International Business Machines Corporation

Hamid Ahmadi

Arvind Krishna

Frederic J Bauchot

David Frederick Bantz

Kadathur S Natarajan

Michelle M Wetterwald

Roch A Guerin

Colin George Harrison

Levent Gun

Jose Louis Martinez

Mahmoud Naghshineh

Ilan Kessler

Jeane S Chen

Ronald Pete Luijten

Antonius Paulus Engbersen

Gerald Arnold Marin

Fabien P Lanne

Johannes G Beha

Wolfgang Emil Denzel

Chee-Seng Chow

Catherine Soler

Theodore E Tedijanto

Amotz Bar-Noy

Michele M Wetterwald

Charles Allen Murphy

Erich Port

Roselyne Bonnet

Anthony M Lee

Khosrow Sohraby

Jeffrey, H Derby

Ofek Yoram

Krishna Arvind

Richard O La Maire

Catherine Solar

Frederic Jacques Bauchot

Michelle Marie Wetterwald

In a wireless communication system ( ), base stations ( ) are connected to a backbone network ( ) such as a wired LAN and act as access points and relays for remote stations ( ). A remote station registers and performs bidirectional communication with one of the base stations designated as its home base station. Base stations have overlapping coverage areas where a remote station is within reception range of several base stations. Such communication system may for instance be a multicell radio LAN using frequency hopping signaling. The method allows to reuse a limited number of network resources such as frequency hopping patterns and assign the same resource to several active base stations. Upon request from a base station, a network controller ( ) connected to the backbone network computes a distance index between the requesting base station and the other active base stations and assigns to the requesting base station the same network resource as the one assigned to another base station with the highest distance index. Information about cells overlaps is centralized in a control database ( ) and used by the network controller to compute distance indexes.

Allocation method and apparatus for reusing network resources in a wireless communication system

In a wireless communication system (106), base stations (118, 120) are connected to a backbone network (116) such as a wired LAN and act as access points and relays for remote stations (128, 132, 136). A remote station registers and performs bidirectional communication with one of the base stations designated as its home base station. Base stations have overlapping coverage areas where a remote station is within reception range of several base stations. Such communication system may for instance be a multicell radio LAN using frequency hopping signaling. The method allows reuse of a limited number of network resources such as frequency hopping patterns and assign the same resource to several active base stations. Upon request from a base station, a network controller (110) connected to the backbone network computes a distance index between the requesting base station and the other active base stations and assigns to the requesting base station the same network resource as the one assigned to another base station with the highest distance index. Information about cells overlaps is centralized in a control database (109) and used by the network controller to compute distance indexes.

Allocation method and apparatus for reusing network resources in a

In a wireless communication system (106), base stations (118, 120) are connected to a backbone network (116) such as a wired LAN and act as access points and relays for remote stations (128, 132, 136). A remote station registers and performs bidirectional communication with one of the base stations designated as its home base station. Base stations have overlapping coverage areas where a remote station is within reception range of several base stations. Such communication system may for instance be a multicell radioLAN using frequency hopping signaling. The method allows reuse of a limited number of network resources such as frequency hopping patterns and assign the same resource to several active base stations. Upon request from a base station, a network controller (110) connected to the backbone network computes a distance index between the requesting base station and the other active base stations and assigns to the requesting base station the same network resource as the one assigned to another base station with the highest distance index. Information about cells overlaps is centralized in a control database (109) and used by the network controller to compute distance indexes.

A method of dynamically allocating bandwidth of channels to cells in a communications cellular network according to user demand. Groups of cells are formed so as to minimize interference within each group, and a particular channel is assigned to each of the groups. The bandwidth of each channel then is dynamically allocated by time division to each of the cells in the assigned group according to user demand in each of the cells thereof.

Multiaccess scheme for mobile integrated local area networks

A communications network having a number of routers, a number of base stations and a number of mobile units maintains communications with the mobile units by assigning a unique address known to the routing entities of the network to each mobile unit. By including the mobile units unique address in topology updates of the network, the location of the mobile unit at any time is made known to all routers of the network. That is, once a mobile unit moves into a domain of a new access point and establishes a new link with the new access point, it uses the topology update mechanism of the network to make its new location known to all routers. Once a router of the network receives topology update information specific to the mobile unit's new location, it updates its routing table such that packets destined to the mobile unit are routed in a path which terminates at the mobile unit and contains its new access point.

Communication system including method and apparatus for maintaining

First and second multi-node communication paths are connected via a bridge node. Each path employs a quota allocation scheme for access thereto by the nodes thereon. A first quota allocation signal is propagated on the first path and a second quota allocation signal is propagated on the second path, the second signal controlling access to the second path for the purpose of transmitting information to the bridge node destined for the first path. The quota allocation signals are synchronized to ensure that there is at most one circulation of the second quota allocation signal for each circulation of the first quota allocation signal. Information from the first path to the second path is deflected from the bridge node and around the first path if the bridge node is full. If the information is transmitted in sequenced packets, a deflected packet is assigned a deflection number. The bridge node tracks deflections via the deflection numbers.

Method and apparatus for managing communications between multi-node

A Medium Access (MAC) Protocol is utilized for wireless radio access for a plurality of remote stations to a base station on a LAN. There is a time division fixed frame structure in which time is slotted, and time slots are grouped into fixed frames consisting of data and control subframes or periods. The fixed frame structure consists of three periods (A, B, and C) along with their respective headers. The first period, the A period, is used exclusively for data transfer from the base station to the remote stations. The following period, the B period, is used for contention-free data transfer from the remote stations to the base station. The allocation of the data slots in the A and B periods is performed by the base station. The last period of the frame, designated as the C period, is used for the transmission of reservation requests and data from the remote stations to the base station in a random-access contention mode using a slotted Aloha protocol. The duration of the three periods may be varied using a movable boundary technique.

Adaptive medium access control scheme for wireless LAN

A congestion control system for packet communications networks in which access to the network is controlled to prevent such congestion. Packets within the prespecified statistical description of each packet source are marked as high priority ('green' packets) while packets exceeding the pre-specified characteristics are marked with a lower priority ('red' packets). The overall red packet rate is limited to prevent red packet saturation of the network. Packets are marked red for a continuous train of successive red packets. The introduction of red packets into the network is subjected to a degree of hysteresis to provide better interaction with higher layer error recovery protocols. The amount of hysteresis introduced into the red packet marking can be fixed or varied, depending on the statistics of the incoming data packets at the entry point to the network.

Rate-based congestion control in packet communications networks

In a packet communications network, the addition or deletion of a connection to the network by a user is governed by a link traffic metric which represents the effective capacity of each link in the network which participates in the packet connection route. The link metric is calculated in real-time and updated by simple vector addition or subtraction. Moreover, this link metric is also used to calculate leaky bucket parameters which govern the access of packets to the network once the connection is set up. A packet network using these link metrics and metric generation techniques provides maximum packet throughput while, at the same time, preserving grade of service guarantees.

Traffic management in packet communications networks

A packet communications system utilizes a route determining mechanism by identifying principal paths between the source and the destination in the system. Principal paths are minimum hop count paths with a transmission delay less than a specified threshold. Principal path links are accepted as legs of the optimum path, if feasible, i.e., if the resulting load on the link is less than a specified principal threshold. Secondary links are accepted only if the resulting load on the link is less than a specified secondary threshold, where the secondary threshold is less than the principal threshold. All paths must also have a transmission delay less than a specified threshold. Each request for a route includes the source node, the destination node, the load required, the maximum transmission delay and, if desired, the quality of service parameters which all of the legs of the route must satisfy. A modified Bellman-Ford breadth-first search algorithm is used to identify the principal links and, using these principal link identifications, determining the optimum path.

Methods and apparatus for optimum path selection in packet transmission

In a switching system interconnecting transmission links (21-i, 23-i) on which circuit switched (CS) and packet switched (PS) information is transferred, a switch fabric (11) is provided which interconnects a plurality of input ports (15-i) to a plurality of output ports (19-i). The information arriving on incoming links is converted in switch adapters (13-i) to uniform minipackets, each having a routing address designating the required output port. The switch fabric consists of parallel equal switching slices, e.g. binary routing trees (71), which transfer in a non-blocking manner each minipacket from its input port to one output port in response to the routing address. Collecting means (73, 75) are provided at each output port for accepting the minipackets arriving from the different input ports.

High-speed modular switching apparatus for circuit and packet switched

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Hamid Ahmadi