (10) and thereby to ensure no neighboring wireless node (10) will be using the same frequency channel (15) to communicate with one another. After time division synchronization, the particular wireless node (10) will be triggered by the time division optimization module to identify unscheduled transmission time slots (25a) of the particular wireless node (10) so that this particular wireless node (10) can optimize its utilization of time slots (25) and minimize energy consumption during data transmission.
As will be readily apparent to those skilled in the art, the present invention may easily be produced in other specific forms without departing from its essential characteristics. The present embodiments is, therefore, to be considered as merely illustrative and not restrictive, the scope of the invention being indicated by the claims rather than the foregoing description, and all changes which come within therefore intended to be embraced therein.

Claims

1. A method for enabling a wireless node (10) to communicate with each of its neighboring wireless nodes (10) in a wireless communication network (100) based on a communication link that is substantially free from interference and collision, wherein the communication link is in the form of frequency channel (15), comprising:
allocating by the wireless node (10), each of its neighboring wireless nodes (10) a specific frequency channel (15), wherein the frequency channel (15) is specifically assigned from either one time slots of the wireless node (10) and to be allocated to a corresponding receiving time slot (25) of one of its neighboring wireless nodes (10); synchronizing the frequency channel allocations between the wireless node and each of its neighboring nodes so as to ensure if each of the time slots (25) of the wireless node (10) overlap with its corresponding receiving time slots (25) of one of its neighboring wireless nodes (10) at which the frequency channel (15) has been specifically allocated;
optimizing sleep time of each of the wireless node (10) by identifying and determining non-overlapping time slots (25) of each of the synchronized wireless nodes (10); and
facilitating channel shifting for each of the wireless nodes (10) based on the optimized time slots (25) and the frequency channels (15) that have been specifically allocated at each of the time slots (25) of the wireless nodes (10).
2. A method as claimed in Claim 1, further comprising generating a neighbor node set of the wireless node (10), wherein the neighbor node set includes information such as the number of the wireless nodes (10) that are discovered within a predetermined transmission range of the wireless node (10) and identity of each of the discovered neighboring wireless nodes (10), prior to the step of allocating a specific frequency channel (15) to each of its neighboring wireless nodes (10).
3. A method as claimed in Claim 1, wherein the step of allocating a specific frequency channel (15) to each of its neighboring wireless nodes (10) by the wireless node (10) further comprising:
dividing a predefined time division unit (20) of the wireless node (10) into equal-sized time slots (25) by the number of its neighboring wireless nodes (10),
verifying if there is any neighboring wireless nodes (10) of the wireless node ( 10) that has not been allocated with a frequency channel (15);
selecting an unallocated frequency channel (15) by the wireless node (10) when there is a neighboring wireless node (10) has not been allocated with a frequency channel (15);
broadcasting a Channel Selection Message to the neighboring wireless node (10), wherein the Channel Selection Message comprises identification information of a frequency channel (15) that has been selected by the wireless node (10) to be allocated to the neighboring wireless node (10); and verifying by the neighboring wireless node (10) of the availability of the selected frequency channel (15) before being allocated to the neighboring wireless node (10).
4. A method as claimed in Claim 3, wherein the step of verifying the availability of the selected frequency channel (15), further comprising:
replying the wireless node (10) a Channel Selection Used Message by the neighboring wireless node (10) when the selected frequency channel (15) has been already in use by the neighboring wireless nodes (10);
forwarding the neighboring wireless node (10) a Channel Request Message by the wireless node (10) when the selected frequency channel (15) is found not to be in used by the neighboring wireless node (10), wherein the Channel Request Message includes the identity of the selected frequency channel (10);
setting a time slot by the neighboring wireless node (10) for allocation of the selected frequency channel (15) upon receipt of the Channel Request Message; and sending the wireless node (10) a Channel Reply Acknowledgement upon allocation of the selected frequency channel (15) to a dedicated time slot (25) of the neighboring wireless node (10).
5. A method as claimed in Claim 1, wherein the step of synchronizing the frequency channel allocations between the time slots (25) of the wireless node (10) and the time slot (25) of each of its neighboring wireless nodes (10), further comprising: setting and recording the time slots (25) that have been specifically allocated by the wireless node (10) for communication with each of its neighboring wireless nodes (10) when the dedicated time slots (25) overlap with the corresponding time slots (25) of its neighboring wireless nodes (10) and
re-scheduling the time slots (25) and thereby selecting an unallocated time slot
(25) by the wireless node (10) to be allocated to the neighboring wireless node (10) for communication when the dedicated time slot (25) of the wireless node (10) does not overlap with the corresponding time slot (25) of the neighboring wireless node (10).
6. A method as claimed in Claim 5, wherein said step of setting and recording the time slots (25) of the wireless node (10), comprising:
verifying if all of the time slots (25) of each of the neighboring wireless nodes (10) has been synchronized with the corresponding time slots of the wireless node (10); sending the neighboring wireless node (10) a Synchronization Message, wherein the Synchronization Message includes the number of time slots (25) of the wireless node (10) and identity of the time slot (25) allocated to the neighboring wireless node (10) when the neighboring wireless node (10) is not synchronized with the wireless node (10);
verifying by the neighboring wireless node (10) if the allocated time slot (25) by the wireless node (10) does overlap with the time slot (25) the neighboring wireless node (10) has allocated to the wireless node (10); and sending the wireless node (10) a Acknowledgement Message when the allocated time slots (25) between the wireless node (10) and the neighboring wireless node (10) overlap, wherein the Acknowledgement Message include the number of time slots (25) and the identity of the time slot (25) the neighboring wireless node (10) has allocated to the wireless node (10).
7. A method as claimed in Claim 5, wherein said step re-scheduling the time slots (25), further comprising:
checking by the neighboring wireless node (10) if there is an unallocated overlapping of time slots (25) between the neighboring wireless node (10) and the wireless node (10)
re-arranging the time slots (25) and sending an Acknowledgement Message by the neighboring wireless node (10) to the wireless node (10) when the time slot (25) of the wireless node (10) has been found to be overlapping with an unallocated time slot (25) of the neighbor wireless node (10), wherein the Acknowledgment Message includes the number of time slots (25) of the neighboring wireless node (10) and the identity of the unallocated time slot (25) of the neighboring wireless node (10) that overlaps with the wireless node (10);
sending the wireless node (10) a message by the neighboring wireless node (10) if the frequency channel (15) assigned by the wireless node (10) has not been allocated to any of the time slots (25) of the neighboring wireless node (10), wherein the message including the number of time slots (25) of the neighboring wireless node (10) and the identity of an unallocated time slot (25) suggested by the neighboring wireless node (10) for communication with the wireless node (10); and
re-arranging unallocated time slots (25) at the wireless node (10) based on the message and the time slot allocation received from the neighboring wireless node (10).
8. A method as claimed in Claim 1, wherein the step of optimizing sleep time of each of the wireless node (10), further comprising calculating differential value of each of the overlapping time slots (25) between the neighboring wireless node (10) and the wireless node (10), wherein each of the resultant differential value is the time interval of each of the corresponding non-overlapping time slots (25) in the neighboring wireless node ( 10) and the wireless node (10).
9. A wireless communication network (100) having one or more wireless nodes (10) configured to communicate and exchange data wirelessly with at least one of its neighboring wireless nodes (10) within a predetermined transmission range, wherein each of the wireless nodes (10) comprising:
a Tx/Rx antenna (45) that enables the wireless node (10) to receive and transmit data within the wireless communication network ( 100);
a neighbor node discovery module, coupled with the Tx/Rx antenna (45), for generating a neighbor node set of the wireless node (10);
a channel allocation module (30) for initiating the wireless node (10) to assign each of its neighboring wireless nodes (10) recorded in the neighbor node set a specific frequency channel (15), wherein the frequency channel (15) is specifically assigned from either one time slots (25) of the wireless node (10) and to be allocated to a corresponding receiving time slot (25) of one of its neighboring wireless nodes (10); a channel allocation synchronization module (35) for allowing the wireless node (10) to be time-synchronized with each of its neighboring wireless nodes (10) and thereby to ensure no neighboring node (10) will be using the same frequency channel (15) to communicate with one another; and
a time division optimization module for identifying unscheduled transmission time slots (25a), and thereby maximizing sleep time of the wireless node (10) for efficient energy conservation.
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