Efficient MAC protocol for OFDMA passive optical networks (PONs)
View Patent ↗Systems and methods are disclosed for providing media access control (MAC) in an optical network by providing a separate control channel and data channel; dedicating each optical network unit (ONU) with one control channel, wherein the control message is transmitted at any time without constraints; sending a grant message to an ONU just before an allocated time is about to start; and sending data traffic from the ONU immediately after receiving the grant message without synchronizing with an optical line terminal (OLT) clock.
1. A method for providing media access control (MAC) in an optical network, comprising:
providing a separate control channel and data channel;
dedicating each optical network unit (ONU) with one control channel, wherein the control message is transmitted at any time without constraints;
sending a grant message to an ONU just before an allocated time is about to start; and
sending data traffic from the ONU immediately after receiving the grant message without synchronizing with an optical line terminal (OLT) clock.
2. The method of claim 1 , comprising providing one or more upstream/downstream subcarriers for a transmission of control messages only.
3. The method of claim 1 , comprising using the dedicated control channel, each ONU reports to the OLT any time a traffic arrives, and the OLT can send grant messages to the ONUs at any time.
4. The method of claim 1 , wherein the OLT sends out grant messages to an ONU just before a transmission of one of the ONUs begins.
5. The method of claim 1 , wherein the ONU begins data transmission immediately after receiving a grant control message instead of transmitting at a time stamp specified in the grant message.
6. The method of claim 1 , wherein the ONUs report traffic information to the OLT, and the OLT allocates subcarriers to the ONUs based on real-time ONU reports.
7. The method of claim 1 , wherein each ONU is dedicated with a predetermined set of upstream/downstream OFDMA subcarriers.
8. The method of claim 1 , wherein the OLT sends out a grant message to an ONU just before an allocated time begins.
9. The method of claim 8 , comprising sending the grant at time t i RTT i , where t is the beginning time of the allocation to ONU i, and RTT i refers to a round trip time between OLT and ONU i.
10. The method of claim 8 , wherein the grant message contains allocated subcarriers and a time duration on each allocated subcarriers.
11. An optical communication system, comprising
a. an optical line terminal (OLT);
b. at least one optical network unit (ONU) with one control channel, wherein the control message is transmitted at any time without constraints;
c. a splitter coupling the OLT to the ONUs; and
d. a media access control protocol controller to send a grant message to an ONU just before an allocated time is about to start, wherein the ONU sends data upon receiving the grant message without synchronizing with an optical line terminal (OLT) clock.
12. The system of claim 11 , wherein each ONU is dedicated with one or more upstream/downstream OFDMA subcarrier for its control message transmission.
13. The system of claim 11 , wherein each ONU keeps updating its queue information to OLT such that OLT can own the latest queue information of ONUs.
14. The system of claim 11 , wherein all OFDMA subcarriers except those dedicated for control message transmission are shared among all ONUs.
15. The system of claim 11 , wherein the OLT sends grant messages to an ONU just before an allocated time duration to the ONU is about to begin, and an ONU begins data traffic transmission immediately after receiving the grant message.
16. The system of claim 11 , wherein upon receiving grants sent from the OLT, the ONU starts data transmission on allocated subcarriers for a time duration specified in the grant message.
17. The system of claim 11 , wherein the ONU begins data transmission immediately after receiving a grant control message instead of transmitting at a time stamp specified in the grant message.
18. The system of claim 11 , wherein the OLT sends a grant at time t i RTT i , where t is the beginning time of the allocation to ONU i, and RTT i refers to a round trip time between OLT and ONU i.
19. The system of claim 18 , wherein the grant message contains allocated subcarriers and a time duration on each allocated subcarriers.
20. The system of claim 11 , wherein the ONUs report traffic information to the OLT, and the OLT allocates subcarriers to the ONUs based on real-time ONU reports.