Adaptive Viterbi decoder for a wireless data network receiver
First Claim
Patent Images
1. An apparatus comprising:
- a radio receiver configured to wirelessly receive radio signals determined from packets of OFDM data transmitted in a wireless network, each packet of OFDM data including one or more fields coded at a pre-defined relatively low data rate and including information on the data rate of the remainder of the packet, and the remainder of the packet coded at the data rate indicated in the one or more fields;
an analog-to-digital converter to provide digital samples; and
a receive signal path coupled to the analog-to-digital converter, the receive signal path includes a discrete Fourier transformer and a configurable Viterbi decoder, the decoder including;
a branch metric generator with an input accepting a coded signal and generating branch metrics;
an ACS subsystem coupled to and accepting the branch metrics from the metric generator;
a survivor memory subsystem coupled to and accepting input from the ACS subsystem, the survivor memory subsystem having a plurality of outputs, each providing a decoded version of the coded signal decoded to a distinct decision depth; and
such that the Viterbi decoder is able to decode the signal to one of a plurality of decision depths by selecting one of the memory unit outputs,wherein the Viterbi decoder is first set to decode at the pre-defined relatively low data rate, and as a result of decoding the one or more fields is set to decode at the data rate of the remainder of the packet indicated in the one or more fields.
0 Assignments
0 Petitions
Accused Products
Abstract
A configurable Viterbi decoder to decode a coded signal for inclusion in a radio receiver for implementing the physical layer receiving function (PHY) of a wireless data network. The decoder includes a branch metric generator with an input to the coded signal, an ACS subsystem coupled to the branch metric generator, and a survivor memory unit coupled to the ACS subsystem. The decoder includes a plurality of outputs each providing a decoded version of the input signal decoded to a distinct decision depth such that the Viterbi decoder is programmable to decode the signal to one of a plurality of decision depths.
-
Citations
20 Claims
-
1. An apparatus comprising:
-
a radio receiver configured to wirelessly receive radio signals determined from packets of OFDM data transmitted in a wireless network, each packet of OFDM data including one or more fields coded at a pre-defined relatively low data rate and including information on the data rate of the remainder of the packet, and the remainder of the packet coded at the data rate indicated in the one or more fields; an analog-to-digital converter to provide digital samples; and a receive signal path coupled to the analog-to-digital converter, the receive signal path includes a discrete Fourier transformer and a configurable Viterbi decoder, the decoder including; a branch metric generator with an input accepting a coded signal and generating branch metrics; an ACS subsystem coupled to and accepting the branch metrics from the metric generator; a survivor memory subsystem coupled to and accepting input from the ACS subsystem, the survivor memory subsystem having a plurality of outputs, each providing a decoded version of the coded signal decoded to a distinct decision depth; and such that the Viterbi decoder is able to decode the signal to one of a plurality of decision depths by selecting one of the memory unit outputs, wherein the Viterbi decoder is first set to decode at the pre-defined relatively low data rate, and as a result of decoding the one or more fields is set to decode at the data rate of the remainder of the packet indicated in the one or more fields. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
wherein the select input is initially set so that the survivor memory output corresponding to the a pre-defined relatively low data rate is selected, and is set as a result of decoding the one or more fields to select the survivor memory output corresponding to the data rate of the remainder of the packet indicated in the one or more fields.
-
-
8. An apparatus as recited in claim 1, implemented as part of a CMOS integrated circuit.
-
9. An adaptive Viterbi decoding system comprising:
-
a Viterbi decoder having a coded signal input configured to accept a coded OFDM signal received in a wireless receiver, the receiver configured to receive packets of information in a wireless network that uses OFDM, each packet having payload data coded at one or more of a set of data rates and modulated according to one of a set of modulation schemes, the packet having a packet structure that includes one or more header symbols containing information on the data rate and modulation scheme of the payload data, the header symbols encoded at a pre-defined first data rate and using a first modulation scheme; a buffer preceding the Viterbi decoder having an output coupled to the coded signal input of the Viterbi decoder and of a length long enough to buffer input data while the decoder decodes the one or more header symbols, the Viterbi decoder further comprising; a branch metric generator with an input to the coded signal and generating branch metrics; an ACS subsystem coupled to and accepting the branch metrics from the branch metric generator; a survivor memory subsystem coupled to and accepting input from the ACS subsystem, the survivor memory subsystem having a plurality of outputs, each providing a decoded version of the coded input signal decoded to a distinct decision depth, wherein the Viterbi decoder is programmable to decode the input signal to one of a plurality of decision depths by selecting one of the memory unit outputs, wherein the Viterbi decoder is initially set to decode at the decision depth suitable for decoding the header symbols, and after the Viterbi decoder decodes the one or more header symbols and the data rate of the remainder of the received packet is determined from the one or more header symbols, the output of the Viterbi decoder is selected to be an output suitable for decoding the input signals at the determined data rate. - View Dependent Claims (10)
-
-
11. An adaptive Viterbi decoding system comprising:
-
a Viterbi decoder having a coded signal input configured to accept a coded OFDM signal received in a wireless receiver, the receiver configured to receive packets of information in a wireless network that uses OFDM, each packet having payload data coded at one or more of a set of data rates and modulated according to one of a set of modulation schemes, the packet having a packet structure that includes one or more header symbols containing information on the data rate and modulation scheme of the payload data, the header symbols encoded at a pre-defined first data rate and using a first modulation scheme; and a buffer preceding the Viterbi decoder having an output coupled to the coded signal input of the Viterbi decoder and of a length long enough to buffer input data while the decoder decodes the one or more header symbols, the Viterbi decoder further comprising; a branch metric generator with an input to the coded signal and generating branch metrics; an ACS subsystem coupled to and accepting the branch metrics from the branch metric generator; and a survivor memory subsystem coupled to and accepting input from the ACS subsystem, the survivor memory subsystem having a plurality of outputs, each providing a decoded version of the coded input signal decoded to a distinct decision depth, wherein the Viterbi decoder is programmable to decode the input signal to one of a plurality of decision depths by selecting one of the memory unit outputs, wherein the Viterbi decoder is initially set to decode at the decision depth suitable for decoding the header symbols, and after the Viterbi decoder decodes the one or more header symbols and the data rate of the remainder of the received packet is determined from the one or more header symbols, the output of the Viterbi decoder is selected to be an output suitable for decoding the input signals at the determined data rate. - View Dependent Claims (12, 13, 14, 15)
-
-
16. An apparatus comprising:
-
an analog radio receiver for receiving signals that correspond to OFDM packets of a wireless network that uses OFDM, each packet having payload data coded at one or more of a set of data rates and modulated according to one of a set of modulation schemes, the packet having a packet structure that includes one or more header symbols coded at a pre-defined relatively low data rate and containing information on the data rate and modulation scheme of the payload data; an analog-to-digital converter to convert the received signals corresponding to packet data from the analog radio receiver to digital samples; and a digital receive signal path coupled to the output of the analog to digital converter and comprising; a discrete Fourier transformer to transform the digital samples to coded signals; and an adaptive Viterbi decoder to decode the coded signals, the Viterbi decoder including; a branch metric generator with an input to the coded signal and generating branch metrics; an ACS subsystem coupled to and accepting the branch metrics from the branch metric generator; and a survivor memory subsystem coupled to and accepting input from the ACS subsystem, the survivor memory subsystem having a plurality of outputs, each providing a decoded version of the coded input signal decoded to a distinct decision depth such that the Viterbi decoder is programmable to decode the input signal to one of a plurality of decision depths, wherein the Viterbi decoder is initially set to decode at the relatively low decision depth suitable for decoding the header symbols coded at the pre-defined relatively low data rate, such that during the decoding of the header symbols, the Viterbi decoder has a relatively low latency, and wherein after the Viterbi decoder decodes the one or more header symbols and determines the data rate of the remainder of the received packet, the output of the Viterbi decoder is selected to be a survivor memory output suitable for decoding the input signals at the determined data rate. - View Dependent Claims (17, 18, 19)
-
-
20. A method comprising:
-
wirelessly receiving a data packet of a wireless network, the packet having payload data coded at one or more of a set of data rates and modulated according to one of a set of modulation schemes, the packet having a packet structure that includes one or more header symbols coded at a pre-defined relatively low data rate and containing information on the data rate and modulation scheme of the payload data, the method comprising; sampling the received signal of the packet to form a sampled signal; discrete Fourier transforming and demodulating the sampled signal to form a demodulated signal; buffering the demodulated signal in a buffer of a length long enough to buffer input data while a decoder decodes the one or more header symbols; initially setting an adaptive Viterbi decoder that has a number of settable decision levels corresponding to a corresponding number of data rates to a decision level corresponding to the pre-defined relatively low data rate, the Viterbi decoder having a latency that monotonically increases with the data rate, such that the Viterbi decoder initially is set to have a relatively low latency; decoding the one or more header symbols in the adaptive Viterbi decoder; determining the data rate of the remainder of the received packet from the one or more header symbols; setting the Viterbi decoder to decode at a level suitable for the remainder of the packet; and decoding the remainder of the packet.
-
Specification