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Abstract-This work analyses the effects of multipath diversity on the performance of wireless code division multiple access (CDMA) ad hoc networks. Expected progress per slot is used as the performance criterion for the capacity of the described model. The fading can unfavorably affect the data transmission in an wireless network. By the application of the well known rake receiver for CDMA systems, it is shown that multipath diversity significantly increases the CDMA ad hoc network performance, decreasing the harmful effects of the fading.

It is investigated the performance of legacy IEEE 802.11a time synchronization algorithms when the synchronization preamble is transmitted by IEEE 802.11n devices with multiple transmitting antennas using cyclic shift diversity. It is concluded that the backward compatibility is achieved when the time synchronization is implemented using an auto-correlation maximum normalization metric.

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In 2005 the Brazilian government supported researches in order to design a new DTV standard which would employ the most recent technologies. One of the proposals for the new standard's physical layer was named Innovative Modulation for the Brazilian Digital TV System (MI-SBTVD).This proposal employs OFDM and has an operation mode where space-time diversity at the transmitter may be employed, requiring at the receiver side a channel estimation algorithm capable of identifying the MIMO channel. This paper presents some algorithms where the estimation at pilot subcarriers is obtained through a linear combination of two received symbols, and interpolation is done to provide channel gains at data carriers. As the proposed system has the pilot subcarriers positioned in such manner to allow bi-dimensional interpolation, four possible algorithms are evaluated through computer simulations. The results for digital TV channel models are compared.