Based on this design, the chromatic dispersion tolerance of the proposed system with 2-wavelength and 4-wavelength-interleaving are shown to improve by about 13%and22%2%, respectively, over a non-interleaved system.
User separation in UL-OFDMA was considered in [15] for interleaved OFDMA systems.
As a result, a fade only affects a single symbol per word in an interleaved in system and the length of the required code is drastically reduced.
To overcome some of the limitations imposed by absorption in tissue and to allow for practical clinical use, an interleaved imaging system will also be implemented.
Figure 4 also shows that the proposed QPSK-FSOK MMSE system with multipath diversity gain leads to better performance as compared to the conventional MC-CDMA and interleaved SC-FDMA systems under the same data rate scenario.
The conventional MC-CDMA and interleaved SC-FDMA systems consist of the KP length-M and length-Q WH codes, respectively, where there are for K users and each user is transmitting data over P subcarriers.
Symbol-error-rate (SER) performance of the proposed system is also better than the conventional random-interleaved OFDMA uplink systems and at par with WHT based random-interleaved OFDMA uplink systems.
For example, the proposed QPSK-FSOK system (N = 4, P = 8, K = 4) with (log2N + 2 PK = 128 bits/sym, the conventional MC-CDMA system (M = 128, P = 16, K = 4) with 2KP = 128 bits/sym, and the interleaved SC-FDMA system (Q = 2, P = 16, K = 4) with 2KP = 128 bits/sym all have the same user data rates and total number of subcarriers M = NPK = QPK = 128.
In this article, a low complexity turbo equalizer was developed which is able to jointly equalize and decode BPSK and 4-QAM coded-modulated signals in systems transmitting interleaved information through a multipath fading channels.
For instances, a CFO estimation scheme for interleaved OFDMA/space division multiple access uplink systems was developed in [17] to support spatially separated users and to maximize the channel throughput.
