摘要:
In MIMO wireless communications employing LMMSE receiver, the symbols transmitted through a transmit antenna are estimated at the receiver in the presence of interference consisting of two main components: one due to the additive noise and the other due to (interfering) symbols transmitted via the remaining antennas. This has been shown to hamper the performance of a communication system resulting in incorrect symbol decisions, particularly at low SNR. IMMSE has been devised as a solution to cope with this problem; In IMMSE processing, the symbols sent via each transmit antenna are decoded iteratively. In each stage of processing, the received signal is updated by removing the contribution of symbols detected in the previous iterations. In principle, this reduces the additive interference in which the desired symbols are embedded in. Therefore, the interference level should reduce monotonically as one goes down in processing order. In a noisy environment, however, any incorrect decision made on a symbol in an iteration leaves its contribution in the updated received signal available for processing in the following iterations. Fortunately, if the level of interference is estimated and the soft bits are scaled appropriately by the estimated interference power, the performance of IMMSE receiver can be greatly improved. Preferred embodiments estimate the interference by computing the probability of error in decoding the symbols of the previous stage(s). The computation of decision error probability depends on the constellation size of transmitted symbols and introduces very little processing overhead.
摘要:
In MIMO wireless communications employing LMMSE receiver, the symbols transmitted through a transmit antenna are estimated at the receiver in the presence of interference consisting of two main components: one due to the additive noise and the other due to (interfering) symbols transmitted via the remaining antennas. This has been shown to hamper the performance of a communication system resulting in incorrect symbol decisions, particularly at low SNR. IMMSE has been devised as a solution to cope with this problem; In IMMSE processing, the symbols sent via each transmit antenna are decoded iteratively. In each stage of processing, the received signal is updated by removing the contribution of symbols detected in the previous iterations. In principle, this reduces the additive interference in which the desired symbols are embedded in. Therefore, the interference level should reduce monotonically as one goes down in processing order. In a noisy environment, however, any incorrect decision made on a symbol in an iteration leaves its contribution in the updated received signal available for processing in the following iterations. Fortunately, if the level of interference is estimated and the soft bits are scaled appropriately by the estimated interference power, the performance of IMMSE receiver can be greatly improved. Preferred embodiments estimate the interference by computing the probability of error in decoding the symbols of the previous stage(s). The computation of decision error probability depends on the constellation size of transmitted symbols and introduces very little processing overhead.
摘要:
A device and a method of characterizing a communications channel. The method includes transmitting a first part of a packet preamble using two or more antennas and transmitting a second part of the packet preamble using the two or more antennas. Each antenna transmits an orthogonal encoding of the second part of the packet preamble. The method also includes transmitting a packet header using the two or more antennas and transmitting a packet payload using the two or more antennas. Each antenna transmits an orthogonal encoding of the packet header. The packet payload may be encoded across the transmissions of the two or more antennas.
摘要:
A Hybrid IMMSE-LMMSE receiver processing technique predicts performance of and selects between iterative and non-iterative decoding of symbols based on an intelligent metric. Based on a pre-specified criterion, the receiver determines if a correct first-stage decision is made or not. If a correct decision is made, then it follows iterative processing like in BLAST. Alternatively, if a wrong decision is found to have occurred, the receiver resorts to LMMSE estimation processing.
摘要:
A resynchronization method for use in a data communication system having a first device configured to transmit data at a symbol rate to a second device. The second device includes a Reed Solomon (RS) decoder having a RS lock indicator and a Moving Picture Experts Group (MPEG) Protocol Interface (MPI) having a MPI lock indicator, wherein the RS and the MPI lock indicators are monitored. Four different states, defined by the values of the RS and MPI lock indicators, determine whether the data communication system will wait for the RS decoder and the MPI hardware block to resynchronize, whether an intermediate-subset of the channel acquisition algorithm is performed or whether the entire channel acquisition algorithm is performed. The method for resynchronization described herein recovers synchronization within a predetermined time without the layers above the physical link layer having knowledge.
摘要:
A resynchronization method for use in a data communication system having a first device configured to transmit data at a symbol rate to a second device. The second device includes a Reed Solomon (RS) decoder having a RS lock indicator and a Moving Picture Experts Group (MPEG) Protocol Interface (MPI) having a MPI lock indicator, wherein the RS and MPI lock indicators are monitored. Four different states, defined by the values of the RS and MPI lock indicators, determine whether the data communication system will wait for the RS decoded and the MPI hardware block to resynchronize, whether an intermediate-subset of the channel acquisition algorithm is performed or whether the entire channel acquisition algorithm is performed. The method of resynchronization described herein recovers synchronization within a predetermined time without the layers above the physical link layer having knowledge.
摘要:
For use with a multiple-input, multiple-output (MIMO) transmitter, a signal field controller, a method of controlling signal fields and a MIMO transmitter incorporating the controller or the method. In one embodiment, the controller includes: (1) a primary signal field mode indicator configured to cause a primary signal field to indicate a presence of a supplemental signal field and provide the primary signal field to the MIMO transmitter for transmission thereby and (2) a supplemental signal field generator coupled to the primary signal field mode indicator and configured to provide a supplemental signal field to the MIMO transmitter for further transmission thereby only when the primary signal field indicates the presence.
摘要:
The present invention provides a versatile system for selectively spreading carrier data across multiple carrier paths within an Orthogonal Frequency Division Multiplexing (OFDM) system (200), particularly an ultra-wideband (UWB) system. The present invention provides a data input (202), which passes data to a randomizer (204). The data then passes to a convolutional code function (206), the output of which is punctured by puncturing function (208). An interleaver function (210) receives the punctured code data, and cooperatively operates with a mapper element (218) to prepare the coded data for pre-transmission conversion by an IFFT (220). The mapper element (218) comprises a dual carrier modulation function (216), which associates and transforms two punctured code data elements into a format for transmission on two separate signal tones.
摘要:
The present invention provides a versatile system for selectively spreading carrier data across multiple carrier paths within an Orthogonal Frequency Division Multiplexing (OFDM) system, particularly an ultra-wideband (UWB) system. The present invention provides a data input, which passes data to a randomizer. The data then passes to a convolutional code function, the output of which is punctured by puncturing function. An interleaver function receives the punctured code data, and cooperatively operates with a mapper element to prepare the coded data for pre-transmission conversion by an IFFT. The mapper element comprises a dual carrier modulation function, which associates and transforms two punctured code data elements into a format for transmission on two separate signal tones.
摘要:
The present invention provides a versatile system for selectively spreading carrier data across multiple carrier paths within an Orthogonal Frequency Division Multiplexing (OFDM) system, particularly an ultra-wideband (UWB) system. The present invention provides a data input, which passes data to a randomizer. The data then passes to a convolutional code function, the output of which is punctured by puncturing function. An interleaver function receives the punctured code data, and cooperatively operates with a mapper element to prepare the coded data for pre-transmission conversion by an IFFT. The mapper element comprises a dual carrier modulation function, which associates and transforms two punctured code data elements into a format for transmission on two separate signal tones.