In the design of filter banks, the cosine-modulated filter bank (CMFB) has
drawn attention due to reduced computational overhead and case of design. I
n the conventional design method for a linear-phase CMFB, delay elements ar
e added to the transfer function in order to realize the paraunitary proper
ty. Therefore, the polyphase structure carries out the rate transformation
in two steps and the computation of the prototype filter is executed in a f
orm where the rate is not completely reduced. Hence, the scheme is not opti
mum in terms of the computational overhead per unit time. Also, the splitti
ng shape of the linear-phase split filter is a special one and is not equal
ly split. In consideration of the above, a new method of realization is con
sidered in this paper for an oversampled linear-phase CMFB. In its realizat
ion, reduction of the overall computation overhead is considered. At the sa
me time, a transfer function with an equally split shape is presented. From
the proposed transfer function, a polyphase structure is derived in which
the computation is possible with a completely reduced rate for an arbitrary
integer sampling. In realization of the perfect reconstruction,I a method
is proposed in which the paraunitary property is removed and the synthesis
side can be constructed with a small amount of computation. (C) 2001 Script
a Technica, Electron Comm Jpn Pt 3, 85(2): 32-42, 2002.