摘要:
To quickly and robustly detect the presence of an incumbent user and rapidly relinquish the spectrum to the incumbent user when necessary, carrier recovery is performed in a receiver of the secondary user's cognitive or software radio prior to performing correlation detection with an upsampled reference signal to correct for large frequency offsets and improve the performance of the correlation detector. To detect a received signal, a pilot value is added to a reference signal. The reference signal is upsampled to a sampling frequency of the received signal. The upsampled reference signal is correlated with a demodulated baseband signal to produce a correlation value. It is then determined whether the received signal is present if the correlation value is greater than a predetermined detection threshold value.
摘要:
A method (900) for medium access reservation in a multiband wireless network comprises determining available slots (220) for reservation in a superframe (210) for reservation across multiple channels (S910); generating channel reservation protocol (CRP) availability information element (IE) (310) to indicate the available slots on a main channel; generating one or more Extended-Channel CRP availability IEs (500) to indicate the available slots on one or more respective extended channels (S920); exchanging the CRP availability IE and the Extended-Channel CRP availability IEs between a receiving device and a transmitting device (S930); and generating a Multiband CRP IE (600) to reserve slots that are available on the receiving device and the transmitting device (S940).
摘要:
A centralized frequency agility technique is employed in conjunction with a plurality of medical body area network (MBAN) systems (10, 35, 36), each of which comprises a plurality of network nodes (12, 14) intercommunicating via short range wireless communication. A central network (20, 22, 23, 24) communicates with the MBAN systems via longer range communication that is different from the short range wireless communication. A central frequency agility sub-system (40) is configured to communicate with the MBAN systems. The central frequency agility sub-system receives current channel quality information for a plurality of available channels for the short range wireless communication, and allocates the MBAN systems amongst the available channels based at least on the received current channel quality information.
摘要:
A method (400) and apparatus for encoding a block-based communication system header. A physical (PHY) layer header and a medium access control (MAC) header of the block-based communication system header are encoded to generate parity bits, wherein the PHY layer header includes at least cyclic prefix (CP) mode bits (S410). Parity bits are appended to the PHY layer header and the MAC layer header to generate a bit vector (S420). The bit vector is divided into at least two data blocks, wherein a first data block includes at least the CP mode bits (S430). A predefined number of tail bits are appended to each data block (S440). The two data blocks are mapped into at least two symbols, wherein the first data block is mapped to a first symbol, such that the first symbol is a first header symbol being transmitted (S450).
摘要:
A system and method for a simplified Maximum Likelihood (ML) decoding (203) for MIMO systems is provided. The full ML decoding gives the lower bound of the decoding for CC coded MIMO systems. However, the computation cost is too high to be implemented in real system. Many alternative methods have been proposed for the decoding. Among them, weighted Zero Forcing (WZF) is one that can give affordable performance with reasonable computation complexity but there are several dB of performance gap for the WZF decoding and ML decoding. This present invention discloses a decoding system and method having improved performance over WZF decoding with affordable implementation complexity.
摘要:
To quickly and robustly detect the presence of an incumbent user and rapidly relinquish the spectrum to the incumbent user when necessary, carrier recovery is performed in a receiver of the secondary user's cognitive or software radio prior to performing correlation detection with an upsampled reference signal to correct for large frequency offsets and improve the performance of the correlation detector. To detect a received signal, a pilot value is added to a reference signal. The reference signal is upsampled to a sampling frequency of the received signal. The upsampled reference signal is correlated with a demodulated baseband signal to produce a correlation value. It is then determined whether the received signal is present if the correlation value is greater than a predetermined detection threshold value.
摘要:
Multiple input multiple output (MIMO) systems are candidates for higher data rate wireless communication systems. Currently, for a single input single output (SISO) 1802.11a system can provide a transmission data rate up to 54 Mbps. The present invention is a 2 by 2 Multiple In Multiple Out (MIMO) system having a decoding apparatus that increases the data rate to over 100 Mbps but at a computation cost about the same as for optimal decoding for a SISO system and 1/64 of the optimal decoding for a 2 by 2 MIMO system. At a bit error rate (BER) of 10-4 level, the 2 by 2 MIMO system of the present invention provides double the transmission data rate of the SISO system with approximately the same signal to noise ratio (SNR).
摘要:
Bit level, rather than symbol level, diversity combining is employed within a wireless communications receiver. Channel estimates and bit metrics are separately computed for signals received by different antenna elements. Bit metrics are calculated by determining a least squares cumulative difference between all bits within the received symbol and corresponding bits within constellation symbols as modified by the channel estimate. The separately-determined bit metrics are then combined for decoding. Performance improvements over both single antenna systems and multiple antenna systems with symbol level diversity combining are achieved.
摘要:
A transmitter (20) of an OFDM system (10) splits a data input signal into a pair of OFDM subcarrier streams (S0, S1). The transmitter further implements a cross subcarrier transmitter diversity encoding of the OFDM subcarrier streams (S0, S1). The result is a pair of encoded OFDM subcarrier stream (ES0, ES1) that are transformed into modulated transmitter signals (s0, s1), respectively, which are transmitted to a receiver antenna (60) via an transmitter antenna (50) and a transmitter antenna (51), respectively.
摘要:
Multiple input multiple output (MIMO) systems are candidates for higher data rate wireless communication systems. Currently, for a single input single output (SISO) 1802.11a system can provide a transmission data rate up to 54 Mbps. The present invention is a 2 by 2 Multiple In Multiple Out (MIMO) system having a decoding apparatus that increases the data rate to over 100 Mbps but at a computation cost about the same as for optimal decoding for a SISO system and 1/64 of the optimal decoding for a 2 by 2 MIMO system. At a bit error rate (BER) of 10-4 level, the 2 by 2 MIMO system of the present invention provides double the transmission data rate of the SISO system with approximately the same signal to noise ratio (SNR).