Adaptive transmission energy consumption

• US 9,253,727 B1
• Filed: 05/01/2015
• Issued: 02/02/2016
• Est. Priority Date: 05/01/2015
• Status: Active Grant

• Current Assignee: Link Labs, Inc.
• Original Assignee: Link Labs, Inc.
• Inventors: Luna, Ricardo Jr., Sapio, Adrian, Sawyer, Richard Kevin Jr.
• Primary Examiner(s): Moore, Ian N
• Assistant Examiner(s): VAN ROIE, JUSTIN T
• Application Number:
  US14/701,564
• Time in Patent Office: 277 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04L 1/0042 Encoding specially adapted to other signal generation operation, e.g. in order to reduce transmit distortions, jitter, or to improve signal shape H04L1/0067 takes precedence
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 52/0245 according to signal strength
• CPC Class Codes: H04W 52/0261 managing power supply demand, e.g. depending on battery level
• CPC Class Codes: H04W 52/0277 according to available power supply, e.g. switching off when a low battery condition is detected
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/20 using error rate
• CPC Class Codes: H04W 52/242 taking into account path loss
• CPC Class Codes: H04W 52/265 taking into account the quality of service QoS
• CPC Class Codes: H04W 72/0473 the resource being transmission power
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method, of operating an end node to wirelessly communicate with a central node, includes: receiving wirelessly a current instance of a beacon signal periodically-transmitted from the central node; measuring a received power, P_B-RX, of the beacon signal; reading locally-stored values of P_B-TX and G representing a presumed transmitted power of the beacon signal and a performance goal of the end node, respectively; determining, for a given channel, a path loss, PL, based on the P_B-RX and the P_B-TX; and adaptively setting an energy level, E_N-TX, of a forthcoming message to be transmitted from the end node based on PL and G.

Claims

1. A method of operating an end node to wirelessly communicate with a central node, the end node comprising a processor and memory the method comprising:

receiving wirelessly a beacon signal periodically-transmitted from the central node;

measuring a received power, P_B-RX, of the beacon signal;

reading locally-stored values of P_B-TX and G representing a presumed transmitted power of the beacon signal and a performance goal of the end node, respectively;

determining, for a given channel, a path loss, PL, based on the P_B-RX and the P_B-TX; and

adaptively setting an energy level, E_N-TX, of a message to be transmitted from the end node based on the PL and the G; and

wirelessly transmitting the message to the central node according to the energy level E_N-TX;

wherein the adaptively setting includes;

solving a standard optimization problem using the PL and the G as inputs to find a desirable minimized combination of at least two of;

a level of power, P_N-TX;

a forward error correction coding rate, c;

a spreading factor, SF; and

a modulation format, M; and

wherein the solving the standard optimization problem uses a cost function as follows;

C(SF,c,P_N-TX,PL,G)=(T(SF,c)+X_T(SF,c,n,P_N-TX,G))*(P(SF,PL)+X_P(SF,c,n,P_N-TX,G))

wherein;

SF is the spreading factor;

c is the forward error correction coding rate;

n denotes time dependence;

P_N-TX is a target value of EIRP (Effective Isotropic Radiated Power) and is assumed to be a constant;

PL is the path loss;

G is the performance goal;

T(SF, c) is a time on air required to transmit the message; and

P(SF, PL) is a power consumed by the end node; and

X_T and X_P are a time-on-air weighting function and a total-transmission-power weighting function based on SF, c, n, P_N-TX and G, respectively; and

such that evaluation of the cost function at the PL and the G is represented as follows;

2. The method of claim 1, wherein the X_T and the X_P weighting functions relate as follows:

to maximize a life of a battery sourcing the end node, then X_T=0 and X_P=0;

to minimize time on air, then X_T>

0 and X_P=0; and

to minimize peak current draw from the battery, then X_T=0 and X_P>

0; and

otherwise X_T>

0 and X_P>

0.

3. The method of claim 1, wherein values of the performance goal G include:

values that maximize data-reliability of the data as received at the central node;

values that optimize the energy level E_N-TX relative to battery-chemistry-specific attributes of the battery sourcing the end node;

values that reflect a desired ratio of data-reliability versus battery management.

4. The method of claim 1, wherein:

the transmitted power, P_B-TX, of the beacon signal changes over time; and

the method further comprises;

receiving a configuration signal periodically-transmitted from the central node, each configuration signal including a value representing the transmitted power, P_B-TX, of forthcoming instances of the beacon signal; and

storing the received value of P_B-TX locally as the presumed transmitted power of the beacon signal.

5. The method of claim 4, wherein:

the configuration signal is received at an interval, I_CONFIG; and

the beacon signal is received at an interval, I_BEACON; and

at least one of the following relations is true;

I_BEACON<

I_CONFIG;

I_CONFIG=15*(I_BEACON); and

I_CONFIG=30 seconds and I_BEACON=2 seconds.

6. The method of claim 1, wherein:

the end node has operational states including;

a non-sleep state; and

a sleep state exhibiting reduced-power-consumption relative to the non-sleep state;

the end node had transitioned from the sleep state into the non-sleep state before the receiving of a current instance B(i) of the beacon signal;

each instance B of the beacon signal includes an instance H of a corresponding configuration token; and

the method further comprises;

reading a locally-stored value H_PRESUMED representing a presumed configuration token;

comparing the presumed configuration token against a current instance H(i) of the configuration token; and

deeming, if H_PRESUMED=H(i), that;

the locally-stored value of P_B-TX is current; and

transitioning from the non-sleep state back into the sleep state does not need to be deferred.

7. The method of claim 6, the method further comprising:

deeming, if H_PRESUMED≠

H(i), that;

the locally-stored value of P_B-TX is not current; and

transitioning from the non-sleep state back into the sleep state should be deferred;

receiving a configuration signal periodically-transmitted from the central node;

the configuration signal including;

a value representing a transmitted power, P_B-TX, of the beacon signal; and

a corresponding value of the configuration token H(i);

awaiting receipt of a next configuration signal; and

locally storing the values of P_B-TX and H(i) included in the received next configuration signal as the presumed transmitted power P_B-TX and the presumed configuration token H_PRESUMED, respectively.

8. The method of claim 1, wherein:

the wirelessly transmitting is performed in an unlicensed spectrum; and

the beacon signal is a non-hopping signal.

9. An end node configured to wirelessly communicate with a central node, the end node comprising:

a wireless unit configured to receive and transmit messages, respectively;

a wireless interface configured to receive, via the wireless unit, a beacon signal periodically-transmitted from the central node;

a received-power sensor configured to measure a received power, P_B-RX, of the beacon signal;

a memory, contents of which include;

a value representing a presumed transmitted power, P_B-TX, of the beacon signal; and

a value, G, representing a performance goal of the end node;

a path-loss unit configured to determine, for a given channel, a path loss, PL, based on the P_B-RX and the P_B-TX; and

a transmit-energy unit configured to adaptively set an energy level E_N-TX of a message, to be transmitted via the wireless interface and the wireless unit, based on the PL and the G;

wherein the transmit-energy unit is further configured to solve a standard optimization problem using the PL and the G as inputs to find a desirable minimized combination of at least two of;

a level of power, P_N-TX;

a forward error correction coding rate, c;

a spreading factor, SF; and

a modulation format, M; and

wherein the transmit-energy unit is further configured to solve the standard optimization problem using a cost function as follows;

C(SF,c,P_N-TX,PL,G)=(T(SF,c)+X_T(SF,c,n,P_N-TX,G))*(P(SF,PL)+X_P(SF,c,n,P_N-TX,G))

wherein;

SF is the spreading factor;

c is the forward error correction coding rate;

n denotes time dependence;

P_N-TX is a target value of EIRP (Effective Isotropic Radiated Power) and is assumed to be a constant;

PL is the path loss;

G is the performance goal;

T(SF, c) is a time on air required to transmit the message; and

P(SF, PL) is a power consumed by the end node; and

X_T and X_P are a time-on-air weighting function and a total-transmission-power weighting function based on SF, c, n, P_N-TX and G, respectively; and

such that evaluation of the cost function at the PL and the G is represented as follows;

10. The end node of claim 9, wherein the transmit-energy unit is further configured to relate the X_T and the X_P weighting functions as follows:

to maximize a life of a battery sourcing the end node, then set X_T=0 and X_P=0;

to minimize time on air, then set X_T>

0 and X_P=0; and

to minimize peak current draw from the battery, then set X_T=0 and X_P>

0; and

otherwise set X_T>

0 and X_P>

0.

11. The end node of claim 9, wherein values of the performance goal G include:

values that maximize data-reliability of the data as received at the central node;

values that optimize the energy level E_N-TX relative to battery-chemistry-specific attributes of the battery sourcing the end node;

values that reflect a desired ratio of data-reliability versus battery management.

12. The end node of claim 9, wherein:

the presumed transmitted power, P_B-TX, of the beacon signal changes over time; and

the wireless interface is further configured to;

receive, via the wireless unit, a configuration signal periodically-transmitted from the central node that includes a value representing a transmitted power, P_B-TX, of forthcoming instances of the beacon signal; and

store, in the memory, the received value of P_B-TX as the presumed transmitted power of the beacon signal.

13. The end node of claim 12, wherein:

the configuration signal is received at an interval, I_CONFIG; and

the beacon signal is received at an interval, I_BEACON; and

at least one of the following relations is true;

I_BEACON<

I_CONFIG;

I_CONFIG=15*(I_BEACON); and

I_CONFIG=30 seconds and I_BEACON=2 seconds.

14. The end node of claim 9, wherein:

the end node has operational states including;

a non-sleep state; and

a sleep state exhibiting reduced-power-consumption relative to the non-sleep state;

the end node had transitioned from the sleep state into the non-sleep state before receipt of a current instance B(i) of the beacon signal;

each instance B of the beacon signal includes an instance H of a corresponding configuration token; and

the transmit-energy unit is further configured to;

read a locally-stored value H_PRESUMED representing a presumed configuration token;

compare the presumed configuration token against a current instance H(i) of the configuration token; and

deem, if H_PRESUMED=H(i), that;

the locally-stored value of P_B-TX is current; and

transitioning from the non-sleep state back into the sleep state does not need to be deferred.

15. The end node of claim 14, wherein:

the transmit-energy unit is further configured to deem, if H_PRESUMED≠

H(i), that;

the locally-stored value of P_B-TX is not current; and

transitioning from the non-sleep state back into the sleep state should be deferred;

the wireless interface is configured to receive, via the wireless unit, a configuration signal periodically-transmitted from the central node;

the configuration signal including;

a value representing a transmitted power, P_B-TX, of the beacon signal; and

a corresponding value of the configuration token H(i); and

the transmit-energy unit is further configured to;

await receipt of a next configuration signal by the wireless interface; and

store, in the memory, the values of P_B-TX and H(i) included in the received next configuration signal as the presumed transmitted power P_B-TX and the presumed configuration token H_PRESUMED, respectively.

16. The end node of claim 9, wherein the transmit-energy unit is further configured to:

send, via the wireless interface and the wireless unit, the message to the central node according to the energy level E_N-TX.

17. The end node of claim 16, wherein:

the transmit-energy unit is further configured to;

send, via the wireless interface and the wireless unit, in an unlicensed spectrum; and

the beacon signal is a non-hopping signal.

18. A method of operating a central node to wirelessly communicate with instances of an end node, the central node comprising a processor and memory, the method comprising:

periodically generating a beacon signal having a transmit power;

wherein the transmit power of the beacon signal changes over time;

periodically transmitting, to the instances of the end node, the beacon signal;

determining if i^th and (i−

1)^th instances of the beacon signal differ;

measuring, if B(i−

1)≠

B(i), a transmitted power, P_B-TX, of the i^th beacon signal B(i);

periodically generating a configuration signal that includes;

a value representing the transmitted power, P_B-TX, of B(i); and

periodically transmitting, to the instances of the end node, the configuration signal;

wherein;

B(i) includes H(i−

1); and

if B(i−

1)≠

B(i), then;

H(i−

1) is outdated; and

the generating of the configuration signal includes;

generating a configuration token H(i) in accordance with B(i); and

including, in the configuration signal, the configuration token H(i);

the generating of the beacon signal includes;

including, in an instance B(i+1) of the beacon signal, the configuration token H(i) corresponding to B(i).

19. The method of claim 18, wherein:

the configuration signal is transmitted at an interval, I_CONFIG; and

the beacon signal is transmitted at an interval, I_BEACON; and

at least one of the following relations is true;

I_BEACON<

I_CONFIG;

I_CONFIG=15*(I_BEACON); and

I_CONFIG=30 seconds and I_BEACON=2 seconds.

20. A central node configured to wirelessly communicate with instances of an end node, the central node comprising:

a wireless unit configured to receive and transmit messages, respectively;

a wireless interface configured to transmit, via the wireless unit, a beacon signal and a configuration signal, respectively;

a beacon-signal generator configured to;

periodically generate a beacon signal B having a transmit power; and

periodically send, to the instances of the end node and via the wireless interface and the wireless unit, the beacon signal B;

wherein the transmit power of the beacon signal changes over time;

a transmitted-power sensor configured to;

determine if i^th and (i−

1)^th instances of the beacon signal B differ such that B(i−

1)≠

B(i); and

measure, if B(i−

1)≠

B(i), a transmitted power, P_B-TX, of B(i);

a configuration-signal generator configured to;

periodically generate a configuration signal that includes a value representing the transmitted power, P_B-TX, of B(i); and

periodically send, to the instances of the end node and via the wireless interface and the wireless unit, the configuration signal;

wherein;

B(i) includes H(i−

1); and

if B(i−

1)≠

B(i), then;

H(i−

1) is outdated; and

the configuration-signal generator is further configured to;

generate a configuration token H(i) in accordance with B(i); and

include, in the configuration signal, the configuration token H(i); and

the beacon-signal generator is further configured to;

include, in an instance B(i+1) of the beacon signal, the configuration token H(i) corresponding to B(i).

21. The central node of claim 20, wherein:

the wireless interface is further configured to;

periodically transmit the configuration signal at an interval, I_CONFIG; and

periodically transmit the beacon signal at an interval, I_BEACON; and

at least one of the following relations is true;

I_BEACON<

I_CONFIG;

I_CONFIG=15*(I_BEACON); and

I_CONFIG=30 seconds and I_BEACON=2 seconds.