Koninklijke Philips Corporation N.v.

Philips Electronics North America Corporation

U.S. Philips Corporation

Chiu Yeung Ngo

Samir N Hulyalkar

Yonggang Du

Christoph Herrmann

Peter May

Dinesh C Verma

Andreas Hettich

Disclosed is a method and system for dynamically selecting a communication channel between an access point (AP) and a plurality of mobile terminals (MTs) in a wireless local area network (WLAN), the method having the steps of (a) measuring a channel quality of a plurality of frequency channels, (b) reporting to the AP from the plurality of MTs of the candidate channels including a received signal strength indication (RSSI) of all channels measured and, (c) selecting one of the channels based on the channel quality report for use in communication between the AP and the plurality of MTs.

Frequency hopping in 5GHz WLAN via dynamic frequency selection

Centrally controlled wireless networks require reliable communications between the central controller and each of the stations within the wireless networks. The structure of a wireless network is often dynamic, or ad-hoc, as stations enter and exit the network, or are physically relocated. The selection of the central controller for the network may also be dynamic, either because the current central controller desires to exit the network, or because the communication between the current central controller and one or more of the stations is poor. This invention discloses a method and apparatus for assessing the quality of the communication paths among all stations in the network. This assessment is useful as a continual monitor of the quality of the network, and can be utilized to select an alternative central control station based upon the quality of communication paths to and from this station. Additionally, the quality assessment can be utilized to establish relay communication paths, as required.

Apparatus and method for peer-to-peer link monitoring of a wireless network with centralized control

There is disclosed a wireless communication device capable of receiving an incoming RF data signal and generating therefrom a base layer data stream and at least one enhancement layer data stream. The wireless communication device comprises: 1) a base layer decoder, 2) at least one enhancement layer decoder, 3) a variable mode receiver for demodulating the RF incoming RF data signals in a plurality of physical modes, such as BPSK, QPSK, QAM, and the like, and at a plurality of code rates and 4) a receiver mode controller for controlling the physical modes of the variable mode receiver. The receiver mode controller causes a first demodulated output signal of the variable mode receiver to be transferred to the base layer decoder when the variable mode receiver is operating in a first physical mode and causes a second demodulated output signal of the variable mode receiver to be transferred to the at least one enhancement layer decoder when the variable mode receiver is operating in a second physical mode. There also is disclosed a second wireless communication device for transmitting an outgoing RF data signal comprising a base layer data stream and at least one enhancement layer data stream. The second wireless communication device comprises: 1) a base layer encoder, 2) at least one enhancement layer encoder, 3) a variable mode transmitter for modulating an input signal in a plurality of physical modes and at a plurality of code rates to produce the outgoing RF data signal; and 4) a transmitter mode controller for controlling the plurality of physical modes of the variable mode transmitter. The transmitter mode controller causes the variable mode transmitter to transmit a base layer output signal from the base layer encoder in a first physical mode and causes the variable mode transmitter to transmit at least one enhancement layer output signal from the at least one enhancement layer encoder in a second physical mode.

System and method for improving video transmission over a wireless network

The system establishes a transmission sequence for effecting communications between plural terminals in a wireless network. This transmission sequence is defined by a control data frame comprised of plural slots, each of which can be allocated for communication between one pair of the plural terminals. In operation, the system begins by generating a transmit/receive matrix for the plural terminals in the wireless network. This transmit/receive matrix includes plural rows and plural columns, where each of the plural rows corresponds to a terminal and each of the plural columns corresponding to a same or different terminal. At each row/column nexus, the transmit/receive matrix includes an entry which indicates whether communications are to be effected between a pair of terminals that corresponds thereto. Slots in the control data frame are then allocated to pairs of the plural terminals based on these entries in the transmit/receive matrix.

System for establishing a transmission sequence for plural terminals in a wireless network

A method for synchronizing timestamps in a network (e.g., a wireless ATM network) that includes a control node and a plurality of other nodes that communicate with one another over a common channel mediated by a medium-access control subsystem (e.g., one that uses a reservation-based TDMA protocol). At the control node, when a timestamp command is sent from MAC to PHY over the MAC-PHY interface, the current timestamp value at the control node is captured from the MAC-PHY interface. The captured timestamp value is then added by a timestamp update interval, T, and stored to become the timestamp value included in the next timestamp transmission exactly T seconds later. At each other node, when the timestamp command is received by PHY and sent to MAC over the MAC-PHY interface, the current timestamp value at the respective other node is captured from the MAC-PHY interface. The captured timestamp value is then compared with the timestamp value contained in the timestamp command and the difference, if any, is stored in an offset_register. This offset value will later be added to the timestamp counter in a non-time-critical manner under software control before the arrival of the next timestamp command.

Method of MAC synchronization in TDMA-based wireless networks

A system which determines whether to accept a wireless connection to a network device receives a request to initiate the wireless connection to the network device, and then determines, in response to the request, a nominal cell rate at which cells are exiting from a buffer in the network device for the requested wireless connection. Thereafter, the system determines an amount of buffer space in the network device required to accommodate the connection, and decides whether to accept the wireless connection based on the nominal cell rate and the amount of buffer space required to accommodate the connection.

Call admission control system for wireless ATM networks

A method of transmitting information in a communications system. The method preferably includes the steps of establishing a communications link between a base station and a temporary node, attempting to maintain a second communication link between the base station and a wireless terminal and upon a determination that the second link cannot be established or satisfactorily maintained, transmitting information from the first base station to the temporary node so that the temporary node can retransmit the information to the wireless terminal, attempting to reestablish the second link and upon such establishment, discontinuing the transmission of subsequent information from the base station to the temporary node and directly transmitting the subsequent information to the wireless terminal from the base station. A system to carry out the foregoing steps is also provided.

Error-recovery mechanism using a temporary forwarder in a wireless-ATM network

A protocol, method, and apparatus for managing network communications which are particularly well suited for ATM communications across a wireless medium. Contiguous time slots within a frame are allocated to each node having traffic to send. Each node is assured a nominal bandwidth, and excess bandwidth is distributed by demand. The allocation of excess bandwidth can be dependent upon the size of the buffer at each node, as well as the time-criticality of each message. Nodes communicate their requests for allocation by appending such control information to the first of their transmitted packets. The allocation, of each node's transmit and receive time slots, is transmitted to all the nodes at the beginning of each frame. Thereafter, each node need not participate on the network until their allocated time periods, thereby allowing portable devices to enter inactive states to conserve power. The network is operated in a connection mode; connections are established in a relatively non-interfering manner by the use of periodically occurring beacons. Inactive, unconnected, nodes need only monitor the network during these beacon periods, further allowing for power conservation.

Medium access control (MAC) protocol for wireless ATM

A method and apparatus for communicating control signals via short energy bursts during a predetermined time interval. This method and apparatus is particularly well suited for wireless communication networks wherein the time intervals are assigned to each station on the network, and the presence of energy in that time interval signals a control signal to or from that station.

Use of energy bursts for wireless networks

A reservation-based wireless asynchronous transfer mode (ATM) local area network includes a system architecture of mobile nodes (MNs), each MN for communicating with various ones of the other MNs. A plurality of services is supported wherein each service has respective quality-of-service (QoS) requirements. A medium access control (MAC) layer using a reservation-based communications protocol is provided, wherein the protocol divides all MAC-based communications between a control channel and a data channel, the control channel and the data channel together making up a control-data superframe (CDS). The protocol further utilizes the control channel for allocating a bandwidth of the data channel to each service. The control channel includes a control frame during which an allocation of data payload slots of the data channel is determined according to (a) a long-term strategy corresponding to a time of service required to complete a service over multiple CDS frames and (b) a short-term strategy within a CDS frame corresponding to instantaneous data payload slot requirements for a particular service. Respective QoS requirements of each service are thus achieved.

Growing community of inventors

Ossining, NY, United States of America

Chiu Yeung Ngo