Supporting Multiple Logical Channels In A Physical Interface

Abstract

A supervisory communications system (such as, a headend cable modem termination system) manages communications with a plurality of remote communications devices (such as, a cable modem). The supervisory system enables each of its physical channels to have multiple logical channels, with each logical channel having differing channel parameters or operating characteristics. As a result, different types of communication devices are permitted to coexist on the same physical spectrum. In other words, a communications device using, for example, spread spectrum modulation technologies require different operating characteristics than a communications device using, for example, time division multiplexing technologies. Although physical layer transmissions from these communications devices are not compatible, the present invention provides methodologies and/or techniques that define multiple logical channels that allow these communications devices to share the same physical spectrum of a transmission medium (such as, a HFC cable plant, wireless path, etc.) and send upstream transmissions to a single upstream receiver.

1 . A communications system configured to communicate over a plurality of logical channels, each of the plurality of logical channels being partitioned into a plurality of assignable slots, each of the plurality of assignable slots being assigned a code, comprising:
 a supervisory communications node configured to provide a first message over a first logical channel and a second message over a second logical channel, the first logical channel and the second logical channel being configured such that only one of the first logical channel and the second logical channel is active at a time, wherein the first message is configured to assign a first assignable slot from the first logical channel to a first code and to assign a second assignable slot from the second logical channel to a second code;   a first remote node configured to be assigned to the first code and to communicate with the supervisory communications node using the first assignable slot; and   a second remote node configured to be assigned to the second code and to communicate with the supervisory communications node using the second assignable slot.   
   
   
       2 . The communications system of  claim 1 , wherein each of the plurality of logical channels are configured to support differing operating characteristics from each other. 
   
   
       3 . The communications system of  claim 2 , wherein the differing operating characteristics comprise at least one of a group consisting of:
 symbol rate;   center frequency;   FEC parameters to be used for various burst types;   transmission modulation; and   multiple access standards.   
   
   
       4 . The communications system of  claim 2 , wherein the supervisory communications node is configured to provide an upstream descriptor message (UCD) for each of the plurality of logical channels, the UCD defining the operating characteristics for each of the plurality of logical channels. 
   
   
       5 . The communications system of  claim 1 , wherein the first logical channel is configured to support synchronous code division multiple access (S-CDMA) and the second logical channel is configured to support time division multiple access (TDMA). 
   
   
       6 . The communications system of  claim 1 , wherein at least one of a group consisting of the first remote node and the second remote node is from among a plurality of remote nodes, each of the remote nodes being configured to operate using similar operating characteristics. 
   
   
       7 . The communications system of  claim 1 , wherein at least one of a group consisting of the first message and the second message is a Data Over Cable Service Interface Specification (DOCSIS™) MAP message. 
   
   
       8 . The communications system of  claim 1 , wherein at least one of a group consisting of the first code and the second code is a Data Over Cable Service Interface Specification (DOCSIS™) service identifier (SID) code. 
   
   
       9 . The communications system of  claim 1 , wherein the first message is configured to assign a null code to the assignable slots of the first logical channel corresponding to the second assignable slot. 
   
   
       10 . The communications system of  claim 9 , wherein the first message comprises:
 a grant to the first code during the first assignable slot; and   a grant to the null code during a duration of the second assignable slot.   
   
   
       11 . The communications system of  claim 1 , wherein the second message is configured to assign a null code to the assignable slots of the second logical channel corresponding to the first assignable slot. 
   
   
       12 . The communications system of  claim 11 , wherein the second message comprises:
 a grant to the second code during the second assignable slot; and   a grant to the null code during a duration of the first assignable slot.   
   
   
       13 . The communications system of  claim 1 , wherein the first logical channel is active when the first remote node communicates with the supervisory communications node during the first assignable slot, the first logical channel being configured such that the first remote node does not communicate with the supervisory communications node while the second remote node communicates with the supervisory communications node. 
   
   
       14 . The communications system of  claim 1 , wherein the second logical channel is active when the second remote node communicates with the supervisory communications node during the second assignable slot, the second logical channel being configured such that the second remote node does not communicate with the supervisory communications node while the first remote node communicates with the supervisory communications node. 
   
   
       15 . A supervisory communications node configured to communicate over a plurality of logical channels, each of the plurality of logical channels being partitioned into a plurality of assignable slots, each of the plurality of assignable slots being assigned a code, comprising:
 a physical layer demodulator configured to receive a first communication from a first remote node over a first logical channel during a first assignable slot and a second communication over a second logical channel during a second assignable slot, the first logical channel and the second logical channel being configured such that only one of the first logical channel and the second logical channel is active at a time; and   a physical layer modulator configured to provide a first message over the first logical channel and a second message over the second logical channel, the first message being configured to the assign the first assignable slot from the first logical channel to a first code corresponding to first remote node the and to assign the second assignable slot from the second logical channel to a second code corresponding to second remote node.   
   
   
       16 . The supervisory communications node of  claim 15 , wherein each of the plurality of logical channels are configured to support differing operating characteristics from each other. 
   
   
       17 . The supervisory communications node of  claim 16 , wherein the differing operating characteristics comprise at least one of a group consisting of:
 symbol rate;   center frequency;   FEC parameters to be used for various burst types;   transmission modulation; and   multiple access standards.   
   
   
       18 . The supervisory communications node of  claim 16 , wherein the physical layer modulator is configured to provide an upstream descriptor message (UCD) for each of the plurality of logical channels, the UCD defining the operating characteristics for each of the plurality of logical channels. 
   
   
       19 . The supervisory communications node of  claim 15 , wherein the first logical channel is configured to support synchronous code division multiple access (S-CDMA) and the second logical channel is configured to support time division multiple access (TDMA). 
   
   
       20 . The supervisory communications node of  claim 15 , wherein at least one of a group consisting of the first remote node and the second remote node is from among a plurality of remote nodes, each of the remote nodes being configured to operate using similar operating characteristics 
   
   
       21 . The supervisory communications node of  claim 15 , wherein at least one of a group consisting of the first message and the second message is a Data Over Cable Service Interface Specification (DOCSIS™) MAP message. 
   
   
       22 . The supervisory communications node of  claim 15 , wherein at least one of a group consisting of the first code and the second code is a Data Over Cable Service Interface Specification (DOCSIS™) service identifier (SID) code. 
   
   
       23 . The supervisory communications node of  claim 15 , wherein the first message is configured to assign a null code to the assignable slots of the first logical channel corresponding to the second assignable slot. 
   
   
       24 . The supervisory communications node of  claim 23 , wherein the first message comprises:
 a grant to the first code during the first assignable slot; and   a grant to the null code during a duration of the second assignable slot.   
   
   
       25 . The supervisory communications node of  claim 15 , wherein the second message is configured to assign a null code to the assignable slots of the second logical channel corresponding to the first assignable slot. 
   
   
       26 . The supervisory communications node of  claim 25 , wherein the second message comprises:
 a grant to the second code during the second assignable slot; and   a grant to the null code during a duration of the first assignable slot.   
   
   
       27 . The supervisory communications node of  claim 15 , wherein the first logical channel is active when the first remote node communicates with the supervisory communications node during the first assignable slot, the first logical channel being configured such that the first remote node does not communicate with the supervisory communications node while the second remote node communicates with the supervisory communications node. 
   
   
       28 . The supervisory communications node of  claim 15 , wherein the second logical channel is active when the second remote node communicates with the supervisory communications node during the second assignable slot, the second logical channel being configured such that the second remote node does not communicate with the supervisory communications node while the first remote node communicates with the supervisory communications node.