Abstract: A selective hopping method for hit avoidance in a frequency hopping spread spectrum communication system utilizing an original hopping sequence, having a plurality of available channels for receiving signal packet traffic utilizing a plurality of receiving signal slots are disclosed. The plurality of available channels all are available for use in frequency hopping. The method includes the steps of dividing the plurality of available channels into a plurality of partitions; distributing the available channels in each of the plurality of partitions into a predetermined distribution; forming a partition sequence by assigning a predetermined number of channels to a plurality of selected receiving signal slot sets; generating a generated hopping sequence by partition mapping, in which the partition mapping is responsive to the partition sequence; and managing the receiving signal packet traffic, in which the receiving signal packet traffic is transmitted only in the selected receiving signal slot sets.

Abstract: A method and an apparatus for determining a hopping sequence for selecting a channel from a plurality of channels divided into a plurality of partitions to reduce probability of data collision in a frequency hopping spread spectrum (FHSS) communication system are provided. The communication system stores multiple predetermined partition sequences and receives a first sequence generated by a convention sequence generator.

Abstract: This invention provides a method for bit detection of the GFSK signals at the receiver end. The bit detection is done digitally after the carrier is removed. It employs differential detection incorporated with decision feedback, which uses previous one (so-called on-bit differential detection), or two (so-called two-bit differential detection) bits as correcting information. In addition, synchronization for bit timing and frequency offset resulted from clocks between the transmitter and receiver are also performed with or without preamble as prior information. If preamble is available, the bit timing and frequency-offset bias are estimated from the preamble, which is the case of this present invention. If preamble is not available, this information is estimated directly from the unknown received signals. Once the information about the bit timing and frequency offset is obtained, it is used for the following bit detection.

Abstract: Two multi-rate transmission schemes, multi-code (MC) and variable-spreading-length (VSL) code, for realizing multimedia communications on three types of OFDM-CDMA systems are proposed. These systems can be integrated into a programmable structure such that the operation can be controlled and adjusted by system parameters and thus the transceiver can be used in different systems without changing the fundamental hardware and software architecture, which serves the trend of software-radio for future application. A transceiver architecture of multi-rate OFDM-CDMA systems is illustrated and showed its programmability such that the general system can operate under different scenarios with a common hardware structure and reconfigure by software implementation.

Abstract: A channel quality assessment with short assessment time and good frequency resolution is disclosed. Some channels are grouped and their detecting results are collected as whale to determine the channel quality. The channel quality is determined by interference collision ratio, which is the ratio of the number of interference events to the sum of the number of interference events and interference-free events. Interfered channels are disabled form the group. The Channel quality of each of plurality of channels is determined from detection results of each of plurality of groups so as to have a short assessment time and meanwhile a good frequency resolution may be retained.

Abstract: A method and apparatus for unifying medium access control (MAC) protocols that can unify the various existed MAC protocols, e.g. slotted ALOHA protocol, carrier sense multiple access (CSMA) protocol, group randomly addressed polling (GRAP) protocol and so forth. The method comprises: grouping the MAC nodes having a ready packet according to preset parameters; and transmitting packets according to the grouping result and the preset parameters. The apparatus comprises a unified MAC processor, a memory and a transmitter/receiver circuit. Therein, the memory further comprises a unified MAC program and a packet buffer and the unified MAC program is used to control the unified MAC processor. After configuring the unified MAC program, the unified MAC processor will operate as the specific MAC protocol. Therefore, the apparatus can transmit its packet via the transmitter/receiver circuit thereon in accordance with the specific MAC protocol.

Abstract: A method, and a system of mitigating interference effects under a communication environment including a first spread spectrum (SS) transmission scheme and a second spread spectrum (SS) transmission scheme in the same frequency band are proposed in this present invention. Firstly, responsive to a received signal, output number of signal of the first SS transmission scheme and the second SS transmission scheme. Secondly, retrieve the timing, phase and amplitude information of signals of the first SS transmission scheme in the received signal, and the timing, phase and amplitude information of signals of the second SS transmission scheme. Generate a plurality of linearly-modulated signals based on a predetermined manner, correlate the received signal based on the plurality of linearly-modulated signals to generate a correlated outputs.

Abstract: A selective hopping method for hit avoidance in a frequency hopping spread spectrum communication system utilizing an original hopping sequence, having a plurality of available channels for receiving signal packet traffic utilizing a plurality of receiving signal slots are disclosed. The plurality of available channels all are available for use in frequency hopping. The method comprises the steps of dividing the plurality of available channels into a plurality of partitions; distributing the available channels in each of the plurality of partitions into a predetermined distribution; forming a partition sequence by assigning a predetermined number of channels to a plurality of selected receiving signal slot sets; generating a generated hopping sequence by partition mapping, wherein said partition mapping is responsive to said partition sequence; and managing the receiving signal packet traffic, whereby the receiving signal packet traffic is transmitted only in said selected receiving signal slot sets.

Abstract: Two multi-rate transmission schemes, multi-code (MC) and variable-spreading-length (VSL) code, for realizing multimedia communications on three types of OFDM-CDMA systems are proposed. These systems can be integrated into a programmable structure such that the operation can be controlled and adjusted by system parameters and thus the transceiver can be used in different systems without changing the fundamental hardware and software architecture, which serves the trend of software-radio for future application. A transceiver architecture of multi-rate OFDM-CDMA systems is illustrated and showed its programmability such that the general system can operate under different scenarios with a common hardware structure and reconfigure by software implementation.

Abstract: A channel quality assessment with short assessment time and good frequency resolution is disclosed. Some channels are grouped and their detecting results are collected as whole to determine the channel quality. The channel quality is determined by interference collision ratio, which is the ratio of the number of interference events to the sum of the number of interference events and interference-free events. Interfered channels are disabled form the group. The Channel quality of each of said plurality of channels is determined from detection results of each of said plurality of groups so as to have a short assessment time and meanwhile a good frequency resolution may be retained.

Abstract: A system and a method for deriving transmitted signals from multiple users for an OFDM-CDMA communication system are described herein. An optimum synchronizer for use in an OFDM-CDMA system is also provided. In one aspect, the system and method incorporate a programmable structure for different OFDM-CDMA systems (e.g., MC-CDMA, MC-DS-CDMA, and MT-CDMA) that can be efficiently implemented. The programmable structure is based on the linear minimum mean square error (LMMSE) or best linear unbiased estimator (BLUE) techniques. In addition, an efficient algorithm for reducing computations of fast Fourier transform (FFT) is presented.

Abstract: A method and an apparatus for determining a hopping sequence for hoppingly selecting a channel from a plurality of channels divided into a plurality of partitions to reduce probability of data collision in a frequency hopping spread spectrum (FHSS) communication system are provided. The communication system stores multiple predetermined partition sequences and receives a first sequence generated by a convention sequence generator.

Abstract: A non-coherent frequency shift keying (FSK) demodulator, for receiving a N-ary FSK modulated input signal, demodulating the signal to obtain output data, in which the N-ary FSK modulation has N symbols, and the output data is constructed by a plurality of symbol intervals. The demodulator includes an A/D converter for converting the input signal in digital form, in which, for the A/D converter sampling, a sampling number M of every symbol interval satisfies an equation M.gtoreq.2K+1, wherein K is the interval number of a carrier of the input signal in each symbol interval. N filter arrays each respectively receive the input signals in digital form, and each one of the N filter arrays has a filtering frequency band, respectively, corresponding to spectrums of N symbols in N-ary FSK modulation. N downsamplers each receive the input signal from the corresponding filter array and reduce the sampling number of the input signal to make each symbol interval include only one sample value.

Abstract: Frequency hopping enables a plurality of channels to share the same bandwidth without interference. The present invention utilizes Galois Field theory to define frequency hopping sequences for a plurality of channels which share the same bandwidth.

Abstract: A method to provide improved medium access control (MAC) protocol for a wireless local area network (LAN) comprising the steps of: (a) pre-arranging a polling cycle to be broadcast from the base station into a sequence of broadcast groups, (b) assigning each active mobile node to a randomly chosen broadcast group, (c) performing a group randomly addressed polling for each of the broadcast groups, and (d) assigning uncollided mobile nodes to their original randomly chosen broadcast group address. The uncollided mobile nodes will also be given the privilege of keeping their random numbers as fixed random numbers, until they collide with other mobile node(s) in subsequent polling cycle(s). All the collided mobile nodes, all newly active mobiles, and all newly joined mobile nodes are subject to a new polling cycle. The method has shown to provide excellent throughput (better than 0.90), stable convergence, and excellent delay behavior.

Abstract: In a wireless infrared communications system, a technique for encoding data for serial transmission and the correlative technique for decoding the transmitted data. A data transmission period is divided into a plurality of slots. In a given pair of slots, the first slot comprises a gray code sequence of bits and a check bit, and the second slot comprises the same gray code sequence of bits and the complement of the check bit in the first slot. The last slot in a transmission time period comprises a guard slot to separate transmission time periods. A decoder receives the encoded data, and for a given slot derives calculated data for the slot from the gray code sequence of bits and the check bit. The check bit for the given slot is compared with a calculated check bit of the previous slot to determine if a predetermined relationship exists.

Abstract: A randomly addressed polling (RAP) method for wireless networks is proposed to meet the requirements for wireless LANs which remain open to the research community. The RAP method has the following steps: When a base station is ready to conduct an up-link communication, it broadcasts a ready message to all users under its coverage; each user whenever has a packet to transmit generates a random number; all random numbers are simultaneously transmitted to the base station in response to the ready message; base station collects the random numbers, and polls the active users according to the collected random numbers; and when the base station successfully/unsuccessfully receives the packet from the user, it sends a positive/negative acknowledgment to the user.