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 |
20100150099 | Unified synchronous ranging channel structure and ranging code generation and detection in wireless OFDMA systems - A unified synchronous ranging channel is provided. The unified synchronous ranging channel has a ranging cyclic prefix length that is the same as a cyclic prefix length of a data channel. The unified synchronous ranging channel is used for one of initial ranging, handover ranging, and periodic ranging between a mobile station and a femto base station. In one embodiment, the synchronous ranging channel spans over a two-dimensional radio resource region having a first number of subcarriers along frequency domain, a second number of OFDM symbols along time domain, and a third number of time-domain repetition. At the transmit side, a ranging code sequence is generated by applying a fixed time-domain cyclic shift per OFDM symbol to a root sequence. At the receive side, the ranging code sequence is decoded by using a summation module, a likelihood-combining module, and a modified peak test module that normalizes a peak value. | 06-17-2010 |
20100150100 | Unified synchronous ranging channel design and allocation in wireless OFDMA systems - A unified synchronous ranging channel is provided. The unified synchronous ranging channel has a ranging cyclic prefix length that is the same as a cyclic prefix length of a data channel. The unified synchronous ranging channel is used for one of initial ranging, handover ranging, and periodic ranging between a mobile station and a femto base station. In one embodiment, the synchronous ranging channel spans over a two-dimensional radio resource region having a first number of subcarriers along frequency domain, a second number of OFDM symbols along time domain, and a third number of time-domain repetition. At the transmit side, a ranging code sequence is generated by applying a fixed time-domain cyclic shift per OFDM symbol to a root sequence. At the receive side, the ranging code sequence is decoded by using a summation module, a likelihood-combining module, and a modified peak test module that normalizes a peak value. | 06-17-2010 |
20100165942 | Synchronization channel for advanced wireless OFDM/OFDMA systems - A hierarchical downlink (DL) synchronization channel (SCH) is provided for wireless OFDM/OFDMA systems. The SCH includes a Primary SCH (P-SCH) for carrying PA-Preambles used for coarse timing and frequency synchronization, and a Secondary SCH (S-SCH) for carrying SA-Preambles used for cell ID detection. The total time length occupied by P-SCH and S-SCH is equal to one OFDM symbol time length of a data channel, and S-SCH is located in front of P-SCH in each DL frame. A perfect multi-period time-domain structure is created and maintained in P-SCH to increase preciseness of frame boundary estimation. With overlapping deployment of macrocells and femtocells, a predefined SCH configuration scheme is provided to separate frequency subbands used for macrocells and femtocells such that interferences in S-SCH can be mitigated. In addition, a self-organized SCH configuration scheme is provided to allow more flexibility for femtocells to avoid or introduce interference in S-SCH. | 07-01-2010 |
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 |
20100169722 | Channel interleaver having a constellation-based unit-wise permuation module - A channel interleaver comprises a novel constellation-based permutation module. The channel interleaver first receives a plurality of sets of encoded bits generated from an FEC encoder. The encoded bits are distributed into multiple subblocks and each subblock comprises a plurality of adjacent bits. A subblock interleaver interleaves each subblock and outputs a plurality of interleaved bits. The constellation-based permutation module rearranges the interleaved bits and outputs a plurality of rearranged bits. The rearranged bits are supplied to a symbol mapper such that a plurality of consecutively encoded bits in the same set of the encoded bits generated from the FEC encoder is prevented to be mapped onto the same level of bit reliability of a modulation symbol. In addition, the plurality of adjacent bits of each subblock is also prevented to be mapped onto the same level of bit reliability to achieve constellation diversity and to improve decoding performance. | 07-01-2010 |
20100169738 | Channel interleaver having a constellation-based block-wise permuation module - A channel interleaver comprises a novel constellation-based permutation module. The channel interleaver first receives a plurality of sets of encoded bits generated from an FEC encoder. The encoded bits are distributed into multiple subblocks and each subblock comprises a plurality of adjacent bits. A subblock interleaver interleaves each subblock and outputs a plurality of interleaved bits. The constellation-based permutation module rearranges the interleaved bits and outputs a plurality of rearranged bits. The rearranged bits are supplied to a symbol mapper such that a plurality of consecutively encoded bits in the same set of the encoded bits generated from the FEC encoder is prevented to be mapped onto the same level of bit reliability of a modulation symbol. In addition, the plurality of adjacent bits of each subblock is also prevented to be mapped onto the same level of bit reliability to achieve constellation diversity and to improve decoding performance. | 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 |
20100246508 | Low latency synchronization scheme for wireless OFDMA systems - In advanced wireless OFDMA communication systems, hierarchical synchronization is adopted to synchronize between a base station (BS) and a mobile station (MS). In a hierarchical synchronization architecture, primary advanced preamble (PA-Preamble) is used for coarse time domain synchronization while cell ID is detected using several accumulated secondary advanced preambles (SA-Preambles). Network entry latency can be reduced by adjusting the relative location of superframe header (SFH), PA-Preamble and SA-Preambles within a superframe. Three different synchronization channel (SCH) architectures are proposed to provide different tradeoffs between network entry latency and the robustness of SA-Preamble design and cell ID detection. | 09-30-2010 |
20110007690 | Preamble partition and cell identification procedure in wireless communication systems - Two preamble partition schemes are provided for flexible network deployment and efficient utilization of limited cell identification resources in a wireless network. In a soft partition scheme, the entire preamble sequences are partitioned into several configurable non-overlapping subsets, and each subset is associated with a corresponding cell type. In a hybrid partition scheme, a combination of fixed and configurable subsets is used for preamble partition. The partitioning information is carried in a broadcasting channel broadcasted from base stations to mobile stations. In one embodiment, after a mobile station performs scanning and synchronization with a first base station, it derives the cell type of the first base station from cell identification and partitioning information. The mobile station completes ranging and network entry with the first base station if the cell type is preferred, and starts to perform scanning and synchronization with a second base station if the cell type is non-preferred. | 01-13-2011 |
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 |
20110117926 | Network-based positioning mechanism and reference signal design in OFDMA systems - A network-based positioning mechanism is proposed. A serving BS first allocates radio resource to a target UE for network-based positioning in a wireless communication system. The target UE then transmits a positioning reference signal (PRS) to the serving BS and a plurality of cooperative BSs at the same time instant. All the cooperative BSs then conduct PRS detection and TOA measurements. Finally, the serving BS conducts positioning estimation based on the TOA measurement results. In one novel aspect, only one PRS transmission is required in one positioning opportunity for one positioning result. Candidates of PRS are selected with respect to different scenarios and allocated in a PRS resource region. Multiple positioning opportunities and multiple reference signals may be multiplexed over time, frequency or code domain in the PRS resource region. In one embodiment, the PRS is configured in such a way that both radio resource consumption and interference is minimized. | 05-19-2011 |
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 |
20110171949 | Two-step uplink synchronization for pico/femtocell - A two-step uplink synchronization method is provided for uplink synchronization between a mobile station and a pico/femto base station that is deployed together with an overlay macro/micro base station. In a first step, the pico/femto BS encodes and broadcasts UL transmission timing advance offset information via a broadcast channel. The MS decodes the received UL transmission timing advance offset information and advances its uplink timing for uplink ranging or reference signal transmission based on the decoded offset value. In a second step, the MS and the pico/femto BS performs regular uplink synchronization and uplink access. In one example, the UL transmission timing advance offset information indicates a round-trip propagation time of radio signals between the pico/femto base station and the overlay macro/micro base station. By using the two-step uplink synchronization method, a unified synchronous ranging channel may be used for ranging and UL access in pico/femtocells with reduced interference. | 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 |
20110310819 | Resource allocation of uplink HARQ feedback channel for carrier aggregation in OFDMA systems - An efficient uplink HARQ feedback channel resource allocation scheme is adopted for carrier aggregation in a multi-carrier LTE/LTE-A system. Two resource allocation schemes (e.g., explicit and hybrid) for HARQ ACK/NACK (A/N) are applied. Part of the resources is allocated based on explicit method via RRC configuration. Another part of the resources is allocated based on hybrid method via both RRC and implicit information carried by downlink schedulers. In an explicit method, the physical resource for A/N feedback information is determined based on a resource index in a DL scheduling grant. The DL grant corresponds to transport blocks over a configured CC. The resource index points to a physical resource from a set of candidate uplink A/N physical resources reserved for the CC. In an implicit method, the A/N physical resources are determined based on a logical address of the DL scheduling grant. | 12-22-2011 |
20110310820 | Uplink HARQ feedback channel design for carrier aggregation in OFDMA systems - HARQ feedback channel design for carrier aggregation (CA) is proposed in a multi-carrier LTE/LTE-A system. In one novel aspect, a predefined rule for HARQ feedback channel format switching is adopted by the system. Different HARQ formats are supported: single component carrier (non-CA) mode, carrier aggregation with small payload size (CA-S) mode, carrier aggregation with large payload size (CA-L) mode, and fallback mode. From the various CA and non-CA formats, the format to be used for uplink HARQ feedback channel is determined based on: UE capability for the maximum number of CCs supported; CC configuration information by RRC layer; and detection results of downlink schedulers. The CC configuration information may include the number of CCs that are configured and a specific HARQ format to be used. Because more reliable upper layer configuration is used to make the HARQ format-switching decision, the risk of UE and eNB mismatch is greatly reduced. | 12-22-2011 |