Due to the characteristics of underwater acoustic channel, media access control (MAC) protocols designed for underwater acoustic sensor networks (UWASNs) are quite different from those for terrestrial wireless sensor networks. Moreover, in a sink-oriented network with event information generation in a sensor field and message forwarding to the sink hop-by-hop, the sensors near the sink have to ...

The overloaded CDMA schemes exploited in direct sequence CDMA (DS-CDMA) systems are mainly to accommodate a greater number of users than the available spreading factor N . In this paper, a superposition coding CDMA (SPC-CDMA) with unequal error protection (UEP) is proposed as one of the overloaded CDMA schemes for the next generation mobile communication systems. It exploits the available power...

__________ Many mobile satellite systems have been proposed to employ Code Division Multiple Access (CDMA) technique at L/S band. These bands have been allocated to the mobile satellite services on a primary basis since 1992, in addition to the existing services. Therefore, the mobile satellite services will be subject to share spectrum with each other and with existing services. This paper dis...

In code division multiple access CDMA systems direct sequence DS applying maximum ratio combining MRC at the receiver has achieved high interest for mobile communications A second and rather novel technique is orthogonal frequency division multi plexing OFDM applying maximum likelihood detection MLD at the receiver In this paper the performance of both tech niques is compared considering the mo...

Direct detection optical code-division multipleaccess (CDMA) communication systems involving overlapping pulse-position modulation (OPPM) is considered. Double optical hardlimiters placed before and after the correlator at the receiver side is proposed for this system. The performance (in terms of the bit error probability) of this system is evaluated taking into account the effect of both the ...

In this paper, we investigate the influence of different Walsh-Hadamard (WH) code allocation techniques on the performance of multi-carrier code division multiple access (CDMA) systems in the presence of high power amplifier (HPA) non-linearities. We consider two different multi-carrier CDMA schemes: multi-carrier CDMA (MCCDMA) and multi-carrier direct sequence CDMA (MC-DSCDMA) and analyse thei...

A hybrid TDMA/CDMA MAC protocol for WSN is proposed that combines the strengths of TDMA and CDMA while offsetting their weaknesses. The proposed scheme allows the network to operate in a collision-free manner, and takes advantage of broadband property provided by CDMA. The main features of this hybrid protocol are high throughput and low latency. Performance of this new protocol is compared wit...

Mobile radio communication systems are affected by the frequency and time selectivity of radio channel due to multipath propagation and Doppler shifts. In an Orthogonal Frequency Division Multiplexing (OFDM) based Code Division Multiple Access (CDMA) system, the spreading schemes will suffer loss of orthogonality between codewords of different users. In this thesis, basic system model of severa...

In this lecture, we present the mathematical analysis on the average bit error rate for multi-users in a single channel of the spread spectrum, Code Division Multiple Access (SS-CDMA) mobile radio system. We present expressions of BER performance of CDMA systems for a wide range of interference conditions for both synchronous case and asynchronous case, including Gaussian approximations (GA), I...