Claims:We Claim:

1. A method for rule based semi reserved TDMA for tactical mobile ad hoc networks, the method comprising:
defining to reserve a certain fixed number of slots (time frame) (1 - 23 slots) to the MANET wireless nodes from TDMA frame of 40 milli time slots based on the semi reserved rule; and
allotting remaining number of slots (24 - 39) dynamically to the nodes depending up on the current tactical MANET scenario from TDMA frame of 40 milli time slots based on semi reserved rule.

2. The method as claimed in claim 1, wherein each node is associated with node identifier number and the fixed time slot numbers are allotted to nodes based on the node identifier value.

3. The method as claimed in claim 1, wherein the least node identifier value leads to higher priority and the highest node identifier value leads to lower priority as per rule.

4. The method as claimed in claim 1, wherein the node with higher priority is designated as a time slot manager, where the time slot manager manages the dynamic time frame (slots) of nodes.

5. The method as claimed in claim 1, wherein all the tactical MANET nodes has the prior knowledge about the time slot location within the fixed time slot of a TDMA frame.

6. The method as claimed in claim 1, wherein if the current time slot manager left the group, next priority node does the time slot manager role and it automatically relinquish when the higher priority nodes resumes back and the same is distributed across all the nodes.

7. The method as claimed in claim 1, wherein only in the process of change over time, lower priority node allocates time slots to higher priority node.

8. The method as claimed in claim 1, wherein the first slot of TDMA frame is a control slot (0 time slot) which is to be shared by all nodes in order to request the basic time slot to the time slot manager.

9. The method as claimed in claim 1, wherein the tactical MANET node uses its own fixed time slot for data transmission without time slot manager permission even if the node faces Line of Sight issue.

10. A method for representing topology discovery information during route discovery process in Tactical MANET networks, the method comprising:
representing a plurality of node topology discovery/configuration messages (TCM) in the form on/off bit vectors, wherein each node will send the entire network snapshot in the form of bit vectors, and the bit vectors positions are fixed with respect to the node identifier values.

11. The method as claimed in claim 10, wherein each node has prior knowledge about its own and other nodes on/off bit vector location, where each node on/off bit vectors represents only the direct node connectivity information.

12. The method as claimed in claim 10, wherein during topology update, the node receives topology configuration and it copies the other node bit only when the received node is reachable to particular node. , Description:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
“A method for rule based semi reserved TDMA for tactical mobile ad hoc networks”
By
BHARAT ELECTRONICS LIMITED
Nationality: Indian
M/s. Bharat Electronics Limited, Corporate Office, Outer Ring Road, Nagavara, Bangalore-560045, Karnataka, India

The following specification particularly describes the invention and the manner in which it is to be performed.

Field of the invention
The present invention mainly relates to mobile ad-hoc network communication system and more particularly to a method for rule based semi reserved time division multiple access and representation of topology discovery for tactical mobile ad-hoc networks.
Background of the invention
A mobile ad hoc network (MANET) is well known in the art which is a continuously self-configuring, infrastructure-less network of mobile connected wirelessly. Each device in a MANET is free to move independently in any direction, and will therefore change its links to other devices frequently. Each must forward traffic unrelated to its own use, and therefore be a router. Such networks may operate by themselves or may be connected to the larger Internet. They may contain one or multiple and different transceivers between nodes. This results in a highly dynamic, autonomous topology.
The mobile Ad-hoc network plays an important role in the tactical military networks. Tactical MANET network is an infrastructure less network, which is built automatically as soon as devices connect or disconnect. Instead of relying on a base station to coordinate the flow of messages to each node in the network, the individual nodes forward packets to and from each other. Tactical MANET is characterized by rapid changes in the network topology due to node mobility and intermittent line-of-sight (LOS) connectivity.
A wide variety of routing protocols were developed for mobile ad hoc networks. These protocols are generally classified into proactive and reactive routing protocols. Proactive based table driven approach routing protocols uses lot of messages to maintain consistent and up-to-date routing information at every node level. These protocols send the entire network connectivity details information for topology consistency, leads to significant bandwidth consumption and overhead. Moreover, traditional TDMA based approach for allocating time slots to the nodes dynamically may not be suitable to provide bare minimum communication.
For example, document US 5729534 titled “Dynamic Allocation of Radio Capacity in TDMA system" describes a method for dynamic division of the radio capacity in a TDMA system between packet radio service and circuit switched service. With this invention some basic numbers of time slots are fixed for packet radio service and the remaining are reserved for circuit switched service. Base transceiver station allocates more time slots to packet radio service when the traffic requirement of packet radio service increases. Further, this particular invention is suitable for 2G mobile communications such as GSM with GPRS.
Another, document US 7782831B1 titled "System and Method for dynamically defining a TDMA Management Cycle for Wireless Network” describes a method for dynamically implementing a TDMA management cycle for a wireless network. The method includes node partition, the TDMA management cycle and assignment of the node to a TDMA management slot number, and dynamically adapting the size of the TDMA management cycle. This method is suitable for mobile communication.
Further, document US 20020001294 A1 titled "Method for dynamically allocating time slots of a common TDMA broadcast channel to a network of Transceiver nodes” describes a method for allocating a set of time slots belonging to a common time division multiple access (TDMA) channel to a network of transceiver nodes is provided. The method includes the steps of dividing the set of time slots into a plurality of time slot sub-sets; defining for each transceiver node a common function that assigns one time slot sub-set of the plurality of time slot sub-sets to each point in space, where each point in space is identified by a unique set of space coordinates; and performing the following steps for each one of the transceiver nodes: periodically identifying a set of space coordinates; and allocating to each transceiver node time slots belonging to the time slot sub-set assigned by the common function to the point in space identified by the periodically identified set of space coordinates.
Furthermore, document US20130100942A1 A1 titled "Mobile Ad hoc Network with Dynamic TDMA Slot assignments and related Methods” describes dynamically allocates the TDMA slots to mobile nodes types based upon a current topologic density in the topologic area relative to a topological density threshold.
To overcome such bandwidth consumption in tactical MANET, the entire topology information representation should be represented in different format resulting in less bandwidth consumption and overhead.
Therefore there is a need in the art with a method with different format of allocating slots to the nodes which results in minimum bandwidth and to solve the above mentioned limitations.
Summary of the Invention
An aspect of the present invention is to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below.
Accordingly, in one aspect of the present invention relates to a method for rule based semi reserved TDMA for tactical mobile ad hoc networks, the method comprising: defining to reserve a certain fixed number of slots (time frame) (1 - 23 slots) to the MANET wireless nodes from TDMA frame of 40 milli time slots based on the semi reserved rule; and allotting remaining number of slots (24 - 39) dynamically to the nodes depending up on the current tactical MANET scenario from TDMA frame of 40 milli time slots based on semi reserved rule.
Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

Brief description of the drawings
The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:
Figure 1 shows a rule based semi reserved TDMA frame format according to one embodiment of the present invention.
Figure 2 shows a single node MANET with node id 21 according to one embodiment of the present invention.
Figure 3 shows a MANET with two nodes node id 21 and node id 22 according to one embodiment of the present invention.
Figure 4 shows a MANET with three nodes node id 21, node id 22 and node id 31 according to one embodiment of the present invention.
Figure 5 shows a MANET with four nodes node id 21, node id 22, node id 31 and node id 32 according to one embodiment of the present invention.
Figure 6 shows a topology discovery information representation bit vector format according to one embodiment of the present invention.
Figure 7 shows a topology discovery information bit vector at node id 11 according to one embodiment of the present invention.
Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.
Detailed description of the invention
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces.
By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.
Figs. 1 through 7, discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way that would limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged communications system. The terms used to describe various embodiments are exemplary. It should be understood that these are provided to merely aid the understanding of the description, and that their use and definitions, in no way limit the scope of the invention. Terms first, second, and the like are used to differentiate between objects having the same terminology and are in no way intended to represent a chronological order, unless where explicitly stated otherwise. A set is defined as a non-empty set including at least one element.
The present invention relates to a method for rule based semi reserved dynamic time division multiple access (TDMA) scheme for tactical MANET to ensure minimum bandwidth for communication in tactical emergency situation. The present invention provides medium access scheme for Time Division Multiple Access (TDMA) based networks. TDMA is a channel access method for shared medium network that are using single frequency for transmission and reception. This access scheme allows multiple communication nodes can share the same frequency without any interference. To provide such interference less communication among the nodes, the TDMA frame is divided into smaller units called time slots. These time slots are allocated to the nodes. This allocation of time slot to the nodes can be either static or dynamic. Static TDMA allocates always fixed number of slots to the nodes whereas dynamic TDMA allocates time slot to the nodes as and when it is required. Tactical MANET is characterized by fast changes in the network topology due to node mobility and intermittent line-of-sight (LOS) connectivity.
The rule based semi reserved approach provides within a TDMA frame, certain fixed numbers of slots are statically assigned the tactical MANET nodes and the remaining slots are dynamically allocated to the nodes depending up on the current tactical MANET scenario. Time slots are managed and controlled by one of the designated node called Time Slot Manager. Time Slot Manager uses rule based semi reserved approach for allocating time slots to the nodes to ensure the minimum communication bandwidth. Also this invention claims a method for representing the topology information during topology discovery process in a tactical MANET. The entire topology discovery/configuration messages (TCM) are represented in the form on/off bit vectors, leads to significant reduction in bandwidth consumption and overhead.
Figure 1 shows a rule based semi reserved TDMA frame format according to one embodiment of the present invention.
The tactical MANET is characterized by rapid changes in the network topology due to node high mobility and intermittent line-of-sight (LOS) connectivity. The method for rule based semi reserved dynamic time division multiple access for tactical MANET to ensure the minimum bandwidth for communication. The rule based semi reserved approach reserves certain fixed number of slots to the MANET wireless nodes and remaining slots are allocated dynamically to the nodes depending up on the current tactical MANET scenario.The figure shows a rule based semi reserved TDMA frame with 40 milli seconds duration each time slot of 1 millisecond. The first 23 slots are fixed and remaining 17 slots are used for relay or dynamic purposes. The time slots are dynamically controlled by one of the designated node called Time Slot Manager. Time slot manager uses rule based semi reserved approach for managing the TDMA frame, to ensure the minimum communication bandwidth. The selection of Time Slot Manager is based on the priority of the node and selection logic is distributed across the network. With this invention, the tactical MANET nodes have the prior knowledge about the time slot location within the fixed time slot of a TDMA frame. A newly joined tactical MANET node can transmit data on its allocated fixed slot without requesting time slot grant to the Time Slot Master/Manager. There by in emergency situation, a tactical node can able to send the data over the network without requesting time slot to the Time Slot Manager. Node time synchronization is achieved through both internal and external clock mechanism. This approach is more suitable for tactical military applications with high mobility.
In one embodiment of the present invention relates to a method for rule based semi reserved TDMA for tactical mobile ad hoc networks, the method comprising: defining to reserve a certain fixed number of slots (time frame) (1 - 23 slots) to the MANET wireless nodes from TDMA frame of 40 milli time slots based on the semi reserved rule; and allotting remaining number of slots (24 - 39) dynamically to the nodes depending up on the current tactical MANET scenario from TDMA frame of 40 milli time slots based on semi reserved rule.
The rule specifies the ratio of total number fixed slot numbers and total number of dynamic slot numbers within the TDMA frame. The ratio can be chosen based on the bandwidth requirement. In the present invention, each node in the network is associated with node identifier number. Within the fixed number of slots of a TDMA frame, the slots numbers are allocated to the nodes based on the node identifier value. The node identifier values are mapped to the slot numbers. These positions are fixed and with this method each node has prior knowledge about its timeslot location in the time frame. The least node identifier value leads to higher priority and the highest node identifier value leads to lower priority.
The time slots (frame) is managed by a designated node called time slot manager and the time slot manager is elected based on the higher priority node. The time slot manager is an additional role given to the high priority node, in addition to its own MANET functionalities. In case, if the current time slot manager left the group, next eligible node will do the time slot manager role. Further, if the higher priority node resumes back, the current time slot manager relinquish (change over time) its role smoothly, thereby time slot manager election logic is distributed across all the nodes in the network. Only during the process of change over time, the lower priority node allocates time slots to higher priority node. For every TDMA frame, the first slot is a control slot and this control slot is shared by all the nodes of the network. This slot will be used to request the basic time slot to the time slot manager. The tactical MANET node uses its own fixed time slot for data transmission without time slot manager permission even if the node faces Line of Sight issue.
Figure 2 shows a single node MANET with node id 21 according to one embodiment of the present invention.
The figure shows a tactical MANET node with node Id 21, which is the first member in the MANET network group. The node id 21 assumes itself as Time Slot Manager since it is the first member and allocates fixed time slot for its own (typically slot 5 and slot 6 for a TDMA frame of 40 ms). The node 21 sends its message periodically on its allocated time slot number 5 and time slot number 6.
Figure 3 shows a MANET with two nodes node id 21 and node id 22 according to one embodiment of the present invention.
The figure shows a MANET with two nodes id 21 and node id 22. The node id 22 is connected with node id 21. And node id 21 retains its time slot manager role because of its high priority. Both node id 21 and node id 22 are in good line of sight. The node id 22 requests node time slot to node id 21 on control time slot (time slot 0). The Node id 21 allocates two time slots to node id 22 typically time slot number 7 and time slot number 8.
Figure 4 shows a MANET with three nodes node id 21, node id 22 and node id 31 according to one embodiment of the present invention.
The figure shows a MANET with three nodes node id 21, node id 22 and node id 31. Further, the figure shows a node with node id 31 joined in the tactical MANET and connected with node id 22. Here the node id 31 is only visible range of node id 22. Since topology information's are exchanged between node id 22 and node id 21, the time slot manager 21 allocates time slot to node id 31. Also time slot manager allocates and additional slot to node id 22 in the dynamic slot allocation portion of the TDMA frame to communicate with node id 31. In the present case, dynamic reservation location starts at time slot number 24.
Figure 5 shows MANET with four nodes node id 21, node id 22, node id 31 and node id 32 according to one embodiment of the present invention
The figure shows MANET with four nodes node id 21, node id 22, node id 31 and node id 32. Further, the figure shows a node with node id 32 connected with node id 22 and node id 22 is reachable from node id 32 but the node id 22 is not reachable from node id 22 because of line-of-sight issue. In this scenario, node id 32 request time slot on control slot to the Time Slot Manager. The time Slot manager allocates the time slot to the node id 32. But allocated time slots are not reached back to node id 32 because of line of sight. The node id 32 waits for 3*TDMA Frame duration and if it does not receive the time slot information, the node id 32 itself send data on its fixed time slot number 18. And now node id 32 is also able to communicate to node id 22.
Figure 6 shows topology discovery information representation bit vector format according to one embodiment of the present invention.
The figure shows a topology discovery information representation bit vector format. Further, the figure illustrates a method for representing the topology information during topology discovery process in a tactical MANET. Generally, the topology information will be represented in the form of byte vector leads to more bandwidth consumption and overhead. In tactical scenario, this information is important and should be represented in the format which consumes less bandwidth and overhead. In the present invention, the entire topology discovery/configuration messages (TCM) represented in the form on/off bit vectors. Each node will send the entire network snapshot in the form of bit vectors. The bit vectors positions is fixed with respect to the node identifier values. This leads to reduce the overhead of topology discovery process and improve the performance.
The figure shows four node (node id 11, node id 21, node id 22 and node id 23) MANET topology information representation in the form on/off bit vector. In this representation, each node has 4 byte local bit vector table. The Byte 1(B1) represents connectivity information of node id 11. The Byte 2(B2) represents connectivity information of node id 21, Byte 3(B3) represents connectivity information of node id 22 and Byte 4(B4) represents connectivity information of node id 23. Within each byte (B1, B2, B3, B4), bit 0 represents node id 11 connectivity, bit 1 represents node id 21 connectivity, bit 3 represents node id 22 connectivity and bit 4 represents node id 23 connectivity.
The present invention relates to a method for representing topology discovery information during route discovery process in Tactical MANET networks, the method comprising: representing a plurality of node topology discovery/configuration messages (TCM) in the form on/off bit vectors, wherein each node will send the entire network snapshot in the form of bit vectors, and the bit vectors positions are fixed with respect to the node identifier values. Each node has prior knowledge about its own and other nodes on/off bit vector location, where each node on/off bit vectors represents only the direct node connectivity information. During topology update, the node receives topology configuration and it copies the other node bit only when the received node is reachable to particular node.
Figure 7 shows topology discovery information bit vector at node id 11 according to one embodiment of the present invention.
The figure shows topology discovery information bit vector at node id 11. Further, the figure shows four node (node id 11, node id 21, node id 22 and node id 23) MANET topology information representation in the form on/off bit vector at node 11. This bit vector shows the representation of node id 11 connected with node id 21 and node id 22, node id 21 connected with node id 11 and node id 11, node id 22 connected only with node id 11 and node id 23 connected with node if 11.
Those skilled in this technology can make various alterations and modifications without departing from the scope and spirit of the invention. Therefore, the scope of the invention shall be defined and protected by the following claims and their equivalents.
FIGS. 1-7 are merely representational and are not drawn to scale. Certain portions thereof may be exaggerated, while others may be minimized. FIGS. 1-7 illustrate various embodiments of the invention that can be understood and appropriately carried out by those of ordinary skill in the art.
In the foregoing detailed description of embodiments of the invention, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the invention require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the detailed description of embodiments of the invention, with each claim standing on its own as a separate embodiment.
It is understood that the above description is intended to be illustrative, and not restrictive. It is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined in the appended claims. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein,” respectively.

We Claim:

1. A method for rule based semi reserved TDMA for tactical mobile ad hoc networks, the method comprising:
defining to reserve a certain fixed number of slots (time frame) (1 - 23 slots) to the MANET wireless nodes from TDMA frame of 40 milli time slots based on the semi reserved rule; and
allotting remaining number of slots (24 - 39) dynamically to the nodes depending up on the current tactical MANET scenario from TDMA frame of 40 milli time slots based on semi reserved rule.

2. The method as claimed in claim 1, wherein each node is associated with node identifier number and the fixed time slot numbers are allotted to nodes based on the node identifier value.

3. The method as claimed in claim 1, wherein the least node identifier value leads to higher priority and the highest node identifier value leads to lower priority as per rule.

4. The method as claimed in claim 1, wherein the node with higher priority is designated as a time slot manager, where the time slot manager manages the dynamic time frame (slots) of nodes.

5. The method as claimed in claim 1, wherein all the tactical MANET nodes has the prior knowledge about the time slot location within the fixed time slot of a TDMA frame.

6. The method as claimed in claim 1, wherein if the current time slot manager left the group, next priority node does the time slot manager role and it automatically relinquish when the higher priority nodes resumes back and the same is distributed across all the nodes.

7. The method as claimed in claim 1, wherein only in the process of change over time, lower priority node allocates time slots to higher priority node.

8. The method as claimed in claim 1, wherein the first slot of TDMA frame is a control slot (0 time slot) which is to be shared by all nodes in order to request the basic time slot to the time slot manager.

9. The method as claimed in claim 1, wherein the tactical MANET node uses its own fixed time slot for data transmission without time slot manager permission even if the node faces Line of Sight issue.

10. A method for representing topology discovery information during route discovery process in Tactical MANET networks, the method comprising:
representing a plurality of node topology discovery/configuration messages (TCM) in the form on/off bit vectors, wherein each node will send the entire network snapshot in the form of bit vectors, and the bit vectors positions are fixed with respect to the node identifier values.

11. The method as claimed in claim 10, wherein each node has prior knowledge about its own and other nodes on/off bit vector location, where each node on/off bit vectors represents only the direct node connectivity information.

12. The method as claimed in claim 10, wherein during topology update, the node receives topology configuration and it copies the other node bit only when the received node is reachable to particular node.

Abstract
A method for rule based semi reserved TDMA for tactical mobile ad hoc networks
The present invention relates to mobile ad-hoc network communication system and more particularly to a method for rule based semi reserved time division multiple access and representation of topology discovery for tactical mobile ad-hoc networks, the method comprising: defining to reserve a certain fixed number of slots (time frame) (1 - 23 slots) to the MANET wireless nodes from TDMA frame of 40 milli time slots based on the semi reserved rule; and allotting remaining number of slots (24 - 39) dynamically to the nodes depending up on the current tactical MANET scenario from TDMA frame of 40 milli time slots based on semi reserved rule.
Figure 1 (for publication)