Patent application number | Description | Published |
20090257342 | Resource block based pilot pattern design for 1/2 - stream mimo ofdma systems - In OFDMA wireless communications systems, pilot pattern design is optimized based on predefined resource block size. The number of pilots and the spacing between pilots within a resource block is determined based on a set of system requirements. In one novel aspect, pilots are allocated within a resource block to avoid channel extrapolation in both frequency domain and time domain. First, four pilots are positioned at four corners of the resource block. Next, the remaining pilots are maximally evenly distributed within the resource block along both the frequency domain and the time domain. Finally, it is verified that an approximately equal number of pilots are evenly distributed along the time domain with respect to each data stream to minimize power fluctuation. For uplink transmission, one or more frequency tones at one or more edges of the resource block are reserved to be pilot-free to reduce multiuser synchronization error effect. | 10-15-2009 |
20090257519 | Pilot pattern design for high-rank MIMO OFDMA systems - In OFDMA wireless communications systems, pilot pattern design is optimized based on predefined resource block size. The number of pilots and the spacing between pilots within a resource block is determined based on a set of system requirements. In one novel aspect, in a high-rank MIMO system, pilots are allocated within a resource block to avoid channel extrapolation in frequency domain only. Because high-rank MIMO only supports low-mobility environment, time-domain extrapolation is no longer a dominant factor. For uplink transmission, one or more frequency tones at one or more edges of the resource block are reserved to be pilot-free to reduce multiuser synchronization error effect. When continuous resource blocks are jointly used for channel estimation, the upper and lower edges of each resource block are left with blanks such that edge pilots of adjacent resource blocks are not too close to each other to improve channel estimation. | 10-15-2009 |
20090257520 | Pilot pattern design for small size resource block in OFDMA systems - In OFDMA wireless communications systems, pilot pattern design is optimized based on predefined resource block size. The number of pilots and the spacing between pilots within a resource block is determined based on a set of system requirements. In one novel aspect, if resource block size is smaller than three in either frequency or time domain, then the pilots are allocated such that average pilot-to-data distance is minimized and that pilot-to-pilot distance is as large as possible. In one example, m pilots are allocated in an i×j resource block. The resource block is partitioned into n equal sub blocks, where m is a multiple of n. Within each sub block, m/n pilots are positioned such that average pilot-to-data distance is minimized. On the other hand, if resource block size is larger than or equal to three in both frequency and time domain, then pilots are allocated to avoid channel extrapolation. | 10-15-2009 |
20100104036 | Contention-based access channel design in mimo OFDM/OFDMA systems - A contention-based multi-antenna access request transmission/receiving procedure in MIMO OFDM/OFDMA systems is provided to reduce access latency. A mobile station encodes and transmits an access request over a shared access channel using multiple transmitting antennas, while a base station receives and decodes a number of access requests using multiple receiving antennas. Each access request comprises an access indictor and an access message. In a first MIMO scheme, the mobile station transmits the access indicator as preambles, while the access message is encoded by SFBC/STBC to obtain spatial diversity. At the receive side, the access indicator is exploited as pilots for channel estimation. The access message is decoded using SFBC/STBC decoding algorithm. In a second MIMO scheme, the mobile station performs precoding/beamforming for each of the transmitting antenna to obtain beamforming gain, while the base station performs virtual beam matching based on the detection results of the access indicators. | 04-29-2010 |
20100165954 | Physical structure and sequence design of midamble in OFDMA systems - In wireless OFDMA systems, midamble is used to facilitate downlink (DL) channel estimation. Midamble signals are transmitted by a base station via a midamble channel allocated in a DL subframe. In a novel symbol-based midamble channel allocation scheme, a midamble channel is allocated in the first or the last OFDM symbol of multiple resource blocks of the subframe, while the remaining consecutive OFDM symbols are used for data transmission. The symbol-based midamble channel provides good coexistence between midamble signals and pilot signals without inducing additional limitation or complexity. Under a novel midamble channel and sequence arrangement, both code sequence and either time-domain or frequency-domain location degrees-of-freedom are considered such that the required number of midamble sequences is substantially smaller than the number of strong interferences. In addition, different midamble sequences are systematically generated based on a base sequence such that the receiving mobile station does not need to memorize all the different code sequences. | 07-01-2010 |
20100165972 | Physical structure and design of sounding channel in OFDMA systems - In wireless OFDMA systems, sounding channels are allocated within predefined resource blocks. In a distributed sounding channel allocation scheme, a sounding channel is allocated to meet various design considerations. First, sounding signals do not collide with original pilots transmitted in the same resource block by other mobile stations to achieve good quality channel estimation. Second, sounding pattern does not affect data transmission behavior of other mobile stations in the same resource block. Third, sounding pattern consistency among multiple tiles within each resource block is maintained so that mobile stations do not need to implement additional data mapping rules. In a symbol-based sounding channel allocation scheme, a sounding channel is allocated in the first or the last OFDM symbol of a resource block, while the remaining consecutive OFDM symbols are used for data transmission. The symbol-based sound channel naturally satisfies all design considerations. | 07-01-2010 |
20100220651 | Method and apparatus for broadcasting and receiving system information in OFDMA systems - A method for broadcasting system information via a broadcast channel (BCH) in an OFDMA system is provided. The BCH comprises one or more two-dimensional resource blocks. A plurality of pilot tones and a plurality of data tones are positioned within each resource block. The system information is mapped onto the plurality of data tones. In one embodiment, the plurality of pilot tones are located in configurable positions such that pilot tones of the same resource blocks transmitted by different base stations in the OFDMA system are interlaced to reduce pilot-to-pilot collision. In another embodiment, data tones that are located in pilot positions of other adjacent cells are nullified to reduce data-to-pilot collision. In one novel aspect, the property of interlaced pilot patterns and tone nullification is leveraged to estimate interference second-order statistics, which facilitates receiver implementation and improves receiver performance. | 09-02-2010 |
20110080901 | Concatenating precoder selection for OFDMA-based multi-BS MIMO - A method of concatenating precoder selection is provided for OFDMA-based multi-BS multiple-input multiple-output (MIMO). A cell-edge mobile station first determines a precoding matrix indexes (PMIs) for a serving base station and one or more cooperative base stations to optimize system performance. The mobile station then determines a plurality of corresponding weight factors for each of the base stations to further optimize system performance. The mobile station recommends the selected PMIs and weight factors to the serving base station, which shares the PMIs and weight factors with the cooperative base stations. Each base station then applies precoding using the recommended PMIs and weight factors. The weight factors are quantized to reduce computation complexity and to facilitate information feedback. In one embodiment, the weight factors are determined based on a pre-defined 3-bit uniform phase quantization rule. The concatenated precoder leads to large performance gain without introducing high computation complexity. | 04-07-2011 |
20110170497 | Resource allocation and signaling method for multi-antenna LTE sounding - A method of multi-antenna resource allocation for uplink channel sounding in a wireless communication system is provided. A base station (eNB) first selects a number of sounding reference signal (SRS) parameters. The eNB then determines each selected SRS parameter for a first antenna of a user equipment (UE) having multiple antennas. The determined parameters are jointly encoded to a first set of parameter combination using a number of signaling bits. The eNB transmits the signaling bits for the first antenna to the UE without transmits additional signaling bits for other antennas. The UE receives the signaling bits for SRS resource allocation for the first antenna and derives a second set of parameter combination for a second antenna based on a predetermined rule. By implicitly signaling SRS resource allocation for multiple antennas, it is easy for the eNB to allocate SRS resource for different antennas of different UEs with reduced overhead. | 07-14-2011 |
20110171964 | Resource allocation and signaling method for LTE sounding - A method of resource allocation for uplink channel sounding in a wireless communication system is provided. A base station (eNB) first selects a number of sounding reference signal (SRS) parameters. The eNB then determines a deviation set for each selected SRS parameter and jointly encodes the selected number of SRS parameters using a number of signaling bits. The signaling bits are transmitted to a user equipment (UE) for uplink channel sounding. Based on system requirements, some parameter combinations are filtered out and only necessary parameter combinations are jointly encoded such that the number of signaling bits is limited to a predefined number. In one embodiment, the signaling bits are contained in downlink control information (DCI) via a physical downlink control channel (PDCCH) for triggering Aperiodic SRS (ap-SRS). By jointly encoding selected SRS parameters, the eNB can dynamically configure ap-SRS parameters and resources for each UE with high flexibility and efficiency. | 07-14-2011 |
20110243080 | Methods of contention-based transmission - A method for contention-based (CB) uplink transmission in a wireless communication network is provided. A base station (eNB) first transmits CB configuration information and CB grant to a user equipment (UE). The UE derives a plurality of transmission opportunities from the uplink CB grant and in response transmits uplink CB data via one of the transmission opportunities. The UE then receives an acknowledgment from the serving base station. If the uplink CB data is non-decodable by the eNB due to multiple contention UEs, then the UE retransmits the uplink data in response to a negative acknowledgment. In one novel aspect, the uplink transmission radio resource carriers both the uplink CB data and UE-selected signature information. In one embodiment, the UE-selected signature information is transmitted via pilot tones. By eliminating a separate phase of contention resolution, the overall latency of CB transmission is reduced and transmission efficiency is improved. | 10-06-2011 |
20110310818 | Sounding mechanism under carrier aggregation - Sounding mechanism for LTE-A systems under carrier aggregation is provided. A UE receives an uplink or downlink grant transmitted from an eNB over a primary carrier in a multi-carrier LTE-A system. The UE determines indicated carrier(s) and detects a triggering condition for aperiodic sounding transmission in the grant. The UE then selects UE-specific sounding reference signal (SRS) parameters. Finally, the UE transmits an aperiodic SRS (ap-SRS) over the indicated carrier(s) using the selected UE-specific SRS parameters. In one embodiment, the uplink or downlink grant is transmitted via a PDCCH carrying various DCI formats. Each DCI format contains a carrier indicator field (CIF) that indicates which carrier is used for ap-SRS transmission if cross-carrier scheduling is enabled. In another embodiment, DCI format 3/3A is transmitted via a PDCCH carrying a plurality of information fields, each field indicates if the UE should enable ap-SRS in a particular carrier. | 12-22-2011 |
20120044906 | Sounding mechanism and configuration under carrier aggregation - A method of multi-set RRC signaling for ap-SRS configuration is provided to enhance ap-SRS flexibility. An eNB transmits a plurality of sets of UE-specific SRS parameters to a UE via upper layer messaging in a multi-carrier wireless communication system. The eNB also determines triggering information of a selected set of UE-specific SRS parameters and an indicated carrier for the UE. The eNB then transmits an uplink or downlink grant over a primary carrier, the grant comprises triggering information for the UE to send an ap-SRS over the indicated carrier using the selected set of UE-specific SRS parameters. In one embodiment of joint signaling, the plurality of sets of UE-specific SRS parameters are signaled together in a single RRC transmission. In another embodiment of separate signaling, each set of UE-specific SRS parameters is signaled independently. | 02-23-2012 |
20130237260 | METHOD FOR SUPPRESSING TRANSMISSION NOISE COMPRISED IN RECEIVED DOWNLINK SIGNAL AND COMMUNICATIONS APPARATUS UTILIZING THE SAME - A communications apparatus is disclosed. A first radio module provides a first wireless communications service and communicates with a first communications device in compliance with a first protocol. A second radio module provides a second wireless communications service and communicates with a second communications device in compliance with a second protocol. A transmission noise suppression device is operative to process downlink signals received by the first radio module to cancel transmission noise comprised in the downlink signals, where the transmission noise is generated when the second radio module is processing uplink signals to be transmitted. | 09-12-2013 |