# US 8,570,889 B2 · Filter or amplifier adaptation by an intermediate device in a multi-hop system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,570,889 B2 - Document ID: US8570889B2 - Status: Granted - Kind: B2 - Application number: 12/992,322 - Filed: 2008-07-04 - Published: 2011-03-17 - Granted: 2013-10-29 - Earliest claimed: 2008-07-04 - Assignees: Telefonaktiebolaget L M Ericsson (publ) - Applicants: Jiansong Gan; Peter Larsson; Qingyu Miao - Inventors: Jiansong Gan; Peter Larsson; Qingyu Miao - Web page: https://patentgrep.com/patent/US8570889B2 ## CPC - H04L 1/0001: {Systems modifying transmission characteristics according to link quality, e.g. power backoff (adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04)} - H04L 25/0202: {Channel estimation} - H04L 25/03343: {Arrangements at the transmitter end} - H04L 2001/0097: {Relays} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A method is performed by an intermediate device in a wireless network. The method includes estimating a first hop channel state based on a transmission originating from a first device. The method further includes estimating an end-to-end signal-to-noise ratio base on a transmission associated with a second device. The method also includes adapting a filter or an amplifier of the intermediate device based on the first hop channel state and the end-to-end signal-to-noise ratio. ## Claims ### Claim 1 A method performed by an intermediate device in a wireless network including a first hop between a first device and the intermediate device, and a second hop between the intermediate device and a second device, the method comprising: estimating a first hop channel state based on a transmission associated with the first device; estimating an end-to-end signal-to-noise ratio based on a transmission associated with the second device; and adapting a filter or an amplifier of the intermediate device based on the first hop channel state and the end-to-end signal-to-noise ratio. ### Claim 2 (depends on 1) The method of claim 1, further comprising: estimate a first hop channel matrix based on the first hop channel state. ### Claim 3 (depends on 2) The method of claim 2, further comprising: performing an eigenvalue decomposition based on the first hop channel matrix. ### Claim 4 (depends on 1) The method of claim 1, further comprising: maximizing a performance metric associated with the first hop channel matrix and the end-to-end signal-to-noise ratio. ### Claim 5 (depends on 4) The method of claim 4, where the performance metric includes channel capacity. ### Claim 6 (depends on 4) The method of claim 4, where the maximizing includes applying a water-filling principle. ### Claim 7 (depends on 1) The method of claim 1, where the intermediate device includes a multiple-input multiple-output antenna system. ### Claim 8 (depends on 1) The method of claim 1, where the wireless network includes a time division duplex system where channel reciprocity exists between the first device and the second device. ### Claim 9 (depends on 8) The method of claim 8, further comprising: estimating channel statistic information of the second hop based on the channel reciprocity; and estimating a covariance matrix based on the channel statistic information. ### Claim 10 (depends on 9) The method of claim 9, further comprising: performing a singular value decomposition of the covariance matrix; and utilizing a resultant of the singular value decomposition to calculate a filter matrix. ### Claim 11 (depends on 1) The method of claim 1, where the first device includes a base station. ### Claim 12 (depends on 1) The method of claim 1, where the second device includes a user terminal. ### Claim 13 (depends on 1) The method of claim 1, where the intermediate device operates according to a long term evolution standard. ### Claim 14 An intermediate device in a wireless environment including a first hop between a first device and the intermediate device and a second hop between the intermediate device and a second device, the intermediate device comprising: one or more antennas; and a processing system configured to: estimate a first hop channel state based on a transmission from the first device; estimate an end-to-end signal-to-noise ratio or a second hop signal-to-noise ratio based on a transmission from the second device; and adapt a filter or an amplifier based on the first hop channel state and at least one of the end-to-end signal-to-noise ratio or the second hop signal-to-noise ratio. ### Claim 15 (depends on 14) The intermediate device of claim 14, where the intermediate device includes a repeater having a multiple-input multiple output antenna system. ### Claim 16 (depends on 14) The intermediate device of claim 14, where channel reciprocity exists between the first device and the second device and where the processing system is further configured to: estimate channel statistic information of the second hop based on the channel reciprocity. ### Claim 17 (depends on 16) The intermediate device of claim 16, where the processing system is further configured to: estimate a covariance matrix based on the channel statistic information. ### Claim 18 (depends on 17) The intermediate device of claim 17, where the processing system is further configured to: perform a singular value decomposition of the correlation matrix; and determine an orthogonal matrix. ### Claim 19 (depends on 18) The intermediate of claim 18, where the adapting of the filter or the amplifier is based on the orthogonal matrix. ### Claim 20 (depends on 14) The intermediate device of claim 14, where the processing system is further configured to: estimate a first hop channel matrix based on the first hop channel state; and perform an eigenvalue decomposition based on the first hop channel matrix. ### Claim 21 (depends on 20) The intermediate device of claim 20, where the processing system is further configured to: calculate a diagonal filter matrix based on a resultant of the eigenvalue decomposition. ### Claim 22 (depends on 21) The intermediate device of claim 21, where the processing system is further configured to: calculate a filter matrix based on the diagonal filter matrix and the resultant of the eigenvalue decomposition. ### Claim 23 A computer program including instructions stored on non-transient computer readable media which, when executed, perform the acts of: estimating a first hop channel state based on a received first hop transmission; estimating second hop signal-to-noise ratio or an end-to-end signal-to-noise ratio based on a received second hop transmission; and adapting at least one of a filter or an amplification parameter based on the first hop channel state and at least one of the second hop signal-to-noise ratio or the end-to-end signal-to-noise ratio. ### Claim 24 (depends on 23) The computer program of claim 23, where the computer program is stored on a computer-readable medium of an intermediate forwarding device operating in a multi-hop wireless network. ### Claim 25 (depends on 1) The method of claim 1, further comprising configuring a filter matrix of the filter or the amplifier of the intermediate device based on the first hop channel state and the end-to-end signal-to-noise ratio. ### Claim 26 (depends on 14) The intermediate device of claim 14, where the processing system is configured to configure a filter matrix of the filter or the amplifier of the intermediate device based on the first hop channel state and the end-to-end signal-to-noise ratio. ### Claim 27 (depends on 23) The computer program of claim 23, wherein when executed the instructions perform the act of configuring a filter matrix of the filter or the amplifier of the intermediate device based on the first hop channel state and the end-to-end signal-to-noise ratio.