Abstract: A system is disclosed that enables the estimation of the location of a wireless terminal in a wireless network. The illustrative embodiment works without requiring modifications to be made to the wireless terminal. Furthermore, the hardware of some embodiments of the present invention can be inexpensively deployed indoors. Some embodiments of the present invention are, therefore, ideally suited for use with legacy indoor systems. The system of the illustrative embodiment of the present invention, in some embodiments, uses an offline process and an online process for location estimation. The described system, however, can be used with other techniques for location estimation.

Abstract: Methods that enable the detection and handling of lost messages during load-balancing routing protocols are disclosed. In accordance with the illustrative embodiment, when a candidate intermediate node N receives a routing-protocol message, node N performs: (1) a first procedure that is capable of detecting some lost routing-protocol messages that were previously transmitted by node N, and (2) a second procedure that is capable of detecting some lost routing-protocol messages that were previously transmitted by a neighbor of node N.

Abstract: An apparatus and methods are disclosed that enable a non-multi-hop wireless terminal (i.e., a wireless terminal that has not been programmed to participate in multi-hop ad-hoc wireless networks) to in fact participate in a multi-hop ad-hoc wireless network, without any changes to the non-multi-hop terminal's software or hardware. In the illustrative embodiment, a wireless terminal T that already belongs to a multi-hop ad-hoc wireless network is assigned to a non-multi-hop wireless terminal W, and a signal is transmitted to terminal W that induces terminal W to use terminal T as a relay for transmitting messages. The assignment of multi-hop-capable terminals in the network to non-multi-hop terminals can be based on a variety of factors, such as signal strengths and the geo-locations of terminals.

Abstract: An apparatus and methods are disclosed that enable load-balancing of routes in ad-hoc wireless networks. In accordance with the illustrative embodiment, when a candidate intermediate node receives a routing-protocol message, the node waits before it transmits a message in response to the received message, where the amount of time that the node waits is based on the value of a load metric at the node and is independent of any other nodes in the network. As a result, a node that has a larger load will wait longer to transmit its routing-protocol message, and consequently, it is less likely that this node will be selected for inclusion in the new route. The techniques of the illustrative embodiment are applicable to both proactive and on-demand routing protocols, and are also applicable to other kinds of networks.

Abstract: A method and apparatus are disclosed for estimating the location of a wireless terminal across multiple building floors. The illustrative embodiment determines the floor where the wireless terminal is presently located by using a majority logic-based heuristic. A plurality of signal monitors measure signals from the wireless terminal and provide those signal strength measurements to a location estimation server. Alternatively, the wireless terminal measures signals that are transmitted by a plurality of transmitting signal devices and provides those signal strength measurements to a location estimation server. The location estimation server determines the floor of the wireless terminal in accordance with the illustrative embodiment of the present invention.

Abstract: A contention-based network which allows real-time traffic to be exist as multiple independent linked-listed chains or under certain conditions to be assembled into multiple linked-list chains. A time separation is enforced between the various multiple chains, which are limited to a predetermined maximum number of stations that each can have in order to allow non-real-time stations to obtain timely access to the medium. Ones of the multiple chains may also be joined into a single chain. Blackburst contention is used to enable a chain to be reconstituted robustly from non-anticipated interruptions, such as the failure of one of its stations.

Abstract: The present invention enables APs to communicate with CNs in a backhaul network configuration in such a manner that the network is dynamically and adaptively self-aligning in terms of bandwidth utilization. A technique known as Black bursts is adapted to a backhaul network configuration to enable access instants in communicating between APs and CNs to be automatically and dynamically self re-aligned in response to APs entering and leaving the network. Thus, APs are not required to explicitly inform each other of these changes. Real-time APs are given priority over non-real-time APs in order to ensure that real-time traffic meets bounded end-to-end delay requirements. This is accomplished by decreasing the period of time that real-time APs must wait while the channel is idle before accessing the channel relative to the time period that non-real-time APs must wait before accessing the channel.

Abstract: A novel method and apparatus for coping with lost acknowledgements from power-saving stations in local-area networks are disclosed. In particular, the illustrative embodiment modifies the access point's and power-saving stations' protocols to prevent repeated lost acknowledgements from occurring. An access point, after transmitting the final downlink frame of a sequence to a station and receiving an acknowledgement from the station, transmits a “double acknowledgement” to the station. A power-saving station, after receiving the final downlink frame of a sequence and transmitting an acknowledgement to the access point, stays awake until one of the following occur: (i) the station receives a double acknowledgement, (ii) the station observes a frame transmitted from the access point to another station, or (iii) the station observes that the shared-communications channel of the local-area network is idle for a particular time interval.

Abstract: A communication architecture switch and method which provide a switch capable of connecting a mobile terminal to one router port of a plurality of router ports substantially independent of a connection path between the mobile terminal and the one router port for a session duration. The connection to the same router port for the duration of a session allows the router to operate as if the mobile terminal had a unique address instead of being a mobile terminal with a variable address. This simplifies the router and other network layer element as the need for a Mobile IP Protocol at the network level is obviated.

Abstract: In a contention-based network, a station, whose transmission is colliding with the transmission of another station and which heretofore would have transmitted a data packet immediately following its colliding transmission—as, for example, in a blackburst contention—suspends transmission immediately upon termination of the collision and, if necessary, at a particular point(s) in time during the collision. The station recommences transmission after a predetermined non-zero duration of time, or “time notch”, during which the medium is idle. In particular, a station that has won a blackburst contention separates its blackburst signal from its subsequent data transmission by a certain amount of time during which the medium is idle. Moreover, a station participating in a blackburst contention may cause the occurrence of a time notch at particular points in time during the contention in order that its access priority vis-a-vis other stations be determined.

Abstract: The present invention enables APs to communicate with CNs in a backhaul network configuration in such a manner that the network is dynamically and adaptively self-aligning in terms of bandwidth utilization. A technique known as Black bursts is adapted to a backhaul network configuration to enable access instants in communicating between APs and CNs to be automatically and dynamically self re-aligned in response to APs entering and leaving the network. Thus, APs are not required to explicitly inform each other of these changes. Real-time APs are given priority over non-real-time APs in order to ensure that real-time traffic meets bounded end-to-end delay requirements. This is accomplished by decreasing the period of time that real-time APs must wait while the channel is idle before accessing the channel relative to the time period that non-real-time APs must wait before accessing the channel.

Abstract: A contention-based network which allows real-time traffic to be assembled into multiple linked-list chains. A time separation is enforced between the various multiple chains, which are limited to a predetermined maximum number of stations that each can have in order to allow non-real-time stations to obtain timely access to the medium. Ones of the multiple chains may also be joined into a single chain. Blackburst contention is used to enable a chain to be reconstituted robustly from non-anticipated interruptions, such as the failure of one of its stations.

Abstract: A contention-based network which allows real-time traffic to exist as multiple independent linked-list chains or under certain conditions to be assembled into multiple linked-list chains. A time separation is enforced between the various multiple chains, which are limited to a predetermined maximum number of stations that each can have in order to allow non-real-time stations to obtain timely access to the medium. Ones of the multiple chains may also be joined into a single chain. Blackburst contention is used to enable a chain to be reconstituted robustly from non-anticipated interruptions, such as the failure of one of its stations.

Abstract: A facility having particular data to transmit over a transmission medium, contends for access to the medium by transmitting a jamming signal over the transmission medium for a particular duration of time that is a small fraction of the amount of time that the facility had to thus far wait to so contend. If the transmission medium is found to be idle at the expiration of that time, then the facility accesses the medium. Otherwise, the facility waits until the transmission medium again becomes idle and then re-contends for access.

Abstract: A contention-based network which allows real-time traffic to be assembled into multiple linked-list chains. A time separation is enforced between the various multiple chains, which are limited to a predetermined maximum number of stations that each can have in order to allow non-real-time stations to obtain timely access to the medium. Ones of the multiple chains may also be joined into a single chain. Blackburst contention is used to enable a chain to be reconstituted robustly from non-anticipated interruptions, such as the failure of one of its stations.

Abstract: The encoding/transmission of information in an OFDM system is enhanced by using complementary codes. The complementary codes, more particularly, are converted into phase vectors and the resulting phase vectors are then used to modulate respective carrier signals. The modulated result is then transmitted to a receiver which decodes the received signals to recover the encoded information.