Direction finding of acoustic sources has special importance in military and industrial applications. Lots of algorithms are proposed for solving this problem but, as the complicated conditions of environment enter the problem, a common method with arbitrary precision does not exist for all situations. One of these cases is finding the direction of acoustic sources in multi reflection media such as shallow waters. In this case, many virtual sources are born which are copies of independent sources and are neither detectable nor removable. When the number of these reflections are more than the number of array sensors, the assumptions of customary direction-finding methods are not satisfied and therefore these methods are no longer applicable. In this case, we are facing a problem that the number of signal sources are more than the number of sensors. An important idea for handling this Multipath phenomenon, is to increase the degree of freedom of the sonar array which can be solved based on the sparse arrays. Actually, employing the MRA array, will increase the number of real array sensors virtually so that the problem will return to the ordinary conditions. In this idea, the array manifold matrix is modified to be proportional to the sparse non-uniform array. Simulations confirm the function of the proposed algorithm in the presence of correlated sources that have low error and high angular resolution so that, by 6 real array sensors, this algorithm could find the direction of 12 sources whether independent or correlated. This algorithm is very close to CRLB limit and is better than all compared methods.

Standard TCP is the de facto reliable transfer protocol for the Internet. It is designed to establish a reliable connection using only a single network interface. However, standard TCP with single interfacing performs poorly due to intermittent node connectivity. This requires the re-establishment of connections as the IP addresses change. Multi-path TCP (MPTCP) has emerged to utilize multiple network interfaces in order to deliver higher throughput. Resilience to link failures can be better supported in MPTCP as the segments’ communication are maintained via alternative interfaces. In this paper, the resilience of MPTCP to link failures against several challenges is evaluated. Several link failure scenarios are applied to examine all aspects of MPTCP including congestion algorithms, path management, and subflow scheduling. In each scenario, the behavior of MPTCP is studied by observing and analyzing the throughput and delay. The evaluation of the results indicates MPTCP resilience to a low number of failed links. However, as the number of failed links increases, MPTCP can only recover full throughput if the link failure occurs on the server side. In addition, in the presence of link failures, the lowestRTT MPTCP scheduler yields the shortest delivery time while providing the minimum application jitter.

Symbol rate is one of the key values that a receiver needs to know to find out the information contained in the received signal. In situations where the receiver is not aware of this value, it is necessary to use an estimation algorithm to achieve the goal. The subject of this article is "symbol rate estimation in frequency selective multi path channels" that is more complicated than the Gaussian channel. In this article, after studying some of available sources and methods in this field, an algorithm is proposed to estimate the symbol rate in frequency selective multi path channel. The performance of the proposed algorithm has been discussed in the HF and LTE frequency selective channels with bursts contained of 100 symbols. The curves that considered to determine the performance of the algorithm are the percentage of correct estimation and the NMSE graphs. for the channels which the estimator's performance is measured, in the SNR equal to zero decibels, percentage of correct estimation is more than 95% and the NMSE of estimations is almost 0. 001.

Spatial Modulation (SM) is a novel method in use of multiple antenna systems. The main idea is based on information block mapping into two carrying units: a transmit symbol unit that is chosen from constellation members and second unit is the number of active antenna that shows the position of transmit antenna. The use of active antenna position as an extra source of transmit data increases the bandwidth efficiency. Also it doesn't have inter-antenna interference (IAI) and inter-channel interference (ICI) and it's caused to decrease the complexity in receiver side. So SM is a competitor in multiple antenna systems like V-BLAST and space-time coding. More recently generalized spatial modulation (GSM) is presented that use some active antennas instead an active antenna. When the symbol is sent from multiple antennas, it'll get a diversity gain. In this paper we show that by using different channel coding in GSM we can improve bit error rate (BER) without decrease in bandwidth efficiency between 15-40 percent.