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Road transportation is one of the main sources of environmental pollution. Electrification seems like the ideal solution for reducing CO2 emissions, while maintaining all the advantages of modern means of transportation. The shift to electric vehicles needs to be accompanied by an appropriate telecommunications network, which is responsible for the reliable transmission of large volumes of information...
In this paper, transmission performance for downlink MU-MIMO (Multiuser Multiple-Input Multiple-Output) systems with computer simulation and field experiment are described. The downlink MU-MIMO system is constructed as a transmitter with 6 antennas and receivers with 2 antennas, and the maximum number of users(receivers) is 3. In computer simulation, MU-MIMO transmission system can be realized by...
This paper presents a generic RAM based FPGA architecture for decoding of Multi Rate Quasi-Cycling LDPC codes. RAM based decoding enables us to reduce permutation networks into simple address controllers. Moreover, utilizing Block RAMs with various aspect ratios in an FPGA provides flexibility ranging from area driven compact designs to fully parallelized high throughput designs. Utilizing the read-first...
Next generation wireless networks are expected to be Heterogeneous consisting of several wireless technologies such as 3G, WLAN, WiMAX, LTE etc. Users of future mobile networks will be able to choose from different radio access technologies. These networks vary widely in service capabilities such as coverage area, bandwidth and error characteristics. Network selection is a challenging task in heterogeneous...
WiMAX is based on the standard IEEE 802.16e-2009 for wireless access in Metropolitan Area Networks. It is one of the solutions for 4G IP based wireless technology. WiMAX utilizes Orthogonal Frequency Division Multiple Access which also supports Multicast and Broadcast Service with appropriate Modulation and Coding Scheme. Presently, Scheduling and Resource allocation algorithm in Opportunistic Layered...
Mobile WiMAX (Worldwide Interoperability for Microwave Access) standardized by IEEE 802.16e is a broadband wireless system based on Scalable OFDMA (Orthogonal Frequency Division Multiple Access). This standard is suitable for the last mile connection in areas where it is not possible to build wired infrastructure, nevertheless it provides a broadband connection for nomadic users and supports cellular...
A power/area aware design is mandatory for the MIMO (Multi-Input Multi-Output) detectors used in LTE and WiMAX standards. The 64-QAM modulation used in the MIMO detector requires more detection effort compared to the smaller constellation sizes widely implemented in the literature. In this work we propose a new architecture for the K-best detector, which unlike the popular multi-stage architecture...
This paper focuses on the coexistence problem of multi-band orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) systems and current radio systems such as IEEE802.11a. Aiming at improving the performance of MB-OFDM UWB, we attempt to avoid interferences from IEEE802.11a systems. The cognitive radio (CR) technology is introduced to detect the distribution of co-channel interferences...
This paper presents a novel technique to significantly reduce the implementation complexity of Low-Density Parity-Check (LDPC) decoders. The proposed technique uses high precision soft messages at the variable nodes but scales down the extrinsic message length, which reduces the number of interconnections between variable and check nodes. It also simplifies the check node operation. The effect on...
In this paper, we propose a bit and power allocation strategy for adaptive modulation and coding (AMC) based spatial multiplexing multi-input-multi-output (MIMO) orthogonal frequency division multiple access (OFDMA) systems. This strategy aims to maximize the average system throughput by allocating the available resources optimally among the utilized bands depending on the corresponding channel conditions...
We propose a strategy that optimally schedules and allocates users for adaptive modulation and coding based orthogonal frequency multiple access systems (AMC-OFDMA). This strategy aims to maximize the average system throughput as a function of bit error rate (BER) and spectral efficiency by exploiting the user diversity. It sorts the available users of an assigned base station (BS) in queues based...
Smart Antenna Systems use the additional degrees of freedom offered by their multiple antennas to exploit, among other things, multipath in the propagation environment. Therefore, by construction, antenna design of smart antenna systems cannot be assessed by simple performance metrics such as gain, polarization and efficiency alone. At a minimum, performance has to be considered in the context of...
The current literature lacks the VLSI realization of high-order multiple-input-multiple-output (MIMO) detectors in the complex domain, which finds applications in advanced wireless standards such as WiMAX and Long Term Evolution (LTE) systems. In this paper, a novel modified complex K-Best algorithm and its VLSI implementation for a 4 × 4, 64QAM complex MIMO detector are proposed. The main contributions...
This paper presents a VLSI architecture of a novel soft-output K-Best MIMO detector. The proposed detector attains low computational complexity using three improvement ideas: relevant discarded paths selection, last stage on-demand expansion, and relaxed LLR computation. A deeply pipelined architecture for a soft-output MIMO detector is implemented for a 4×4 64-QAM MIMO system realizing a peak throughput...
Video surveillance on public transport is a useful tool to fight against anti-social behaviour like vandalism, harassment, graffiti and terrorism. Real-time video surveillance on moving public transport faces serious technological challenges mainly due to limited throughput offered by existing communication technologies at high vehicular speeds. Success of real-time video surveillance on public transport...
A tailbiting block-interleaved pipelining (TB-BIP) is proposed for deeply-pipelined turbo decoders. Conventional sliding window block-interleaved pipelining (SW-BIP) turbo decoders suffer from many warm-up calculations when the number of pipeline stages is increased. However, by using TB-BIP, more than 50% of the warm-up calculations are reduced as compared to SW-BIP. We have implemented a TB-BIP...
In this paper, a tailbiting block-interleaved pipelining (BIP) architecture is proposed for high-throughput and energy efficient WiMAX turbo decoders. Conventional sliding window (SW) BIP turbo decoders suffer from many warm-up calculations and large memory size when the number of pipeline stages is increased. Instead of the SW, we combined the tailbiting method with BIP. Consequently, more than 50%...
Turbo codes are widely used in many radio systems due to its superior performance and Software Radio (SR) is an emerging paradigm of the wireless communication system design due to its good flexibility and adaptability. However, since turbo decoding is computationally intensive, the SR implementation of turbo decoding is always challenging. In this paper, an efficient software implementation of the...
Antenna subset selection methods are feasible to reduce the hardware complexity of multiple-input multiple-output (MIMO) systems. Numerous methods have been devised to resolve this problem. Most of these selection schemes were applied to specific system models and for frequency flat systems. In broadband systems like WiMAX (IEEE 802.16-2004), the overall channel under consideration is typically frequency...
This paper presents WiMax system performance results especially spectral efficiency and throughput under severe multi-path fading and noisy channel conditions. These results are obtained by simulating enhanced WiMax physical layer models with and without transmit diversity. The system behavior is shown to be marginal for modulations beyond 16-QAM under worse conditions necessitating the mandatory...
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