This invention generally relates to networks of communications devices, in particular ultra wideband (UWB) communications devices. An ultra-wideband (UWB) network comprising a plurality of UWB devices each forming a node of said network, pairs of said UWB devices being configured for communication with one another using one of a plurality of UWB channels, each said UWB device comprising a UWB transceiver for bidirectional communication over one or more of said UWB channels with at least one other of said UWB devices; and a device controller coupled to said UWB transceiver, said controller being configured to determine a said UWB channel for use in establishing a communication link with each other UWB device; whereby said network is configured for automatic construction of a set of communications links between said nodes of said network.

Communications systems and methods

An adaptation to Carrier Interferometry synthesis and analysis provides for complex coding and decoding in a sliding window transform Coding and decoding functionality can be extended to spatial processing in systems employing multiple transceiver elements Poly-amplitude codes permit successive interference cancellation in spatial and frequency-domain processing Handoffs in cellular systems are facilitated by selecting spectral/base station combinations that optimize link performance

Orthogonal superposition coding for direct-sequence communications

An adaptation to Carrier Interferometry synthesis and analysis provides for frequency-varying subcarriers. Coding and decoding functionality can be extended to orthogonal chirped and frequency-hopped waveforms. Poly-amplitude codes permit successive interference cancellation in spatial and frequency-domain processing. Dynamic re-sectorization and bandwidth exchange are facilitated by subcarrier allocation.

Carrier interferometry coding with applications to cellular and local area networks

A cooperative multi-user multiple input, multiple output (MIMO) system coordinates spatially distributed network transceiver nodes for communicating with wireless client devices. A MIMO processor pre-codes data for transmission from the network transceiver nodes, wherein the pre-coding comprises subspace coding derived from channel measurements between the network transceiver nodes and the wireless client devices. A network controller coordinates the network transceiver nodes to transmit simultaneous non-interfering channels within a common frequency to the wireless client devices such that each client device receives a subspace-coded transmission from each of the network transceiver nodes. The client devices and/or the network transceiver nodes may be selected based on channel state information and/or measured channel quality.

Cooperative wireless networks

An OFDM transmitter spreads original data symbols with a complex-valued spreading matrix derived from a discrete Fourier transform. Spread data symbols are mapped to OFDM subcarriers. Spreading and mapping are configured to produce a transmitted spread-OFDM signal with a low peak-to-average power ratio (PAPR) and orthogonal code spaces. In MIMO systems, the complex-valued spreading matrix can comprise a MIMO precoding matrix, and the code spaces can comprise MIMO subspaces. In Cooperative-MIMO, a combination of low code-space cross correlation and low PAPR can be achieved.

Spreading and precoding in OFDM

Methods and systems for generating a variable spacing pulse position modulated (VSPPM) signal for transmission across an ultra-wideband communications channel. The variable pulse position modulated spread spectrum signal is created by encoding every M input data bits from an input data stream into a symbol consisting of Nc chips. Each chip is divided into 2M sub-chips and each sub-chip is further divided into Np time slots. A pulse is transmitted for each chip in the symbol. During each chip period, the pulse is placed in the sub-chip corresponding to the binary M-tuple (or symbol) value. A time hopping code sequence consisting of Nc elements with a one-to-one chip association is then applied to each symbol so that the position of each pulse is shifted to the appropriate time slot that corresponds to the time hopping code value.

Variable spacing pulse position modulation for ultra-wideband communication links

An adaptive pulse position modulated CDMA scheme for use in UWB communications systems is disclosed. A stream of input bits is encoded with spreading code sequence. The spreading code sequence consists of a number of code elements that may have one of two values. Each bit is encoded into a symbol consisting of a predefined number of chips, which are transmitted during a symbol period. Next, at least one code element is associated with each chip in the symbol. Then, an encoded pulse is generated in each chip. Each encoded pulse has a value determined by multiplying the data bit with the code value associated with the particular chip. The encoded pulse is then pulse position modulated by shifting the position of the pulse to a first position or a second position within the chip depending upon the encoded value of the pulse.

Tingfang Ji

Papers

Variable spacing pulse position modulation for ultra-wideband communication links

Systems and methods for providing adaptive pulse position modulated code division multiple access for ultra-wideband communication links