Orthogonal codes for CDMA optical fibre LANs with variable bit interval

Multiple Access Techniques for Fiber-Optic Networks

“…Several variants of DS-CDMA codes verifying the above conditions have been proposed in the literature [147][148][149][150][151]. It is noteworthy that these codes differ from their electrical counterparts found, e.g., for RF mobile communications since they can take on only positive values, either 1's or 0's.…”

CDMA Techniques in Optical Fiber LANs

“…In Figure 2 a we plotted an example [11] of a coded optical signals with indicated basic parameters.…”

“…In any event, it can be The above requirements lead to code sets [3,10] with the undesirable feature that the bit intervals have to be strictly controlled, within a fraction of T c , which is difficult to achieve at high bit rates. This requirement can be dropped if we introduce another rule in the code set design [11] which states that all ones have to be in the first half of code word. In such a way the distance between the last pulse in one codeword and the first pulse in the next codeword is larger than distance between any two pulses inside codewords and can be further increased in order to accommodate possible deviations of bit interval durations.…”

“…CDMA (Code Division Multiple-Access) techniques, also called spread spectrum techniques, have been proposed for optical fiber systems by various authors, [1][2][3][4][5][6][7][8][9][10][11]. Typically, the passive star topology, as represented in Fig.…”

Variable-length code construction for incoherent optical CDMA systems

“…In order to provide such multirate services, multicode and variable-length spreading techniques were proposed in RF CDMA [10,11]. These two approaches were used in optical CDMA as well [12][13][14][15][16][17][18]. The idea of variable-length codes for optical fiber LANs was first proposed by Petrovic et al in 1990 [12].…”