In a method for admitting new connections based on measured quantities in a wireless communications network having a base station and remote hosts, the base station measures and computes performance metrics to determine whether admission of the new connection could cause a failure to meet the Quality of Service (QoS) promised to already admitted connections. Only if the QoS can be maintained is the new connection is admitted. In one embodiment, the base station may optionally disconnect one or more already admitted lower priority connections if doing so will allow a higher priority new connection to be admitted without loss of QoS to the remaining already admitted connections. In one embodiment, each connection request specifies the average bit rate required and a traffic burstiness factor, the base station measures the number of bytes sent by each connection for a certain period of time and a burstiness factor for the traffic in either direction. The base station computes an equivalent number of admitted connections and determines whether the new equivalent number of admitted connections, after admission of the new connection, would exceed a threshold. The measured quantities can be various metrics related to interference. In one embodiment, uplink Frame Error Rate (FER), an average uplink bit rate, a burstiness factor of the uplink trafc, and a packet loss rate are measured at the base station. Downlink FER is similarly measured at each already admitted remote host and is sent to the base station. Alternatively, the average downlink bit rate, burstiness factor of downlink traffic, and packet loss rate may also be sent from each remote host to the base station. Considering the effect of the average rate and packet loss rate requested by a new connection and the computed equivalent bandwidth, the base station decides whether to admit the new connection based on whether the QoS of all admitted connections can be maintained.

Method for admitting new connections based on usage priorities in a multiple access system for communications networks

In the method for overload control in a wireless communications network employing On-Demand Multiple Access Fair Queuing, if the downlink/uplink buffer occupancy of the network has exceeded a high threshold, the base station determines if this is caused by a specific remote host or by a group of remote hosts. If caused by a specific remote host, the base station normally sends a flow control signal to the remote host to prevent it from sending more data, but may alternatively elect to disconnect other remotes if the remote experiencing bad performance is of a higher priority. The base station may additionally reduce the bandwidth shares allocated to any remote that have indicated tolerance for a variable allocated bandwidth. If the measured frame error rates for many remote hosts are increasing, then the base station may elect to disconnect those remote hosts that permit service interruption in order that more bandwidth may be allocated to the remaining users. If a majority of all associated remote hosts experience high uplink frame error rates, the base station may instead send a signal to a wireless hub which can coordinate the actions of other access points. Short packets queued up for so long at the base station that they exceed the time-to-live value allocated will be thrown away. The base station may also or alternatively elect to disconnect some users of a lower priority or redirect them to other nearby base stations that have a lower load. In a particular embodiment, an uplink Frame Error Rate (FER), an average uplink bit rate, a burstiness factor of uplink traffic, and a packet loss rate are measured at the base station for each remote host. Similarly, a downlink Frame Error Rate is measured at each remote host and then each FER is sent to the base station. If an overload condition exits, connections with a Frame Error Rate that has exceeded a threshold for a specified time and that have indicated that their connections can be interrupted are disconnected. Other combinations of the possible actions are suitable, with the exact combination being determined by the base station depending on the particular congestion conditions observed in the network.

Method for overload control in a multiple access system for communication networks

A method for access control in a wireless network having a base station and a plurality of remote hosts includes the optional abilities of making dynamic adjustments of the uplink/downlink transmission ratio, making dynamic adjustments of the total number of reservation minislots, and assigning access priorities by message content type within a single user message stream. The method of the invention further provides for remote wireless host paging and for delayed release of active channels by certain high priority users in order to provide low latency of real-time packets by avoiding the need for repeated channel setup signaling messages. In the preferred embodiment, there are N minislots available for contention in the next uplink frame organized into a plurality of access priority classes. The base station allows m access priority classes. Each remote host of access priority class i randomly picks one contention minislot and transmits an access request, the contention minislot picked being in a range from 1 to Ni where N(i+1) < N i and N 1=N. In an alternate embodiment of a method for access control according to the present invention, each remote host of access priority class i and with a stack level that equals 0, then transmits an access request with a probability Pi where P(i+1) < Pi and P1=1.

Method for access control in a multiple access system for communications networks

In a method for conflict resolution among remote hosts in a wireless network where remotes make bandwidth requests to the base station via uplink frames partitioned into one or more reservation minislots, a collision occurs where two or more remotes have transmitted a request in the same minislot. Each remote is characterized by a stack level, and only remotes with a stack level equal to 0 are permitted to transmit access request packets. Newly active remotes are allowed to join in with those remotes already having stack level 0 during any particular conflict resolution period by setting their stack levels to 0 and entering the request state. If the stack level of a remote is 0, the remote randomly picks a minislot for transmission of an access request. If the outcome is SUCCESS, and the queue at the remote is empty, the remote transmits the current packet after receiving a transmit permit and exits the request state. If the queue is not empty, then, after receiving a permit, the current packet is transmitted with a piggybacked reservation request for transmission of the next packet in the queue, continuing until the queue is empty. If the outcome of the reservation request was not SUCCESS, the remote participates in a random draw to determine whether to increment its stack level by 1 or leave it at 0. If the stack level of any remote is not 0, then in one embodiment if the outcome of the previous reservation request was COLLIDED, the remote increments its stack level by 1, otherwise decrementing it by 1. In an alternate embodiment, if the outcome of all the reservation requests during the previous cycle was COLLIDED for greater than or equal to some threshold, the remote increments its stack level by 1, otherwise decrementing it by 1. The number of reservation minislots available in any particular uplink frame may be dynamically changed based on the percentage of idle minislots and the total uplink queue length.

Bandwidth reservation and collision resolution method for multiple access communication networks where remote hosts send reservation requests to a base station for randomly chosen minislots

A number of features for enhancing the performance of a cable transmission system in which data is transmitted between a cable modem termination system at a headend and a plurality of cable modems located different distances from the headend. The power transmission level, slot timing, and equalization of the cable modems are set by a ranging process. Data is transmitted by the modems in fragmented form. Various measures are taken to make transmission from the cable modems robust. The upstream data transmission is controlled to permit multiple access from the cable modems.

Robust techniques for optimal upstream communication between cable modem subscribers and a headend

This paper presents a broadband multiple access protocol for bidirectional hybrid fiber-coax (HFC) networks. The Adaptive Digital Access Protocol (ADAPt+) supports a full range of subscriber services via HFC networks with tree and branch topologies. The protocol efficiently accommodates different circuit- and packet-based access modes, such as synchronous transfer mode (STM), asynchronous transfer mode (ATM), and inherently variable length (VL) native data (for example, the Internet protocol [IP]). ADAPt+ allocates the available bandwidth efficiently and adapts to the changing traffic mix. In addition, the paper describes the medium access control (MAC) protocol for upstream and multiplexing/demultiplexing for downstream communication, its applicability to STM, ATM, and other native data applications, and its performance with respect to throughput, latency, and bandwidth efficiency. While discussed in the context of an HFC network, many aspects of ADAPt+ have relevance to wireless, fiber to the curb (FTTC), and fiber to the home (FTTH).

http://ieeexplore.ieee.org/iel7/6731002/6780039/06780043.pdf

A broadband multiple access protocol for STM, ATM, and variable length data services on hybrid fiber-coax networks

FiberVista is a fiber-to-the-home (FTTH) or fiber-to-the-curb (FTTC) system that provides more bandwidth for emerging broadband services, such as Internet data, than existing deployed residential systems, while tapping predictable revenue streams from telephony and analog- and digital-video broadcast television service. At the same time, FiberVista minimizes development costs by reusing existing or emerging technology from other systems, such as cable modems and low-cost residential optical transceivers. It also allows for incremental, “pay-as-you-grow” provisioning of capacity. Like cable-television (CATV) hybrid fiber-coax (HFC) networks, FiberVista uses subcarrier multiplexing to offer a flexible mix of services. The system is superior to HFC in that it offers more total bandwidth, both upstream and downstream, which can be shared among fewer homes. By limiting the coax plant to a small passive run in FTTC, or eliminating it altogether in FTTH, FiberVista minimizes the most unreliable and maintenance-intensive portion of the HFC network. Furthermore, it utilizes new technologies, such as high-power erbium-doped fiber amplifiers (EDFAs), coarse wavelength division multiplexing (CWDM), and passive optical networks (PONs), to make the extension of optical fiber deep into the network practical. In this paper, we describe the FiberVista network architecture, potential upgrade scenarios, and experimental system demonstrations.

FiberVista: An FTTH or FTTC system delivering broadband data and CATV services

Described here is an adaptive MAC-layer protocol that supports multiservice (STM and ATM) applications in the context of subscriber access to tree and branch (e.g., fiber-coaxial cable) networks. The protocol adapts to changing demands for a mix of circuit and cell mode applications, and efficiently allocates upstream and downstream bandwidth to a variety of bursty and isochronous traffic sources. In the case of a hybrid fiber-coaxial (HFC) network the protocol resides in customer premises equipment and a common head-end controller. A medium-access control (MAC) processor provides for dividing the time domain for a given digital bitstream into successive frames, each with multiple STM and ATM time slots. Within the STM region of a frame, variable length time slots are allocated to calls (e.g., telephony, video telephony) requiring different amounts of bandwidth. A contention access signaling channel is also provided in this region for call control and set-up requests. Within the ATM region fixed-length time slots accommodate one individual ATM cell. These ATM time slots may be reserved for a user for the duration of a call or burst of successive ATM cells, or shared via a contention process. At least one contention time slot is available for signaling messages related to ATM call control and set-up requests. Further, the fixed-length ATM time slots may be reserved by a user for the duration of a call, or shared through a contention process. This paper describes the MAC-layer protocol, its relation to circuit- and ATM- amenable applications, and its performance with respect to signaling throughput and latency, and bandwidth efficiency for several service scenarios.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Adaptive MAC-layer protocol for multiservice digital access via tree and branch communication networks

Accurate mode partition data from a laser are collected simply and rapidly in accordance with the principles of the invention wherein the laser output is directed to a filter which separates a central longitudinal mode from the side modes. The filter operates to present all side modes in a predetermined wavelength range simultaneously and continuously at the output of the filter. By subsequently comparing the intensity or power in the side modes delivered to the filter output with a predetermined threshold, it is possible to determine the frequency of occurrence and magnitude of mode partition events for side modes in the predetermined wavelength range. In one exemplary embodiment, the filter is realized by the combination of a Fabry-Perot etalon, whose longitudinal axis is angled with respect to the longitudinal axis (propagation axis) of the laser output beam directed onto the filter, together with an external reflector which is parallel to the Fabry-Perot etalon to permit multi-passing of the beam between the Fabry-Perot etalon and the reflector. The beam is reflected by the Fabry-Perot etalon so that after two or more passes within the filter only the side modes are output by the filter. In this arrangement, the filter acts as a notch filter having a wide passband and having an output for the side modes which is separate from an output for the main mode.

Peter D. Magill

Papers

A broadband multiple access protocol for STM, ATM, and variable length data services on hybrid fiber-coax networks

FiberVista: An FTTH or FTTC system delivering broadband data and CATV services

Adaptive MAC-layer protocol for multiservice digital access via tree and branch communication networks

Mode partition noise screening apparatus

Mode partition screening apparatus