Pilot Symbol Assisted Modulation Research Articles

Unitary Space-Time Modulation Based on Coherent Codes

This paper analyzes the relationship between pilot symbol-assisted modulation (PSAM) and unitary space-time modulation (USTM). In particular, we present a map that transforms any PSAM into a USTM and vice versa. USTMs are known to be capacity-achieving. However, most of the proposed USTM construction methods in the literature are computationally expensive, and the resulting constellations do not have a known structure that could simplify their decoding. Using the relationship between PSAM and USTM, and inspired by a graphical representation of these constellations used in this paper, we propose new USTM construction methods, which ensure that the USTM has a good performance compared to the corresponding PSAM, and a feasible construction and decoding, even for high data rates.

Low-Complexity Power Allocation in Pilot-Pouring Superimposed-Training Over CB-FMT

Pilot-pouring superimposed training (PPST) is a novel channel estimation technique specially designed for cyclic block filtered multi-tone (CB-FMT), where the pilot symbols are poured into the subcarriers taking advantage of the power left unused by the data symbols. Hence, since this technique is based on superimposed training (ST) principles, the data rate is not reduced, unlike the pilot symbol assisted modulation (PSAM). Besides, it exploits a weighted average at the receiver side that is capable of minimizing the mean squared error (MSE) of the channel estimation, and then enhancing the performance of the system. However, the existing proposal on PPST is limited to the minimization of the MSE to improve channel estimation for a given power allocation factor, without solving the joint optimization of channel estimation and data detection procedures. With this aim, this work addresses the whole problem to reach the best performance for both tasks, thus taking into account also the power allocation factor in the optimization process, where the spectral efficiency must be maximized through the signal-to-interference plus noise ratio (SINR). Two optimization approaches are proposed, where the first one, referred as pilot-pouring optimization (PPO), is focused on performance at the expense of a high complexity, while the second one, denoted as low-complexity PPO (LPPO), is able to trade-off between performance and execution time. Numerical results are provided in order to show the validity of our proposal, where the different optimization problems are compared in terms of SINR and execution time.

Pilot Pouring in Superimposed Training for Channel Estimation in CB-FMT

Cyclic block filtered multi-tone (CB-FMT) is a waveform that can be efficiently synthesized through a filter-bank in the frequency domain. Although the main principles have been already established, channel estimation has not been addressed yet. This is because of assuming that the existing techniques based on pilot symbol assisted modulation (PSAM), implemented in OFDM-like schemes, can be reused. However, PSAM leads to an undesirable loss of data-rate. In this paper, an alternative method inspired by the superimposed training (ST) concept, namely pilot pouring ST (PPST), is proposed. In PPST, pilots are superimposed over data taking advantage of the particular spectral characteristics of CB-FMT. Exploiting the sub-channel spectrum, the pilot symbols are poured in those resources unused for data transmission. This spectral shaping of pilots is also exploited at the receiver to carry out channel estimation, by enhancing those channel estimates that exhibit a low data interference contribution. Furthermore, a frequency domain resource mapping strategy for the data and poured pilot symbols is proposed to enable an accurate estimation in strongly frequency-selective channels. The parameters of the proposed scheme are optimized to minimize the channel estimation mean squared error (MSE). Finally, several numerical results illustrate the performance advantages of the proposed technique as compared to other alternatives.

Differential Data-Aided Channel Estimation for Up-Link Massive SIMO-OFDM

Pilot symbol assisted modulation (PSAM) is widely used to obtain the channel state information (CSI) needed for coherent demodulation. It allows the density of pilot symbols to be dynamically chosen depending on the channel conditions. However, the insertion of pilots reduces the spectral efficiency, more severely when the channel is highly time-variant and/or frequency-selective. In these cases a significant amount of pilots is required to properly track the channel variations in both time and frequency dimensions. Alternatively, non-coherent demodulation does not require any CSI for the demodulation independently of the channel conditions. For the particular case of up-link (UL) based on massive single input - multiple output (SIMO) combined with orthogonal frequency division multiplexing (OFDM), we propose to replace the traditional reference signals of PSAM by a new differentially-encoded data stream that can be non-coherently detected. The latter can be demodulated without the knowledge of the CSI and subsequently used for the channel estimation. We denote our proposal as hybrid demodulation scheme (HDS) because it exploits both the benefits of a coherent demodulation scheme (CDS) and a non-coherent demodulation scheme (NCDS) to increase the spectral efficiency. The mean squared error (MSE) of the channel estimation, bit error rate (BER), achieved throughput and complexity are analyzed to highlight the benefits of this differential data-aided channel estimation as compared to other approaches. We show that the channel estimation is almost as good as PSAM, while the BER performance and throughput are improved for different channel conditions with a very small complexity increase.

Performance Analysis of a Multicarrier Spread Spectrum System in Doubly Dispersive Channels With Emphasis on HF Communications

In this paper, we present a bit error rate (BER) analysis of a multicarrier spread spectrum (MC-SS) system that accounts for several non-ideal factors that exist in actual systems; specifically, channel estimation error, correlated subcarriers, and frequency selectivity over each subcarrier frequency band. The particular MC-SS system that is addressed makes use of filter banks to keep subcarrier bands non-overlapping. In this analysis, the time varying multipath channel is modeled using the wide-sense stationary uncorrelated scattering (WSSUS) channel model, and the channel is estimated using a pilot symbol assisted modulation (PSAM) method. Numerical results that demonstrate the accuracy of the developed theoretical results when applied to design transceivers for high frequency (HF) skywave communications show the usefulness of the developed theory in a practical case study.

Power Allocation and Capacity Analysis for FBMC-OQAM With Superimposed Training

Superimposed training (ST) is a semiblind channel estimation technique, proposed for orthogonal frequency division multiplexing (OFDM), where training sequences are added to data symbols, avoiding the use of dedicated pilot-subcarriers, and increasing the available bandwidth compared with pilot symbol assisted modulation (PSAM). Filter bank multicarrier offset quadrature amplitude modulation (FBMC-OQAM) is a promising waveform technique considered to replace the OFDM, which takes advantage of well-designed filters to avoid the use of cyclic prefix and reduce the out-band-emissions. In this paper, we provide the expressions of the average channel capacity of the FBMC-OQAM combined with either PSAM or ST schemes, considering imperfect channel estimation and the presence of the pilot sequences. In order to compute the capacity expression of our proposal, ST-FBMC-OQAM, we analyze the channel estimation error and its variance. The average channel capacity is deduced considering the noise, data interference from ST, and the intrinsic self-interference of the FBMC-OQAM. Additionally, to maximize the average channel capacity, the optimal value of data power allocation is also obtained. The simulation results confirm the validity of the capacity analysis and demonstrate the superiority of the ST-FBMC-OQAM over existing proposals.

Cubic interpolation based channel estimator for rectangular M-QAM

This paper propose a Pilot Symbol Assisted Modulation (PSAM) channel estimation and compensation technique for rectangular M-QAM based on Cubic interpolation in order to determine the channel state information (CSI) over flat Rayleigh fading channels. The proposed Cubic channel estimator technique is based on sliding window approach and pilot symbol estimates adjustment in order to reduce its computational time complexity. The Cubic estimator is combined with the Koetter and Vardy (KV) Reed-Solomon (RS) decoder to test its performance. The simulation results show that the Cubic interpolation gives the same performance as the Linear, and Sinc interpolators over slow flat Rayleigh fading channel; however, it achieves significant performance improvement of +1.0dB in symbol error rate (SER) over fast flat Rayleigh fading channel.

Optimizing the Bit Transmission Power for Link Layer Energy Efficiency Under Imperfect CSI

In this paper, we study the issue of selecting the transmission power (energy per symbol) to minimize the expected energy required to successfully deliver a link-layer packet to the destination node in a wireless link performing the automatic repeat request. We consider the system that has a slow-fading channel and employs a minimum mean square error-based channel estimation scheme for a pilot symbol-assisted modulation. We derive a closed-form expression for the packet error probability (PkEP) in the presence of channel estimation error, and we use this expression for minimizing the PkEP in allocating the transmission energy among the pilot and data symbols. We also derive the expected energy required to successfully deliver a link-layer packet as a function of the transmission power and present an optimization method based on the properties of this function.

Pilot Assisted Channel Estimation in MIMO-STBC Systems over Time-Varying Fading Channels- A Review

this paper, challenge about the condition of channel state info (CSI) in multiple-input multiple-output (MIMO) systems supported space time block codes (STBC) over slow time- varying Rayleigh attenuation channels are addressed. We develop a novel MIMO control assessment algorithmic rule that adopts a pilot symbol assisted modulation (PSAM) which has been proved to be effective for attenuation channels. In this approach, pilot symbols are periodically inserted into the information stream that's sent through the orthogonal STBC encoder. At the receiver, we propose a simple MIMO channel estimation methodology before getting used by STBC decoder. Simulation results indicate that the proposed pilot- assisted MIMO conception provides accurate channel estimates. The impact of Doppler frequency on performance scheme is also investigated by simulation. Keywords-input- multiple-output (MIMO), pilot assisted systems, rate distortion. Channel Estimation.

Polynomial based Channel Estimation Technique with Sliding Window for M-QAM Systems

Pilot Symbol Assisted Modulation (PSAM) channel estimation techniques over Rayleigh fading channels have been analysed in recent years. Fluctuations in the Rayleigh fading channel gain degrades the performance of any modulation scheme. This paper develops and analyses a PSAM Polynomial interpolation technique based on Least Square (LS ) approxi-mations to estimate the Channel State Information (CSI) for M-ary Quadrature Amplitude Modulation (M-QAM) over flat Rayleigh fading channels. A Sliding window approach with pilot symbol adjustment is employed in order to minimize the computational time complexity of the estimation technique. The channel estimation performance, and its computational delay and time complexity is verified for di?erent Doppler frequen-cies ( fd), frame lengths (L), and Polynomial orders (P-orders). Simulation results show that the Cubic Polynomial interpolation gives superior Symbol Error Rate (SER) performance than the Quadratic Polynomial interpolation and higher P-orders, and the performance of the Polynomial estimation techniques degrade with increase in the P-orders.

고속 모바일 환경에서 fast 페이딩 극복을 위한 가우시안 보간 GPSAM 기법

페이딩 채널에서 야기되는 진폭 및 위상 왜곡을 예측하여 보상하는 PSAM(Pilot Symbol Assisted Modulation)방식의 경우에는 fast 페이딩 채널에서 도플러확산에 의해 심한 성능 저하를 갖는다. 이에 대한 문제점을 분석하고, 이를 개선하기 위한 페이딩 보상 방식을 제안한다. 도플러 확산은 BER 성능을 저하시키는 주된 원인이 된다. 기존의 PSAM 방식과 비교해 보면, 한 심벌 주기 이내의 지연파의 간섭이 있는 환경에서는 기존 PSAM 방식은 도플러확산에 의해 BER이 <TEX>$10^{-1}$</TEX> 정도의 매우 심각한 성능저하를 보이지만 제안된 방식은 도플러 확산이 클수록 성능저하는 발생하지만 기존 방식에 비해 BER이 <TEX>$10^{-2}$</TEX> 이하로 성능이 우수함을 알 수 있다. In the case of the Pilot Symbol Assisted Modulation (PSAM) method predicting and compensating amplitude and phases caused on fading channels, there can be severe performance deterioration by Doppler spread on fast fading channels. In this paper, the fading compensation method suggested so as to improve occurring problems as well as analyze them. Doppler spread is the major cause of the bit error rate(BER) performance deterioration. Compared to the existing PSAM method, the more performance deterioration occurs, the larger Doppler spread appears but performance shows well its less <TEX>$10^{-2}BER$</TEX> performance than the existing PSAM method in the suggested method whereas the existing PSAM method has about <TEX>$10^{-1}BER$</TEX> its considerable performance deterioration that caused by Doppler spread within a symbol cycle with the level of delay wave interference.

주파수 선택적 Rayleigh 페이딩 채널에서 고차 PS QAM 채널 보상에 대한 연구

본 논문에서는 파일럿 심벌을 이용하여 플랫 페이딩 채널에서 페이딩 정보를 예측하여 보상하는 방식인 PSAM(Pilot Symbol Assisted Modulation) 방식에 대해 주파수 선택적 Rayleigh 페이딩 채널에서 지연파의 영향을 받는 경우 발생하는 문제점 등을 분석하고 이를 개선하기 위하여 고차 PS(Pilot Symbol) QAM 채널보상 방식을 제안한다. 기존의 PSAM 방식은 지연파의 지연강도가 조금만 영향을 미치더라도 SNR(Signal-to-Noise Ratio)에 상관없이 심각한 성능저하를 보이지만 제안된 방식은 지연파의 지연강도에 영향을 받지만 안정적인 성능개선을 보인다. In this paper, the method of multiple PS(pilot symbol) QAM channel compensation is suggested in order to analyze and improve occurring problems in case of delay waves in Frequency-Selective Rayleigh fading channels through Pilot Symbol Assisted Modulation(PSAM) which is a method predicting and compensating fading information, using Pilot Symbol in flat fading channels. This suggested method shows stable improvement in its performance even though it is effected by the level of delay on delay waves while the existing PSAM method has severe malfunction with a small amount of level of delay on delay waves regardless of signal-to-noise ratio(SNR).

주파수 선택적 채널에서의 OFDM 시스템을 위한 PSAM 채널 추정 기법의 성능 개선

본 논문에서는 주파수 선택적 채널 환경의 OFDM 시스템에서 파일럿 심볼을 이용한 채널 추정 기법인 pilot Symbol Assisted Modulation(PSAM) 채널 추정 성능을 개선하는 방법을 제안한다. OFDM시스템에서는 채널 추정에 쓰이는 파일럿의 밀도가 적을수록 시스템의 유효 데이터량과 전력 효율이 증가되는 장점이 있다. 이를 위해 송신단에서는 채널 추정에 사용되는 파일럿의 수를 적게 사용하는 것이 좋다. 본 논문에서의 수신단에서는 인접한 파일럿 중간에 위치한 채널값이 먼저 추정된 후, 기존의 파일럿 값과 추정된 중간값을 사용하여 나머지 채널값을 추정한다. 그 후 채널의 최대 응답 길이를 고려하여 설계된 보호 구간의 길이를 이용하여 추정된 채널값의 오차를 줄여준다. 제안된 채널 추정 기법의 평균 제곱 오차(MSE) 성능은 기존의 PSAM 채널 추정 방법에 비해 신호대 잡음비 면에서 약 2 dB 정도의 개선 효과를 보여주었다. In this paper, we propose a method to improve performance of pilot symbol assisted modulation(PSAM) channel estimation method for OFDM systems over frequency selective channel. When channel values are estimated, the low pilot density used for channel estimation increases not only the effective data rate but also power efficiency. Thus, the lower pilot density which is used for channel estimation is better for OFDM system. At first, we estimate the channel values which are located at the middle of adjacent pilots, and then all of the possible channel values are estiamted by using original pilot values and previously estimated pilot values. Furthermore, the error of estimated channel values is reduced by introducing guard interval which is designed acccording to maximum channel delay. Performance achieved with the proposed method is illustrated by simulation experiments in comparison with the existing methods in terms of mean squared error(MSE).

To Study Channel Estimation Techniques In Mimo Ofdm System

A multiple-input multiple output (MIMO) communication system is used with orthogonal frequency division multiplexing(OFDM) modulation technique to achieve high and reliable data rate transmission over broadband wireless channels. The need of MIMO OFDM is important because of only MIMO improves the system capacity without additional bandwidth.(1) The performance of MIMO-OFDM system is evaluated on the basis of Bit Error Rate(BER) and Mean Square Error(MSE). The correct channel estimation requires channel response of subcarriers between the pilot tones. Usually the received signal is distorted by channel characteristics. To recover the transmitted bits channel effects must be estimated. By orthogonality principle, each component of received subcarrier is to be expressed as product of transmitted signal and channel frequency response of subcarriers. So, the transmitted signal is recovered by estimating the channel response just at each subcarrier. Generally, data signal as well as training signal, or both , can be used for channel estimation. In this Paper, we will discuss channel estimation techniques in brief. The estimation of channel estimation technique will be carried out through MATLAB simulation.(3) Orthogonal frequency division multiplexing (OFDM) is based on multicarrier communication techniques. The idea of multicarrier communications is to divide the total signal bandwidth into number of subcarriers. A disadvantage of the OFDM approach, is the increased complexity over the conventional system caused by employing N modulators and filters at the transmitter and N demodulators and filters at the receiver. However, this complexity can be removed by the use of the FFT and IFFT at the receiver and transmitter, respectively. The MIMO OFDM system consists of Nt transmit and Nr receiving antenna. Training symbols are used along with pilots in frequency domain.(2) MIMO OFDM is a new broadband wireless technology used in channel estimation due to high data rate and because of its robustness against multipath fading effects. The major problem faced in channel estimation is how to obtain the channel state information correctly. In training symbol based channel estimation the two types of arrangements are used along with the pilot symbol assisted modulation(PSAM) technique. One is the block type and the another is comb type, the block type arrangement channel estimation is done under the assumption of slow fading(channel transfer function not changes rapidly) while in comb type, the interpolation(linear and cubic spline) is used for the estimation. The another techniques are LS(least square) and MMSE(minimum mean square estimation) are widely used for estimation. In the LS estimation, the estimation is done in such a way such that the cost function should be minimized. This method is simple to use. In MMSE, the estimation vector is used by orthogonality principle. This technique is better but more complex than LS estimation. In DFT based, effect of noise outside the maximum channel delay is eliminated and in this, performance is improved as compare to LS and MMSE estimation. In Decision Directed(DD) estimation, the coefficients of channel are updated after the initial estimation is made with preamble or pilots.(2) It uses the detected signal feedback to for tracking the time varying channel to detect the signal.

Error Probability of DF Relaying with Pilot-Assisted Channel Estimation over Time-Varying Fading Channels

In this paper, we investigate the error rate performance of a cooperative network with adaptive decode-and-forward (DF) relaying over time-selective frequency-flat Rayleigh-fading channels. We assume pilot-symbol-assisted modulation (PSAM) for the estimation of time-varying fading channel coefficients. For the system under consideration, we derive an exact closed-form expression for the average bit/symbol error rate, which is further validated through Monte Carlo simulations. Such closed-form solutions are highly desirable because they allow for rapid and efficient performance evaluation. Through the derived expression, we also demonstrate the effect of various system parameters such as the number of relays, Doppler values, and filter length on system performance.

Blind channel estimation for equalisation in dispersive fading channel

A new blind channel estimation technique is presented for non-linear/linear equalisation in a frequency-selective Rayleigh fading channel. At each symbol interval, a decision algorithm first makes a primary data estimate based on constrained linear minimum mean square error criterion, and then this is applied to subsequent channel estimation. Channel estimates are obtained in the form of two alternative, related methods: directly from the Wiener solution or Kalman-based recursion. The former performs better but requires more values from the normalised time-correlation function. The performance is evaluated by simulation, allowing fair comparison with the benchmark of equalised coherent detection; optimal uncoded orthogonal frequency division multiplexing with perfect channel state information at the receiver; the conventional decision-directed Kalman filtering which employs channel tracking with delay; and for the special case of flat fading, an optimised, pilot symbol-assisted modulation system.

PSAM 방식의 SFBC OFDM 전송 시스템의 성능

OFDM 시스템에서 전송채널의 추정은 보통 파일럿 심볼을 사용하여 이루어진다. 본 논문에서는 파일럿 심볼을 사용하는 PSAM 방식의 OFDM 전송 시스템에서 신호가 주파수 선택적인 시변 채널을 통하여 전송될 때 데이터의 비트 오류율을 구한다. 그러나 PSAM 채널 추정 시 에러로 인하여 비트 오류율이 증가된다. 비트 오류율 성능을 향상시키기 위하여, SFBC 안테나 다이버시티를 사용하는 OFDM 전송시스템이 사용될 수 있다. 이러한 PSAM SFBC OFDM 시스템들에서 데이터가 시간과 주파수 선택적인 페이딩 환경 하에서 전송될 때, 채널 추정 에러의 영향을 고려하여 데이터 비트 오류율 성능을 분석한다. Pilot symbol assisted modulation (PSAM) can be used for the channel estimation in orthogonal frequency division multiplexing (OFDM) transmission systems. However, imperfect channel estimates in PSAM systems degrade the bit error rate (BER) performance. I derive the BER of PSAM OFDM systems over time dispersive fading channels. The BER performance of OFDM systems with SFBC antenna diversity are analyzed, where data is transmitted over time and frequency selective Rayleigh fading channel. The performance of this PSAM SFBC OFDM systems, gauged by the average bit error rate, is analyzed considering the channel estimation error.

레일레이 페이딩 채널 보상을 위한 적응형 MPSAM 기술

본 논문에서는 파일럿 심벌을 이용하여 페이딩 채널에서 야기되는 진폭 및 위상 왜곡을 예측하여 보상하는 단일 파일럿 방식인 PSAM(Pilot Symbol Assisted Modulation) 방식에 대한 지연파의 영향을 받는 경우 발생하는 문제점 등을 분석하고, 이를 개선하기 위하여 적응형 MPSAM 방식을 제안한다. 또한, 기존 Basic 방식에 대해서도 분석했고 제안된 방식과 적절하게 접목시킴으로써 성능을 향상시킬 수 있었다. Basic 방식과 비교하면 제안된 방식이 지연파의 지연정도가 0.75 이하로 영향을 끼칠 경우 BER 성능이 상당히 우수함을 알 수 있지만 지연파의 지연정도가 심할수록 인접 심벌의 영향을 많이 받기 때문에 BER 성능이 열악하게 된다. 그러나 Basic 방식은 역방향 보상을 사용하기 때문에 오히려 지연파의 지연정도가 심한 부분에서 BER 성능이 향상됨을 알 수 있다. 그러므로 제안된 방식에 접목시킬 경우 한 심벌내 지연파의 영향을 받는 모든 영역 내에서 안정된 성능향상을 기대할 수 있다. In this paper, the adaptive MPSAM is suggested in order to analyze and improve problems caused by the case of the impact of delay waves on Pilot Symbol Assisted Modulation (PSAM), a singular Pilot method. PSAM predicts and compensates amplitude and phases caused on fading channels, using the Pilot Symbol. In addition, the Basic method is not only analyzed but also grafted onto the suggested method properly; therefore, the performance could be improved. Comparing to the Basic method, the BER performance can be distinguished in case that the level of delay on delay waves with the suggested method goes below 0.7. On the other hand, the BER performance can be inferior due to a considerable effect of the adjacent symbol in the event that the level of delay on delay waves is worse. However, the BER performance is rather improved on the point where the level of delay on delay waves is serious because the Basic method uses reciprocal compensation. Hence, stable improvement can be expected in all areas which receive the influence of delay waves within one symbol once grafted onto the suggested method.

Thresholding-Based Optimal Detection of Wireless Optical Signals

The receiver design for a high-speed free-space (wireless) optics (FSO) signal is necessarily highly complex when channel state information (CSI) is not available. Currently, although most approaches provide high detection performance in terms of bit error, receiver design is difficult to implement. This paper proposes two practical thresholding-based detection schemes, which offer significant improvement to receiver throughput on a computational load basis when CSI is not available. The first is based on a simple maximum likelihood (ML) function where the bit error rate (BER) is the same as conventional symbol-by-symbol detection. This method, however, causes a loss of BER performance. The second uses the aid of pilot-symbol-assisted modulation (PSAM) to modify the ML function when channel coefficients are temporally correlated. While numerical analysis based on this method shows that the BER performance in a log-normally distributed fading channel is very close to detection achieved with perfect CSI, the receiver suffers from increased complexity. If random processes for fading and noise are assumed as stationary and given that the detection threshold is quickly calculated and applied during a given period, such complexity of PSAM-based and symbol-by-symbol detection methods can be reduced.

Generalized MIMO transmit preprocessing using pilot symbol assisted rateless codes

In this paper, we propose a generalized multipleinput multiple-output (MIMO) transmit preprocessing system, where both the channel coding and the linear MIMO transmit precoding components exploit the knowledge of the channel. This was achieved by exploiting the inherently flexible nature of a specific family of rateless codes that are capable of modifying their code-rate as well as their degree distribution based on the channel state information (CSI), in an attempt to adapt to the time-varying nature of the channel. Moreover, we also propose a novel technique, hereby referred to as pilot symbol assisted rateless (PSAR) coding, where a predetermined fraction of binary pilot symbols is interspersed with the channel-coded bits at the channel coding stage, instead of multiplexing the pilots with the data symbols at the modulation stage, as in classic pilot symbol assisted modulation (PSAM). We will subsequently demonstrate that the PSAR code-aided transmit preprocessing scheme succeeds in gleaning more beneficial knowledge from the inserted pilots, because the pilot bits are not only useful for estimating the channel at the receiver, but they are also beneficial in terms of significantly reducing the computational complexity of the rateless channel decoder. Our results suggest that more than a 30% reduction in the decoder's computational complexity can be attained by the proposed system, when compared to a corresponding benchmarker scheme having the same pilot overhead but using the PSAM technique.