Hybrid protocol transceiver for V2V communication
View Patent ↗A device for use in, and system for, a vehicle-to-vehicle (V2V) communication and safety system that uses a hybrid combination of TDMA and CSMA protocols. The synchronized TDMA frame is partitioned into three prioritized time interval classes with differing priorities and dynamically changing sizes based on demand of higher-priority messages. The TDMA portions of a repeating time interval uses self-assigned dense time slots for high-priority safety messages, with one portion for emergency vehicles and road-side units. The CSMA protocol uses remaining available time for lower-priority and overflow messages. The higher-priority time interval classes change size dynamically based on the number of current transmissions. Modulation schemes, but not data link formats, use existing Standards. Embodiments include optimized traffic flow and signal timing.
1. A device of manufacture for sending and receiving vehicle-to-vehicle (V2V) safety messages, in a V2V communication system, comprising a transceiver in a subject vehicle wherein the transceiver is configured to wirelessly broadcast and receive messages comprising a protocol comprising:
a synchronized time base used by all V2V transceivers in the V2V communication system;
a basic time interval, of a predetermined duration, repeating continuously and contiguously, responsive to the synchronized time base;
n contiguous time slots, of a predetermined duration, enumerated from 1 to integer n, wherein the basic time interval comprises the n time slots;
wherein at least some messages are transmitted in a time-division, multiple-access (TDMA) protocol comprising the basic time interval and the time slots;
an algorithm for self-selecting a selected time slot by the V2V transceiver;
a first range of contiguous time slots p1 to p2 used for a first priority class of messages using TDMA protocol;
a second range of contiguous time slots p3 to p4 used for a second priority class of messages using collision-sense, multiple-access (CSMA) protocol, wherein the second range does not overlap with the first range; and wherein no transmissions of the second priority class occur outside the time window consisting of p3 to p4 inclusive; and
wherein p1, p2, p3 and p4 are in the range of 1 to n inclusive, and p2>p1 and p4>p3;
wherein the protocol is free of a requirement of road-side units (RSU's).
2. The device of claim 1 wherein the protocol further comprises:
the quantity of time slots in the first range (the value p2 minus p1) is responsive to the number of time slots in use in the first range, such that when more time slots in the first range are in use the quantity of time slots in the first range increases.
3. The device of claim 1 wherein the protocol further comprises:
a third range of contiguous time slots p5 to p6, used for a third priority class of messages; wherein none of the three ranges overlap; and
wherein the third priority class of messages is restricted to messages from emergency vehicles, or messages from government authorized road-side units (RSU), or both;
wherein p5 and p6 are in the range of 1 to n inclusive, and p6>p5.
4. The device of claim 3 wherein the protocol further comprises:
the quantity of time slots in the third range (the value p6 minus p5) is responsive to the number of time slots in use in the third range, such that when more time slots in the third range are in use the quantity of time slots in the third range increases.
5. The device of claim 3 wherein the protocol further comprises:
the quantity of time slots in the second range (the value p4 minus p3) is responsive to the quantity of time slots in the first range and the quantity of time slots in the third range, such that when the quantity of time slots in the first range and the quantity of time slots in the third range increase, the quantity of time slots in the second range (p4 minus p3) decreases.
6. A system that uses a plurality of the device of claim 1 .
7. A vehicle comprising the device of claim 1 .
8. A device of manufacture for sending and receiving vehicle-to-vehicle (V2V) safety messages, in a V2V communication system, comprising a transceiver in a subject vehicle wherein the transceiver is configured to wirelessly broadcast and receive messages comprising a protocol comprising:
a synchronized time base used by all V2V transceivers in the V2V communication system;
a basic time interval, of a predetermined duration, repeating continuously and contiguously, responsive to the synchronized time base;
n contiguous time slots, of a predetermined duration, enumerated from 1 to integer n, wherein the basic time interval comprises the n time slots;
wherein at least some messages are transmitted in a time-division, multiple-access (TDMA) protocol comprising the basic time interval and the time slots;
an algorithm for self-selecting a selected time slot by the V2V transceiver;
a first range of contiguous time slots p1 to p2 used for a first priority class of messages using TDMA protocol;
a second range of contiguous time slots p3 to p4 used for a second priority class of messages using collision-sense, multiple-access (CSMA) protocol, wherein the second range does not overlap with the first range; and wherein no transmissions of the second priority class occur outside the time window consisting of p3 to p4 inclusive; and
wherein p1, p2, p3 and p4 are in the range of 1 to n inclusive, and p2>p1 and p4>p3;
a first buffer zone and a second buffer zone of time slots between the first range and the second range, and between the second range and the third range, respectively, and
wherein the time slots in the first and second buffer zones may not be used for transmissions in any of the first, second or third priority class of messages.