The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
One of the prominent candidate of recent technology is OFDM-IDMA (Orthogonal Frequency Division Multiplexing Interleave Division Multiple Access). IDMA (Interleave Division Multiple Access) inherits most of the advantages of CDMA (Code Division Multiple Access). Adaptive Modulation improves the speediness of digital transmission over fading channels. The performance of system with adaptive modulation...
Scheduling is a fundamental component in resource (bandwidth and power) management in NG wireless networks and plays the main role in providing QoS requirements such as delay, throughput and packet loss for different classes of service in 802.16d networks. In this paper we propose a novel scheduling algorithm Strict Priority Based Adaptive modulation and Coding (SP_AMC_Based) that can grantee QoS...
This paper gives an analysis about OFDM based WiMAX 802.16e with optimum training symbols. In further, performance is evaluated by considering the variable Delay Spread, Frequency Diversity, and with different Adaptive Modulation and Coding. The evaluation of system is performed over simulations showing, Packet error ratio [PER] versus mean Eb/No with Rayleigh fading. The system is considered with...
In this paper, we introduce a new satellite radio interface technology to provide efficient IMT-Advanced services. Maximizing the commonalities with the terrestrial system is one of the most important factors for cost-effective service delivery, which will finally bring successful deployment of the system. For this purpose, we adopt an OFDM based radio interface. At the same time, the interface should...
This paper develops cross-layer adaptive modulation and coding as an efficient method for bit interleaved coded OFDM packet transmission. As objective function, we adopt the goodput, or the number of data bits delivered without error per unit of time. After the formalization of the optimization problem through an accurate modeling on the link performance, an iterative solution is derived based on...
Modern wireless communication demands reliable data communication at high throughput in severe channel conditions like narrowband interference, frequency selective fading due to multipath and attenuation of high frequencies. Traditional single carrier systems address this set of problems by the use of complex, computationally intensive equalization filters. The Orthogonal Frequency Division Multiplexing...
A conventional OFDM system often poses a stringent linearity requirement to the transmitter, especially the radio-frequency power amplifier (RFPA), to maintain its bit error rate (BER). As a result, the output power from a RFPA is often limited, thus, the communication distance is compromised. With the deployment of WiMAX (IEEE 802.16), which is targeting at the mobile market, the communication distance...
The downlink of the Long Term Evolution (LTE) would be OFDMA based and combination of Hybrid ARQ at the data link layer with adaptive modulation and coding (AMC) at the physical layer might be employed. Constellation rearrangement (CR) technique is used in HARQ to enhance MQAM performance. An improved mapping method is used in full IR to enhance system performance. An improved SNR estimation algorithm...
Both orthogonal frequency division multiplexing (OFDM) and single-carrier (SC) with frequency division multiple access (FDMA) have been regarded as a possible solution for improving the performance of future generation wireless communication systems. OFDM can better exploit the frequency diversity gain while SC-FDMA is less sensitivity to non-linearity of amplifier with lower peak-to-average power...
In this paper, we study the performance of an Orthogonal Frequency Division Multiplexing (OFDM) WiMAX transmission system with adaptive modulation and coding (AMC) over different fading channels. An explanation necessary to understand the block diagram of the system is briefly given and a MATLAB code is written to simulate the basic processing involved in this system. The simulation is performed for...
Link layer abstraction is crucial both the cross layer simulation and design and the interface to complete a system level simulator. The calibration takes an important role within this design. In this paper we have used several kinds of algorithms like EESM, CESM and LESM for the instantaneous channel, calibration and evaluation of the link level interface in WiMAX system 802.16e. In order to have...
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...
Adaptive modulation and coding (AMC) is a powerful technique to enhance the link performance by adjusting the transmission power, channel coding rates and modulation levels according to channel state information. In order to efficiently utilize the AMC scheme, an accurate signal-to-noise ratio (SNR) value is normally required for determining the AMC level. In this paper, we propose a simple method...
As good candidates for uplink multiple access scheme in broadband wireless communication systems, orthogonal frequency division multiplexing (OFDM) and single-carrier (SC) with frequency division multiple access (FDMA) have gained enough attention recently. However, the non-linearity of amplifier deteriorates the performances of these two schemes. On the assumption of non-linear amplifier applied,...
In this paper, we consider frequency-selective adaptation from a link and a MAC layer perspective. In particular, we focus on the question of how to combine forward error correction with adaptive modulation and hybrid ARQ. The link adaptation scheme is then fitted into a packet-oriented multi-user OFDM system with a dynamic scheduler.
Future wireless communication systems being characterized by tight frequency reuse, adaptive modulation and coding schemes and diversified data services will be interference limited by interfering signals of diverse rates and strengths. Keeping in view such a scenario, we propose in this paper the application of a proposed low complexity match filter (MF) based detector for spatial interference cancellation...
In accordance with the channel status information, modulation and coding method can be changed adaptively to enhance the throughput in Long Term Evolution Time Division Duplexing (LTE TDD) system. With the scheme of Exponential Effective SNR Mapping (EESM) and Mutual Information Effective SNR Mapping (MIESM), two Adaptive modulation and coding mechanisms are proposed in this paper. Simulation results...
This paper presents a joint adaptive modulation and coding (AMC) scheme, which exploits the coherence bandwidth of the wireless channel to divide the transmitted frame into independent sub-channels that correspond to the channel coherence bandwidth. This strategy is implemented for orthogonal frequency division multiplexing (OFDM) systems with channel state information (CSI) feedback. Low density...
In this paper, we have carried out a detailed analysis of IEEE 802.16-2004 256-point FFT OFDM PHY layer and also simulated the important features of the PHY layer to have a better understanding of the standard. Our main objective is to analyze, evaluate and compare the performance of the PHY layer under various AMC (Adaptive modulation and coding) modes and channel conditions. The discussions based...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.