The IEEE 802.11 Wireless LAN standards allow multiple non-overlapping frequency channels to be used simultaneously to increase the aggregate bandwidth available to end-users. Such bandwidth aggregation capability is routinely used in infrastructure mode operation, where the traffic to and from wireless nodes is distributed among multiple interfaces of an access point or among multiple access points to balance the traffic load. However, bandwidth aggregation is rarely used in the context of multi-hop 802.11-based LANs that operate in the ad hoc mode. Most past research efforts that attempt to exploit multiple radio channels require modifications to the MAC protocol and therefore do not work with commodity 802.11 interface hardware. In this paper, we propose and evaluate one of the first multi-channel multi-hop wireless ad-hoc network architectures that can be built using standard 802.11 hardware by equipping each node with multiple network interface cards (NICs) operating on different channels. We focus our attention on wireless mesh networks that serve as the backbone for relaying end-user traffic from wireless access points to the wired network. The idea of exploiting multiple channels is particularly appealing in wireless mesh networks because of their high capacity requirements to support backbone traffic. To reap the full performance potential of this architecture, we develop a set of centralized channel assignment, bandwidth allocation, and routing algorithms for multi-channel wireless mesh networks. A detailed performance evaluation shows that with intelligent channel and bandwidth assignment, equipping every wireless mesh network node with just 2 NICs operating on different channels can increase the total network goodput by a factor of up to 8 compared with the conventional single-channel ad hoc network architecture.

Centralized channel assignment and routing algorithms for multi-channel wireless mesh networks

The disclosed embodiments include system and method for routing communications over a communications network. In one embodiment, a determination is made as to whether to establish a communication along a communication path based on network performance information. The disclosed embodiments provide several alternatives for establishing the communication and improving communications along the communication path in response to a determination that at least one network node along the communication path is impaired or congested.

System and method for routing data on a packet network

Embodiments disclosed herein for MAC processing for efficient use of high throughput systems and that may be backward compatible with various types of legacy systems. In one aspect, a data transmission structure comprises a consolidated poll and one or more frames transmitted in accordance with the consolidated poll. In another aspect, a Time Division Duplexing (TDD) data transmission structure comprises a pilot, a consolidated poll, and zero or more access point to remote station frames in accordance with the consolidated poll. In one aspect, frames are transmitted sequentially with no or substantially reduced interframe spacing. In another aspect, a guard interframe spacing may be introduced between frames transmitted from different sources, or with substantially different power levels. In another aspect, a single preamble is transmitted in association with one or more frames. In another aspect, a block acknowledgement is transmitted subsequent to the transmission of one or more sequential frames.

High speed media access control

A system for monitoring and optimizing network performance to a wireless device including a wireless router in communication with the wireless device for transmitting and receiving RF signals between the wireless router and the wireless device, the wireless router configured to determine network performance information of the wireless network; concatenate the network performance information into data packets; a packet network switch in communication with the wireless router for communicating the data packets between the wireless router and the packet network switch; and a network management device in communication with the packet network switch for instructing the packet network switch to route the data packets to the wireless router based on the network performance information to optimize the network performance to the wireless device. A method for monitoring and optimizing network performance to a wireless device is also included.

System and method for monitoring and optimizing network performance to a wireless device

A valve housing has a communication passage communicating a suction port of the compressor with a crank chamber of the compressor. A valve element opens and closes the communication passage, and a spring member resiliently biases the valve element toward the closed position. A pressure actuated unit moves the valve element toward the open position by a suction pressure of the compressor. The spring member includes a spring made of a temperature responsive material. The spring decreases in its resilient force in an opening direction of the valve element with increase of an outer-air temperature. The spring member has a primary spring made of an ordinary resilient material for resiliently biasing the valve element toward the closed position and a correction spring made of a material having a temperature positive characteristic. The correction spring provides a correction spring force smaller than a primary force of the primary spring in the opposite direction to the primary force. The combined spring force of the primary spring and the correction spring acting on the valve element.

Control valve for variable displacement compressor

Determining the location of a radio tag or client station of a wireless network, and the location of coverage holes by receiving from a plurality of wireless stations of the wireless network path loss information of the path loss of one or more location frames received at the respective wireless stations. The location frames transmitted by the radio tag or client station having a pre-defined frame structure. The radio tags and client stations use a common infrastructure for transmitting a location frame configured for radiolocation by path loss measurement. The common infrastructure includes a pre-defined protocol common for both radio tags and client stations for transmitting information for reception by the plurality of stations of the wireless network for radiolocation. The pre-defined protocol includes using the location frame having the pre-defined frame structure.

Tag location, client location, and coverage hole location in a wireless network

In a wireless LAN (WLAN), methods, apparatuses and systems directed to facilitating configuration of a wireless network is provided. According to one implementation of the present invention, sensors are used to collect data associated with locations and other properties of access points of the wireless network. The collected data can then be used to assist in automatically configuring one or more aspects of the wireless network. In some implementations, the collected data can be used to dynamically re-configure the wireless network in real time. According to another implementation of the present invention, location computation mechanisms are used to collect data associated with the location of one or more wireless clients, and the data is used to dynamically adjust one or more radio frequency (RF) coverage maps in real time. The revised RF coverage maps can then be used to re-configure one or more operational parameters of the wireless network. Implementations of the present invention provide many advantages, such as automating the configuration of the wireless network in real time and facilitating network management decisions.

Automated configuration of RF WLANs via selected sensors

Methods, apparatuses and systems directed to facilitating load balancing and bandwidth a) location in wireless mesh networks. Generally, according to one implementation of the present invention., routing nodes implement a contention-based media access mechanism and self-allocate bandwidth within a wireless mesh network by dynamically modifying one or more contention-based transmission control parameters. The routing nodes determine a hop count and adjust one or more contention parameters based at least in part, on the hop count.

Dynamic modification of contention-based transmission control parameters achieving load balancing scheme in wireless mesh networks

A method and an apparatus for detecting the start-of-packet in a wireless receiver operating in a packetized wireless network. One method embodiment includes calculating a plurality of start of packet (SOP) indicators, each for one or more of a plurality of receive chains in the receiver; determining one or more linear combinations of respective pluralities of the calculated SOP indicators to form one or more combined SOP indicators; comparing each of a plurality of SOP indicators or combined SOP indicators, including at least one of the combined SOP indicators to a respective threshold to form one or more respective SOP events; and, in the case there is more than one SOP event, determining a logic function of the SOP events to form a SOP decision event.

Start of packet detection for multiple receiver combining and multiple input multiple output radio receivers

One embodiment includes tracking utilization of the backhaul wireless bandwidth of a mesh network related to time sensitive packet data, receiving a call admission request for a call from a client station of a first mesh access point of the mesh, ascertaining using the tracked utilization whether to approve the call admission request using a backhaul call admission control method, and approving the call by sending a positive call admission response if the backhaul call admission control method approves the call and if an access level call admission control method ascertains to approve the call admission request at the access level.

Bretton Lee Douglas

Papers

Tag location, client location, and coverage hole location in a wireless network

Automated configuration of RF WLANs via selected sensors

Dynamic modification of contention-based transmission control parameters achieving load balancing scheme in wireless mesh networks

Start of packet detection for multiple receiver combining and multiple input multiple output radio receivers

Backhaul-level call admission control for a wireless mesh network