# US 9,520,972 B2 · Pilot signal transmission for an orthogonal frequency division wireless communication system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,520,972 B2 - Document ID: US9520972B2 - Status: Granted - Kind: B2 - Application number: 11/083,708 - Filed: 2005-03-17 - Published: 2006-09-21 - Granted: 2016-12-13 - Earliest claimed: 2005-03-17 - Assignees: QUALCOMM Incorporated - Applicants: Alexei Gorokhov; Ayman Fawzy Naguib; Arak Sutivong; Dhananjay Ashok Gore; Tingfang Ji - Inventors: Alexei Gorokhov; Ayman Fawzy Naguib; Arak Sutivong; Dhananjay Ashok Gore; Tingfang Ji - Web page: https://patentgrep.com/patent/US9520972B2 ## CPC - H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)} - H04L 5/0023: {Time-frequency-space} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Transmission patterns for pilot symbols transmitted from a mobile station or base station are provided. The pattern allows for improved receipt of the pilot symbols transmitted. In addition, schemes for improving the ability to multiplex pilot symbols without interference and/or biasing from different mobile stations over the same frequencies and in the same time slots. ## Claims ### Claim 1 A wireless communication apparatus, comprising: at least one antenna; a memory that stores: at least one time selective pilot pattern comprising first and second clusters of time selective pilot symbols, said at least one time selective pilot pattern corresponding to a plurality of pilot symbols located in pilot symbol clusters each of which comprises a plurality of contiguous pilot symbols spanning multiple frequency tones and one symbol period, wherein the first and second clusters of time selective pilot symbols have orthogonal pilot symbols, and wherein only one pilot symbol in each of the first and second clusters of time selective pilot symbols is assigned to a maximum or minimum frequency of a hop region and none of the pilot symbols in the first and second clusters of time selective pilot symbols are assigned to a first or last symbol period of the hop region, and at least one frequency selective pilot pattern comprising first and second clusters of frequency selective pilot symbols, said at least one frequency selective pilot pattern corressponding to another plurality of pilot symbols located in pilot symbol clusters each of which comprises a plurality of contiguous pilot symbols spanning multiple symbol periods and one frequency subcarrier, wherein the first and second clusters of frequency selective pilot symbols have orthogonal pilot symbols , and wherein only one pilot symbol in each of the first and second clusters of frequency selective pilot symbols is assigned to the first or last symbol period of the hop region and none of the pilot symbols in the first and second clusters of frequency selective pilot symbols are assigned to the maximum or minimum frequency of the hop region; and a processor coupled with the at least one antenna and the memory, the processor configured to select one pilot pattern of the at least one time selective pilot pattern or the at least one frequency selective pilot pattern, wherein the processor is configured to place the pilot symbols of the selected pilot pattern close to the edges of the hop region according to a first order approximation of a communications channel. ### Claim 2 (depends on 1) The wireless communication apparatus of claim 1, wherein the at least one time selective pilot pattern comprises a plurality of time selective pilot patterns, the at least one frequency selective pilot pattern comprises a plurality of frequency selective pilot patterns, and wherein the processor is configured to select at least one of the plurality of time selective pilot patterns or at least one of the plurality of frequency selective pilot patterns. ### Claim 3 (depends on 1) The wireless communication apparatus of claim 1, wherein the processor is adapted to select a time selective pilot pattern or a frequency selective pilot pattern based upon a parameter. ### Claim 4 (depends on 3) The wireless communication apparatus of claim 3, wherein the parameter comprises a predetermined threshold. ### Claim 5 (depends on 3) The wireless communication apparatus of claim 3, wherein the parameter is dynamically updated in response to a signal received at the wireless communication apparatus. ### Claim 6 (depends on 3) The wireless communication apparatus of claim 3, wherein the parameter comprises a pre-determined optimization of the network in which the wireless communication apparatus is to operate. ### Claim 7 (depends on 1) The wireless communication apparatus of claim 1, wherein the memory further stores a plurality of sequences that are orthogonal to each other sequence of the plurality of sequences and wherein the processor is configured to selectively instruct multiplication of the pilot symbols of the pilot pattern with some of the sequences of the plurality of sequences prior to transmission of the pilot pattern. ### Claim 8 (depends on 7) The wireless communication apparatus of claim 7, wherein the memory further stores another plurality of sequences and wherein the processor is configured to selectively instruct multiplication of the pilot symbols of the pilot pattern with both some of the sequences of the plurality of sequences and some of the another plurality of sequences prior to transmission of the pilot pattern. ### Claim 9 (depends on 1) The wireless communication apparatus of claim 1, wherein the memory is adapted to store a frequency selective pilot pattern having quasi-orthogonal pilot symbols. ### Claim 10 (depends on 1) The wireless communication apparatus of claim 1, wherein the memory is adapted to store a time selective pilot pattern having quasi-orthogonal pilot symbols. ### Claim 11 A method of pilot symbol transmission in a wireless communication system, comprising: obtaining information regarding channel conditions of a channel from at least one sector of a base station; determining a selectivity of the channel based upon the information; choosing a pattern of pilot symbols based upon the selectivity of the channel, wherein the pattern of pilot symbols is selected from at least one time selective pilot pattern comprising first and second clusters of time selective pilot symbols, said at least one time selective pilot pattern corresponding to a plurality of pilot symbols located in pilot symbol clusters each of which comprises a plurality of contiguous pilot symbols spanning multiple frequency tones and one symbol period, wherein the first and second clusters of time selective pilot symbols have orthogonal pilot symbols, and wherein only one pilot symbol in each of the first and second clusters of time selective pilot symbols is assigned to a maximum or minimum frequency of a hop region and none of the pilot symbols in the first and second clusters of time selective pilot symbols are assigned to a first or last symbol period of the hop region, and at least one frequency selective pilot pattern comprising first and second clusters of frequency selective pilot symbols, said at least one frequency selective pilot pattern corresponding to another plurality of pilot symbols located in pilot symbol clusters each of which comprises a plurality of contiguous pilot symbols spanning multiple symbol periods and one frequency subcarrier, wherein the first and second clusters of frequency selective pilot symbols have orthogonal pilot symbols, and wherein only one pilot symbol in each of the first and second clusters of frequency selective pilot symbols is assigned to the first or last symbol period of the hop region and none of the pilot symbols in the first and second clusters of frequency selective pilot symbols are assigned to the maximum or minimum frequency of the hop region; and placing the pilot symbols of the selected pilot pattern close to the edges of the hop region according to a first order approximation of a communications channel. ### Claim 12 (depends on 11) The method of claim 11, wherein in the step of determining the selectivity of the channel the channel is classified as frequency selective or time selective. ### Claim 13 (depends on 11) H The method of claim 11, wherein in the step of determining the selectivity of the channel, a frequency selectivity and a time selectivity is determined. ### Claim 14 (depends on 11) The method of claim 11, wherein in the step of choosing the pattern of clustered pilot symbols the clustered pilot symbols are optimized for one or both frequency selective and time selective conditions. ### Claim 15 (depends on 11) The method of claim 11, further comprising transmitting information indicating the pattern of clustered pilot symbols to a plurality of users so that the users transmit pilot symbols according to the pattern to the sector of the base station. ### Claim 16 A wireless communication apparatus capable of transmitting a plurality of symbols each of which is transmitted utilizing a frequency subcarrier of a group of contiguous frequency subcarriers that range from a minimum frequency to a maximum frequency and during a symbol period of a group of contiguous symbol periods that range from a first symbol period to a last symbol period, the wireless communication apparatus comprising: at least one antenna; a memory that stores a plurality of time selective pilot patterns comprising first and second clusters of time selective pilot symbols each comprising a plurality of clusters each of which comprises a plurality of contiguous pilot symbols located in pilot symbol clusters each of which comprises a plurality of contiguous pilot symbols spanning multiple frequency tones and one symbol period, wherein the first and second clusters of time selective pilot symbols have orthogonal pilot symbols, and wherein only one pilot symbol in each of the first and second clusters of time selective pilot symbols is assigned to a maximum or minimum frequency of a hop region and none of the pilot symbols in the first and second clusters of time selective pilot symbols are assigned to a first or last symbol period of the hop region, and at least one frequency selective pilot pattern comprising first and second clusters of frequency selective pilot symbols, the at least one frequency selective pilot pattern corresponding to another plurality of pilot symbols located in pilot symbol clusters each of which comprises a plurality of contiguous pilot symbols spanning multiple symbol periods and one frequency subcarrier, wherein the first and second clusters of frequency selective pilot symbols have orthogonal pilot symbols, and wherein only one pilot symbol in each of the first and second clusters of frequency selective pilot symbols is assigned to the first or last symbol period of the hop region and none of the pilot symbols in the first and second clusters of frequency selective pilot symbols are assigned to the maximum or minimum frequency of the hop region; and a processor coupled with the plurality of antennas and the memory, the processor configured to cause one pilot pattern of the plurality of pilot patterns to be transmitted from the at least one antenna during the group of contiguous symbol periods utilizing the group of contiguous frequency subcarriers, wherein the processor is configured to place the pilot pattern close to the edges of the hop region according to a first order approximation of a communications channel. ### Claim 17 (depends on 16) The wireless communication apparatus of claim 16, wherein the plurality of pilot patterns comprise at least one time selective pilot pattern and at least one frequency selective pilot pattern. ### Claim 18 (depends on 16) The wireless communication apparatus of claim 16, wherein the memory further stores a plurality of sequences that are orthogonal to each other sequence of the plurality of sequences and wherein the processor is configured to selectively instruct multiplication of the pilot symbols of the pilot pattern with some of the sequences of the plurality of sequences prior to decoding the pilot symbols. ### Claim 19 (depends on 16) The wireless communication apparatus of claim 16, wherein the memory further stores a plurality of sequences that are quasi-orthogonal to each other sequence of the plurality of sequences and wherein the processor is configured to selectively instruct multiplication of the pilot symbols of the pilot pattern with some of the sequences of the plurality of sequences prior to decoding the pilot symbols. ### Claim 20 (depends on 19) The wireless communication apparatus of claim 19, wherein the memory further stores another plurality of sequences and wherein the processor is configured to selectively instruct multiplication of the pilot symbols of the pilot pattern with both some of the sequences of the plurality of sequences and some of the another plurality of sequences prior to decoding the pilot symbols. ### Claim 21 (depends on 16) The wireless communication apparatus of claim 16, wherein the processor is configured to select selects the pilot pattern to be transmitted based upon an instruction received at the at least one antenna. ### Claim 22 (depends on 16) The wireless communication apparatus of claim 16, wherein the at least one antenna comprises a plurality of antennas and wherein the processor is configured to cause multiple pilot patterns of the plurality of pilot patterns to be transmitted from the multiple antennas during the group of contiguous symbol periods utilizing the group of contiguous frequency subcarriers. ### Claim 23 (depends on 22) The wireless communication apparatus of claim 22, wherein the memory further stores a plurality of sequences that are orthogonal to each other sequence of the plurality of sequences and wherein the processor is configured to selectively instruct multiplication of the pilot symbols of each of the multiple pilot pattern with a different sequences of the plurality of sequences prior to transmission of the multiple pilot patterns. ### Claim 24 (depends on 16) The wireless communication apparatus of claim 16, wherein the processor is configured to utilize one pilot pattern of the plurality of pilot patterns to decode multiple pilot symbol groups transmitted by a plurality of wireless devices and received at the at least one antenna. ### Claim 25 A non-transitory computer readable medium encoded with computer executable instructions for reading a data packet for transmission in a wireless network, the data packet including a preamble portion that identifies a cluster pilot pattern having a plurality of time or frequency selective clusters to be transmitted by a receiver of the data packet including at least one each of a frequency-selective pilot pattern or a time-selective pilot pattern, wherein the time selective pattern comprises first and second clusters of time selective pilot symbols and the first and second clusters of time selective pilot symbols have orthogonal pilot symbols, and wherein only one pilot symbol in each of the first and second clusters of time selective pilot symbols is assigned to a maximum or minimum frequency of a hop region and none of the pilot symbols in the first and second clusters of time selective pilot symbols are assigned to a first or last symbol period of the hop region, and wherein the frequency selective pilot pattern comprises first and second clusters of frequency selective pilot symbols and the first and second clusters of frequency selective pilot symbols have orthogonal pilot symbols, and wherein only one pilot symbol in each of the first and second clusters of frequency selective pilot symbols is assigned to the first or last symbol period of the hop region and none of the pilot symbols in the first and second clusters of frequency selective pilot symbols are assigned to the maximum or minimum frequency of the hop region, and instructions for placing the symbols of the cluster pilot pattern close to the edges of the hop region according to a first order approximation of a communications channel. ### Claim 26 (depends on 25) The computer readable medium of claim 25, wherein the computer executable instructions are adapted to read a packet having a preamble portion that includes information as to which sequence of a plurality of orthogonal sequences available at a receiver is to be utilized by the receiver of the data packet to multiply the samples that comprise pilot symbols of the pilot pattern prior to transmission of the pilot symbols by the receiver of the data packet. ### Claim 27 A non-transitory computer readable medium encoded with: computer executable instructions for pilot symbol transmission in a wireless communication system, the computer executable instructions comprising: instructions for obtaining information regarding channel conditions from at least a sector of a base station; instructions for determining, based upon the information, a selectivity of the channel; instructions for setting a pattern of pilot symbols having a plurality of time or frequency selective clusters based upon the selectivity of the channel, wherein the time selective pattern comprises first and second clusters of time selective pilot symbols and the first and second clusters of time selective pilot symbols have orthogonal pilot symbols, and wherein only one pilot symbol in each of the first and second clusters of time selective pilot symbols is assigned to a maximum or minimum frequency of a hop region and none of the pilot symbols in the first and second clusters of time selective pilot symbols are assigned to a first or last symbol period of the hop region, and wherein the frequency selective pilot pattern comprises first and second clusters of frequency selective pilot symbols and the first and second clusters of frequency selective pilot symbols have orthogonal pilot symbols, and wherein only one pilot symbol in each of the first and second clusters of frequency selective pilot symbols is assigned to the first or last symbol period of the hop region and none of the pilot symbols in the first and second clusters of frequency selective pilot symbols are assigned to the maximum or minimum frequency of the hop region; and instructions for placing the pattern of pilot symbols close to the edges of the hop region according to a first order approximation of a communications channel. ### Claim 28 A processing system comprising: an input port; an output port; and processing circuitry configured to: obtain information from an input port regarding channel conditions from at least a sector of a base station; determine, based upon the information, a selectivity of the channel; set a pattern of clustered pilot symbols having a plurality of time or frequency selective clusters based upon the selectivity of the channel and to output a selection of the set pattern of pilot symbols through the output port, wherein the time selective pattern comprises first and second clusters of time selective pilot symbols and the first and second clusters of time selective pilot symbols have orthogonal pilot symbol , and wherein only one pilot symbol in each of the first and second clusters of time selective pilot symbols is assigned to a maximum or minimum frequency of a hop region and none of the pilot symbols in the first and second clusters of time selective pilot symbols are assigned to a first or last symbol period of the hop region, and wherein the frequency selective pilot pattern comprises first and second clusters of frequency selective pilot symbols and the first and second clusters of frequency selective pilot symbols have orthogonal pilot symbols, and wherein only one pilot symbol in each of the first and second clusters of frequency selective pilot symbols is assigned to the first or last symbol period of the hop region and none of the pilot symbols in the first and second clusters of frequency selective pilot symbols are assigned to the maximum or minimum frequency of the hop region; and place the pilot pattern of pilot symbols close to the edges of the hop region according to a first order approximation of a communications channel. ### Claim 29 A non-transitory computer-readable medium encoded with instructions for processing a communication signal, the instructions comprising code for: obtaining information regarding channel conditions from at least a sector of a base station; determining, based upon the information, a selectivity of the channel; setting a pattern of pilot symbols having a plurality of time or frequency selective clusters based upon the selectivity of the channel, wherein the time selective pattern comprises first and second clusters of time selective pilot symbols and the first and second clusters of time selective pilot symbols have orthogonal pilot symbols, and wherein only one pilot symbol in each of the first and second clusters of time selective pilot symbols is assigned to a maximum or minimum frequency of a hop region and none of the pilot symbols in the first and second clusters of time selective pilot symbols are assigned to a first or last symbol period of the hop region, and wherein the frequency selective pilot pattern comprises first and second clusters of frequency selective pilot symbols and the first and second clusters of frequency selective pilot symbols have orthogonal pilot symbols, and wherein only one pilot symbol in each of the first and second clusters of frequency selective pilot symbols is assigned to the first or last symbol period of the hop region and none of the pilot symbols in the first and second clusters of frequency selective pilot symbols are assigned to the maximum or minimum frequency of the hop region; and placing the pattern of pilot symbols close to the edges of the hop region according to a first order approximation of a communications channel.