Method and Apparatus for Directional Centralized Contention Based Period in a Wireless Communication System

Abstract

A method of communication includes allocating a portion of a superframe centralized contention based period where the access method is based on directional ALOHA. The centralized contention based period is divided into equal time slots, and each sequential set of N time slots forms a time cycle. During a time cycle, a wireless device listens for requests from other wireless devices while it changes its receiving direction from one time slot to another.

1 . A digital computer network comprising:
 a first transmitter component residing on a first wireless device employing a sequence of time slots paired with a plurality of transmit directions for transmitting at least one request frame to a second wireless device;   a first receiver component residing on the first wireless device configured for receiving at least one response frame from the second wireless device;   a second receiver component residing on the second wireless device employing a different one of a plurality of receive directions for each of the sequence of time slots to listen for the at least one request frame transmitted by the first transmitter;   a second transmitter component residing on the second wireless device configured for transmitting at least one response frame to the first wireless device; and   a digital computer system comprising a memory for storing instructions and a processor for executing the instructions for selecting a preferred set of uplink and downlink directions for further communication between the first wireless device and the second wireless device.   
     
     
         2 . The digital computer network of  claim 1 , wherein a time cycle comprises a plurality N of consecutive time slots, where N equals the plurality of receive directions; and wherein the second receiver component is configured for cycling through the plurality of receive directions in each time cycle. 
     
     
         3 . The digital computer network of  claim 2 , wherein each time cycle has a time-cycle boundary selected by at least one of the first wireless device and the second wireless device. 
     
     
         4 . The digital computer network of  claim 2 , wherein each time cycle has a time-cycle boundary selected by at least one of the first wireless device and the second wireless device. 
     
     
         5 . The digital computer network of  claim 1 , wherein the preferred set comprises a preferred transmit direction for transmitting from the second wireless device to the first wireless device, a preferred receive direction for receiving transmissions from the second wireless device to the first wireless device, and a preferred transmit direction for transmitting from the first wireless device to the second wireless device. 
     
     
         6 . The digital computer network of  claim 1 , wherein the digital computer system selects the preferred set based on measurements of link quality. 
     
     
         7 . The digital computer network of  claim 1 , wherein the digital computer system performs at least one of a full double sweep and a partial double sweep of all possible uplink and downlink direction pairs when selecting the preferred set. 
     
     
         8 . The digital computer network of  claim 1 , wherein the preferred set comprises at least one of a set of directions having an optimal link quality and a set of directions having a link quality above a predetermined threshold. 
     
     
         9 . The digital computer network of  claim 1 , wherein selecting the preferred set comprises performing at least one of a full double sweep and a partial double sweep of all possible uplink and downlink direction pairs. 
     
     
         10 . The digital computer network of  claim 1 , wherein selecting the preferred set comprises selecting an uplink pair from beacon frames and selecting a downlink pair during a C-CBP direction search. 
     
     
         11 . The digital computer network of  claim 1 , wherein the digital computer system is configured for maintaining a plurality of downlink direction pairs, updating a link quality indicator measurement for each of the plurality of downlink direction pairs, and updating at least one of the set of uplink and downlink directions. 
     
     
         12 . The digital computer network of  claim 1 , configured for performing at least one of directional slotted ALOHA and directional cycle-based ALOHA. 
     
     
         13 . The digital computer network of  claim 1 , configured for performing at least one of authentication, association, direction finding, direction tracking, communicating control frames, service period reservation, communicating command frames, communicating management frames, and communicating data frames. 
     
     
         14 . A digital computer system, comprising:
 a transmitter configured for selecting a sequence of time slots paired with a plurality of transmit directions for transmitting at least one request frame to at least one wireless device, the at least one wireless device employing a different one of a plurality of receive directions for each of the time slots;   a receiver configured for listening for at least one response frame transmitted by the at least one wireless device; and   a memory for storing instructions and a processor for executing the instructions for selecting a preferred set of uplink and downlink directions for further communication with the at least one wireless device.   
     
     
         15 . The digital computer system of  claim 14 , wherein selecting the sequence further comprises employing a first transmit direction for a first plurality N of the time slots, and a second transmit direction for a second plurality N of the time slots, where N equals the plurality of receive directions. 
     
     
         16 . The digital computer system of  claim 14 , wherein the transmitter is configured for employing a different transmit direction for each of a plurality of time cycles when transmitting the at least one request, wherein each of a plurality of time cycles comprises a plurality N of consecutive time slots. 
     
     
         17 . The digital computer system of  claim 14 , wherein each of the time slots comprises a request frame slot, a first guard interval, a response frame slot, and a second guard interval. 
     
     
         18 . The digital computer system of  claim 14 , wherein the transmitter employs a set of back-off numbers corresponding to receive directions for determining back-off times for transmitting request frames. 
     
     
         19 . The digital computer system of  claim 14 , wherein the transmitter employs an algorithm for selecting transmit directions and time cycles for transmitting request frames. 
     
     
         20 . The digital computer system of  claim 14 , configured to perform at least one of directional slotted ALOHA and directional cycle-based ALOHA. 
     
     
         21 . A digital computer system, comprising:
 a receiver configured for employing a different one of a plurality of receive directions for each of a sequence of time slots to listen for at least one transmitted request frame from a wireless device;   a transmitter configured for transmitting at least one response frame in response to a received request frame; and   a memory for storing instructions and a processor for executing the instructions for selecting a preferred set of uplink and downlink directions for further communication with the wireless device.   
     
     
         22 . The digital computer system of  claim 21 , wherein a time cycle comprises a plurality N of consecutive time slots, where N equals the plurality of receive directions; and wherein listening for the at least one transmitted request frame comprises cycling through the plurality of receive directions in each time cycle. 
     
     
         23 . The digital computer system of  claim 21 , wherein the request frame comprises a preferred transmit direction. 
     
     
         24 . The digital computer system of  claim 21 , wherein selecting the preferred set further comprises measuring an uplink link quality indicator and transmitting the uplink link quality indicator to the wireless device. 
     
     
         25 . A digital computer system, comprising:
 a transmitter configured for transmitting a request frame to a receiver employing a plurality of receive directions to listen for the request frame; and   a memory for storing instructions and a processor for executing the instructions for:
 generating a plurality of time cycle numbers, each of the time cycle numbers being associated with one of the receive directions and having a value within a predetermined back-off window size; 
 sequentially organizing the plurality of time cycle numbers with respect to their values for producing a sequence of time cycle numbers; and 
 generating a sequence of time slot numbers from the sequence of time cycle numbers and the plurality of receive directions, the sequence of time slot numbers being used by the transmitter to select time slots for transmitting the request frame.