te that Pn,k(t) of (5.24), for all choices of n and k, will form a set of complex-valued orthogonal basis functions, if p(t) is chosen such that (5.26) otherwise. Filter design methods that satisfy the orthogonality conditions (5.26) have been proposed. A more widely known design is presented in [5] and is called isotropic orthogonal transform algorithm (IOTA) filter. An alternative design proposed in [17], on the other hand, con- structs the filter p(t) based on a linear combination of a set of Hermite functions. This design gives a great degree of flexibilities as demonstrated in [18]. Discussion on IOTA design can be found in [5, 7]. More on both IOTA design and Hermite design can be found in [8]. 5.5 Synchronization and Tracking Methods Synchronization methods are necessary in any receiver to compensate for carrier and clock mismatch between the transmitter and receiver. In majority of standards, including 5.5 Synchronization and Tracking Methods those of OFDM and FBMC, pilot aided approaches have been adopted. For instance, all the OFDM packet formats that have been proposed for WiFi and WiMAX as well as those suggested in Long-Term Evolution (LTE), LTE-Advanced, and 5G new radio (NR) start with a short-training periodic preamble, for coarse carrier acquisition. This is followed by a long preamble, consisting of two or more similar OFDM symbols that are used for fine-tuning of the carrier, timing acquisition, and channel estimation; e.g. see [19]. In addition, to be able to track channel variations during the payload of each packet, it is often proposed to insert distributed pilots in the time-frequency space. Interpolation methods are then used to obtain the channel gain, and accordingly equalizer gains, at the data points. A few researchers who have looked at the packet design for FBMC have also suggested a similar packet format to those of the OFDM [20-22]. In particular, a periodic training con- sisting of a few repetitions of a pilot FBMC symbol is suggested to be used along with a least squares or a ma