Yueheng Li

The Effect of Mutual Coupling on Capacity of 4-Element Squared Antenna Array MIMO Systems

The channel capacity of an MIMO (multiple input multiple output) system is affected greatly in the case of a compact array configuration by antenna array element mutual coupling (MC). In this paper, we propose a 4-element squared antenna array (SAA) which is considered to be the transmit or receive antenna array due to its symmetric structure instead of linear array. As the beginning of researching this specific SAA configuration, a precise expression of MC, mutual impedance, is firstly derived in this document according to basic antenna theory; next, combined with the equivalent MC network, the effects of MC on the spatial correlation and the average receive power of each antenna array element are investigated; at last, we analyzed and compared the effects of MC on the final channel capacity of SAA and traditional linear array. Theoretical analysis plus numerical simulations are presented to conclude that this symmetric SAA can provide quite stable channel capacity than that of the conventional linear array.

Analysis of Antenna Mutual Coupling in the X-Type Polarization Diversity System

Polarization diversity gain of the X-type polarization diversity system is determined by two factors: spatial correlation and average power ratio. These two factors are affected by mutual coupling (MC) greatly. Base on the polarization diversity antenna construction, a precise expression of MC, that is, mutual impedance is derived in this document. Combined with the equivalent MC network, the effects of MC on the spatial correlation and on the average power ratio are investigated firstly; next the effects of MC on the final polarization diversity gain through these two factors are further analyzed. Theoretical analysis plus numerical simulations are both presented. It is finally concluded that MC can raise the spatial correlation but also decrease the average power difference between the two array elements, thus changing the performance of polarization diversity system.

Outage and Capacity Performance Evaluation of Distributed MIMO Systems over a Composite Fading Channel

The exact closed-form expressions regarding the outage probability and capacity of distributed MIMO (DMIMO) systems over a composite fading channel are derived. This is achieved firstly by using a lognormal approximation to a gamma-lognormal distribution when a mobile station (MS) in the cell is in a fixed position, and the so-called maximum ratio transmission/selected combining (MRT-SC) and selected transmission/maximum ratio combining (ST-MRC) schemes are adopted in uplink and downlink, respectively. Then, based on a newly proposed nonuniform MS cell distribution model, which is more consistent with the MS cell hotspot distribution in an actual communication environment, the average outage probability and capacity formulas are further derived. Finally, the accuracy of the approximation method and the rationality of the corresponding theoretical analysis regarding the system performance are proven and illustrated by computer simulations.

PNCIA: An interference aware wireless multicast scheme with partial network coding

The conventional network coding based multicast schemes usually do not consider the influence of interference of nodes. However, in practical systems, the interference in wireless ad-hoc networks (WANETs) plays an important role on the performance of multicast schemes. By addressing this issue, this paper proposes a partial network coding based interference-aware (PNCIA) multicast scheme for real-time multicast services over WANETs. The core idea is to use a kind of interference measure criterion for multicast routing schemes. On the one hand, the proposed scheme uses partial network coding technique for guarantying real-time transmissions. On the other hand, it will select the path with less interference for the final data transmission. The simulation results show that, compared with traditional network coding based schemes, the proposed scheme can achieve higher throughput and better robust performances.

Impact of mutual coupling on performance of MIMO systems based on network theory analysis

In this paper, we investigated the performance of multiple elements array system such as receive power, signal correlation, channel capacity, and etc., in the presence of mutual coupling based on microwave network theory analysis. Combining S-parameter method and network analysis, the performance of MIMO receiver was studied detailedly. Computer simulations were operated for three different matching conditions: characteristic impedance match, self-impedance match and optimal multiport conjugate (MC) match. The results show that the impact of different matching condition on system’s performance is quite distinct, that is, the matching network plays an important role on improving the performance of MIMO system. Introduction In wireless communication, multiple input multiple output (MIMO) system equipped with multiple antennas at both transmitter and receiver sides can increase the channel capacity greatly[1][2]. Due to this attractive performance improvement, MIMO technique has been considered by many academic researchers, which leads to a great deal of publications. However, mutual coupling among antennas occurs when multiple antenna elements are placed in a small assembling place, such as in a mobile phone, a compact MIMO base station platform, etc [3]. Such coupling will lead to increasement of correlation of antenna signals [4]-[5]. Correlation of the receiver signals can considerably decrease the capacity of multiple element array (MEA) systems [6]. [7]-[11] have investigated the impact of different matching networks on the correlation of signals and MIMO capacity. In this paper, an alternative analysis method based on microwave network theory is presented to describe the compact MIMO communication systems. Using the so-called S-parameter representation, we will analyze the performance of the MIMO systems when there is serious mutual coupling among different antennas elements. Antenna Network Model Fig.1 shows complete network structure model of compact MIMO communication system. Here, we regard 0 b as the excitation source of receiver antenna array. From Fig.1 and microwave network theory [12], we can lead to 0 RR R R b b S a = + (1) 11 R R a S b = (2) In order to make the power transmitted to the load maximally, a matching network with scattering matrix M S is placed in the position between the antenna network and load. It is assumed 4th International Conference on Machinery, Materials and Computing Technology (ICMMCT 2016)

Simulation Performance of MMSE-BLE-SD Detector in the Downlink of TD-SCDMA System

Time division - synchronization code division multiple access (TD-SCDMA) is one of the international protocols for the 3rd generation mobile communication systems. One of its key features is the so-called joint detection (JD), which is adopted to combat the serious multiple access interference (MAI) and inter- symbol interference (ISI) caused by multipath propagation in the case of a short spreading factor (SF). The normally used JD algorithm in TD-SCDMA receiver is zero-forcing block linear equalizer (ZF-BLE), which is a little complex to implement. In this paper, a new candidate algorithm, i.e. MMSE-BLE-SD (minimum mean squared error block linear equalizer for single user detection), which could be implemented with Fast Fourier Transform (FFT), is considered and performance analyzed in the TD- SCDMA linklevel simulation platform. The results show that this less complex detector could provide improved performance than the current used ZF-BLE in the case of 12.2k bit/s voice traffic.

Iterative Feedback Multipath Interference Cancellation Noise Variance Estimator Using Dedicated Pilot Sequence

In this paper, a new method of iterative feedback multipath interference cancellation is applied to estimate the background noise variance in TD-SCDMA receiver during the period of dedicated downlink pilot time slot (DwPTS). Applying this method, the background noise variance could be estimated fast and accurately in all the three testing channels recommended by 3GPP.