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The Long-Term Evolution (LTE) is the next generation of current mobile telecommunication networks. LTE has a new flat radio-network architecture and a significant increase in spectrum efficiency. In this paper a link level implementation in a system-level LTE simulator is proposed. There are two important functions at link level to increase the network capacity: Link Adaptation and Dynamic Scheduling...
The cooperative techniques have recently taken a lot of attention in the recent few years due to their efficiency in radio mobile networks specially when the direct link between the source and the destination is lost. However, their combination with the multiple input multiple output (MIMO) schemes requires further study since new strategies of cooperation are expected when the MIMO component is added...
We analyse mobile propagation channels which occur in the context of car-to-car communications in the 24~GHz ISM band. From the information gathered, we design robust frame designs for combined radar and communication systems using high-bandwidth OFDM signals. Two solutions are proposed: the combination of a spread spectrum technique and a standard convolutional encoder, as well as a low rate Reed-Muller...
We propose the use of simple full interference cancellation (FIC) and orthogonal frequency-division multiplexing (OFDM) within a two-hop asynchronous cooperative four relay network. This approach can achieve the full available diversity and asymptotically full rate. The four relay nodes are arranged as two groups of two relay nodes with offset transmission scheduling. Therefore, the source can serially...
In this paper ways of increasing transmission speed, inter-symbol interference reason and combat techniques which caused by signal reverberation in mobile communication systems are given.
This paper concentrates on the correlative coding used to cancel the frequency offset in orthogonal frequency division multiplexing (OFDM) systems in mobile radio applications, such as 802.11 (WLAN), 802.16 (WiMAX), and digital video broadcasting (DVB) systems, e.g., DVB-CS2. This frequency offset may result due to the time variations of the channel during one OFDM symbol interval, or the transmitter...
The focus of this paper is on the correlative coding used to mitigate frequency offset in orthogonal frequency division multiplexing (OFDM) systems in mobile radio applications, such as 802.11a, 802.16, and digital video broadcasting (DVB) systems, e.g., DVB-CS2. This frequency offset may result due to the time variations of the channel during one OFDM symbol interval, or the transmitter and receiver...
Orthogonal frequency division multiple access (OFDMA) is a multi-carrier transmission technique that has been recently recognized as an excellent method for high speed bi-directional wireless data communication and it is one of the strong candidates as multiple access technique for the next generation of downlink receivers In this paper we aim to investigate the effect of fading channel on the performance...
There are a few core technologies to enable high-performance 4th generation (4G) broadband wireless communication system. A multiple input multiple output (MIMO) provides high-rate transmission through expended channels by multiple array antennas in both sender and receiver side. Also orthogonal frequency division multiplexing (OFDM) is well-known as the most appropriate technique for high data rate...
In this paper, we consider the performance of a dedicated short range communication (DSRC) system for inter-vehicle communications (IVC). The DSRC standard employs convolutional codes for forward error correction (FEC). The performance of the DSRC system is evaluated in three different channels with convolutional codes and regular LDPC codes. In addition, we compare the complexity of these codes....
By retransmission and combining multiple copies of a packet, conventional hybrid ARQ (automatic-repeat-request) schemes are effective to increase the SNR (signal-to-noise ratio) of received signal but not capable of reducing ICI (inter-carrier interference). This paper proposes an adaptive HARQ scheme, which incorporates ICI cancellation into the conventional IR (incremental redundancy)-based HARQ...
The VHF COM band currently used for air-ground communications is becoming congested, and the future air traffic management concepts will require much greater use of data communications than today. The wireless communication system discussed in this paper, L-DACS1, is considered a candidate system for this purpose. It has been derived from B-AMC, TIA-902 (P34), and WiMAX (IEEE 802.16e). The presented...
We first review recent developments in multiple-input multiple-output (MIMO) techniques for mobile WiMAX systems and discuss full-rate and high-rate space-time codes of low decoder complexity. Next, we discuss the frequency reuse issue in sectored cells and point out the limitations due to overlapping of antenna radiation patterns of adjacent sectors and the resulting interference. Then, we discuss...
Conventional time-varying (TV) channel estimation (CE) methods for OFDM systems need optimal evenly spaced pilots to track channel time variations in one symbol period and the inter-carrier interference (ICI) on pilots caused by Doppler spread are regarded as noise. For practical OFDMA systems, the required evenly spaced pilots are unsatisfied and the ICI on pilots increase estimation errors. In this...
The usage of networkspsila speech channels for secure communications or data transmission could be interesting in the case of lack of data channels. In this paper, a scheme for secure communications over voice-dedicated channels of mobile networks, using digital modulations, is proposed. When transmitted over speech channels, the secure communication signal transmission could be subjected to a high...
Orthogonal frequency division multiplexing (OFDM) communication systems, the frequency offsets in mobile radio channels distort the orthogonality between subcarriers resulting in intercarrier interference (ICI). This paper studies an efficient ICI cancellation method termed ICI self-cancellation scheme. The scheme works in two very simple steps. At the transmitter side, one data symbol is modulated...
In this paper, we propose a multipath division SC/MMSE turbo equalizer for multicarrier systems with insufficient cyclic prefix (CP). In the proposed scheme, the received paths, which include paths that exceed the length of the CP, are divided into several blocks. Therefore, inter-symbol interference and inter-carrier interference, which are caused by large delayed paths, can be mitigated by making...
Adaptive modulation enables a WiMAX system to optimize the throughput based on propagation conditions. IEEE 802.16 (WiMAX) system support BPSK, QPSK, 16-QAM and 64-QAM and the access scheme is OFDM. This paper presents the performance of different variants of transmission control protocols with different modulation schemes when density of mobile nodes changes.
Radio platform is one of the upcoming technologies that have the efficient characteristics like flexibility, adaptability and reconfigurability. The best effort service is also provided by this platform. The concepts related to radio flexibility can be defined and explored by the radio platforms. SDR is one of the radio platforms which is adaptive and provides future proof solutions to the wireless...
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