Compared with channel estimation method based on explicit training sequences,bandwidth is saved for those methods using superimposed training sequences,while it is wasted when Cyclic Prefix(CP) is added.In previous work of McLernon,the Mean Square Error(MSE) performance of Data-Dependent Superimposed Training(DDST) without CP for Single-Input Single-Output(SISO) system was analyzed under the assumption that the data-dependent sequence matrix was a circulant matrix and not interfered by others.In fact,for the system without CP,the data-dependent sequence matrix is not circulant any more and will be interfered.This paper derives the exact expression of MSE for the system without CP and also gives its extension to Multiple-Input Multiple-Output(MIMO) system without CP.
In this paper, a multicarrier DS-CDMA system which employs Z-Complementary Se- quences (ZCS) as spreading code is investigated. The new system can not only eliminate multipath interference and Multiple Access Interference (MAI), but also support flexible number of users com- pared with system using Orthogonal Complementary (OC) codes. Multicarrier DS-CDMA using OC codes can be regarded as a special case of our proposed system. Zero Correlation Zone (ZCZ) of ZCS can be flexibly adjusted to meet the requirements on the user number and maximum multipath and in- ter-user delay, in this way, more users can be supported without losing interference-free property. The effectiveness of the proposed system is validated through theoretical analysis and simulation results.
A new construction method of two-dimensional (2D) variable-weight optical orthogonal codes (VWOOCs) is proposed for high-speed optical code-division multiple-access (OCDMA) networks supporting multiple qualities of services (QoS). The proposed codes have at most one-pulse per wavelength (AM-OPPW) property. An upper bound of the codeword cardinality of the 2D VWOOCs with AM-OPPW property is derived. It is then shown that the constructed codes have ideal correlation properties and optimal cardinality. Moreover, the code length and the bit-error-rate (BER) performance of the proposed codes are compared with those of the codes proposed previously.
