CLIAMS:
1. A method for providing data communication for machine type communication (MTC) devices in a group-based wireless communication, the method comprising steps of:
receiving, by a cluster head, a data traffic transfer request from one or more MTC devices;
determining availability of one or more network resources for transferring the data traffic; and
establishing, by the cluster head, a dedicated connection with a base station for transferring a data traffic from the one or more MTC devices to the base station based on the availability of the one or more network resources.

2. The method of claim 1, wherein the data transfer request comprises at least one of an activation status, a buffer occupancy status and a delay tolerance of the one or more MTC devices.

3. The method of claim 2, wherein the determining availability of base station resources for transferring data traffic comprises of:
creating a priority list of active MTC devices based on the delay tolerance;
comparing the delay tolerance of the active MTC devices with a time required for establishing a connection with a base station; and
triggering a connection request with the base station when the delay tolerance for a high priority MTC device is equal to a pre-set time;
wherein the delay tolerance is a total tolerable time of communication without impacting a quality of service for the MTC device.

4. The method of claim 1, further comprising:
sending, by the cluster head, at least one of an ACK or a NACK message from the base station through the dedicated connection established between the cluster head and the base station; and
relaying at least one of an ACK or NACK message from the base station to a corresponding MTC device.

5. The method as claimed in claim 1, wherein the cluster head establishes and releases the dedicated connection with the base station based on an incoming traffic from the one or more MTC devices.

6. The method as claimed in claim 1, wherein the preset time is the time interval required for the establishment of dedicated connection between the cluster head and the base station.

7. The method as claimed in claim 1, further comprises of performing sub-clustering of the plurality of MTC devices within a cluster based on a first set of parameters, wherein the first set of parameters comprises of a congestion level and Signal-to-noise ratio (SINR) associated with the plurality of MTC devices.

8. The method as claimed in claim 7, wherein the congestion level based sub cluster formation is performed based on a load index, wherein the load index is an average of a resource utilization at the base station.

9. The method as claimed in claim 8, further comprising:
calculating the load index of a selected base station ; and
redirecting one or more MTC devices from a first base station to a second base station if the load index of the second base station is greater than a previous load index and less than a maximum load index, wherein the maximum load index is associated with a maximum availability of network resources.

10. The method as claimed in claim 8, further comprising redirecting one or more MTC devices from the first base station to the second base station having a load index between the maximum load index and a minimum load index, if the load index of the first base station is less than the previous load index and is equal to or less than the minimum load index, wherein the minimum load index is associated with the minimum availability of network resources.

11. The method as claimed in claim 8, further comprising:
redirecting one or more MTC devices from the first base station to the second base station if the load index of the first base station is greater than the maximum load index; and
shutting down the primary base station.

12. The method as claimed in claim 7, wherein the SINR based sub-cluster formation comprises of:
measuring the SINR by each MTC device with respect to each base station;
reporting the SINR value to a serving base station;
sharing the SINR report with a plurality of neighboring base stations by the serving base station;
sorting, by each base station, the reported SINR for the one or more MTC devices with respect to each base station; and
creating a sub cluster based on the common SINR sequence for the one or more MTC devices with respect to each base station.

13. The method as claimed in claim 7, wherein the cluster head have the highest SINR with serving cell and have decreasing order of SINR for the neighboring base stations or cooperative base stations which are jointly serving cluster head .

14. A method for providing data communication for machine type communication (MTC) devices for multiple base-stations in a wireless communication, the method comprising steps of:
informing, by a cluster head, to one or more MTC devices in a cluster a primary base station to which each MTC device is assigned;
updating an activation status of the one or more MTC devices to the cluster head by each of the MTC device;
requesting for a network resource from a particular base station whenever a transmission is ready for a sub-cluster MTC device;
requesting for a secondary base station, by the primary base station, if there is a disruption in communication due to unavailability of network resources;
shifting the one or more MTC devices from a sub cluster corresponding to the primary base station to a sub cluster corresponding to the secondary base station, wherein the shifting occurs when half of a delay tolerance associated with the one or more MTC devices is over and the MTC device does not get the network resources associated with the base station; and
informing by the cluster head of the secondary base station on which one or more MTC devices corresponding to the sub cluster can shift.

15. A method for providing data communication for machine type communication (MTC) devices for multiple base-stations in a wireless communication, the method comprising steps of:
informing, by a sub-cluster head, to one or more MTC devices in a cluster a primary base station to which each MTC device is assigned;
updating an activation status of the MTC device to the sub-cluster head by each of the MTC device;
requesting for a network resource from a particular base station whenever a transmission is ready for a sub-cluster MTC device;
requesting for a secondary base station, by the primary base station, if there is a disruption in communication due to unavailability of network resources;
providing information of the secondary base station from which the sub cluster head can initiate MTC communication;
searching for the sub cluster head which is linked to the secondary base station in the grouping information;
shifting the one or more MTC devices from a sub cluster corresponding to the primary base station to a sub cluster corresponding to the secondary base station,
informing by the sub cluster head of the secondary base station on which one or more MTC devices corresponding to the sub cluster can shift; and
initiating data traffic transfer from the one or more MTC devices to the secondary database through the connection established between the sub cluster head and the secondary base station.

16. The method as claimed in claim 14, wherein the sub cluster head requests for the secondary base station when half of a delay tolerance associated with the one or more MTC devices is over and the MTC device does not get the network resources associated with the base station.

17. The method as claimed in claim 14, further comprising:
providing the information of the one or more MTC devices that require network resources to the sub-cluster corresponding to the secondary base station;
storing the one or more MTC devices that require network resources as sub cluster members; and
requesting for network resources from the secondary base station by the sub cluster head.

18. The method as claimed in claim 14 , wherein each sub cluster head serving one or more related MTC devices is connected to a serving base station through a dedication connection.

19. The method of claim 14, further comprising:
providing a grouping information of secondary MTC devices to the plurality of MTC devices in the cluster , wherein the grouping information informs the MTC device which base station is associated to which MTC device; and
enabling the MTC devices of one sub cluster to join another sub cluster through one or more MTC devices using a device to device communication.

20. The method as claimed in claim 18, wherein the MTC devices of one sub cluster joins another sub cluster through the device to device communication during at least one of:
expiry of the delay tolerance of the MTC device and the MTC device is in a sub cluster does not get resources from the associated base station; and
if the sub cluster head connected to macro base station cannot serve the MTC device in the sub cluster.

21. A method for providing data communication for machine type communication (MTC) devices in a group-based wireless communication, the method comprising steps of:
selecting, at least one cluster head for a plurality of clusters, wherein each of the plurality of clusters comprises of one or more MTC devices which are members of a cluster associated with the cluster head;
receiving, by the cluster head, a message from the one or more MTC devices for data traffic transfer when the one or more MTC devices are activated, wherein the message comprises at least one of an activation status, a buffer occupancy status and a delay tolerance of the one or more MTC devices;
determining availability of a network resources for transferring the data traffic based on the buffer occupancy status of the one or more MTC devices;
establishing a dedicated connection with a base station for transferring the data traffic; and
transferring the data traffic from the one or more MTC devices to the base station through the connection established between the cluster head and the base station;
wherein delay tolerance is defined as a total tolerable time of communication without impacting a quality of service for the MTC member device.

22. A system for providing data communication for machine type communication (MTC) devices in a group-based wireless communication, the system comprising at least one network element adapted for:
selecting, at least one cluster head for a plurality of clusters, wherein each of the plurality of clusters comprises of one or more MTC devices which are members of a cluster associated with the cluster head;
receiving a message from the one or more MTC devices for data traffic transfer when the one or more MTC devices are activated, wherein the message comprises at least one of an activation status, a buffer occupancy status and a delay tolerance of the one or more MTC devices;
determining availability of a network resources for transferring the data traffic based on the buffer occupancy status of the one or more MTC devices;
establishing a dedicated connection with a base station for transferring the data traffic; and
transferring the data traffic from the one or more MTC devices to the base station through the connection established between the cluster head and the base station;
wherein delay tolerance is defined as a total tolerable time of communication without impacting a quality of service for the MTC member device.

23. The system as claimed in claim 21, further comprises at least one element adapted for performing sub-clustering of the plurality of MTC devices within a cluster based on a first set of parameters, wherein the first set of parameters comprises of a congestion level and Signal-to-noise ratio (SINR) associated with the plurality of MTC devices.

24. A system for providing data communication for machine type communication (MTC) devices for multiple base-stations in a wireless communication, the system comprising:
a cluster head adapted for:
informing to one or more MTC devices in a cluster a primary base station to which each MTC device is assigned;
requesting for a network resource from a particular base station whenever a transmission is ready for a sub-cluster MTC device;
requesting for a secondary base station, by the primary base station, if there is a disruption in communication due to unavailability of network resources;
shifting the one or more MTC devices from a sub cluster corresponding to the primary base station to a sub cluster corresponding to the secondary base station, wherein the shifting occurs when half of a delay tolerance associated with the one or more MTC devices is over and the MTC device does not get the network resources associated with the base station; and
informing the secondary base station on which one or more MTC devices corresponding to the sub cluster can shift.

25. A system for providing data communication for machine type communication (MTC) devices for multiple base-stations in a wireless communication, the system comprising:
a sub-cluster head adapted for:
informing one or more MTC devices in a cluster a primary base station to which each MTC device is assigned;
requesting for a network resource from a particular base station whenever a transmission is ready for a sub-cluster MTC device;
requesting for a secondary base station, by the primary base station, if there is a disruption in communication due to unavailability of network resources;
providing information of the secondary base station from which the sub cluster head can initiate MTC communication;
searching for the sub cluster head which is linked to the secondary base station in the grouping information;
shifting the one or more MTC devices from a sub cluster corresponding to the primary base station to a sub cluster corresponding to the secondary base station,
informing by the sub cluster head of the secondary base station on which one or more MTC devices corresponding to the sub cluster can shift; and
initiating data traffic transfer from the one or more MTC devices to the secondary database through the connection established between the sub cluster head and the secondary base station.

26. The system as claimed in claim 24, wherein the sub-cluster head is further adapted for:
providing the information of the one or more MTC devices that require network resources to the sub-cluster corresponding to the secondary base station;
storing the one or more MTC devices that require network resources as sub cluster members;
requesting for network resources from the secondary base station by the sub cluster head.
providing a grouping information of secondary MTC devices to the plurality of MTC devices in the cluster , wherein the grouping information informs the MTC device which base station is associated to which MTC device; and
enabling the MTC devices of one sub cluster to join another sub cluster through one or more MTC devices using a device to device communication.

27. The system as claimed in claim 24 , wherein each sub cluster head serving one or more related MTC devices is connected to a serving base station through a dedication connection.

28. A system for providing data communication for machine type communication (MTC) devices in a group-based wireless communication, the system comprises at least one element adapted for:
selecting, at least one cluster head for a plurality of clusters, wherein each of the plurality of clusters comprises of one or more MTC devices which are members of a cluster associated with the cluster head;
receiving, by the cluster head, a message from the one or more MTC devices for data traffic transfer when the one or more MTC devices are activated, wherein the message comprises at least one of an activation status, a buffer occupancy status and a delay tolerance of the one or more MTC devices;
determining availability of a network resources for transferring the data traffic based on the buffer occupancy status of the one or more MTC devices;
establishing a dedicated connection with a base station for transferring the data traffic; and
transferring the data traffic from the one or more MTC devices to the base station through the connection established between the cluster head and the base station;
wherein delay tolerance is defined as a total tolerable time of communication without impacting a quality of service for the MTC member device. ,TagSPECI:FIELD OF THE INVENTION

The present invention relates to the field of machine type communications (MTC), and more particularly relates to a method and system for enabling data communication through a cluster head via a dedicated connection for MTC based group communications.

BACKGROUND OF THE INVENTION

Machine-to Machine (M2M)/Machine Type Communications (MTC) applications are applications where machines communicate with each other directly without human intervention. Examples of applications include smart metering, safety applications, health monitoring, fleet management, data applications and remote applications.

The MTC devices can be embedded in cars, consumer electronic devices, vending devices, etc. These devices are large in number and are wide spread. The applications should communicate through widely deployed networks connecting the MTC devices to the Internet forming Internet of Things (IoT). While some existing MTC deployments use short range communications, it would be ideal to use cellular networks as the infrastructure is established in a stable manner and can support a large number of MTC devices.

The enormous amount of signaling flow generated by the large number of MTC devices trying to connect to the network at the same time leads to congestion in radio access network (RAN) and the core network (CN). This in turn causes intolerable delays, packet loss and also service unavailability. Also, congestion in MTC would also affect the non MTC devices.

Generally at the RAN side, the congestion occurs when a large number of MTC devices try to communicate concurrently with the eNodeB. For example, MTC devices which are used for monitoring (bridge monitoring or rainfall/flood monitoring) will transmit the monitored data concurrently. As the devices are connected to the same eNodeB, using the same common channels (Random accesses), can lead to congestion. Consequently the network should be optimized to support these communication requests from the devices simultaneously.

In Release 11, 3GPP System Architecture working group 1 (SA1) has defined system aspects and technical specifications for MTC device to device communication, group based services and possible enhancements to improve the network for MTC. Various solutions such as Access Class Barring schemes, Separate Random Access Channel (RACH) resources for MTC, Dynamic allocation of RACH resources, MTC Specific Back off scheme, slotted access and the like are proposed by the 3GPP to overcome the problem of congestion. These solutions from 3GPP will distribute the RACH load. However, in case of super dense deployment of Pico cells it will either impair the M2M devices or Human to Human (H2H) users.

The deployment scenarios herein take into consideration a combination environment where there is constant movement of MTC devices alongside the static MTC devices. This creates congestion at the RAN due to random access contention during uplink transmission where multiple MTC devices try to send data to the network. Further, during downlink transmission and capacity should be improved while supporting large number of MTC devices along with the existing H2H interaction in downlink transmission. Further, the RACH burst from MTC devices will overload the RACH access at eNodeB which deprives the cellular users from normal service due to over loading of RACH by higher density of M2M devices.

In view of the foregoing, there is a need for an MTC device friendly system and method for minimizing RACH load and provide accesses to MTC devices in MTC based communication.

SUMMARY OF THE INVENTION

The various embodiments of the present invention disclose a method and system for providing data communication for machine type communication (MTC) devices. The method comprising the steps of selecting, at least one cluster head, receiving a data traffic transfer request from the one or more MTC devices by the cluster head and determining the availability of one or more network resources for transferring the data traffic. The cluster then establishes a dedicated connection with a base station for transferring the data traffic from the one or more MTC devices to the base station based on the availability of the one or more network resources. The data transfer request comprises at least one of an activation status, a buffer occupancy status and a delay tolerance of the one or more MTC devices.

According to an embodiment of the present invention, determining availability of base station resources for transferring data traffic comprises of creating a priority list of active MTC devices based on the delay tolerance, comparing the delay tolerance of the active MTC devices with a time required for establishing a connection with a base station, triggering a connection request with the base station when the delay tolerance for a high priority MTC device is equal to the pre-set time and establishing a dedicated connection with the base station for transferring the data traffic. The delay tolerance herein is defined as a total tolerable time of communication without impacting a quality of service for the MTC member device.

According to an embodiment of the present invention, the method further comprises of sending, by the cluster head, at least one of an ACK or NACK message from the base station through the dedicated connection established between the cluster head and the base station and relaying at least one of an ACK or NACK message from the base station to a corresponding MTC device.
According to an embodiment of the present invention, the cluster head establishes and releases the dedicated connection with the base station based on an incoming traffic from the one or more MTC devices.

According to an embodiment of the present invention, the preset time is the time interval required for the establishment of dedicated connection between the cluster head and the base station.

According to an embodiment of the present invention, the method further comprises of sub-clustering a plurality of MTC devices within a cluster based on a first set of parameters. The first set of parameters comprises of a congestion level and Signal-to-Noise Ratio (SINR) associated with the plurality of MTC devices.

According to an embodiment of the present invention, the congestion level based sub-cluster formation is performed based on a load index, wherein the load index is an average of a resource utilization at the base station.

According to an embodiment of the present invention, the method further comprises of calculating the load index of a selected base station and redirecting one or more MTC devices from a first base station to a second base station if the load index of the second base station is greater than a previous load index and less than a maximum load index, wherein the maximum load index is associated with a maximum availability of network resources.

According to an embodiment of the present invention, the method further comprises of redirecting one or more MTC devices from the first base station to the second base station having a load index between the maximum load index and a minimum load index, if the load index of the first base station is less than the previous load index and is equal to or less than the minimum load index. The minimum load index is associated with the minimum availability of network resources.

According to an embodiment of the present invention, the method further comprises of redirecting one or more MTC devices from the first base station to the second base station if the load index of the first base station is greater than the maximum load index and shutting down the primary base station.

According to an embodiment of the present invention, the SINR based sub-cluster formation comprises of measuring the SINR by each MTC device with respect to each base station, reporting the SINR value to a serving base station, sharing the SINR report with a plurality of neighboring base stations by the serving base station, sorting, by each base station, the reported SINR for the one or more MTC devices with respect to each base station and creating a sub cluster based on the common SINR sequence for the one or more MTC devices with respect to each base station.

According to an embodiment of the present invention, the cluster head have the highest SINR with serving cell and have decreasing order of SINR for the neighboring base stations or cooperative base stations which are jointly serving cluster head .

The embodiments herein further disclose a method for providing data communication for machine type communication (MTC) devices for multiple base-stations in a wireless communication. The method comprising steps of informing, by a cluster head, to one or more MTC devices in a cluster a primary base station to which each MTC device is assigned, updating an activation status of the one or more MTC devices to the cluster head by each of the MTC device, requesting for a network resource from a particular base station whenever a transmission is ready for a sub-cluster MTC device, requesting for a secondary base station, by the primary base station, if there is a disruption in communication due to unavailability of network resources, shifting the one or more MTC devices from a sub cluster corresponding to the primary base station to a sub cluster corresponding to the secondary base station, wherein the shifting occurs when half of a delay tolerance associated with the one or more MTC devices is over and the MTC device does not get the network resources associated with the base station and informing by the cluster head of the secondary base station on which one or more MTC devices corresponding to the sub cluster can shift.

The various embodiments herein further describe a method for providing data communication for machine type communication (MTC) devices with multiple base-stations in a wireless communication. The method comprising steps of informing, by a sub-cluster head, to one or more MTC devices in a cluster a primary base station to which each MTC device is assigned, updating an activation status of the MTC device to the sub-cluster head by each of the MTC device, requesting for a network resource from a particular base station whenever a transmission is ready for a sub-cluster MTC device, requesting for a secondary base station, by the primary base station, if there is a disruption in communication due to unavailability of network resources, providing information of the secondary base station from which the sub cluster head can initiate MTC communication, searching for the sub cluster head which is linked to the secondary base station in the grouping information, shifting the one or more MTC devices from a sub cluster corresponding to the primary base station to a sub cluster corresponding to the secondary base station, informing by the sub cluster head of the secondary base station on which one or more MTC devices corresponding to the sub cluster can shift and initiating data traffic transfer from the one or more MTC devices to the secondary database through the connection established between the sub cluster head and the secondary base station.

According to an embodiment of the present invention, the sub cluster head request for the secondary base station when half of a delay tolerance associated with the one or more MTC devices is over and the MTC device does not get the network resources associated with the base station.

According to an embodiment of the present invention, the method further comprises of providing the information of the one or more MTC devices that require network resources to the sub-cluster corresponding to the secondary base station, storing the one or more MTC devices that require network resources as sub cluster members and requesting for network resources from the secondary base station by the sub cluster head.

According to an embodiment of the present invention, each sub cluster head serving one or more related MTC devices is connected to a serving base station through a dedication connection.

According to an embodiment of the present invention, the method further comprises of providing grouping information of secondary MTC devices to the plurality of MTC devices in the cluster. The grouping information informs the MTC device which base station is associated to which MTC device and enabling the MTC devices of one sub cluster to join another sub cluster through one or more MTC devices using a device to device communication.
According to an embodiment of the present invention, the MTC devices of one sub cluster joins another sub cluster through the device to device communication during at least one of an expiry of the delay tolerance of the MTC device and the MTC device is in a sub cluster does not get resources from the associated base station and if the sub cluster head connected to macro base station cannot serve the MTC device in the sub cluster.

Embodiments herein further describe a method for providing data communication for machine type communication (MTC) devices in a group-based wireless communication. The method comprising steps of selecting, at least one cluster head for a plurality of clusters, wherein each of the plurality of clusters comprises of one or more MTC devices which are members of a cluster associated with the cluster head, receiving, by the cluster head, a message from the one or more MTC devices for data traffic transfer when the one or more MTC devices are activated, wherein the message comprises at least one of an activation status, a buffer occupancy status and a delay tolerance of the one or more MTC devices, determining availability of a network resources for transferring the data traffic based on the buffer occupancy status of the one or more MTC devices, establishing a dedicated connection with a base station for transferring the data traffic and transferring the data traffic from the one or more MTC devices to the base station through the connection established between the cluster head and the base station.

Embodiments herein further provide a system for providing data communication for machine type communication (MTC) devices in a group-based wireless communication. The system comprising at least one network element adapted for selecting, at least one cluster head for a plurality of clusters, wherein each of the plurality of clusters comprises of one or more MTC devices which are members of a cluster associated with the cluster head, receivinga message from the one or more MTC devices for data traffic transfer when the one or more MTC devices are activated, wherein the message comprises at least one of an activation status, a buffer occupancy status and a delay tolerance of the one or more MTC devices, determining availability of a network resources for transferring the data traffic based on the buffer occupancy status of the one or more MTC devices, establishing a dedicated connection with a base station for transferring the data traffic and transferring the data traffic from the one or more MTC devices to the base station through the connection established between the cluster head and the base station. The delay tolerance is defined as a total tolerable time of communication without impacting a quality of service for the MTC member device.

According to an embodiment of the present invention, the system further comprises at least one element adapted for performing sub-clustering of the plurality of MTC devices within a cluster based on a first set of parameters. The first set of parameters comprises of a congestion level and Signal-to-noise ratio (SINR) associated with the plurality of MTC devices.

The foregoing has outlined, in general, the various aspects of the invention and is to serve as an aid to better understanding the more complete detailed description which is to follow. In reference to such, there is to be a clear understanding that the present invention is not limited to the method or application of use described and illustrated herein. It is intended that any other advantages and objects of the present invention that become apparent or obvious from the detailed description or illustrations contained herein are within the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:
Figure 1 is a high-level architecture of an LTE system, illustrating a working environment according to an embodiment of the present invention.

Figure 2 is a scenario diagram illustrating the RAN overload problem due to requests from the MTC devices, according to a prior art illustration.

Figure 3 is a scenario diagram illustrating a method of communicating data to MTC devices through a dedicated connection with the cluster head, according to an embodiment of the present invention.

Figure 4 is a schematic diagram illustrating a RAN overload problem solved by a dedicated connection between the MTC device and the cluster head, according to an embodiment of the present invention.

Figure 5 is a schematic representation of a timing diagram for single base station based MTC communication, according to an embodiment of the present invention.

Figure 6 is a scenario diagram illustrating data transmission for single base station based MTC communication, according to an embodiment of the present invention.

Figure 7 is a flow diagram illustrating a messaging sequence for MTC dedicated connection based communication, according to an embodiment of the present invention.

Figure 8 is a schematic representation of a timing diagram for MTC dedicated connection based communication, according to an embodiment of the present invention.

Figure 9 is a scenario diagram illustrating data transmission for multiple base stations dedicated connection based communication for MTC devices, according to an embodiment of the present invention.

Figure 10 is a schematic diagram illustrating a load index and SINR based sub cluster information, according to an embodiment of the present invention.

Figure 11 is a scenario diagram illustrating data transmission through a cluster head dedicated connection based communication for MTC devices for multiple base stations, according to an embodiment of the present invention.

Figure 12 is a schematic representation of a timing diagram for multiple base station cluster head dedicated connection based communication for MTC devices, according to an embodiment of the present invention.

Figure 13 is a flow diagram illustrating a messaging sequence for cluster head dedicated connection based communication for MTC devices, according to an embodiment of the present invention.

Figure 14 is a scenario diagram illustrating data transmission through a sub cluster head dedicated connection based communication for MTC devices for multiple base stations, according to an embodiment of the present invention.

Figure 15 is a flow diagram illustrating a messaging sequence for sub cluster head dedicated connection based communication for MTC devices, according to an embodiment of the present invention.

Figure 16 is a schematic representation of a timing diagram for multiple base station sub cluster head dedicated connection based communication for MTC devices, according to an embodiment of the present invention.

Although specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments. The present invention can be modified in various forms. Thus, the embodiments of the present invention are only provided to explain more clearly the present invention to the ordinarily skilled in the art of the present invention. In the accompanying drawings, like reference numerals are used to indicate like components.

The specification may refer to “an”, “one” or “some” embodiment(s) in several locations. This does not necessarily imply that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes”, “comprises”, “including” and/or “comprising” when used in this specification, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. Furthermore, “connected” or “coupled” as used herein may include operatively connected or coupled. As used herein, the term “and/or” includes any and all combinations and arrangements of one or more of the associated listed items.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Figure 1 is a high-level architecture of an LTE system, illustrating a working environment according to an embodiment of the present invention. The MTC Gateway is a type of MTC device with 3GPP mobile communication capability. The MTC Gateway connects to the MTC Capillary network which contains local access devices using short range technologies for communication. The MTC Gateway device acts as a middle agent between the local access devices and the MTC Server. The MTC Server operates within the 3GPP network.

Figure 2 is a scenario diagram illustrating the RAN overload problem due to requests from the MTC devices, according to a prior art illustration. The plurality of MTC devices are generally deployed in massive numbers. Consequently the RACH burst from MTC devices overloads the RACH access at the eNodeB. This in turn deprives cellular users from normal service due to over loading of RACH by higher density of M2M devices.

Figure 3 is a scenario diagram illustrating a method of communicating data to MTC devices through a dedicated connection with the cluster head, according to an embodiment of the present invention. The user equipment establishes a dedicated connection from a cluster head to the eNodeB based on a pattern of the data traffic received from the MTC devices. Similarly, the UE releases the dedicated connection based on the traffic pattern of the MTC devices. The traffic pattern should provide a duration of a dedicated RRC connection since most of the traffic is expected to be intermittent in nature. In order to release the dedicated connection, the cluster head uses the RRC connection release timer.

The dedicated connection established between the cluster head the eNodeB as shown in Figure. 3, provides continuous flow of traffic from cluster head to eNodeB, thereby minimizing the RACH access for RRC Connection, brings more adaptive power control between MTC device and eNodeB for MTC traffic and reduces the latency to access the eNodeB.

Figure 4 is a schematic diagram illustrating a RAN overload problem solved by a dedicated connection between the MTC device and the cluster head, according to an embodiment of the present invention. At a time instance T1, a dedicated connection is assumed to be established between the cluster head and the base station and the MTC devices D1 and D2 will be active for MTC transmission/reception. Here the data from D2 and D1 devices will be either carried /received through the cluster head. The embodiments herein avoid the opportunistic RACH transmission to the base station, thereby preventing the overload at RAN. The dedicated connection between the cluster head and base station to carry data from the MTC devices which are associated with the cluster head to come under the vicinity of the cluster head.

Figure 5 is a schematic representation of a timing diagram for single base station based MTC communication, according to an embodiment of the present invention. The MTC devices herein corresponds to cluster members of a cluster wherein the cluster members updates the cluster head of its activation status, buffer occupancy and delay tolerance once the cluster members are activated. The cluster head prepares a priority list of the active MTC devices based on their delay tolerances left. For instance, let TBS be the time required for establishing a dedicated connection between the cluster head and the base station. The delay tolerance left of the higher priority device is then with the TBS. The channel head triggers a connection request with the base station, when the delay tolerance left for the higher priority device is equal to the TBS. The channel head then asks for the network resources with a buffer occupancy BOTotal . Here, buffer occupancy is defined as:
BOtotal = ?_(i=1)^n¦?BO?_i ,
where i= 1 to N and N is the maximum number of active cluster members.

At instant t1, the channel head triggers connection request to base station as the delay tolerance left for device 2 (the highest priority device at that instant) becomes equal to TBS. At instant t2, the channel head sends a buffer occupancy report to eNb, which is summation of all buffer occupancy of the plurality of MTC devices at the eNb. For example, if buffer occupancy for device Di is BOi, then BO_(total )= ?_(i=1)^n¦BO_i . At instant t2, the data transfer occurs through a dedicated connection formed between the channel head and the network.

Figure 6 is a scenario diagram illustrating data transmission for single base station based MTC communication, according to an embodiment of the present invention.

The cluster head receives Acknowledgement of Packet Delivery (ACK) or Non-Acknowledgement of Packet Delivery (NACK) message from the network 601 is received through the dedicated channel established between the channel head 701 (ref:Fig.7) and the network (eNb) 601. The cluster head 701 then relay the ACK/NACK message from the network to the respective MTC devices.

Figure 7 is a flow diagram illustrating a messaging sequence for MTC dedicated connection based communication, according to an embodiment of the present invention. When one or more MTC devices/Cluster members CM-1, CM-2 and CM-3 701a, 701b and 701c respectively sends a message to the selected cluster head 701 for data transfer when the one or more MTC devices are activated. The message comprises the activation status, the buffer occupancy status and the delay tolerance left of the one or more MTC devices. The channel head 701 then creates a priority list of active MTC devices based on the delay tolerance. The delay tolerance is defined as a total tolerable time of communication without impacting a quality of service for the MTC member device, The cluster head 701 then compares the delay tolerance of the active MTC devices with a time required for establishing a connection with a base station, triggers a connection request with the base station when the delay tolerance for a high priority MTC device is equal to the pre-set time. The cluster head 701 further determines the availability of network resources for transferring the data traffic based on the buffer occupancy status of the plurality of MTC devices and further establishes a dedicated connection with the base station for transferring the data traffic. The cluster head 701 then sends at least one of an ACK or NACK message from the base station through the dedicated connection established between the cluster head 701 and the base station and relay at least one of an ACK or NACK message from the base station to a corresponding MTC device.

Figure 8 is a schematic representation of a timing diagram for MTC dedicated connection based communication, according to an embodiment of the present invention. The timing diagram illustrates the various activities or actions performed by each of the cluster member or MTC device, cluster head and the network and their time instances.

Figure 9 is a scenario diagram illustrating data transmission for multiple base stations dedicated connection based communication for MTC devices, according to an embodiment of the present invention. According to an embodiment of the present invention, the following factors are taken into consideration according to the standards for clustering procedure in a multi-station based scenario. Consider, CHi be the cluster head of cluster i, where i=1,2,..n, N be the total number of MTC devices in the system nd Ni be the number of devices in cluster i. The Ni devices are connected by short range communication using single hop. The short range technology which dictates the transmission range between devices is assumed to be TR in metres. Out of Ni devices, there are S devices serving safety applications, P devices serving periodic applications, NP devices serving non periodic applications and D devices serving non real time and real time applications. Each CHi maintains four queues one for each application S, P, NP and D. A MTC device can be in any one of state such as a cluster member (CLM) or a cluster head (CH). The MTC device can either be an active device where it has its own application running with service requests to send or receive data or a passive device where there is no current data transmission.

Consider BSj,BSj+1…BSm be the base stations in the system where j=1,2,…m. CHi be under the coverage range of multiple base stations BSk (where k ? {j+1, j+2...m}). The method for selecting a cluster head considers four main parameters mobility of the device, drain rate of the device, Signal to Noise Ratio and Passive Device. A weight factor is chosen for each metric dependent based on system requirements and is combined with the system parameters effectively. The method uses a combined weight metric of the above four parameters to select a cluster head. The MTC device with the highest weight is chosen as a cluster head 701. For determining the SINR parameter, any device which is closer to the BS is assumed to have good SINR values and higher data rates and will be chosen as a candidate for CH. In multi base station scenario, the BSj with which the CHi has higher SINR value is selected as a Master BS. The remaining BSs which cover CHi are considered as Secondary BSs. A ranking table is generated by the CHi with a list of BS sorted in the descending order of SINR values. The first BSj in the list is the Master BS and second BSj+1 is the first secondary and so on. This list will cover the entire BSs with which CHi has coverage. Further a group of Secondary BSs referred to as “candidate Secondary BSs” are determined from the SINR ranking table, Qos requirement of the CHi and resource availability at each secondary BS. For delay non sensitive applications, low SINR is tolerable but for delay sensitive applications SINR is taken at priority. So, in all, cooperation of BS should be based on nature of the application.

The Master BS together with candidate Secondary BSs forms a virtual cell for the CHi. The CSI (CQI/PMI/RI) of the UE is exchanged between the BSs of the virtual cell to co-ordinate between the BS. Consider Ri is the data rate between CHi and BSj in bits/second. The rate Ri is decided based on the physical channel conditions between CHi and BSj, ?1, ?2… ?Ni is the mean arrival rate of the data in the devices being served by CHi, assuming the arrival rates are in poisson process and µi is the mean service rate for CHi offered by the BSj. ?_(i=1)^(N^i)¦?_(i" " ) = µ_i ; where the sum of the arrival rate of the packets at CHi queue should be less than or equal to the mean service rate offered by the BSj to CHi. Let RAi be the resources allocated to CHi, dS, dP, dNP and dD, be the delay tolerance for S, P, NP and D applications and E (DELa) be the expected delay for the application a (where a ? {S,P,NP,D}). It is defined as sum of the queuing delay at the cluster head, transmission delay and propagation delay. E (DELa) for each application type should satisfy the following constraints:
E(DELS) = dS
E(DELP) = dP
E(DELNP) = dNP
E(DELD) = dD
Let ßS, ßP, ßNP and ßD, be the packet loss ratio tolerance for S, P, NP and D applications.
Let EPLR(.) be the expected packet loss ratio of application (.) and is defined as the ratio of number of packets lost to the total number of packets transmitted.
EPLR (.) for each application type should satisfy the following constraints
EPLR(S) = ß S
EPLR(P) = ß P
EPLR(NP) = ß NP
EPLR(D) = ß D

In this scenario, the mean arrival rate of packets at CHi is greater than the service rate at CHi. ?_(i=1)^(N^i)¦?_(i" " ) > µ_i , this implies that queues at CHi increases without bounds causing an increase in E (DELa) and EPLR. There will be a dedicated connection to the set of base stations, either from the cluster head or a sub cluster head, which are in the vicinity of the CHi. The cluster device get resources for transmission from the serving or master base station.

The secondary cluster devices CMk (where k ? {1, 2...n}) are grouped into sub-clusters (grouping of sub-clusters) that are then associated to particular BSk (where k ? {j+1, j+2...m}) from which it obtain resources for communication, wherein BSk (where k ? {j+1, j+2...m}) are assumed to be the in descending order of received SINR by the cluster head CHi. The grouping of sub-clusters within a cluster comprises of Congestion Level Based sub cluster formation and SINR Based sub cluster formation.

Figure 10 is a schematic diagram illustrating a load index and SINR based sub cluster information, according to an embodiment of the present invention. In a network assisted grouping, network (BSj) gives the information of the congestion level of the base stations BSk (where k ? {j+1, j+2...m}). Depending on the information provided by the network, the congestion level based grouping is based on the information of Load Index (LI) of BS’s BSk (where k ? {j+1, j+2...m}). Load index, as per definition provides time average occupancy of the physical resources at each BS. The primary network (BSj) asks for the Load Index from the secondary BS’s via the BACK HAUL link and forward to CH(CHi) the Load Index values LIk (where k ? {j+1, j+2...m}) corresponding to secondary BS’s through the dedicated connection. The Load index (LI, ratio of free to allocated resources) of a particular BS is calculated on taking the time average of ‘n’ samples of load index samples a certain time interval.
(LI)retrieved = {?_(i=1)^n¦?(LI)i?}/n
If the Load Index {(LI) retrieved} of any network is too less i.e. the network is too congested to provide resources for the MTC devices. If the Load index {(LI) retrieved} is very high i.e. very few devices are using that network. From the power optimization purpose, it is required to power shut down such BS. The MTC devices must not be allocated to the network if the load index is very less or very high. Instead shifting of current devices to other BS helps to shut down the serving BS. A threshold (Th) is to be defined for the Load Index values such that the MTC devices must not be associated to the network, if the Load index values LIk (where k ? {j+1, j+2...m}) is greater than the (Th)max Load Index or less than the (Th)min Load Index.
For allocation of MTC devices to a particular BS, the Load Index value LIk (where k ? {j+1, j+2...m}) should be in the range:
(Th)min Load Index < LIk < (Th)max Load Index (where k ? {j+1, j+2...m})

The base station with the lowest congestion level is allocated first to the number of the cluster devices according to the load index of the base station (LIk) and the devices are selected on the basis of SINR values to that BS. The secondary MTC devices within a cluster are supposed to send the SINR values corresponding to all of the secondary BS’s to the cluster head.

The grouping of secondary MTC devices is performed at the cluster head:

The grouping is done such that if there are n MTC devices that are to be grouped in BS’s BSk (where k ? {j+1, j+2...m}) arranged in an increasing congestion level sequence with info of Load Index.
BSj+1 ? (LIj+1) MTC devices
BSj+2 ? (LIj+2) MTC devices
BSj+3 ? (LIj+3) MTC devices
:
:
BSm ? (n-((LIj+1)+(LIj+2)+…+(Lim-1)))
Where (CL)j+1<(CL)j+2<(CL)j+3<…<(CL)m
(Th)min Load Index < LIk (where k ? {j+1, j+2...m}) < (Th)max Load Index

Further triggering condition is added. The devices CMk (where k ? {1, 2...n}) are first allocated to the BS with lowest Congestion Level (BSj+1) depending on their SINR values to that BS. The number of devices allocated is the Load Index of that BS (LIj+1). In the same way all BS’s BSk are allocated to the secondary MTC devices in the way that the base station, BSk with lowest congestion level is allocated first and then moving on to highest. The MTC devices are grouped into sub-clusters SCk (where k ? {j+1, j+2...m}) based on the SINR values corresponding to different BSk and the load index information of the BS’s. Since the Load index of the BS’s keeps on changing, the grouping of devices needs to be updated corresponding to the new load index values of BS’s. The time interval (Tnew LI) after which new load index is retrieved and grouping needs to be updated depends on the scheduling mechanism.

CASE 1 – LI new > LI previous
When the new load index (LInew) of a particular BS (BSj+1) is greater than the number of devices allocated to it (the previous load index) i.e. it can allocate resources to more devices.
(LInew) < (Th)max Load Index
In this case, (BSj+1) can be allocated to more of the MTC devices, so the MTC devices those are allocated to the BS with high congestion level(BSm,BSm-1) for those Lim, Li m-1 < (Th)min Load Index is allocated to this Base Station (BSj+1).

The grouping will be such that if there are ‘n’ MTC devices that are to be grouped in BS’s BSk (where k ? {j+1, j+2...m}), arranged in an increasing congestion level sequence according to the load index LIk (where k ? {j+1, j+2...m}), the BSj+1 can be allocated further to ‘x’ devices.
(BSj+1) ? ((LIj+1) + x) MTC devices
(BSj+2) ? (LIj+2) MTC devices
:
:
(BSm-1) ? ((Lim-1) - (Lim-1)) MTC devices
(BSm) ? ((LIm) - (LIm)) MTC devices
Where (CL)j+!<(CL)j+2<(CL)j+3<…<(CL)m
The BSm-1 and BSm is removed from the cloud cell with respect to this cluster, as devices allocated to these BS’s earlier are now allocated to BSj+1.

CASE 2 – LI new < LI previous and LI new < (Th) min Load Index
When the load index retrieved (LInew) from a particular BS (BSj+1) is less than the previous Load Index (LI previous) i.e. it cannot allocate resources efficiently to all the MTC devices allocated to this BS (BSj+1) earlier. In this case, as the number of MTC devices allocated to BS (BSj+1) is much higher than the resources it can allocate to MTC devices, so the extra MTC devices that can create congestion on this BS is shifted to next BS, provided that the next BS should have Load index higher than the resources allocated to it.
If the BS next to the BSj+1 also have a load index lower than the required, then devices from BSj+1 and BSj+2 will be shifted to BSj+3.

The grouping is such that if there are ‘n’ MTC devices that are to be grouped in BS’s BSk (where k ? {j+1, j+2...m}) arranged in an increasing congestion level sequence according to the load index, the BSj+1 cannot allocate ‘x’ devices among the devices allocated to it earlier.
(BSj+1) ? ((LIj+1) -x) MTC devices
(BSj+2) ? ((LIj+2) +x) MTC devices
:
:
(BSm) ? (LIm) MTC devices
Where (CL)j+!<(CL)j+2<(CL)j+3<…<(CL)m
(LI)New ?(LIj+1) – x

CASE 3– LI new > (TH)max load Index
When the load index retrieved (LInew) from a particular BS (BSj+1) is higher than the maximum bound of Load Index i.e. it contains very few number of devices. In this case, where the (BSj+1) has a Load Index higher than the upper bound of Load Index, the MTC devices associated with this BS will be shifted to next BS for power optimization (as proposed by 3GPP), provided that the next BS should have Load index higher than the previous value. In such case (BSj+1) can be power shut down in order to optimize the BS power. If the BS next to the BSj+1 also has a load index higher than the threshold, then devices from BSj+1 and BSj+2 will be shifted to BSj+3. The grouping will be such that if there are ‘n’ MTC devices that are to be grouped in BS’s BSk (where k ? {j+1, j+2...m}) arranged in an increasing congestion level sequence according to the load index, the MTC devices associated to BSj+1 will be shifted to BSj+2 for power optimization.
(BSj+1) ? ((LIj+1) – (LIj+1)) MTC devices
(BSj+2) ? ((LIj+2) + (LIj+1)) MTC devices
:
:
(BSm) ? (LIm) MTC devices
Where (CL)j+!<(CL)j+2<(CL)j+3<…<(CL)m
(LI)New > (TH)max load Index

SINR Based sub cluster formation

When there is no information of the Load Index values of BS’s from the network, then the sub clusters SCk (where k ? {j+1, j+2...m}) are formed on the basis of the SINR values corresponding to BS’s BSk (where k ? {j+1, j+2...m}). The CHi will retrieve the SINR values from each of the secondary MTC devices CMk (where k ? {1, 2...n}) corresponding to the BS’s BSk (where k ? {j+1, j+2...m}) and then divides the MTC devices into sub clusters accordingly. The MTC devices of sub-clusters formed (sub-cluster members) will be having the high SINR values corresponding to the particular BS allocated to them and sub-Cluster Head sCHk (where k ? {j+1, j+2...m}) is also assigned for each sub-cluster SCk (where k ? {j+1, j+2...m}) which will do the contention resolution in its sub-cluster. The conditions for a cluster device to become a sub cluster head will be same as the one described earlier in cluster formation model in case of single BS.

The s-CH sCHk (where k ? {j+1, j+2...m}) asks for resources from the BS {BSk where k ? (j+1, j+2...m)} for the active devices in its sub-cluster via dedicated connection to associated BS.

The grouping on the basis of SINR values to secondary BS’s can be shown by the following example. Assume there are ‘6’ secondary MTC devices in a cluster and ‘3’ secondary BS’s and the SINR values as shown earlier-

The groups are formed on the basis of the sequences of SINR values corresponding to the BS’s and devices:
(BS)1 ? {device1}
(BS)2 ? {device2, device 5 , device 6 }
(BS)3 ? {device 4, device 3}
The devices 1, 2 and 4 are the sCH’ s of the sub clusters formed corresponding to the base station 1,2 and 3 respectively as they have highest SINR value corresponding to that BS. After grouping by any of the method, the grouping info message is to be sent to all MTC devices from Cluster head (CHi).

The grouping info message: (secondary BS’s {BSk where k ? (j+1, j+2...m)})

Device association to BS Sub cluster head
{CM2,CM3,…,CMm} ? BSj+1 sCHj+1 ? CM2
{CM1,CM5,…,CMp} ? BSj+2 sCHj+2 ? CM1
:
:
{CMi,CM21,…,CMz} ? BSm sCHm ? CMi

Hybrid Grouping:
Hybrid grouping based on the joint optimization of SINR and load balancing is not in the scope of this document and left for the future work. Once grouping is done, there are two ways in which a dedicated channel can be formed from the sub-cluster to the respective BS such as CH based dedicated connection and Sub cluster head (sCH) based dedicated connection.

Figure 11 is a scenario diagram illustrating data transmission through a cluster head dedicated connection based communication for MTC devices for multiple base stations, according to an embodiment of the present invention. In a CH based connection, there will be a dedicated connection from the CHi to the plurality of base stations {BSk where k ? (j+1, j+2...m)} and all the communication from the sub-clusters to their respective BS is performed through the cluster head. Each of the MTC devices in a cluster will update the CHi with its information i.e. its activation. The contention resolution of each sub cluster will be handled at the CHi i.e. the CH will accordingly request for resources from a particular base station whenever a transmission is ready for any sub-cluster device. There will be the chances of congestion at a respective base station and sub-cluster devices don’t get resources for communication and thus disruption in the MTC occurs. Each BS will have a secondary base station (‘n’ secondary BS’s) to whom it can handover the devices whenever there is a chance of disruption in M2M communication. The shifting of devices (CM1) from the sub cluster corresponding to the serving BS (BS-2) to the sub cluster corresponding to the secondary BS (BS-3). The shifting takes place when half of the delay tolerance interval is passed and the device (CM1) does not get the resources associated base station BS (BS-2). The secondary BS’s (BS-2) then informs the cluster head of the secondary BS (BS-3) on which devices (CM-1) corresponding to its sub-cluster can shift.

Figure 12 is a schematic representation of a timing diagram for multiple base station cluster head dedicated connection based communication for MTC devices, according to an embodiment of the present invention. Each of the MTC devices in a cluster will update the cluster head with its activation status. The cluster head will accordingly request for resources from a particular base station whenever a transmission is ready for any sub-cluster device. There will be the chances of congestion at a respective base station and sub-cluster devices don’t get resources for communication and thus disruption in the MTC occurs. The cluster head will then handover the MTC devices from a first base station to a second base station when it does not get network resources in the first half of the delay tolerance. Further, the second base station requests for resources from its network keeping the MTC devices in high priority.

Figure 13 is a flow diagram illustrating a messaging sequence for cluster head dedicated connection based communication for MTC devices, according to an embodiment of the present invention. The cluster head 701 informs the plurality of MTC devices in a cluster of a primary base station 1301a to which each MTC device is assigned. When the MTC device becomes active, the MTC device updates the activation status to the respective cluster head 701. The cluster head 701 then requests for network resources from a particular base station whenever a transmission is ready for a sub-cluster MTC device. The cluster head 701 then requests the primary base station (BS-2) 1301a to provide a secondary base station (BS-2) 1301b if there is a disruption in the communication due to unavailability of network resources. The primary base station 1301a informs the cluster head 701 of the secondary base station 1301b from which it can perform MTC communication. The cluster head 701 then shifts the one or more MTC devices from a sub cluster corresponding to the primary base station (BS-2) 1301a to a sub cluster corresponding to the secondary base station (BS-3) 1301ab as suggested by the network. The shifting occurs when half of a delay tolerance associated with the one or more MTC devices is over and the MTC device does not get the network resources associated with the base station. The cluster head 701nthen enquires the secondary base station (BS-3) 1301b for network resources and initiate the data communication for the MTC devices.

Figure 14 is a scenario diagram illustrating data transmission through a sub cluster head dedicated connection based communication for MTC devices for multiple base stations, according to an embodiment of the present invention. In a sub cluster head (sCH) based dedicated connection, there is a dedicated connection from the sub-cluster head sCHk {where k ? (j+1, j+2...m)} of a particular sub-cluster SCk {where k ? (j+1, j+2...m)} to the associated base station. The contention in each sub-cluster is handled at the sCH of that sub-cluster as the dedicated connection is from the sCH to the BS. The sCH starts the connection request to the associated BS for resources, as soon as any UE within its sub-cluster becomes active.

The CHi after grouping of sub-clusters forwards the information message (grouping information of secondary MTC devices) to all of the MTC devices so that each MTC device knows which BS is associated to which device. Each of the sCH knows information about the sCH’s corresponding to different BS’s. The handover message from a particular sCH (sCH1) to other sCH (sCH2) includes the information of the MTC devices that is to be handover. The grouping information that is sent to each of the MTC devices from the CHi contains the information as provided below.
Device association to BS Sub cluster head
{CM2,CM3,…,CMm} ? BSj+1 sCHj+1 ? CM2
{CM1,CM5,…,CMp} ? BSj+2 sCHj+2 ? CM1

In the sCH based connection, the delay tolerance is updated to half of its original value for communication from a primary BS allocated to it. If the delay tolerance is passed and still the MTEC device does not get any resources from the associated BS (in case of congestion at the associated BS), then it will be hand over to the secondary BS for resources. The secondary BS corresponding to each BS will be then selected for handover of devices. The sCH (sCH1) will send the information to the sCH (sCH2) corresponding to the secondary base station (BS3), about the devices (sCM1) that require resources for communication. The sCH (sCH2) handover the MTC devices (sCM1) as its sub cluster members and start the request for resources from its base station.

Figure 15 is a flow diagram illustrating a messaging sequence for sub cluster head dedicated connection based communication for MTC devices, according to an embodiment of the present invention. The cluster head 701 informs the plurality of TC devices in a cluster of the grouping information that which base station is allocated to which MTC device. The MTC device on activation informs the activation status to the sub-cluster head. The sub cluster head requests for a network resource from a particular base station whenever a transmission is ready for a sub-cluster MTC device 1303. The sub cluster head requests for a secondary base station (BS-3) 1301b if half of the delay tolerance is passed and no resource is found for MTC. The primary base station 1301a then provides information of the secondary base station 1301b from which the sub cluster head sCH2 1501can initiate MTC. The sub cluster head sCH2 1501then searches in the grouping information for the sub cluster head which is linked to the secondary base station 1301b. The sub cluster then performs handover of the MTC devices from a sub cluster corresponding to the primary base station 1301a to a sub cluster 1501b corresponding to the secondary base station 1301b as suggested by the network 601. The sub cluster head 1501 of the secondary base station 1301b informs on which sub cluster the one or more MTC devices can shift. The sub cluster head 1501b then initiates data traffic transfer from the one or more MTC devices to the secondary base station 1301b through the connection established between the sub cluster head 1501b and the secondary base station 1301b.

According to an embodiment of the present invention, the sub cluster head 1501b request for the secondary base station 1301b when half of a delay tolerance associated with the one or more MTC devices is over and the MTC device does not get the network resources associated with the base station. Each sub cluster head serving one or more related MTC devices is connected to a serving base station through a dedication connection.

According to an embodiment herein, the MTC devices of one sub cluster joins another sub cluster through the device to device communication during at least one of expiry of the delay tolerance of the MTC device and the MTC device is in a sub cluster does not get resources from the associated base station and if the sub cluster head connected to macro base station cannot serve the MTC device in the sub cluster.

Figure 16 is a schematic representation of a timing diagram for multiple base station sub cluster head dedicated connection based communication for MTC devices, according to an embodiment of the present invention. As shown in Figure 16, at t1, the sub cluster head sends grouping information to each of the cluster head sends grouping information to each of the sub-cluster head. At t2, the MTC devices of subcluster-2 are active for communication. At t5, half of the delay tolerance is passed and no resources are allocated from the network. At t6, the primary base station asks for secondary base station. At t8, the network informs the sub cluster head-2 of its secondary network so that the sub cluster head-2 can shift its sub-cluster devices to sub-cluster-3. Further at t8, the sub cluster head-2 searches for grouping information for sub cluster head corresponding to that base station. At t9, sub cluster head -2 handover its sub cluster devices to sub cluster head -3 as suggested by the network. At t11, the handover devices get network resources from secondary base station.

According to an embodiment herein, the clustering based mechanism provides for the cluster head to establish a dedicated connection with eNB and other MTC device only communicate to cluster head and not to the base station. Further a semi-persistence scheduling grant is allocated to a cluster head and the cluster head receives downlink data on behalf of all the MTC devices. MTC cluster head then shares the MTC downlink data to each MTC device.

The present embodiments have been described with reference to specific example embodiments; it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the various embodiments