Meaning
Subcarrier subdivisions partition the available wireless channel bandwidth into smaller blocks of orthogonal frequencies for multi-user access. In modern orthogonal frequency-division multiple access systems, resource units represent these allocated blocks which are assigned to different users by the scheduler. Each block consists of a specific number of tones, including data and pilot subcarriers, designed to carry an independent data stream.
This partition allows the access point to serve multiple client devices at the same time.
Bandwidth Division
Standards define several sizes for these blocks ranging from twenty-six tones up to nearly one thousand tones depending on the channel bandwidth. Large resource units provide high data rates for single users, while smaller groupings allow more devices to connect simultaneously. This flexibility allows the system to support a mix of low-speed and high-speed applications.
Scheduler Allocation
The access point maps these blocks to specific stations based on their channel quality. This dynamic assignment ensures that each station transmits on the subcarriers that suffer the least attenuation.
Interference Management
Guard bands separate these allocated blocks to prevent leakage between adjacent transmissions. When different stations transmit on their assigned resource units, slight synchronization errors can cause their signals to overlap in frequency. These guard bands absorb these frequency offsets to maintain high signal quality across all active links.
