A Joint QR-LS Based Coarse-Fine Channel Estimation and QR-LRL Detection for Mobile WiMAX 802.16m
01 Dec 2011-pp 1-5
TL;DR: This work extended the previous work of QR-RLS based MIMO(Multiple input Multiple output) channel estimation to Mobile Wimax 802.16m system, where both preamble and pilots are jointly used for robust channel estimation.
Abstract: In this paper, We extended our previous work of QR-RLS based MIMO(Multiple input Multiple output) channel estimation to Mobile Wimax 802.16m system. Mobile wimax system provides high data rate, also fulfills user's requirement like VOD(Video on demand)at very high vehicle speed and also provides better cell coverage area. Channel estimation is crucial part to achieve this goals especially in fast fading environment. Generally, Mobile Wimax systems uses Preamble and Pilots for channel estimation purpose. In the proposed method both preamble and pilots are jointly used for robust channel estimation. At First, QR-RLS Estimator uses Preamble for coarse channel estimation at start of every frame. Once the coarse channel is estimated, then pilots (scattered throughout time-frequency grid) are jointly used with the coarse channel component to derive the channel fading rate. This fading rate is then used to finely estimate the channel at pilot as well as data subcarrier. Thus robust estimation results without adding any overhead. Jointly estimated channel is then used with QR-LRL based data detection, where hard decision values are calculated. Simulation results are shown under various slow-fast channel fading conditions. Results are compared with pilot based channel estimation with LS(least square) interpolation, which shows that joint coarse-Fine estimation gives better performance.
Citations
More filters
01 Sep 2020
TL;DR: It is observed that MMSE-IRC receiver successfully mitigates the interferences compared to only MMSE based receiver and simulation results also show performance improvement over various parameters like sum-rate, interference mitigation and BER compared to prior technologies i.e. 4G-LTE, WiMAX, etc.
Abstract: In this work, we investigated the performance of single input single output (SISO) downlink channel considering 5G new radio (NR). A number of parameters such as different modulation schemes, channel coding with varying code rates, scalable numerology μ and 3GPP channel models have been considered for evaluation. In addition, the minimum mean square error-interference rejection combining (MMSE-IRC) technique for interference mitigation and bit error rate (BER) performance is analyzed and presented. We also compared the sum-rate performance of LTE and 5G NR. It is observed that MMSE-IRC receiver successfully mitigates the interferences compared to only MMSE based receiver. Simulation results also show performance improvement over various parameters like sum-rate, interference mitigation and BER compared to prior technologies i.e. 4G-LTE, WiMAX, etc.
3 citations
Cites background from "A Joint QR-LS Based Coarse-Fine Cha..."
...e 4G (LTE, WiMAX) in terms of BER, sum-rate and interference mitigation [8] ....
[...]
01 Mar 2016
TL;DR: This paper introduces a novel joint channel estimation and detection method for very large MIMO system that uses enlarged QR-LRL based ordered Detection jointly with the EVD based estimated channel, which not only results in less complexity but also provides better BER performance compared to conventional EVD-ILSP method.
Abstract: This paper introduces a novel joint channel estimation and detection method for very large MIMO system. Conventionally, orthogonal pilot sequences are used to determine correct CSI(channel state information). It falls behind due to pilot contamination and spectral inefficiency in large MIMO systems. Many authors suggested promising approaches of blind and semi blind channel estimation[2][3], which work well with a trade-off for complexity. Author[1] suggested EVD-ILSP based estimation, which results in high spectral efficiency compared to conventional method, However, suffers from high complexity due to ILSP method. Here, the proposed method uses enlarged QR-LRL[5] based ordered Detection jointly with the EVD based estimated channel, which not only results in less complexity but also provides better BER performance compared to conventional EVD-ILSP method. Thus the throughput of large MIMO system is increased with reduced complexity. Simulation results demonstrate remarkable improvement in the performance of proposed method over conventional method.
References
More filters
01 Jan 2013
TL;DR: In this article, two major types of pilot arrangement such as block type and comb-type pilot have been focused employing Least Square Error (LSE) and minimum mean square error (MMSE) channel estimators.
Abstract: Orthogonal frequency division multiplexing (OFDM) provides an effective and low complexity means of eliminating inter symbol interference for transmission over frequency selective fading channels. This technique has eceived a lot of interest in mobile communication research as the radio channel is usually frequency selective and time variant. In OFDM system, modulation may be coherent or differential. Channel state information (CSI) is required for the OFDM receiver to perform coherent detection or diversity combining, if multiple transmit and receive antennas are deployed. In practice, CSI can be reliably estimated at the receiver by transmitting pilots along with data symbols. Pilot symbol assisted channel estimation is especially attractive for wireless links, where the channel is time-varying. When sing differential modulation there is no need for a channel estimate but its performance is inferior to coherent system. In this paper we investigate and compare various efficient pilot based channel estimation schemes for OFDM systems. In this present study, two major types of pilot arrangement such as block type and comb-type pilot have been focused employing Least Square Error (LSE) and Minimum Mean Square Error (MMSE) channel estimators. Block type pilot sub-carriers is especially suitable for slow-fading radio channels whereas comb type pilots provide better resistance to fast fading channels. Also comb type pilot arrangement is sensitive to frequency selectivity when comparing to block type arrangement. The channel estimation algorithm based on comb type pilots is divided into pilot signal estimation and channel interpolation. The symbol error rate (SER) performances of OFDM system for both block type and comb type pilot subcarriers are presented in this paper.
412 citations
"A Joint QR-LS Based Coarse-Fine Cha..." refers background or methods in this paper
...An amendment of this standard is IEEE 802.16e. Current Wimax revision of this standard provides data rate upto 40Mbits/s, which is still not fulfilling the Video on demand(VOD) requirements for high speed mobiles (max. speed 350 km/hr) and cell coverage 50 km radius....
[...]
...I. INTRODUCTION Mobile Wimax refers to telecommunication protocol which provides fixed and mobile internet access at very high speed....
[...]
...To achieve these requirements Wimax is updated to a new standard 802.16m which is targeted to achieve the above mentioned goals as well as providing data rates upto 1 Gbits/s. IEEE 802.16m uses SOFDMA(Scalable Orthogonal frequency division multiple access) as its advanced air interface....
[...]
...Various channel estimation methods including two major methods LS(Least-Square) and MMSE(Minimum Mean Square error) [1][2], have been widely used for MIMOOFDM channel estimation....
[...]
...In this paper, we advanced our work [5] by jointly estimating the channel in fast fading environment for Mobile Wimax....
[...]
TL;DR: This work exploits the one-to-one correspondences between the recursive least-squares (RLS) and Kalman variables to formulate extended forms of the RLS algorithm that are applicable to a system identification problem and the tracking of a chirped sinusoid in additive noise.
Abstract: We exploit the one-to-one correspondences between the recursive least-squares (RLS) and Kalman variables to formulate extended forms of the RLS algorithm. Two particular forms of the extended RLS algorithm are considered: one pertaining to a system identification problem and the other pertaining to the tracking of a chirped sinusoid in additive noise. For both of these applications, experiments are presented that demonstrate the tracking superiority of the extended RLS algorithms compared with the standard RLS and least-mean-squares (LMS) algorithms.
281 citations
"A Joint QR-LS Based Coarse-Fine Cha..." refers background in this paper
...[KI002143, Development of IMT-Advanced based WiBro Platform Technologies]. is an efficient modulation scheme to achieve high data rate transmission over frequency-selective fading channels due to its capability to combat the inter symbol interference (ISI), low complexity, and spectral efficiency....
[...]
06 Jul 2003
TL;DR: A channel tracking and equalization method stemming from Kalman filtering is proposed for time-frequency selective channels and the computational complexity is significantly reduced by applying the matrix inversion lemma.
Abstract: In this paper we address the problem of channel estimation for multiple-input multiple-output OFDM systems for mobile users. A channel tracking and equalization method stemming from Kalman filtering is proposed for time-frequency selective channels. Tracking of the MIMO channel matrix is performed in the time-domain and equalization in the frequency domain. The computational complexity is significantly reduced by applying the matrix inversion lemma. Simulation results are presented using a realistic channel model in typical urban scenarios.
42 citations
TL;DR: It is shown that the selection of the first layer impacts the error performance significantly, and based on the observation, a novel signal detection method QR-LRL is proposed, which is shown to be the best choice in terms of noise enhancement in detecting the other layers.
Abstract: The performance of the ordered successive interference cancellation (OSIC) signal detection method is well known to depend on the successful detection of the first layer. In a previous work, in an effort to mitigate the error propagation effect, all the constellation points were tried as the first layer symbol, thereby achieving a better performance. In this letter, we show that the selection of the first layer impacts the error performance significantly, and based on the observation, we propose a novel signal detection method QR-LRL. In the proposed work, the least reliable layer (LRL) is chosen to be the first layer, which is shown to be the best choice in terms of noise enhancement in detecting the other layers. Also, we discuss Log Likelihood Ratio (LLR) computation when the proposed method is used. Computer simulations confirm the efficacy of the proposed method.
31 citations
08 Oct 2007
TL;DR: This work synthesizes the uneven pilot estimation and preamble estimation together to get more accurate joint channel estimation in the WiMAX system and makes some modification to a typical interpolation method based on DFT/IDFT.
Abstract: The theoretical research on comb-pilot OFDM system is mostly based on pilots' even distribution in whole frequency band. With this even characteristic many interpolation methods are found. While in the WiMAX system many factors should be taken into consideration, which results in that pilots are uneven inserted. In order to apply the theoretical interpolation methods into practical system, we make some modification to a typical interpolation method based on DFT/IDFT. Furthermore, each WiMAX physical frame begins with 2 OFDM preamble symbols which we can use to get coarse channel estimation. We synthesize the uneven pilot estimation and preamble estimation together to get more accurate joint channel estimation. In the end, the feasibilities and availabilities of this method are proved by simulations on 6 SUI channel modes, and the excellent performances are also confirmed by WiMAX system testing platform.
6 citations
"A Joint QR-LS Based Coarse-Fine Cha..." refers background in this paper
...In such circumstances channel tracking is required to keep a track and estimate mobile environments....
[...]