Synchronized multi-channel access system
View Patent ↗Systems and methods are provided for synchronizing multiple channels in an access network, where the multiple channels are neighboring channels such that a guard band between them or use of a diplexer to prevent inter-channel interference is not required. Synchronization is achieved by defining channel MAP (media access plan) cycle structures such that all channels work in the same direction (upstream US or downstream DS) at any given time. Moreover, the network controller of channel may send out a beacon to allow new nodes to join. A long MAP cycle ( 402 ) may be followed by three consecutive regular MAP cycles ( 404, 406 ), and ( 408 ). These MAP cycles are repeated between beacon transmissions. Synchronization allows multiple channels to be configured contiguous (without a guard band between neighboring channels) and without utilizing diplexers. A plurality of customer premises equipment may operate on each of the communications channels.
1. A method of synchronizing multiple channels of an access network, the method comprising:
defining a Media Access Plan (MAP) cycle for each of a plurality of access network channels;
dividing the MAP cycle for each of the plurality of access network channels into an upstream cycle and a downstream cycle; and
synchronizing the defined and divided MAP cycles of the plurality of access network channels, said synchronizing comprising synchronizing the defined and divided MAP cycles such that both upstream and downstream traffic do not occur at the same time.
2. The method of claim 1 , wherein the synchronized MAP cycles comprise a repeating pattern comprising a regular MAP cycle and a long MAP cycle, the length of the long MAP cycle exceeding that of the regular MAP cycle.
3. The method of claim 2 , wherein the dividing of the MAP cycle into the upstream cycle and the downstream cycle comprises defining an upstream to downstream cycle ratio for each of the regular MAP cycle and the long MAP cycle, and determining the upstream cycle and the downstream cycle based on the defined ratio.
4. The method of claim 1 , further comprising:
maintaining a transmit state impedance of each customer premises equipment (CPE) operating on the access network channels during the entire upstream cycle, both when transmitting and when not transmitting; and
maintaining a receive state impedance of each CPE operating on the additional access network channels during the entire downstream cycle, both when receiving and when not receiving.
5. The method of claim 1 , wherein each of the access network channels corresponds to a respective network controller that controls access to said each of the access network channels, and the method further comprises synchronizing clock signals, channel timer counters, and beacon signals utilized by the respective network controllers.
6. The method of claim 1 , wherein:
a first network controller corresponding to a first access network channel of the plurality of access network channels transmits a first beacons on the first access network channel; and
remaining network controllers corresponding to remaining access network channels of the plurality of access network channels, synchronize their respective channel timer counter by tuning to the first access network channel to listen to the first beacons.
7. A method of synchronizing multiple channels of an access network, the method comprising:
defining a Media Access Plan (MAP) cycle for each access network channel of the access network;
dividing the MAP cycle for each access network channel into an upstream cycle and a downstream cycle; and
synchronizing beacon cycles and the defined and divided MAP cycles of each access network channel, such that transmission of upstream traffic of each access network channel occurs during the upstream cycle and transmission of downstream traffic of each access network channel occurs during the downstream cycle, wherein said synchronizing comprises transmitting information describing the synchronizing to a respective network controller of each access network channel.
8. The method of claim 7 , wherein the synchronized MAP cycles comprise a repeating pattern comprising a regular MAP cycle and a long MAP cycle, the length of the long MAP cycle exceeding that of the regular MAP cycle.
9. The method of claim 8 , wherein the dividing of the MAP cycle into the upstream cycle and the downstream cycle comprises defining an upstream to downstream cycle ratio for each of the regular MAP cycle and the long MAP cycle, and determining the upstream cycle and the downstream cycle based on the defined ratio.
10. The method of claim 7 , wherein each of the access network channels corresponds to a respective network controller that controls access to said each of the access network channels, and the method further comprises synchronizing clock signals, channel time counters, and beacon signals utilized by the respective network controllers.
11. The method of claim 1 , further comprising, upon startup, a customer premises equipment (CPE) attempting to gain admission to a first access network channel of the plurality of access network channels by scanning for a beacon transmitted by a network controller of the first access network channel.
12. The method of claim 11 , further comprising the CPE scanning for a beacon transmitted by a respective network controller of each subsequent additional access network channel of the plurality of access network channels until the CPE is admitted onto the access network.
13. The method of claim 12 , further comprising the CPE storing a channel frequency associated with the first access network channel or one of the additional access network channels over which the CPE gains admission to the access network.
14. The method of claim 12 , wherein movement of the CPE from one of the first or additional access network channels to an alternative one of the first or additional access network channels occurs during a turnaround gap period defined between upstream and downstream cycles, wherein the turnaround gap period is free of any transmissions.
15. The method of claim 7 , further comprising:
maintaining a transmit state impedance of each customer premises equipment (CPE) operating on each access network channel during the entire upstream cycle, both when transmitting and when not transmitting; and
maintaining a receive state impedance of each CPE operating on each access network channel during the entire downstream cycle, both when receiving and when not receiving.
16. The method of claim 7 , further comprising, upon startup, a customer premises equipment (CPE) attempting to gain admission to a first access network channel of the access network channels by scanning for a beacon transmitted by a network controller of the first access network channel.
17. The method of claim 16 , further comprising the CPE scanning for a beacon transmitted by a respective network controller of each subsequent additional access network channel of the access network channels until the CPE is admitted onto the access network.
18. The method of claim 17 , further comprising the CPE storing a channel frequency associated with the first access network channel or one of the additional access network channels over which the CPE gains admission to the access network.
19. The method of claim 7 , wherein:
a first network controller corresponding to a first access network channel of the access network channels transmits first beacons on the first access network channel; and
remaining network controllers corresponding to remaining access network channels of the access network channels, synchronize their respective channel timer counter by tuning into the first access network channel to listen to the first beacons.
20. The method of claim 7 , wherein respective network controllers of remaining access network channels synchronize their respective channel timer counter by communicating with a first network controller of a first access network channel, either through hardware pins, or a media independent interface management interface.