Method and system for allocation guaranteed time slots for efficient transmission of time-critical data in IEEE 802.15.4 wireless personal area networks

• US 8,976,763 B2
• Filed: 12/21/2010
• Issued: 03/10/2015
• Est. Priority Date: 12/21/2009
• Status: Expired due to Fees

• Current Assignee: Telecommunications Research Laboratories
• Original Assignee: Telecommunications Research Laboratories
• Inventors: Shrestha, Bharat, Hossain, Abu Zafar Ekram, Camorlinga, Sergio Guido, Krishnamoorthy, Rajagopalan, Niyato, Dusit
• Primary Examiner(s): Rinehart, Mark
• Assistant Examiner(s): Kirillova, Ellen A
• Application Number:
  US12/974,718
• Publication Number:
  US 20110158206A1
• Time in Patent Office: 1,540 Days
• Field of Search: 370/336
• US Class Current: 370/336
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0024 for multiple sensor units attached to the patient, e.g. using a body or personal area network
• CPC Class Codes: A61B 5/02055 Simultaneously evaluating both cardiovascular condition and temperature
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: G01D 21/00 Measuring or testing not otherwise provided for
• CPC Class Codes: G16H 40/67 for remote operation
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 72/52 based on load
• CPC Class Codes: H04W 72/569 of the traffic information
• CPC Class Codes: H04W 74/02 Hybrid access
• CPC Class Codes: H04W 74/04 Scheduled access hybrid access H04W74/02
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02
• CPC Class Codes: H04W 84/10 Small scale networks; Flat hierarchical networks
• CPC Class Codes: H04W 84/18 : Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

A guaranteed time slot allocation scheme is provided for the IEEE 802.15.4 standard for use in wireless personal area networks having sensor devices to overcome bandwidth under-utilization for time-critical or delay-sensitive data transmissions. A fractional knapsack problem is formulated to obtain optimal guaranteed time slot allocation with which a minimum bandwidth requirement is guaranteed for the sensor devices.

Claims

1. A method for allocating a guaranteed time slot (“

GTS”

) for data or at least one data packet generated from at least one sensor device configured to be disposed on a person for wireless transmission over a wireless body area sensor network, the method comprising the steps of;

a) buffering and storing the data or at least one data packet in a device transmission buffer disposed in the at least one sensor device;

b) determining the amount of data or number of data packets stored in the device transmission buffer;

c) when the amount of data or number of data packets stored in the device transmission buffer of the at least one sensor device is greater than a predetermined data or data packet threshold for the at least one sensor device in a superframe for wireless transmission over the wireless body area sensor network, the superframe comprising a contention access period (“

CAP”

) and a contention free period (“

CFP”

) further comprising a plurality of guaranteed time slots, then generating a bandwidth demand for the at least one sensor device and transmitting the bandwidth demand to a network coordinator, wherein the step of generating the bandwidth demand comprises carrying out the steps of a bandwidth demand algorithm comprising the steps of;

i. receiving a beacon frame at a beginning of the superframe,

ii. computing the amount of data packets in the device transmission buffer of the at least one sensor device (“

B_i^t”

), the number of guaranteed time slots for the at least one sensor device (“

S_i^t”

) and a number of requested data packets requested in a previous superframe for the at least one sensor device (“

R_i<sup>t−

1</sup>”

),

iii. when the superframe is a first frame, setting a number of requested packets for the at least one sensor device (“

R_i^t”

) to zero, otherwise setting R_i^t to (R_i<sup>t−

1</sup>−

S_i^tP_slot,i) where P_slot,i is a number of data packets per slot for the at least one sensor device,

iv. when B_i^t−

R_i^t−

S_i^tP_slot,i is greater than the data packet threshold, setting a bandwidth demand (“

b_i^t”

) to a lesser of V_i^t−

R_i^t−

S_i^tP_slot,i and D_max, where D_max is a demand capacity in terms of packets of the superframe,

v. when b_i^t is successfully transmitted, updating R_i^t to be R_i^t+b_i^t, otherwise when b_i^t is not successfully transmitted, setting b_i^t to zero, and

vi. when S_i^t is equal to zero and when R_i^t is greater than zero, decrementing R_i^t by one for each packet transmitted during the CAP;

d) collecting the bandwidth demands from the at least one sensor device during the CAP; and

e) allocating guaranteed time slots in the CFP for the data or at least one data packet generated by the at least one sensor device.

2. The method as set forth in claim 1 wherein the step of allocating guaranteed time slots comprises the steps of:

a) carrying out the steps of a fractional knapsack algorithm to prioritize the data or at least one data packet generated by the at least one sensor device; and

b) carrying out the steps of a slot allocation algorithm to assign guaranteed time slots to the prioritized data or at least one data packet.

3. The method as set forth in claim 1, wherein the wireless body area sensor network comprises a wireless body area sensor network.

4. A system for allocating a guaranteed time slot (“

GTS”

) for data or at least one data packet generated from at least one sensor device configured to be disposed on a person for wireless transmission over a wireless body area sensor network, the system comprising;

a) means for buffering and storing the data or at least one data packet in a device transmission buffer disposed in the at least one sensor device;

b) means for determining the amount of data or number of data packets stored in the device transmission buffer;

c) means for generating a bandwidth demand for the at least one sensor device and transmitting the bandwidth demand to a network coordinator when the amount of data or number of data packets stored in the device transmission buffer of the at least one sensor device is greater than a predetermined data or data packet threshold for the at least one sensor device in a superframe for wireless transmission over the wireless body area sensor network, the superframe comprising a contention access period (“

CAP”

) and a contention free period (“

CFP”

) further comprising a plurality of guaranteed time slots;

d) means for collecting the bandwidth demands from the at least one sensor device during the CAP, wherein the means for generating the bandwidth demand further comprise means for carrying out the steps of a bandwidth demand algorithm, wherein the bandwidth demand algorithm comprises the steps of;

i. receiving a beacon frame at a beginning of the superframe,

ii. computing the amount of data packets in the device transmission buffer of the at least one sensor device (“

B_i^t”

), the number of guaranteed time slots for the at least one sensor device (“

S_i^t”

) and a number of requested data packets requested in a previous superframe for the at least one sensor device (“

R_i<sup>t−

1</sup>”

),

iii. when the superframe is a first frame, setting a number of requested packets for the at least one sensor device (“

R_i^t”

) to zero, otherwise setting R_i^t to (R_i^t−

S_i^tP_slot,i) where P_slot,i is a number of data packets per slot for the at least one sensor device,

iv. when B_i^t−

R_i^t−

S_i^tP_slot,i is greater than the data packet threshold, setting a bandwidth demand (“

b_i^t”

) to a lesser of B_i^t−

R_i^t−

S_i^tP_slot,i and D_max, where D_max is a demand capacity in terms of packets of the superframe,

v. when b_i^t is successfully transmitted, updating R_i^t to be R_i^t+b_i^t, otherwise when b_i^t is not successfully transmitted, setting b_i^t to zero, and

vi. when S_i^t is equal to zero and when R_i^t is greater than zero, decrementing R_i^t by one for each packet transmitted during the CAP; and

e) means for allocating guaranteed time slots in the CFP for the data or at least one data packet generated by the at least one sensor device.

5. The system as set forth in claim 4, wherein the means for allocating guaranteed time slots further comprises:

a) means for carrying out the steps of a fractional knapsack algorithm to prioritize the data or at least one data packet generated by the at least one sensor device;

b) means for carrying out the steps of a slot allocation algorithm to assign guaranteed time slots to the prioritized data or at least one data packet.

6. The system as set forth in claim 4, wherein the wireless body area sensor network comprises a wireless body area sensor network.

7. A system for transmitting physiological data of a person, comprising:

a) at least one sensor device disposed on the person, the at least one sensor device configured to sense physiological data of the person, the at least one sensor device configured to buffer and store the physiological data in a device transmission buffer disposed therein, the at least one sensor device comprising first wireless transmission means for wirelessly transmitting the buffered and stored physiological data;

b) a network coordinator configured to wirelessly receive the physiological data transmitted from the at least one sensor device, the network coordinator comprising second wireless transmission means for wirelessly transmitting a superframe to global telecommunications network, the superframe comprising a contention access period (“

CAP”

) and a contention free period (“

CFP”

) further comprising a plurality of guaranteed time slots;

c) means for determining the amount of physiological data stored in the device transmission buffer;

d) means for generating a bandwidth demand for the at least one sensor device and transmitting the bandwidth demand to the network coordinator when the amount of physiological data stored in the device transmission buffer of the at least one sensor device is greater than a predetermined physiological data threshold for the at least one sensor device, wherein the means for generating the bandwidth demand further comprise means for carrying out the steps of a bandwidth demand algorithm, wherein the bandwidth demand algorithm comprises the steps of;

i. receiving a beacon frame at a beginning of the superframe,

ii. computing the amount of data packets in the device transmission buffer of the at least one sensor device (“

B_i^t”

), the number of guaranteed time slots for the at least one sensor device (“

S_i^t”

) and a number of requested data packets requested in a previous superframe for the at least one sensor device (“

R_i<sup>t−

1</sup>”

),

iii. when the superframe is a first frame, setting a number of requested packets for the at least one sensor device (“

R_i^t”

) to zero, otherwise setting R_i^t to (R_i<sup>t−

1</sup>−

S_i^tP_slot,i) where P_slot,i is a number of data packets per slot for the at least one sensor device,

iv. when B_i^t−

R_i^t−

S_i^tP_slot,i is greater than the data packet threshold, setting a bandwidth demand (“

b_i^t”

) to a lesser of B_i^t−

R_i^t−

S_i^tP_slot,i and D_max, where D_max is a demand capacity in terms of packets of the superframe,

v. when b_i^t is successfully transmitted, updating R_i^t to be R_i^t+b_i^t, otherwise when b_i^t is not successfully transmitted, setting b_i^t to zero, and

vi. when S_i^t is equal to zero and when R_i^t is greater than zero, decrementing R_i^t by one for each packet transmitted during the CAP;

e) means for collecting the bandwidth demands from the at least one sensor device during the CAP;

f) means for allocating guaranteed time slots in the CFP for the physiological data stored in the device transmission buffer; and

g) means for inserting the physiological data stored in the device transmission in the guaranteed time slots of the superframe, wherein the physiological data is transmitted to the global telecommunications network.

8. The system as set forth in claim 7, wherein the means for allocating guaranteed time slots further comprises:

a) means for carrying out the steps of a fractional knapsack algorithm to prioritize the data or at least one data packet generated by the at least one sensor device; and

b) means for carrying out the steps of a slot allocation algorithm to assign guaranteed time slots to the prioritized data or at least one data packet.

9. The system as set forth in claim 7, wherein the first wireless transmission means is configured to operate in a wireless body area sensor network.

10. The system as set forth in claim 7, wherein the second wireless transmission means is configured to operate in a wireless local area network.

11. The system as set forth in claim 7, further comprising a monitoring centre operatively connected to the global telecommunications network and configured to receive the physiological data transmitted by the network coordinator wherein the physiological data can be monitored by a health care provider.