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Digital Hardware Block to Estimate Channel Energy and Measure Signal Quality

IP.com Disclosure Number: IPCOM000012801D
Original Publication Date: 2003-May-28
Included in the Prior Art Database: 2003-May-28
Document File: 2 page(s) / 66K

Publishing Venue

Motorola

Related People

David Taubenheim: AUTHOR [+2]

Abstract

This digital circuit estimates the energy of a radio channel so that a decision can be made on whether to transmit immediately or wait for an open channel, depending if the channel is determined to be idle or busy. The circuit also estimates the quality of a received data signal, which assists with scanning for like networks and building routing tables. All of these functions operate using the same digital circuit and require little or no intervention from the microprocessor running the communication stack. The need for this circuit comes from the design of a very low cost ISM-band personal area network transceiver, which operates in shared spectrum such that the busy/idle state of the channel prior to transmission and the quality of the received data signal during reception must be monitored.

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Digital Hardware Block to Estimate Channel Energy and Measure Signal Quality

David Taubenheim

Vivek Bhan

Abstract:� This digital circuit estimates the energy of a radio channel so that a decision can be made on whether to transmit immediately or wait for an open channel, depending if the channel is determined to be idle or busy.� The circuit also estimates the quality of a received data signal, which assists with scanning for like networks and building routing tables.� All of these functions operate using the same digital circuit and require little or no intervention from the microprocessor running the communication stack.� The need for this circuit comes from the design of a very low cost ISM-band personal area network transceiver, which operates in shared spectrum such that the busy/idle state of the channel prior to transmission and the quality of the received data signal during reception must be monitored.

This digital circuit is comprised of a hardware signal processing block and associated control logic to perform measurements of radio channel energy and a received data signal. The hardware block is used for measurements during scanning for an IEEE 802.15.4 network, before the transmission of a packet and during the reception of a data packet.� The hardware block is used for the Clear Channel Assessment (CCA) in the Carrier Sense Multiple Access (CSMA) algorithm, Energy Detection (ED), Signal Detection (SD), and Link Quality (LQ) measurements in the hardware implementation of the physical layer of the IEEE 802.15.4 standard.�

The block is initially programmed with an energy threshold, above which a radio channel is determined to be busy after the measurement is complete.� There are different modes into which the block can be programmed to measure different characteristics of the channel:� (1) The presence of an amount of generic energy in the channel, (2) The presence of any detectable 802.15.4 signal in the channel, and (3) The presence of a 802.15.4 signal in the channel with strength above a specified level.� The result of one of these measurements is “busy” or “idle”.� For each of these types of measurements, a relevant metric about the signal is provided.� For instance, (1) The amount of generic energy, (2) The quality of the 802.15.4 signal, and (3) Another combined metric.� If the measurement using thi...