They get access to the resource once every x frames, and need to wait relatively long, because they need to gather enough data to send a large quantity at once. Figure 12 shows the maximum latency that occurs for each integer requested bandwidth, with a maximum capacity of 2400 bytes per second and 8 slots per frame.
For the OFDM signal, the center frequency is 5.25 GHz, the subcarrier spacing Δ follows that employed in [20], i.e., Δ = 312.5 kHz, and the set of used subcarrier indexes is {k| − K ≤ k ≤ K}, where K is an integer controlling the bandwidth.
In the performance analysis for fragment-based spectrum allocation, all the operators employ same subcarrier spacing and radio interfaces with OFDM waveforms, however, the DFT sizes vary depending on the sizes of frequency fragments (i.e., depending on the number of subcarriers as fragments are integer multiples of subcarrier bandwidth) the operators are assigned with.
BEM [18] operates by allowing a user to expand his limited bandwidth by an integer factor of α while preserving the already achieved data rate.
A fragment is defined as a contiguous band, and its bandwidth must be an integer multiple of the subcarrier bandwidth Δ sub and complies with B low and other system parameters.
When the time-bandwidth product is an integer multiple of 2, the BFT impulse peak is at the discrete k.
The simulations are performed for various bandwidths, that is, every possible integer rate in bytes per second, lower than the maximal capacity.
subject to the PU interference constraint (42), power budget (55), the integer bit granularity (57), bounds on the sub-carrier bandwidth (30), and the integer variable for assigning sub-carriers to users (44).
The idea is to match the bandwidth of one sub-band with an integer multiple of the carrier spacing, Δ, used by the opportunist transmitter.
