# US 8,787,927 B2 · Apparatus and method for frequency-selective occupancy detection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,787,927 B2 - Document ID: US8787927B2 - Status: Granted - Kind: B2 - Application number: 13/098,188 - Filed: 2011-04-29 - Published: 2011-10-27 - Granted: 2014-07-22 - Earliest claimed: 2008-10-31 - Assignees: Innovationszentrum fuer Telekommunikationstechnik GmbH IZT - Applicants: Rainer Perthold; Dieter Weninger; Holger Schlegel - Inventors: Rainer Perthold; Dieter Weninger; Holger Schlegel - Web page: https://patentgrep.com/patent/US8787927B2 ## CPC - H04B 17/382: for resource allocation, admission control or handover - H04B 17/318: Received signal strength - H04W 16/14: Spectrum sharing arrangements {between different networks} - H04W 24/00: Supervisory, monitoring or testing arrangements - H04W 72/23: in the downlink direction of a wireless link, i.e. towards a terminal - H04B: TRANSMISSION - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract An apparatus for frequency-selective occupancy detection of a channel in a frequency band includes a detector for detecting a receive spectrum in the frequency band, a provider for providing node frequencies, a determiner for determining node level values, a determiner for determining the threshold curve and a comparer. The provider provides the node frequencies for a threshold curve with respect to a noise floor in the frequency band. The determiner determines the node level values at the node frequencies based on receive level values of the receive spectrum. The determiner determines the threshold curve in the frequency band based on the provided node frequencies and the node level values at the node frequencies. The comparer compares a current power of the receive level values in the channel with a reference power in the channel predetermined by the threshold curve to detect occupancy or non-occupancy of the channel depending on the comparison. ## Claims ### Claim 1 Apparatus for frequency-selective occupancy detection of a channel in a frequency band, comprising: a detector for detecting a power spectrum density PSD in the frequency band; a provider for providing node frequencies for a threshold curve with respect to a noise floor in the frequency band; a determiner for determining node power levels at the node frequencies based on receive power levels of the power spectrum density, wherein the determiner for determining node power levels is implemented to integrate a previously determined node power level into the determination of a node power level currently to be determined such that heavily varying node power levels are attenuated; a determiner for determining the threshold curve in the frequency band based on the provided node frequencies and on the node power levels at the node frequencies; and a comparer for comparing a current power of the receive power levels in the channel with a reference power in the channel predetermined by the threshold curve, for determining, in dependence on the comparison, an occupancy or non-occupancy of the channel. ### Claim 2 (depends on 1) Apparatus according to claim 1, wherein the detector is implemented to detect the power spectrum density several times within time intervals. ### Claim 3 (depends on 1) Apparatus according to claim 1, wherein the provider for providing the node frequencies is implemented to change a difference of adjacent node frequencies with increasing frequency in the frequency band by a factor of change. ### Claim 4 (depends on 3) Apparatus according to claim 3, wherein the difference of adjacent node frequencies increases with increasing frequency in the frequency band. ### Claim 5 (depends on 1) Apparatus according to claim 1, wherein the frequency band comprises an initial and a terminal frequency, and wherein the provider for providing the node frequencies is implemented to select adjacent node frequencies such that a first node frequency corresponds to the initial frequency, and a last node frequency corresponds to the terminal frequency within a tolerance range. ### Claim 6 (depends on 5) Apparatus according to claim 5, wherein the provider for providing node frequencies is implemented to match the first node frequency with the initial frequency and the last node frequency with the terminal frequency by means of the Newton method. ### Claim 7 (depends on 1) Apparatus according to claim 1, wherein the provider is implemented to take the node frequencies for the frequency band from a table. ### Claim 8 (depends on 1) Apparatus according to claim 1, wherein the determiner for determining node power levels is implemented to determine the node power levels based on successive receive power levels. ### Claim 9 (depends on 8) Apparatus according to claim 8, wherein the determiner for determining node power levels is implemented to form a histogram from the successive receive power levels and to further determine the node power levels by a lower power level limit in the histogram. ### Claim 10 (depends on 1) Apparatus according to claim 1, wherein the determiner for determining node power levels is implemented to form a histogram from successive receive power levels, and to further determine the node power levels by a power level with a specific distance to a lower power level limit. ### Claim 11 (depends on 1) Apparatus according to claim 1, wherein the determiner for determining node power levels is implemented to average successive receive power levels and to further use an averaging result as new receive power level. ### Claim 12 (depends on 1) Apparatus according to claim 1, wherein the determiner for determining the node power levels comprises a leaky integrator and the leaky integrator is implemented to acquire the attenuation. ### Claim 13 (depends on 1) Apparatus according to claim 1, wherein the determiner for determining the threshold curve is implemented to determine the threshold curve by interpolation between the node power levels at the node frequencies. ### Claim 14 (depends on 13) Apparatus according to claim 13, wherein the interpolation comprises linear interpolation or cubic interpolation or constrained cubic interpolation. ### Claim 15 (depends on 1) Apparatus according to claim 1, wherein the determiner for determining the threshold curve is implemented to add an offset in the determination of the threshold curve, so that the threshold curve comprises an offset distance to the noise floor. ### Claim 16 (depends on 1) Apparatus according to claim 1, wherein the comparer is implemented to classify the channel as occupied when the current power of the receive power levels is higher than the reference power of the threshold curve. ### Claim 17 (depends on 1) Apparatus according to claim 1, wherein the comparer is implemented to determine an average value of the current power in the channel and an average value of the reference power in the channel, and to classify the channel as occupied when the average value of the current power is above the average value of the reference power. ### Claim 18 Method for frequency-selective occupancy detection of a channel in a frequency band, comprising: detecting a power spectrum density in the frequency band; providing node frequencies for a threshold curve with respect to a noise floor in the frequency band; determining node power levels at the node frequencies based on receive power levels of the power spectrum density, wherein the determining node power levels comprises integrating a previously determined node power level into the determination of a node power level currently to be determined such that heavily varying node power levels are attenuated; determining the threshold curve in the frequency band based on the provided node frequencies and on the node power levels at the node frequencies; and comparing a current power of receive power levels in the channel with a reference power in the channel predetermined by the threshold curve, in order to detect an occupancy or non-occupancy of the channel based on the comparison. ### Claim 19 (depends on 18) Method according to claim 18, wherein providing the node frequencies is performed such that a difference of adjacent node frequencies increases with increasing frequency in the frequency band by a factor of change. ### Claim 20 (depends on 18) Method according to claim 18, wherein the frequency band comprises an initial and a terminal frequency, and wherein providing the node frequencies is performed such that a first node frequency corresponds to the initial frequency and a last node frequency to the terminal frequency within a tolerance range. ### Claim 21 (depends on 18) Method according to claim 18, wherein determining node power levels further comprises forming a histogram of successive receive power levels, and further determining the node power levels by a power level with a certain distance to a lower power level limit. ### Claim 22 (depends on 18) Method according to claim 18, wherein determining the threshold curve further comprises interpolating between the node power levels, so that the threshold curve is determined by the interpolation. ### Claim 23 (depends on 18) Method according to claim 18, wherein comparing further comprises determining an average value of the current power in the channel and, further, of a further average value of the reference power in the channel, and the channel is classified as occupied when the average value of the current power is above the further average value of the reference power. ### Claim 24 A non-transitory computer-readable medium comprising a program code for causing a computer to perform a method for frequency-selective occupancy detection of a channel in a frequency band, the method comprising: detecting a power spectrum density in the frequency band; providing node frequencies for a threshold curve with respect to a noise floor in the frequency band; determining node power levels at the node frequencies based on receive power levels of the power spectrum density, wherein the determining node power levels comprises integrating a previously determined node power level into the determination of a node power level currently to be determined such that heavily varying node power levels are attenuated; determining the threshold curve in the frequency band based on the provided node frequencies and on the node power levels at the node frequencies, and comparing a current power of receive power levels in the channel with a reference power in the channel predetermined by the threshold curve, in order to detect an occupancy or non-occupancy of the channel based on the comparison.