Many wireless networks, including UWB networks, send information between devices in the network through the use of discrete data frames. Data at a transmitter is broken up into discrete pieces of data, which are processed, placed into frames, and sent over a wireless channel. The receiver then takes the received frames, extracts the embedded information, and reconstructs the data that was sent by the transmitter.
Some of the parameters for a data frame must remain fixed, such as its header composition. But others, such as frame size can vary a great deal. For example, frame size can be varied in response to the quality of the channel being used for transmission. Smaller data frames generally have a lower probability of packet error rate and so using smaller packets can improve the probability that a frame will be successfully transmitted.
A device could thus use a large frame size when the channel is of good quality, and then move to a smaller frame size when the channel quality deteriorates. Then, if the channel quality improves, the device could return to using the larger frame size.
Frame size is generally handled at a medium access control (MAC) layer. The MAC layer receives data in discrete blocks and then can either forward these blocks on for transmission as they are, group multiple blocks together for transmission, or break a block up into multiple pieces for transmission. Aggregation is what happens when multiple blocks of data are grouped together, and fragmentation is what happens when one block of data is broken up into multiple pieces.
But although aggregation and fragmentation provide advantages in allowing for greater flexibility in frame size, they also impose some disadvantages. Primarily, they require additional circuitry and time to handle the aggregation and fragmentation on the transmitting end, and also additional time and circuitry on the receiving end split apart aggregated data and reassemble fragmented data (called defragmentation). Of these two, defragmentation data is much more complex and is also more time consuming.
Accordingly, it would be desirable in the art for a solution to the problems associated with fragmentation. In particular, it would be desirable to provide a UWB device that avoids the use of fragmentation, yet still provides flexibility in determining data frame size.