Detecting a narrow band ranging signal in an OFDM frame
AssigneeCisco Technology, Inc.
InventorHang Jin
Life of this patent
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Abstract
Techniques are presented for a first device configured to be in communication with a second device in a digital communication system to receive an orthogonal frequency division multiplexed (OFDM) ranging signal from the second device. The OFDM ranging signal comprises a plurality OFDM symbols that encode a known bit sequence within a subset of available OFDM communication subcarriers and a subset of available time slots. The OFDM ranging signal is analyzed to determine a timing offset for the second device due to a time for signals to travel between the first device and second device over a communication channel. A message is transmitted from the first device to the second device, the message including information configured to indicate the timing offset.
Claims20
A method comprising:
- at a first device configured to be in communication with a second device in a digital communication system, receiving an orthogonal frequency division multiplexed (OFDM) ranging signal from the second device, wherein the OFDM ranging signal comprises a plurality OFDM symbols that encode a known bit sequence within a subset of available OFDM subcarriers and a subset of available time slots, wherein each of the plurality of OFDM symbols is duplicated in time without a guard time or cyclic prefix between consecutive duplicates of the respective symbol to ensure that each of the consecutive duplicates received at the first device overlaps a respective scheduled single symbol receive period duration;
- analyzing the OFDM ranging signal to determine a timing offset for the second device due to a time for signals to travel between the first device and second device over a communication channel based on alignment of at least one of the consecutive duplicates of the plurality of OFDM symbols and a respective overlapped scheduled single symbol receive period duration;
- and
- transmitting a message from the first device to the second device, the message including information configured to indicate the timing offset.
An apparatus comprising:
- a network interface unit configured to receive and transmit signals over a communication channel;
- and
- a processor coupled to the network interface unit, and configured to:
- receive an orthogonal frequency division multiplexed (OFDM) ranging signal from a client device, wherein the OFDM ranging signal comprises a plurality OFDM symbols that encode a known bit sequence within a subset of available OFDM subcarriers and a subset of available time slots, wherein each of the plurality of OFDM symbols is duplicated in time without a guard time or cyclic prefix between consecutive duplicates of the respective symbol to ensure that each of the consecutive duplicates received at the apparatus overlaps a respective scheduled single symbol receive period duration;
- analyze the OFDM ranging signal to determine a timing offset for the client device due to a time for signals to travel between the apparatus and the client device over a communication channel based on alignment of at least one of the consecutive duplicates of the plurality of OFDM symbols and a respective overlapped scheduled single symbol receive period duration;
- and
- generate a message to be transmitted to the client device, the message including information configured to indicate the timing offset.
A non-transitory computer readable storage medium storing instructions that, when executed by a processor, cause the processor to:
- receive an orthogonal frequency division multiplexed (OFDM) ranging signal at a first device from a second device, wherein the OFDM ranging signal comprises a plurality OFDM symbols that encode a known bit sequence within a subset of available OFDM communication subcarriers and a subset of available time slots, wherein each of the plurality of OFDM symbols is duplicated in time without a guard time or cyclic prefix between consecutive duplicates of the respective symbol to ensure that each of the consecutive duplicates received at the first device overlaps a respective scheduled single symbol receive period duration;
- analyze the OFDM ranging signal to determine a timing offset for the second device due to a time for signals to travel between the first device and second device over a communication channel based on alignment of at least one of the consecutive duplicates of the plurality of OFDM symbols and a respective overlapped scheduled single symbol receive period duration;
- and
- generate a message to be transmitted to the second device, the message comprising information configured to indicate the timing offset.
Dependencies are inferred from the claim text.