This paper proposes a novel signal discrimination scheme for spatially multiplexed optical signals using a spatial intensity distribution detection technique and applies it to a space division multiple access (SDMA) in hybrid line-of-sight (hybrid– LOS) indoor optical wireless communication system. In the proposed scheme, multiple terminals simultaneously transmit their optical signals to acces...

Third generation partnership project (3GPP) long term evolution (LTE) uses single carrier frequency division multiple access (SC-FDMA) in uplink transmission and multiple input multiple output orthogonal frequency division multiple access (MIMOOFDM) scheme for the downlink. A variable step size based least mean squares (LMS) algorithm is formulated for a single carrier frequency division multip...

Optical code division multiplexing (OCDM) is the other class of multiplexing techniques than time division multiplexing (TDM), wavelength division multiplexing (WDM) and space division multiplexing (SDM). OCDM has been proposed in mid ’70s. It has been long since OCDM remains outside the mainstream of research community of optical communications, however, possible scarcity of the wavelength res...

It is well known that low correlation zone sequences have been adopted as spreading sequences in the quasi-synchronous code division multiple access (QS-CDMA) systems of wireless communication systems, where time delay among different users is allowed to be within a few chips. In this paper, numerical analysis shows that the QS-CDMA systems using low correlation zone (LCZ) sequences outperform ...

In this letter, we extend our investigation of generalized multicarrier direct-sequence code-division multiple access by considering two additional types of chip waveforms, namely, the time-domain half-sine and raised-cosine chip waveforms, in addition to the rectangular chip waveform. A range of closed-form equations are provided for quantifying the effect of both the multipath interference an...

Code Division Multiple Access (CDMA) technology allows a large number of mobile radio users to share limited bandwidth simultaneously. This is achieved by spreading individual users’ signals over available bandwidth with orthogonal spreading codes—the orthogonality of the spreading codes allows individual signals to be distinguished. The effective use of bandwidth in this system is a considerab...

SUMMARY We propose a novel asynchronous direct-sequence code-division multiple access (DS-CDMA) using feedback-controlled spreading sequences (FCSSs) (FCSS/DS-CDMA). At the receiver of FCSS/DS-CDMA, the code-orthogonalizing filter (COF) produces a spreading sequence , and the receiver returns the spreading sequence to the transmitter. Then the transmitter uses the spreading sequence as its upda...

The requirements for the digital signal processing of broadband wireless access systems are investigated. A discussion of different multiple access schemes considering the boundary conditions of future services is given, resulting in a Time Division Multiple Access (TDMA) proposal. The dominant TDMA component is the adaptive equalizer. Different eligible equalizer structures and adaptation algo...

Joint Detection is used to reduce both inter-symbol interference (ISI) and multiple-access interference (MAI) in the Time Division-Synchronous Code Division Multiple Access (TDSCDMA) system. Conventional rake receivers only consider desired user’s signal, while joint detection receivers take into account both desired user’s signal and other user signals for interference cancellation. If the tra...