Title of Invention

SYSTEM AND METHOD FOR MEDIUM ACCESS CONTROL IN WIRELESS MOBILE AD-HOC NETWORKS

Abstract This invention relates to the field of wireless mobile ad-hoc networks. Further, this invention relates to medium access control for wireless personal area networks that are based on wireless mobile ad-hoc networks. A system and a method for medium access control in wireless mobile ad-hoc networks are proposed in this invention comprising a new medium access control mechanism .involving a new superframe structure; a new beacon frame structure containing a new information element Association Status IE (ASIE), heart beat frame and a new means of association.
Full Text

FIELD OF THE TECHNOLOGY
This invention relates to the field of wireless mobile ad-hoc networks. Further, this invention relates to medium access control for wireless personal area networks that are based on wireless mobile ad-hoc networks. Particularly, this invention relates to effective mechanisms of medium access control to identify association status of all devices in the wireless personal area networks, faster association of a device in the network, and effective channel time utilization in the wireless personal area networks. More particularly, this invention encompasses a system and method for medium access control in wireless personal area networks based on ultra wide band (UWB) systems.
DESCRIPTION OF RELATED ART
The wireless personal area networks are defined to operate in the personal operating space, i.e. at a distance of approximately 10 meters. The IEEE (Institute of Electrical and Electronics Engineers) (http://www.ieee.org) is involved in defining standards for such wireless personal area networks. The Ultra Wide Band (UWB) technology can provide data rates exceeding several hundreds of Mbps in this personal operating space. Medium Access Control mechanisms to deal with such high data rates are currently being discussed in IEEE draft P802.15.3/D17. The medium access control mechanisms broadly include how a device may join the network, how it can transfer data at the required rate to another device, how the medium is best used etc.
Figure 1 illustrates the piconet in WPAN ad-hoc network system. The piconet range, different piconet elements like DEV and PNC, frames being transferred in piconet like beacon and data transfer between DEV to DEV, PNC to DEV and DEV to PNC are shown;

Figure 1 show the wireless personal area network, which is based on lEEE-802.15.3. It involves a network referred as piconet. in which a device may act as coordinator (referred as piconet coordinator or PNC in literature). The PNC performs the functions of allowing a device (referred as DEV) to join, allocating it a channel (time slot) to transmit to another device, synchronization mechanisms etc. This is a centralized WPAN system which is formed in an ad-hoc fashion. The PNC periodically broadcasts the information to all the associated devices in the beacon.
Figure 2 illustrates the superframe structure. Superframe is channel distribution specified by the PNC among the DEVs in piconet. It is informed to DEVs through beacon frame, which is being broadcasted by PNC.
Superframe is comprised of 3 parts:
1. Beacon: It is used to set the timing allocations and to communicate management Information for the piconet. All the associated devices listen to this beacon.
2. Contention access period (CAP): It is used to communicate commands from the DEV to PNC or vice versa. It may also be used for asynchronous data if it is present in the superframe. The length of the CAP is determined by the PNC and communicated to the DEVs in the piconet via the beacon. The CAP uses CSMA/CA protocol for the medium access.
3. Channel time allocation period (CTAP): It consists of channel time allocations (CTAs), including management CTAs (MCTAs). CTAs are used for commands, isochronous streams and asynchronous data connections. A PNC may choose to use MCTAs instead of the CAP for sending command frames, unless otherwise restricted by the physical layer (PHY). An open MCTA is one where the SrcID is the BcstID; Any DEV that is associated in the piconet may attempt to send a command frame to the PNC in an open MCTA. An MCTA with the UnassocID as the SrcID is an association MCTA. Any DEV not currently associated in the piconet may

attempt to send an Association Request command to the PNC in an association MCTA.
The CTAP, in contrast to CAP, uses a standard TDMA protocol where the devices (DEVs) have specified time windows which are called the CTAs. MCTAs are either assigned to a specific source/destination pair and use TDMA for access or they are shared CTAs that are accessed using the slotted aloha protocol.
Beacon frame is illustrated in figure 3. Information Elements (lEs) in figure 3 are encoded in type, length, value format. The lEs in the beacon payload may appear in any order except for the channel time allocation (CTA) lEs, which is the first lEs of the beacon payload following the piconet synchronization parameters field. CTA IE consists of information about the CTAs in the superframe.
Figure 4 shows message sequence chart (MSC) for association procedure for a device as defined in IEEE 802.15.3. Before a DEV has completed the association process, all frames sent to the PNC by the DEV are either in the CAP of the superframe or in an association MCTA. The association procedure is performed in the following steps:
1. An unassociated DEV initiates the association process by sending an Association Request command, to the PNC.
2. When the PNC receives an Association Request command, it sends an Association Response command, indicating that the DEV has been associated and the device identifier (DEVID) it has been assigned or that the request has been rejected with the reason for the rejection. For association using MCTAs, the Association Response command is sent in an MCTA with PNCID as source address and UnassocID as destination address.
3. The unassociated DEV receiving the Association Response command with the DEV address matching its own sends during the CAP or an association

MCTA a second Association Request command with the SrcID field set to its newly assigned DEVID.
4. The PNC upon receiving this Association Request command responds with an acknowledgement (Imm-ACK) with the DestID set to the SrcID of the Association Request command.
5. The PNC after acknowledging this second request then initializes the DEV Association IE with the requesting DEV's DEVID, DEV address, DEV Capabilities field, and Association Status field set to "associated". The requesting DEV upon receiving the Imm-ACK to its second Association Request command considers itself associated. All other DEVs that are members of the piconet receiving the beacon containing the DEV Association IE may use the DEV Association IE to update their internal list of associated DEVs in the piconet.
The present state of art in this field, as discussed in IEEE 802.15.3 (http://www.ieee.org), has certain limitafions, namely, there is no mechanism where the PNC can broadcast the information related to each associated device, along with its DEVID, in each beacon. Consequently, it takes two superframes for a device to be associated. Also, a device 1 is unable to know whether a device 2, which is also associated to the PNC, is directly reachable or not. This information may be very useful for routing as well as in spafial reuse to improve the channel ufilization.
Currently in the medium access control mechanism as defined in IEEE-802.15.3 system; there is no mechanism for the following:
1. No mechanism for PNC to broadcast the information about all the associated devices in the beacon;
2. No way for a device to know about all other associated devices through the beacon;
3. No simple mechanism for a device to know whether another associated

device is directly reachable (in range) or not;
4. Under utilization of the channel time because of the contention based systems for channel access like CSMA/CA and slotted aloha;
5. Multiple association request for association in centralized association approach;
6. MCTA allocation by PNC and shared MCTA like open and association MCTA; and
7. No mechanism for extension for routing and spatial reuse.
SUMMARY OF THE INVENTION
The primary object of the present invention is therefore to provide a system and method for medium access control for the UWB wireless personal area networks, which are based on wireless ad-hoc networks, in a centralized network topology where one of the devices undertakes the role of a coordinator.
It is another object of the invention to provide a mechanism where the PNC can broadcast the information about all the associated devices through the beacon, and thus, by listening to the beacon, a device may get to know about all other associated devices.
It is another object of the invention to provide the mechanism for faster association of DEV to PNC.
It is another object of the invention to provide a mechanism for improved channel utilization in the UWB WPAN.
It is another object of the invention to provide a mechanism for improved routing capability in UWB based wireless personal area network.
It is another object of the invention to provide capability of spatial reuse in the

UWB WPAN.
The present invention relates to a system that allows an improved medium access control in the Wireless Personal Area Networks based on mobile ad-hoc networks.
This invention further relates to a system and method which allows all devices to know about all the associated devices in the network.
The system for the invention comprises of a new medium access control mechanism involving a new superframe structure, a new beacon frame structure, heart beat frame and a new association procedure.
The present invention comprises of a system and method which would solve the problems associated with current art, in the following manner:
1. The proposed superframe structure has a new entity, called Device Access Period (DAP) in the superframe structure, which can be used by all the associated DEVs in piconet to send their respective heart beat frames. By listening to the heart beat frames as contained in DAP, it is possible for a first associated device to know exactly whether a second associated device is in range (reachable) or not, depending upon whether the first associated device was able to listen to the heart beat frame sent by the second associated device in the DAP.
2. Open and association MCTA in the superframe of related art has been removed in the proposed invention in consideration of reduction of contention based channel access.
3. In the current invention, the beacon frame is modified to include a new entity called Association Status Information Element (ASIE). This contains association status of all the devices in the piconet. When a device listens to the beacon, it can therefore exactly know whether a particular device

(DEVID) is associated or not.
4. In proposed mechanism, beacon frame is also being modified by removing the field for MCTA used, which is part of piconet mode field.
5. The proposed ASIE, since it contains information about all the devices (associated or unassociated) in the piconet, can be used by PNC to construct the Device Access Period (DAP) since ASIE contains total information about all the associated devices which can use the DAP.
6. The proposed ASIE is used to calculate optimum size of DAP and for calculation of the position of the heart beat frame in superframe.
7. PNC response parameter of piconet synchronization parameter of beacon frame in current art has been reused as CAP frequency parameter in proposed mechanism.
8. By listening to the Heart beat frame in DAP in present invention, mechanism is provided for a first associated device to know if a second associated device is in range (directly reachable) or not. Accordingly, it can be used to route data from the first associated device to the second associated device, even when both are not directly reachable.

9. By listening to the Heart beat frame in DAP in present invention, mechanism is provided for a first associated device to know if a second associated device is in range (directly reachable) or not. Accordingly, it can be used to spatially reuse the channel without causing interference, thereby improving the channel utilization.
10. It is another object of the present invention to define the mechanism for usage of heart beat frame for request based MCTA allocation for DEV to PNC.

11. By using information provided by ASIE, association procedure is optimized by reducing number of messages for association of DEV to PNC in present invention compared to current art. In present invention, the DEV which is trying to get associated with the PNC will use the ASIE bitmap, which is provided by the beacon and suggest its DEVID itself to PNC.
Accordingly, the present invention explains a system for medium access control in wireless mobile ad-hoc networks comprising a medium access control mechanism involving a superframe structure; a beacon frame structure containing an Association Status Information Element (ASIE), heart beat frame along with corresponding association.
Accordingly, this invention also explains a method for medium access control in wireless mobile ad-hoc networks wherein the said method comprising the steps of:
(a) providing a method for faster association for a device to the piconet;
(b) improving the channel access by reducing the contention based access;
(c) knowing whether another associated device is directly reachable or not;
(d) routing of data from one associated device to another associated device whether or not both are in range of each other; and
(e) spatially reuse the channel when the associated devices are not directly reachable.
The other objects, features and advantages of the present invention will be more apparent from the ensuing detailed description taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 illustrates the piconet in WPAN ad-hoc network system.
Figure 2 illustrates the superframe structure in current art, which includes the

beacon, CAP, MCTA and CTA.
Figure 3 illustrates the beacon frame in current art.
Figure 4 illustrates the Message Sequence Chart (MSC) for association
procedure in current art.
Figure 5 illustrates the proposed superframe structure, which includes the DAP
and heart beat frames;
Figure 6 depicts the proposed (modified) piconet synchronization parameter of
the beacon frame.
Figure 7 shows the proposed device access period and position of the heart beat
of different DEVs with its DEVIDs.
Figure 8 shows the structure of information element in the current art.
Figure 9 illustrates the invented payload part of association status information
element (ASIE).
Figure 10 shows the structure of heart beat frame.
Figure 11 displays the MSC for proposed association procedure.
Figure 12 illustrates the example for CTA allocation for the data traffic from a DEV
with the usage of the channel time in proposed superframes.
DETAILED DESCRIPTION OF THE INVENTION
The preferred embodiments of the present invention will now be explained with reference to the accompanying drawings. It should be understood however that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. The following description and drawings are not to be construed as limiting the invention and numerous specific details are described to provide a thorough understanding of the present invention, as the basis for the claims and as a basis for teaching one skilled in the art how to make and/or use the invention. However in certain instances, well-known or conventional details are not described in order not to unnecessarily obscure the present invention in detail.

The present invention relates to a system that allows an improved medium access control in the Wireless Personal Area Networks based on mobile ad-hoc networks. Figure 4 illustrates the Message Sequence Chart (MSC) for association procedure in current art;
The invention relates to a system and method which allows all devices to know about all the associated devices in the network.
The system for the invention comprises of a new medium access control mechanism involving a new superframe structure, a new beacon frame structure by including new information element Association Status IE (ASIE), heart beat frame and a new association procedure.
The system and method of the invention comprises of new superframe structure, which removes open and association MCTA as present in current art, and adds a new time period called DAP. The new beacon frame contains a new information element Association Status IE (ASIE). A new frame called heart beat frame is then added in the DAP, and an inventive method is proposed for sending heart beat frame.
Accordingly, the invention provides a method for faster association procedure for a device to join a piconet than present in current art.
Accordingly, the invention further provides a method to improve the channel access by reducing the contention based access.
Accordingly, the invention further provides a method to an associated device to know whether another associated device is directly reachable or not.
Accordingly, the invention provides for routing of data from one associated device to another associated device whether or not both are in range of each other.

Accordingly, the invention also provides a method to spatially reuse the channel when the associated devices are not directly reachable.
The subsequent subsections describe the individual entities to effect the invention:
Figure 5 illustrates the proposed new superframe structure where:
- The open MCTAs have been removed. Instead, all the MCTAs are of peer-to-peer type.
- In the invention one new period is being added in superframe, which is called as Device Access Period (DAP).
- In the invention one new frame is being added called Heart Beat frame, which is being broadcasted by all associated DEVs in DAP.
- Usage of association MCTA in current art is proposed to be accommodated by CAP in the invention.
1. In the invention, a new structure of the beacon frame is being proposed for adding DAP after beacon. The proposed beacon frame differs from that in the current art in the following way:
" Basic structure of beacon remains unchanged; however specific modifications have been proposed to carry out the invention to solve the limitations/weaknesses of current art.
" Figure 6 illustrates the proposed piconet synchronization parameter field of the beacon frame.
- PNC response field is removed in the proposed beacon frame in the invention. In the current art, it is used for assigning open MCTA allocation rate. In proposed solution, we do not use open MCTA, so PNC response field is not required.
- Byte space for PNC response field in current art has been used for newly introduced field called CAP frequency in the invention, which would specify the CAP allocation rate similar to MCTA allocation rate in current art.

- Similar to the current art, in the invention 1 byte of CAP Frequency field is being divided in CAP Allocation Rate (b3-b0) and Reserved bits (b7-b4).
- MCTA used field in Piconet Mode field of Piconet synchronization parameter of the beacon frame in current art indicates that open or association MCTA usage, but mechanism of the invention does not allocate any open or association MCTA so there is no use of that filed, so that field is changed as reserved filed in the proposed invention.
- In the mechanism of the invention, newly added association status information element (ASIE) will always be sent as a part of beacon frame, if at least one device has been associated with the PNC.
The subsequent subsections describe the additional entities introduced to effect the invention.
1. Device Access Period
Device Access Period is proposed to be located after beacon period in the proposed superframe. In the mechanism proposed in the invention, all associated devices send heart beat frames in this period with inter frame space (IFS). Length of the DAP (DAP duration) depends on number of associated devices (N), because length of the heart beat frames will always be fixed, and can be calculated as below:
DAP duration (ps) = N * ((Length of Heart Beat Frame Data part + MAC Frame Header Length) in |js + IFS in ps).
In the proposed mechanism, this length need to be calculated by each of the devices using information of number of associated devices specified in beacon frame. This length is required because after that CAP will start and beacon must specify the CAP end time. CAP duration can then be calculated as below:

CAP duration = CAP end time from beacon in [js -
(Beacon Length in \}s + Length of DAP in ps)
In the proposed mechanism, the heart beat frames need to be sent by all the associated devices and position of the heart beat frames is assigned based on the information available in ASIE of beacon, which includes a bit map of the associated DEVIDs. Thus, all the associated DEVs will send their Heart Beat frames in the increasing order of DEVID.
In the proposed mechanism, all the devices which intend to transmit the Heart Beat frame in DAP should calculate the position of its Heart Beat, by looking into the associated devices bit map in beacon.
Offset of Heart Beat frame in DAP in |js = Position of device in bit map * (Length of Heart Beat frame in |js + IFS in ps)
As an example, if there are 5 devices associated with the PNC and respective DEVIDs of those are 0x01, 0x02, 0x07, 0x10, 0x2a. In this case, Heart Beat frame distribution in DAP will be as illustrated in figure 7. Figure 7 shows the proposed device access period and position of the heart beat of different DEVs with its DEVIDs;
2. Heart Beat Frame
Figure 8 shows the structure of information element in the current art. Figure 9 illustrates the invented payload part of association status information element (ASIE);
Heart beat frame is being newly introduced by the invention. Heart beat frame is a very small MAC frame which is always broadcasted by all the associated DEVs in the piconet. Format of the heart beat frame is illustrated in figure 10.

In the proposed mechanism, purpose of the heart beat frame is to advertise the presence of the device to its neighbors and PNC. In the proposed mechanism, it also serves as a request of MCTA to PNC for some command directed to PNC from the DEV which is sending Heart Beat frame. So, in subsequent superframes, PNC would allocate an MCTA from DEV to PNC in which DEV can send the command to PNC.
In proposed heart beat frame, MAC Header and FCS parts are similar to MAC frames of the current art. Heart beat frame data part is 2 bytes long.
In the proposed mechanism, request for MCTA duration is being used by device to request a MCTA for sending a command frame from DEV to PNC, this duration need to be specified In time required to send the command frame depending on the size of the command frame. Requested MCTA is allocated for DEV to use in the subsequent superframe. This MCTA is a dedicated peer to peer MCTA without contention, which Is a replacement of open MCTA with contention to peer to peer request based MCTA. If DEV does not require any MCTA In next superframe for sending any command to PNC then DEV should set this field to 0x00 (zero).
3. Association Status Information Element
In order that the association status information about all devices In the piconet to be made available to all the devices in the piconet, we propose to Introduce a new information element (IE), called Association Status Information Element (ASIE). as part of the beacon frame which Is broadcasted by the PNC to all the devices in the piconet.
One usage of the ASIE is to provide the information to all the devices to schedule their heart beat frames in DAP. This information element must be sent with beacon if there Is at least one device is associated with the PNC.
As one of the options, it is proposed to use 0x10 as an element ID

hexadecimal value for Association Status IE, which is provided from reserved pool of element IDs of current art.
The invention does not change the format of Information Element of the current art which has been illustrated in figure 8. IE payload structure for proposed ASIE has been illustrated in figure 9.
In the proposed ASIE payload, all the bit position indicates the DEVID. As an example, if some device is associated with PNC and its DEVID is 0x03 then b3 should be set to 1. Other unused DEVIDs should be set to zero. Considering 1 byte of DEVID, as specified in current art, total length of IE payload is 32 byte.
Number of devices represented by DEVID = 2 ^ Length of DEVID field in bits = 2 '^ 8 = 255
Length of IE payload (bytes) =
Number of devices represented by DEVID / 8 = 255 / 8 = 32 bytes
So, Total Length of information element (bytes) =
IE Payload length (Ln) + Size of Length field + Size of Element ID field = 32 + 1 + 1 = 34 bytes
The subsequent subsections describe the operation of the invention:
1. Association
Association procedure in the current art uses Association MCTA or CAP. In our proposed inventive method for association, the DEV uses CAP for association process.

From the beacon information, the DEV obtains information of the used DEVIDs and free DEVIDs from the proposed ASIE. So, DEV which is trying to associate to PNC would suggest its DEVID from the DEVID bit map of association status IE. DEV will randomly choose one of the DEVID which is not being used by any of the associated devices and send the association request to PNC. This would allow the association to be completed in one lesser superframe compared to the current art.
Since the DEV has information about all the associated DEVs by ASIE, whether only one new DEV tries to join the PNC in a superframe, or more than one DEV try to join in a single superframe but since DEVs generate different DEVID (random generation leaving all used DEVIDs), then the procedure of the association can be reduced by one message. MSC for this case has been shown in figure 11. Detail description for this case is below:
- An unassociated DEV initiates the association process by sending an Association Request command to the PNC. In proposed mechanism, DEV will also suggest its DEVID in association request command in place of UnassocID in current art. This DEVID will be chosen randomly from the information provided by ASIE, by taking one of the unused DEVID from the bit map which was provided by the PNC.
- When the PNC receives an Association Request command, it should check that the requested DEVID from the DEV is not being assigned to some other DEV.
- Then, PNC sends an Association Response command, indicating that the DEV has been associated and the DEVID it has been assigned or that the request has been rejected with the reason for the rejection for association using MCTAs, the Association Response command is sent in an MCTA with PNCID as source and DEVID as destination. To describe this case, we assume that reason

code of association response is success. - If there is no conflict in DEVID, then association response command is a directed frame. The ACK Policy field for this association response command is set to Imm-ACK, so DEV would send Imm-ACK to PNC for its association response and the DEVID is being accepted for all future communications.
Figure 11 displays the MSC for proposed association procedure. If more than one DEVs try to join the PNC in a single superframe and if two DEVs end up in generating same random unused DEVID, then there is a collision of the DEVIDs. In this case, PNC will ask these devices to re-generate the random DEVIDs. In this case, the number of messages will be same as the number of messages in current art.
The PNC shall acknowledge all correctly received Association Request commands by sending an Imm-ACK frame with the DestID set to the UnassoclD. The ACK to an Association Request command does not mean that the DEV is associated for the PNC. The PNC needs some time to ensure that the DEV should be allowed in the piconet, to ensure that there are enough resources available to support another DEV in the piconet, to allocate a DEVID and DEVID is not already being allocated to some other DEV.
The PNC may maintain a list of DEV addresses that are allowed to join the piconet. If the list is in use, when the PNC receives an Association Request command, the PNC consults the list to determine if the DEV address in the request is included in the list. If the DEV address is not in the list, the PNC sends an Association Response command with the reason code set to "association denied", indicating that the association request has failed. If the PNC determines that there are not enough resources available to support the new DEV, the PNC sends an Association Response command with the reason code set to the appropriate value.

If the PNC determines that the DEV can be associated, the PNC sends an Association Response command with the reason code set to "success". The time difference between when the PNC sends the Imm-ACK to the Association Request command from a DEV and when it sends an Association Response command meant for the same DEV shall not exceed mAssocRespConfirmTime.
Accordingly, the invention provides a method for faster association procedure for a device to join a piconet than present in current art.
The following subsection describes how the proposed invention works to perform CTA allocation for the data traffic from a DEV:
In proposed mechanism, allocation of the MCTA for sending a command from DEV to PNC is done using Heart Beat frame. Unidirectional MCTA for command from PNC to DEV is allocated by PNC depending on requirement. Figure 12 illustrates the example with the usage of the channel time in superframes.
- In superframe 'm' associated DEV requests for an MCTA in next superframe for MCTA to send a Channel Time Request command from DEV to PNC.
- DEV sends Channel Time Request command in allocated MCTA (DEV-PNC) to PNC in superframe 'm + 1'.
- PNC analyzes the request and sends a Channel Time Response command in next superframe 'm + 2' by allocating an MCTA (PNC-DEV).
- If Channel Time Response is SUCCESS, then PNC allocates a CTA for data transfer for the DEV who is requesting.
Accordingly, the invention also provides a method to an associated device to know whether another associated device is directly reachable or not. By knowing whether a first associated device is in range of a second associated device (from the heart beat frame of DAP), the routing method may be peer-to-peer or DEV1-PNC-DEV2. Accordingly, the invention provides for routing of data from one

associated device to another associated device whether or not both are in range of each other.
Since the invention provides information on whether one associated device is in range of another associated device, accordingly the invention also provides a method to spatially reuse the channel when the associated devices are not directly reachable.
It will also be obvious to those skilled in the art that other control methods and apparatuses can be derived from the combinations of the various methods and apparatuses of the present invention as taught by the description and the accompanying drawings and these shall also be considered within the scope of the present invention. Further, description of such combinations and variations is therefore omitted above. It should also be noted that the host for storing the applications include but not limited to a computer, mobile communication device, base station, or a multi function device.
Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are possible and are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.

GLOSSARY OF TERMS AND DEFINITONS THEREOF
ACK: Acknowledgement
ASIE: Association Status Information Element
ATP: Association Timeout Period
CAP: Contention Access Period
CSMA/CA: Carrier Sense Multiple Access - Collision Avoidance
CTA: Channel Time Allocation
CTAP: Channel Time Allocation Period
DAP: Device Access Period
DEV: Device
DEVID: Device Identifier
FCS: Frame Check Sequence
ID: Identifier
IE: Information Element
IEEE: Institute of Electrical and Electronics Engineers
MAC: Medium Access Control
MCTA: Management Channel Time Access
MSC: Message Sequence Chart
PHY: Physical Layer
PNC: Piconet Coordinator
IFS: Inter frame Space
TDMA: Time Division Multiple Access
UWB: Ultra Wide Band
WPAN: Wireless Personal Area Network






WE CLAIM
1. A system for medium access control in wireless mobile ad-hoc networks comprising a medium access control mechanism involving a superframe structure; a beacon frame structure containing an Association Status Information Element (ASIE), heart beat frame along with corresponding association.
2. A system as claimed in claim 1 wherein the superframe structure removes open and association Management Channel Time Access (MCTA) and adds a time period Device Access Period.
3. A system as claimed in claim 1 wherein the beacon frame contains a information element Association Status IE (ASIE).
4. A system as claimed in claim 1 wherein a frame, a heart beat frame is added, which is transmitted in the Device Access Period.
5. A system as claimed in claim 1 wherein the superframe structure has an entity Device Access Period which is used by all the associated Devices in piconet to send the respective heart beat frames.
6. A system as claimed in claim 1 wherein by listening to the heart beat frames as contained in Device Access Period, a first associated device knows exactly whether a second associated device is in range.
7. A system as claimed in claim 1 wherein range information obtained is used to route data from the first associated device to the second associated device, when both are not directly reachable.

A system as claimed in claim 1 wherein range information obtained is used for spatially reusing the channel without causing interference, and improve the channel utilization.
A system as claimed in claim 1 wherein said listing of the devices in range is done depending upon whether an associated device listens to the heart beat frame sent by the other associated device(s) in the Device Access Period.
A system as claimed in claim 1 wherein a reduction of contention based channel access is done.
A system as claimed in claim 1 wherein the new information element Association Status IE contains association status of all the devices in the piconet.
A system as claimed in claim 1 wherein a device listens to the beacon, and exactly identify whether a particular Device Identifier is associated or not.
A system as claimed in claim 1 wherein beacon frame is modified by removing the field for Management Channel Time Access used.
A system as claimed in claim 1 wherein the Association Status Information Element contains information about all the devices in the piconet, which is used by Piconet Coordinator to construct the Device Access Period (DAP).
A system as claimed in claim 1 wherein Association Status Information Element is used to calculate optimum size of Device Access Period.
A system as claimed in claim 1 wherein Association Status Information Element is used for calculating the position of the heart beat frame in superframe.

17. A system as claimed in claim 1 wherein all the Management Channel Time Access s are of peer-to-peer type.
18. A system as claimed in claim 1 wherein the field Contention Access Period frequency specifies the Contention Access Period allocation rate.
19. A system as claimed in claim 1 wherein 1 byte of Contention Access Period Frequency field is divided into Contention Access Period Allocation Rate (b3-bO) and Reserved bits (b7-b4).
20. A system as claimed in claim 1 wherein Management Channel Time Access used field in Piconet Mode field of Piconet synchronization parameter of the beacon frame are reserved fields.
21. A system as claimed in claim 1 wherein association status information element (ASIE) is sent as a part of beacon frame, if at least one device is associated with the Piconet Coordinator.
22. A system as claimed in claim 1 wherein the Device Access Period is located after beacon period in the superframe.
23. A system as claimed in claim 1 wherein all associated devices send heart beat frames in the Device Access Period with inter frame space (IFS).
24. A system as claimed in claim 1 wherein length of the Device Access Period duration depends on number of associated devices (N) and is given by
Device Access Period duration (|js) = N * ((Length of Heart Beat Frame Data part +
Medium Access Control Frame Header Length) in ps + Inter frame Space in ps).

.A system as claimed in claim 24 wherein the said length is calculated by each of the devices using information of number of associated devices specified in beacon frame.
.A system as claimed in claim 1 wherein Contention Access Period duration is given by
Contention Access Period duration = Contention Access Period end time from beacon in ps -
(Beacon Length in |js + Length of Device Access Period in MS)
.A system as claimed in claim 1 wherein the heart beat frames is sent by all the associated devices and position of the heart beat frames is assigned based on the information available in Association Status Information Element of beacon, which includes a bit map of the associated Device Identifiers.
.A system as claimed in claim 1 wherein the devices which transmit the Heart Beat frame in Device Access Period calculate the position of its Heart Beat, by looking into the associated devices bit map in beacon and is given by
Offset of Heart Beat frame in Device Access Period in fjs = Position of device in bit map *
(Length of Heart Beat frame in ps + Inter frame Space in MS).
.A system as claimed in claim 1 wherein a heart beat frame is a very small MAC frame which is broadcast by all the associated Device s in the piconet.
.A system as claimed in claim 1 wherein a heart beat frame advertise the presence of the device to its neighbors and Piconet Coordinator.

A system as claimed in claim 1 wherein heart beat frame serves as a request of Management Channel Time Access to Piconet Coordinator, for command directed to PNC from the Device.
A system as claimed in claim 1 wherein Piconet Coordinator allocates an Management Channel Time Access from Device to Piconet Coordinator in which Device sends the command to Piconet Coordinator.
A system as claimed in claim 1 wherein requested Management Channel Time Access is allocated for Device to use in the subsequent superframe.
A system as claimed in claim 1 wherein Association Status Information Element provide the information to all the devices to schedule their heart beat frames in Device Access Period.
, A system as claimed in claim 1 wherein in Association Status Information Element payload, all the bit position indicates the Device Identifier.
A system as claimed in claim 1 wherein said means for association is Contention access period means.
A system as claimed in claim 1 wherein from the beacon information, the Device obtains information of the used Device Identifier s and free Device Identifier s.
A system as claimed in claim 1 wherein Device suggests its Device Identifier and it is chosen randomly from the information provided by Association Status Information Element, by taking one of the unused Device Identifier from the bit map provided by the Piconet Coordinator.
A system as claimed in claim 1 wherein an unassociated Device initiates the association process by sending an Association Request command to the

Piconet Coordinator.
A system as claimed in claim 1 wherein when the Piconet Coordinator receives an Association Request command, a check is made to confirm that the requested Device Identifier from the Device is not assigned to some other Device.
A system as claimed in claim 1 wherein Piconet Coordinator sends an Association Response command, indicating the Device association and the Device Identifier assignment or that the request has been rejected with the reason for the rejection for association.
A system as claimed in claim 1 wherein Association Response command is sent in an Management Channel Time Access with Piconet Coordinator ID as source and Device Identifier as destination.
A system as claimed in claim 1 wherein if there is no conflict in Device Identifier, then association response command is a directed frame.
A system as claimed in claim 1 wherein the ACK Policy field of association response command is set to Imm-ACK.
A system as claimed in claim 1 wherein Device send Imm-ACK to Piconet Coordinator for its association response and the Device Identifier is accepted for future communication.
A system as claimed in claim 1 wherein re-generation of the random Device Identifier s is done when there is a collision of the Device Identifier s.
A system as claimed in claim 1 wherein the Piconet Coordinator acknowledges all correctly received Association Request commands by sending an Imm-ACK frame with the DestID set to the UnassoclD.

A system as claimed in claim 1 wherein Piconet Coordinator maintains a list of Device addresses that are allowed to join the piconet.
A system as claimed in claim 48 wherein if the said list is in use, the Piconet Coordinator consults the list to determine if the Device address in the request is included in the said list.
A system as claimed in claim 49 wherein if the Device address is not in the list, the Piconet Coordinator sends an Association Response command with the reason code set to "association denied", indicating that the association request has failed.
A system as claimed in claim 1 wherein if there is not enough resources available to support the new Device, the Piconet Coordinator sends an Association Response command with the reason code set to the appropriate value.
A system as claimed in claim 1 wherein if the Piconet Coordinator determines that the Device is associated, the Piconet Coordinator sends an Association Response command with the reason code set to "success".
A system as claimed in claim 1 wherein the time difference between when the Piconet Coordinator sends the Imm-ACK to the Association Request command from a Device and when it sends an Association Response command meant for the same Device will not exceed mAssocRespConfirmTime.
A system as claimed in claim 1 wherein allocation of the Management Channel Time Access for sending a command from Device to Piconet Coordinator is done using Heart Beat frame.

55. A system as claimed in claim 1 wherein unidirectional Management Channel
Time Access for command from Piconet Coordinator to Device is allocated by
Piconet Coordinator.
56. A method for medium access control in wireless mobile ad-hoc networks
wherein the said method comprising the steps of:
(a) providing a method for faster association for a device to the
piconet;
(b) improving the channel access by reducing the contention based access;
(c) ascertaining whether another associated device is directly reachable or not;
(d) routing of data from one associated device to another associated
device whether or not both are in range of each other; and
(e) spatially reusing the channel when the associated devices are not
directly reachable.
57. A system for medium access control in wireless mobile ad-hoc networks
substantially as herein described particularly with reference to the drawings.
58. A method for medium access control in wireless mobile ad-hoc networks
substantially as herein described particularly with reference to the drawings.


Documents:

221-che-2004-abstract.pdf

221-che-2004-claims duplicate.pdf

221-che-2004-claims original.pdf

221-che-2004-correspondnece-others.pdf

221-che-2004-correspondnece-po.pdf

221-che-2004-description(complete) duplicate.pdf

221-che-2004-description(complete) original.pdf

221-che-2004-drawings.pdf

221-che-2004-form 1.pdf

221-che-2004-form 26.pdf

221-che-2004-form 5.pdf

221-che-2004-form 9.pdf


Patent Number 211564
Indian Patent Application Number 221/CHE/2004
PG Journal Number 50/2007
Publication Date 14-Dec-2007
Grant Date 05-Nov-2007
Date of Filing 12-Mar-2004
Name of Patentee M/S. SAMSUNG INDIA SOFTWARE OPERATIONS PRIVATE LIMITED
Applicant Address BAGMANE LAKEVIEW, BLOCK 'B', NO. 66/1, BAGMANE TECH PARK, C V RAMAN NAGAR, BYRASANDRA, BANGALORE - 560 093,
Inventors:
# Inventor's Name Inventor's Address
1 JOGI SUNIL BAGMANE LAKEVIEW, BLOCK 'B', NO. 66/1, BAGMANE TECH PARK, C V RAMAN NAGAR, BYRASANDRA, BANGALORE - 560 093,
2 WASON PRASHANT BAGMANE LAKEVIEW, BLOCK 'B', NO. 66/1, BAGMANE TECH PARK, C V RAMAN NAGAR, BYRASANDRA, BANGALORE - 560 093,
3 HOLUR, BALAJI SRINIVAS BAGMANE LAKEVIEW, BLOCK 'B', NO. 66/1, BAGMANE TECH PARK, C V RAMAN NAGAR, BYRASANDRA, BANGALORE - 560 093,
4 CHOUDHARY, DR. MANOJ BAGMANE LAKEVIEW, BLOCK 'B', NO. 66/1, BAGMANE TECH PARK, C V RAMAN NAGAR, BYRASANDRA, BANGALORE - 560 093,
PCT International Classification Number H04 B 7/216
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA