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International audienceLinear closed-loop MIMO precoders are attractive owing to their scalability. They can significantly improve the received signal via optimization of pertinent criterion. The solution of max-dmin precoding is optimal for 4-QAM as it utilizes the channel state information at the transmitter (CSIT) to minimize the system error probability making it very attractive. However, as M increases the solution which is dependent on channel angle gets complex, due to its multi-form precoder search. Motivated by a requirement to provide MIMO system evaluation parameters to upper layer protocol(s) as a function of precoder optimization criterion, we propose deriving a general expression for the probability density function (pdf) of max-dmin. Our approach applies numerical approximations to derive the system bit error rate (BER) and ergodic capacity for any values of M, nr, and nt, and with b = 2 data streams. Results show that the performance of our numerical approximation approach is close to the analytical simulation method

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The evolutionary path taken by cellular standards to the current and future standards is incomplete without fully understanding the older standards. The comprehension of the GSM standard, specifically the procedures for protocols exchange over the air interface will help students understand radio resource allocation procedures in GPRS and UMTS, and will ultimately assist future communication engineers to be able to design and solve problems related to these cellular standards. In this paper we describe the novel architecture of our teaching software, developed and programmed in Java. We present all the user interfaces and show how it can be used to assist in teaching, by presenting how the Mobile station and the GSM/GPRS network exchange data frames over the air interface with their associated protocols. Finally the uniqueness of this teaching tool was proved from the stand point of our modular architecture.

Node location is of main importance for several areas of applications based on Wireless Sensor Networks (WSNs), for instance location-based services. In this paper, we propose a new distributed approach for nodes'position estimation based on distance measurements. Our approach is close to the cooperative approach based on Curvilinear Component Analysis (CCA) proposed in [13]. The complexity of the proposed approach is O(N) for all the network, but as the approach is distributed, the computation time is quasi-constant per node in the network.