Slotted mode decoder state metric initialization

A method of decoding a continuously convolutionally encoded stream of data for use in a remote unit in a slotted mode wireless communication system, wherein the remote unit only receives a portion of said continuously convolutionally encoded stream of symbols during an active state of said remote unit and receives none of said stream during an inactive state, the method comprises:

• receiving a stream of coded symbols;
• accumulating said symbols until a full frame of symbols has been received;
• determining whether the received stream of coded symbols is an interrupted stream of coded symbols;
• if the received stream of coded symbols is an interrupted stream of coded symbols, biasing end node metrics of a trellis within a convolutional decoder to valid values that would have been present from receiving an uninterrupted stream of coded symbols;
• presenting said full frame of coded symbols to said convolutional decoder wherein said convolutional decoder continues construction of said trellis using said coded symbols;
• computing a metric for each node on the trellis in response to said received coded symbols;
• generating decoded bits in response to said metric values.

A remote unit for use in a communication system comprising:

• a receiver configured to receive wireless link signals including a stream of coded symbols;
• a deinterleaver configured to receive the coded symbols from said receiver and accumulate said coded symbols into a series of data blocks ordered in a time-sequence order;
• a decoder configured to receive said series of data blocks ordered in a time sequence order, continue construction of a trellis stored in said decoder to decode said data blocks and output decoded data;
• and
• a controller configured to determine whether the received stream of coded symbols is an interrupted stream of coded symbols,
• wherein if the received stream of coded symbols is an interrupted stream of coded symbols, the controller biases end node metrics of the trellis within the decoder to valid values that would have been present from receiving an uninterrupted stream of coded symbols.

A system for decoding convolutionally encoded codewords comprising:

• means for receiving a stream of coded symbols;
• means for accumulating said symbols until a full frame of symbols has been received;
• means for determining whether the received stream of coded symbols is an interrupted stream of coded symbols;
• means for biasing end node metrics of a trellis within a convolutional decoder to valid values that would have been present from receiving an uninterrupted stream of coded symbols if the received stream of coded symbols is an interrupted stream of coded symbols;
• means for presenting said full set of symbols to a convolutional decoder wherein said convolutional decoder continues construction of said trellis using said symbols;
• means for computing a metric for each node on the trellis in response to said received symbols;
• and
• means for generating decoded bits in response to said metric values.