Architecture repartitioning to simplify outside-plant component of fiber-based access system
First Claim
1. A fiber optic communication system comprising:
- a host digital terminal (HDT) for connection to a core communications network; and
at least one optical network unit (ONU) for interfacing to a corresponding plurality of subscriber loops and connected by optical fiber to the HDT;
wherein, for each subscriber loop communicating with the core network, said subscriber loop transmits analog or digital data to its corresponding ONU (and vice versa) in a corresponding one of a plurality of analog formats;
said corresponding ONU transmits digital data to the HDT (and vice versa) in a common, high-bandwidth digital format; and
the HDT transmits digital data to the core network (and vice versa) in a corresponding one of a plurality of digital formats;
wherein the HDT executes digital signal processing functions for converting data from any of the plurality of digital formats to the common digital format (and vice versa).
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Abstract
An improved access system for use in a Fiber-In-The-Loop (FITL) communications network is disclosed. The access system comprises a host digital terminal (HDT) and a plurality of subtending optical network units (ONUs). The digital signal processing (DSP) functions traditionally executed by line interface units (LIUs) within the ONUs are migrated to the HDT, rendering the individual ONUs simpler, cheaper and more reliable. This is made possible by the provision in each ONU of an oversampling codec for sampling (and conversion) of upstream and downstream data at a very high bit rate. The large bandwidths of the data communicated between the ONUs and the HDT are easily handled by the fiber optic medium therebetween. In the HDT, DSP functions are executed by a common pool, or bank, of DSP ASICs. Decimators are provided in the HDT in order to properly format the data for processing by the DSPs. Interpolators are provided in the HDT for creating a high rate bit stream that can be easily converted to analog format by a codec. A high degree of processing efficiency can be achieved by reducing complex processing tasks to a sequence of individual steps through the DSP bank and rerouting the result of each step through the bank. Such “hair pinning” can be performed in either the upstream (subscriber-to-core-network) or downstream (core-network-to-subscriber) directions. Optionally, decimators and interpolators can be provided in the LIUs.
132 Citations
57 Claims
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1. A fiber optic communication system comprising:
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a host digital terminal (HDT) for connection to a core communications network; and
at least one optical network unit (ONU) for interfacing to a corresponding plurality of subscriber loops and connected by optical fiber to the HDT;
wherein, for each subscriber loop communicating with the core network, said subscriber loop transmits analog or digital data to its corresponding ONU (and vice versa) in a corresponding one of a plurality of analog formats;
said corresponding ONU transmits digital data to the HDT (and vice versa) in a common, high-bandwidth digital format; and
the HDT transmits digital data to the core network (and vice versa) in a corresponding one of a plurality of digital formats;
wherein the HDT executes digital signal processing functions for converting data from any of the plurality of digital formats to the common digital format (and vice versa). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. In a fiber optic communication system comprising a host digital terminal (HDT) for connection to a core communications network and at least one optical network unit (ONU) for interfacing to a corresponding plurality of subscriber loops and connected by optical fiber to the HDT;
- wherein the HDT comprises a digital switch matrix and a plurality of programmable digital signal processors (DSPs) executing respective processing functions and connected to the digital switch matrix, a method of communicating data between the HDT and the at least one ONU, comprising;
in a downstream direction, the switch matrix routing data received by the HDT from the core network in any of a plurality of distinct digital formats to selected ones of the DSPs;
the DSPs performing respective processing functions, yielding downstream data in a common, high-bandwidth digital format;
the switch matrix routing the downstream data to the at least one ONU; and
in an upstream direction, the switch matrix routing data received from the at least one ONU in said common, high-bandwidth digital format to selected ones of the DSPs;
the DSPs performing respective processing functions, yielding upstream data in at least one of said plurality of distinct digital formats;
the switch matrix routing the upstream data to the core network.- View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
- wherein the HDT comprises a digital switch matrix and a plurality of programmable digital signal processors (DSPs) executing respective processing functions and connected to the digital switch matrix, a method of communicating data between the HDT and the at least one ONU, comprising;
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41. A host digital terminal (HDT) for enabling bidirectional communication between a core network and at least one optical network unit (ONU) having a plurality of line interface units (LIUs), the HDT comprising:
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a digital switch matrix, a plurality of programmable digital signal processors (DSPs) connected to the digital switch matrix for executing the signal processing functions;
at least on first optical transceiver connected between the optical fiber and the switch matrix;
at least one second optical transceiver for connection to the core network and connected to the switch matrix; and
means to control the digital switch matrix so as to select, for each LIU, at least one first signal processing function to be executed by a first subset of the plurality of DSPs on data arriving from the core network through the at least one second optical transceiver and destined for the LIU, and at least one second signal processing function to be executed by a second subset of the plurality of DSPs on data arriving from the LIU through the at least one first optical transceiver and destined for the core network. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57)
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Specification