Pilot decontamination for multi-cell massive MIMO systems using asynchronous pilot design and data-aided channel estimation

Han, Huy-Dung; Nguyen, Dang-An; Nguyen, Vinh; Nguyen, Tien-Hoa; Muhammad, Zia

doi:10.1016/j.phycom.2018.07.006

Cited by 8 publications

(11 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Nevertheless, OPSs cannot be too long as the OPS length is limited by the coherence time of the channel [9]. Besides, the reuse of OPSs of several cochannel cells leads to pilot contamination worsening the MIMO performance [10].…”

Section: Rician Fading Distribution and Orthogonal Piloting In Mimomentioning

confidence: 99%

Influence of Doppler Effects on 2×2 to 4×4 Mimo Systems With Direct Line-of-Sight Path by Rician Fading Distribution

Romanuke

2020

Information and Telecommunication Sciences

View full text Add to dashboard Cite

Background. For multiplying the capacity of a radio link by using multiple antennas at the transmitter and receiver ends, wireless communication networks use the MIMO technique. The quality of MIMO wireless communication may worsen when either the transmitter or receiver end is in motion, or they both are in motion. To sustain high quality of links, MIMO operates, in particular, on channel state information by using orthogonal pilot sequences.Objective. The goal is to estimate the bit-error-rate performance of 2×2, 3×3, and 4×4 MIMO systems with orthogonal pilot sequences for a range of Doppler shifts by the Rician fading distribution modeling the scenario of direct line-of-sight path. The estimation is believed to answer the question on MIMO efficiency by ascertaining whether increasing the number of antennas mitigates the Doppler effect in 2×2 to 4×4 MIMO systems with direct line-of-sight path.Methods. To achieve the goal, 2×2 to 4×4 MIMO systems with channel state estimation are simulated. The simulation is configured and carried out by using MATLAB ® R2019a Communications System Toolbox TM functions. The 35 subcases of the frame length and number of pilot symbols per frame are considered.Results. The near-exponential-type decreasing of the bit-error-rate performance is almost not violated by no motion, whereas further speed increments destroy it for 2×2 MIMO systems. It is revealed that too long packet transmissions by short orthogonal pilot sequences (with respect to the packet length) are prone to errors. This especially concerns 2×2 MIMO systems, where channel state estimation by short orthogonal pilot sequences appears to be ineffective or weakly effective.Conclusions. In general, to maintain an appropriate MIMO link data rate, the packet length should be shortened as the motion speed increases. Increasing the number of antennas additionally mitigates Doppler effects. So, 4×4 MIMO system transmissions are indeed efficient. The shortest possible packet transmissions are not affected by Doppler effects if three or four antennas are used.

show abstract

Section: Rician Fading Distribution and Orthogonal Piloting In Mimomentioning

confidence: 99%

Influence of Doppler Effects on 2×2 to 4×4 Mimo Systems With Direct Line-of-Sight Path by Rician Fading Distribution

Romanuke

2020

Information and Telecommunication Sciences

View full text Add to dashboard Cite

show abstract

“…Many works in the literature have studied this problem (see [1,5] and references therein). In [6,7], semi-blind algorithms have been proposed to perform pilot decontamination by using the Constant Modulus Algorithm (CMA) [8,9]. Indeed, the CMA is one of the most famous blind equalization algorithms thanks to its simplicity and flexibility.…”

Section: Introductionmentioning

confidence: 99%

Semi-blind channel estimation based on Modified CMA and unitary scrambling for massive MIMO systems

Sellami

Siala²

2021

Preprint

View full text Add to dashboard Cite

Pilot contamination is one of the main impairments in multi-cell massive Multiple-Input Multiple-Output (MIMO) systems. In order to improve the channel estimation in this context, we propose to use a semi-blind channel estimator based on the constant modulus algorithm (CMA). We consider an enhanced version of the CMA namely the Modified CMA (MCMA) which modifies the cost function of the CMA algorithm to the sum of cost functions for real and imaginary parts. Due to pilot contamination, the channel estimator may estimate the channel of a contaminating user instead of that of the user of interest (the user for which the Base Station wants to estimate the channel and then the data). To avoid this, we propose to scramble the users sequences before transmission. We consider different methods to perform unitary scrambling based on rotating the transmitted symbols (one Dimensional (1-D) scrambling) and using unitary matrices (two-Dimensional (2-D) scrambling). At the base station, the received sequence of the user of interest is descrambled leading to a better convergence of the channel estimator. We also consider the case where the Automatic Repeat reQuest (ARQ) protocol is used. In this case, using scrambling leads to a significant gain in terms of BLock Error Rate (BLER) due to the change of the contaminating users data from one transmission to another induced by scrambling.

show abstract

“…Nevertheless, in fact, MIMO is a technique using multiple antennas at the transmitter and receiver ends of a wireless communication system [1]. This is why MIMO systems are used in wireless communication standards, including IEEE 802.11n (Wi-Fi), IEEE 802.11ac (Wi-Fi) [2], HSPA+ (3G), WiMAX, Long Term Evolution (4G LTE) [3], [4], and 5G by implementing massive MIMO [5], [6]. MIMO technology has been officially standardized for wireless LANs, 3G and 4G mobile phone networks, but it is being increasingly tested and spread in many other wireless communication standards.…”

Section: Introduction To Mimo With Channel Estimationmentioning

confidence: 99%

“…To sustain high quality of links, MIMO operates on channel state information (CSI) [1], [3], [5], [6]. The CSI is required to know how a signal propagates from the transmitter to the receiver for adapting transmissions to current channel conditions, which is crucial for achieving reliable communication with high data rates in multiantenna systems.…”

Section: Introduction To Mimo With Channel Estimationmentioning

confidence: 99%

Improvement of Pilot Symbol Orthogonal Sequences in 2×2 to 4×4 MIMO Wireless Communication Systems with Channel State Estimation

Romanuke

2021

Electrical, Control and Communication Engineering

View full text Add to dashboard Cite

MIMO wireless communication systems with channel state estimation, in which 2 to 4 transmit-receive antenna pairs are employed, are simulated. The channel estimation is fulfilled by the orthogonal pilot signal approach, where the Walsh Hadamard-ordered sequences are commonly used for piloting. The signal is modulated by applying the quaternary phase shift keying method. Maximum 250 000 packets are transmitted through flat-fading Rayleigh channels, to which white Gaussian noise is added. Based on simulating 10 subcases of the frame length and number of pilot symbols per frame, it is ascertained that pilot symbol orthogonal sequences in 2×2 to 4×4 MIMO systems can be improved by substituting Walsh functions with partially unsymmetrical binary functions constituting the eight known orthogonal bases. The benefit is that the bit-error rate is substantially decreased, especially for 2×2 MIMO systems. Considering three cases of the pilot signal de-orthogonalization caused by two indefinite and definite pilot sequence symbol errors, the relative decrement varies from 0.123 % to 14.7 %. However, the decrement becomes less significant as the number of transmit-receive antenna pairs is increased.

show abstract

Pilot decontamination for multi-cell massive MIMO systems using asynchronous pilot design and data-aided channel estimation

Cited by 8 publications

References 17 publications

Influence of Doppler Effects on 2×2 to 4×4 Mimo Systems With Direct Line-of-Sight Path by Rician Fading Distribution

Influence of Doppler Effects on 2×2 to 4×4 Mimo Systems With Direct Line-of-Sight Path by Rician Fading Distribution

Semi-blind channel estimation based on Modified CMA and unitary scrambling for massive MIMO systems

Improvement of Pilot Symbol Orthogonal Sequences in 2×2 to 4×4 MIMO Wireless Communication Systems with Channel State Estimation

Contact Info

Product

Resources

About