Norman Ashton Whitaker

Bio: Norman Ashton Whitaker is an academic researcher from Alcatel-Lucent. The author has contributed to research in topics: Broadband networks & Frame (networking). The author has an hindex of 2, co-authored 2 publications receiving 107 citations.

Adaptive digital access protocol: a MAC protocol for multiservice broadband access networks

Abstract: The authors describe a protocol that can adapt to the changing demands of a mix of synchronous transfer mode (STM) and asynchronous transfer mode (ATM) applications and efficiently allocate bandwidth to a variety of bursty traffic sources. In the case of a hybrid fiber-coaxial (HFC) network, the protocol resides in customer premises equipment (CPE) and a common head-end/central-office (HE/CO) 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. In the upstream channels, a contention access signaling time slot is also provided in the STM region for call control and setup 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 either the duration of a call or a 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 setup requests. The MAC-layer protocol, its relation to circuit- and ATM-amenable applications, and its performance with respect to throughput, latency, and bandwidth efficiency for several service scenarios are examined.

Bit robbing ATM channels

Abstract: A method and system for robbing bits in an ATM channel for forming a robbed bit stream. Unused portions of the header in an ATM cell stream are robbed to form a new robbed bit stream. Information is inserted into the new robbed bit stream and sent to a service area. The information in the robbed bit stream is then extracted and input into information appliances in, for example, homes. The information in the robbed bit stream can include an additional video channel, a program guide or other information.

System for controlling access and distribution of digital property

Abstract: A method and device are provided for controlling access to data. Portions of the data are protected and rules concerning access rights to the data are determined. Access to the protected portions of the data is prevented, other than in a non-useable form; and users are provided access to the data only in accordance with the rules as enforced by a mechanism protected by tamper detection. A method is also provided for distributing data for subsequent controlled use of those data. The method includes protecting portions of the data; preventing access to the protected portions of the data other than in a non-useable form; determining rules concerning access rights to the data; protecting the rules; and providing a package including: the protected portions of the data and the protected rules. A user is provided controlled access to the distributed data only in accordance with the rules as enforced by a mechanism protected by tamper protection. A device is provided for controlling access to data having protected data portions and rules concerning access rights to the data. The device includes means for storing the rules; and means for accessing the protected data portions only in accordance with the rules, whereby user access to the protected data portions is permitted only if the rules indicate that the user is allowed to access the portions of the data.

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

Abstract: 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.

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

Abstract: 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.

Method And System For Restricting Access To User Resources

Abstract: A user's set top box (STB), or other client, executes a shell and has an application program interface (API) by which certain features of the client can be controlled. The client is in communication with a walled garden proxy server (WGPS), which controls access to a walled garden. The walled garden contains links to one or more servers providing network-based services. The client sends a request to the WGPS to access a service provided by a site in the garden. To provide the service, the site sends the client a message containing code calling a function in the API. The WGPS traps the message from the site and looks up the site in a table to determine the access control list (ACL) for the site. The ACL is a bit-map that specifies which functions of the client's API can be invoked by code from the site. The WGPS includes the ACL in the header of the hypertext transport protocol (HTTP) message to the client. The shell receives the message and extracts the ACL. The shell uses the ACL to determine whether the code has permission to execute any called functions in the API. If the code lacks permission, the shell stops execution and sends a message to the site indicating that the site lacks permission. Otherwise, the shell allows the code to call the function.

Method and apparatus for embodying and synchronizing downlink signal in mobile communication system and method for searching cell using the same

Abstract: In an OFDMA-based cellular system, a frame of a downlink signal includes a common slot and traffic slots. The common slot includes a synchronization preamble and a cell search preamble. The synchronization preamble has a structure for synchronizing time and frequency, and the cell search preamble has a cell search structure. The traffic slot includes pilot symbols provided on the time and frequency axes. A cyclic prefix is used to estimate initial symbol synchronization, and the initial symbol synchronization and the synchronization preamble are used to synchronize the frame. The synchronization frame and the cell search preamble are used to estimate time and frequency synchronization. The cell search preamble is used to search cells. When the initial synchronization is performed, the cyclic prefix is used to track the frequency, the synchronization preamble is used to track symbol synchronization, and the cell search preamble is used to track fine frequency synchronization.