VARIABLE DOWNLINK-UPLINK BOUNDARY

• US 20170127403A1
• Filed: 11/02/2015
• Published: 05/04/2017
• Est. Priority Date: 11/02/2015
• Status: Active Grant

• Current Assignee: Link Labs, Inc.
• Original Assignee: Link Labs LLC
• Inventors: SAPIO, Adrian, SAWYER, Jr., Richard Kevin, WELKIE, Allen Parker, LUNA, Jr., Ricardo
• Granted Patent: US 9,860,882 B2
• Time in Patent Office: Days
• CPC Class Codes: H04L 5/1469 using time-sharing
• CPC Class Codes: H04L 5/16 Half-duplex systems; Simplex/duplex switching; Transmission of break signals non-automatically inverting the direction of transmission
• 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 74/006 in the downlink, i.e. towards the terminal
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02

Abstract

A method of operating an end node to communicate with a central node, the method comprising: wirelessly receiving, a beacon signal periodically-transmitted from the central node; each beacon signal denoting the start of a single frame; each frame being organized to include a downlink (DL) phase which precedes an uplink (UL) phase; and a payload of the beacon signal including an offset which represents a starting time of the UL phase. The method further comprises: generating a message; selecting, unbeknownst to the central node, at least one UL logical-channel, respectively; and wirelessly transmitting, during the UL phase, at least a portion of the message from the end node over the selected at least one UL logical-channel according to a slotted ALOHA technique.

Claims

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

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

each beacon signal denoting the start of a single frame;

each frame being organized to include a downlink (DL) phase which precedes an uplink (UL) phase; and

a payload of the beacon signal including an offset which represents a starting time of the UL phase; and

generating a message;

selecting, unbeknownst to the central node, at least one UL logical-channel, respectively; and

wirelessly transmitting, during the UL phase, at least a portion of the message from the end node over the selected at least one UL logical-channel according to a slotted ALOHA technique.

2. The method of claim 1, wherein the wirelessly transmitting includes:

packetizing the message according to a slot size common to a predefined first group of M orthogonal spreading factors, respectively, thereby yielding one or more packets, with M being a non-zero, positive integer; and

awaiting, based on the offset, a start of the UL phase; and

sending, during the frame, at least one of the one or more packets as the at least a portion of the message.

3. The method of claim 2, wherein:

the selecting the at least one UL logical-channel includes;

selecting one amongst the first group of M orthogonal spreading factors; and

randomly selecting one amongst a predefined second group of N physical-channels, respectively, with N being a non-zero, positive integer; and

the sending includes;

using the selected at least one UL logical-channel corresponding to the one or more packets, respectively.

4. The method of claim 2, wherein:

the packetizing includes;

decomposing the message into Z packets such that

5. The method of claim 1, wherein:

the wirelessly receiving is performed in half-duplex; and

the wireless transmitting is performed in half-duplex.

6. The method of claim 1, wherein:

the beacon signal is wirelessly received on a DL logical-channel corresponding to a predefined physical channel and a predefined spreading factor; and

the physical channel has a sufficiently wide bandwidth such that the beacon signal is exempted from a frequency-hopping requirement.

7. The method of claim 1, wherein:

the wirelessly transmitting uses an unlicensed spectrum.

8. The method of claim 1, wherein:

each of the wirelessly receiving and the wirelessly transmitting is performed according to a low-power, low-bandwidth modulation format.

9. An end node configured to 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;

each beacon signal denoting the start of a single frame;

each frame being organized to include a downlink (DL) phase which precedes an uplink (UL) phase;

a payload of the beacon signal including an offset which represents a starting time of the UL phase; and

a message generator configured to generate a message;

an LC selector configured to select, unbeknownst to the central node, at least one UL logical-channel, respectively;

the wireless interface being further configured to transmit, during the UL phase, at least a portion of the message over the selected at least one UL logical channel according to a slotted ALOHA technique.

10. The end node of claim 9, further comprising:

a timer configured to elapse a delay time based on the offset and thereby then indicate a start of the UL phase; and

a packetizer configured to packetize the message according to a slot size common to a predefined first group of M spreading factors, respectively, thereby yielding one or more packets, with M being a non-zero, positive integer; and

wherein the wireless interface is further configured to;

await, based on the offset, the start of the UL phase; and

sending, during the frame, at least one of the one or more packets as the at least a portion of the message.

11. The end node of claim 10, wherein:

the LC selector is further configured to select the at least one UL logical-channel on a per-packet basis by;

selecting one amongst the first group of M orthogonal spreading factors; and

randomly one amongst a predefined second group of N physical-channels, respectively, with N being a non-zero, positive integer; and

the wireless interface is further configured to;

use the selected at least one UL logical-channel corresponding to the one or more packets, respectively.

12. The end node of claim 10, wherein:

the packetizer is further configured to;

decompose the message into Z packets such that

13. The end node of claim 9, wherein the wireless interface is further configured to:

wirelessly receive, via the wireless unit, in half-duplex; and

wirelessly transmit, via the wireless unit, in half-duplex.

14. The end node of claim 9, wherein:

the wireless interface, via the wireless unit, is further configured to wirelessly receive the beacon signal on a DL logical-channel corresponding to a predefined physical channel and a predefined spreading factor selected from the second group of N orthogonal spreading; and

the physical channel has a sufficiently wide bandwidth such that the beacon signal is exempted from a frequency-hopping requirement.

15. The end node of claim 9, wherein:

the wireless interface, via the wireless unit, is further configured to use an unlicensed spectrum.

16. The end node of claim 9, wherein:

the wireless interface, via the wireless unit, is further configured to wirelessly receive and to wirelessly transmit according to a low-power, low-bandwidth modulation format.

17. A method of operating a central node to wirelessly communicate with an end node, the method comprising:

generating periodically a beacon signal;

each beacon signal denoting the start of a single frame; and

each frame being organized to include a downlink (DL) phase which precedes an uplink (UL) phase;

adaptively determining a duration of the DL phase and a start of the UL phase;

configuring the beacon signal with a payload which includes;

an offset indicating when the UL phase will begin;

wirelessly transmitting periodically the beacon signal;

awaiting a start of the UL phase based on the offset; and

wirelessly listening, beginning at the UL phase-start, as follows;

on each of M*N UL logical-channels resulting from a predefined first group of M physical-channels, respectively, and a predefined second group of N orthogonal spreading factors usable on each physical-channel, respectively; and

for one or more messages transmitted from the end node, respectively, according to a slotted ALOHA technique;

wherein M and N are non-zero, positive integers, respectively.

18. The method of claim 17, wherein:

the transmitting is performed in half-duplex; and

the listening is performed in half-duplex.

19. The method of claim 17, wherein:

the transmitting periodically of the beacon signal is performed on a logical DL channel corresponding to a predefined physical channel and a predefined spreading factor selected from the second group of N orthogonal spreading; and

the physical channel has a sufficiently wide bandwidth such that the beacon signal is exempted from a frequency-hopping requirement.

20. The method of claim 17, wherein:

the method further comprises;

generating, as needed, a DL wish list including one or more non-beacon signals;

wirelessly transmitting at least some of the DL wish list;

a duration of the beacon signal is T_BEACON;

a maximum duration of the DL phase is T_DL-MAX;

the adaptively determining the duration of the DL phase includes;

determining whether to send, in addition to the beacon signal, a full DL wish list or a truncated DL wish list; and

the configuring the beacon signal with a payload includes;

determining the offset based on;

a cumulative duration of the full DL wish list (T_DL-WISH) if an actual duration (T_ACTUAL) of the DL phase is less than or equal to the maximum duration of the DL phase such that T_ACTUAL=(T_BEACON+T_DL-WISH)≦

T_DL-MAX;

or else

a duration of the truncated DL wish list (T_DL-TRUNC) where T_DL-TRUNC<

T_DL-WISH and T_ACTUAL=(T_BEACON+T_DL-TRUNC)≦

T_DL-MAX.

21. The method of claim 17, wherein:

the first group of M physical-channels is located in an unlicensed spectrum.

22. The method of claim 17, wherein:

each of the wirelessly transmitting and the wirelessly receiving is performed according to a low-power, low-bandwidth modulation format.

23. A central node configured to wirelessly communicate with an end node, the central node comprising:

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

a beacon-signal generator configured to generate periodically a non-hopping beacon signal;

each beacon signal denoting the start of a single frame;

each frame being organized to include a downlink (DL) phase which precedes an uplink (UL) phase;

a time-boundary unit configured to adaptively determine a duration of the DL phase and a start of the UL phase;

the beacon-signal generator being further configured to include, in a payload of the beacon signal, an offset indicating when the UL phase will begin;

a wireless interface configured to transmit periodically, via the wireless unit, the beacon signal;

a timer configured to elapse a delay time based on the offset and thereby then indicate a start of the UL phase;

the wireless interface being further configured to listen, via the wireless unit and beginning at the UL phase-start, as follows;

on each of M*N UL logical-channels resulting from a predefined first group of M physical-channels, respectively, and a predefined second group of N orthogonal spreading factors usable on each physical-channel, respectively; and

for one or more messages transmitted from the end node, respectively, according to a slotted ALOHA technique;

wherein M and N are non-zero, positive integers, respectively.

24. The central node of claim 23, wherein:

the wireless interface being further configured to;

wirelessly receive via the wireless unit, in half-duplex; and

wirelessly transmit via the wireless unit, in half-duplex.

25. The central node of claim 23, wherein:

the wireless interface, via the wireless unit, is further configured to wirelessly transmit the beacon signal on a DL logical channel corresponding to a predefined physical channel and a predefined spreading factor selected from the second group of N orthogonal spreading; and

the physical channel has a sufficiently wide bandwidth such that the beacon signal is exempted from a frequency-hopping requirement.

26. The central node of claim 23, wherein:

the central node further comprises;

a non-beacon-signal generator configured to;

generate, as needed, a DL wish list including one or more non-beacon signals;

the wireless interface is further configured to transmit as least some of the DL wish list;

a duration of the beacon signal is T_BEACON;

a maximum duration of the DL phase is T_DL-MAX; and

the time-boundary unit is further configured to;

determine whether to send, in addition to the beacon signal, a full DL wish list or a truncated wish list of non-beacon signals; and

determine the offset based on;

a duration of the full DL wish list, T_DL-WISH, if an actual duration, T_ACTUAL, of the DL phase is less than or equal to the maximum duration of the DL phase such that T_ACTUAL=(T_BEACON+T_DL-WISH)≦

T_DL-MAX;

or else

a duration of the truncated DL wish list, T_DL-TRUNC, where T_DL-TRUNC<

T_DL-WISH and T_ACTUAL=(T_BEACON+T_DL-TRUNC)≦

T_DL-MAX.

27. The central node of claim 23, wherein:

the first group of M physical-channels is located in an unlicensed spectrum.

28. The end node of claim 23, wherein:

the wireless interface, via the wireless unit, is further configured to wirelessly receive and to wirelessly transmit according to a low-power, low-bandwidth modulation format.