# Averting BER Floor with Iterative Source and Channel Decoding for Layered Steered Space-Time Codes
## 1 Introduction
### Related Work
Another useful technique, namely beamforming [19], effectively mitigates the multiple-access interference and multiuser interference. Beamforming guarantees high directivity and gain for the desired user by reducing the gain towards interfering users. Sphere packing (SP) modulation provides the maximum Euclidean distance and is becoming popular due to its high achievable performance when integrated with DSTS [14]. SP modulation attains diversity gain by transmitting symbols from multiple antennas, achieving maximum coding rate due to the maximum Euclidean distance between the SP symbols [14]. The SP modulation based on two orthogonal transmit antennas of size (\(2\times 2\)) using STBCs is represented as in Equation (1). \[G_{2}(x_{1},x_{2})=\left[ \begin{array}{cc}x_{1}&x_{2}\\ x_{2}^{*}&x_{1}^{*}\end{array} \right] \tag{1}\]Here, (*) represents the complex conjugate of the symbol and \(G_{2}\) denotes the transmitted symbols by the two transmitting antennas. The columns in Equation (1) represent the spatial dimension while temporal dimension is represented by the rows for two successive time slots. The modulated signals for transmission are chosen from the available legitimate space time signals. Moreover, SP enhances the error resilience feature of the communication system by jointly designing the complex symbols [14]. Authors in [20] investigated the performance of various source-bit coding (SBC) schemes using DSTS-SP for the iterative JSCD system. Moreover, performance improvement is observed due to DSTS-SP in turbo detection [21], irregular variable length coding [22], and self-concatenated coding [23]. Authors in [24] analyzed the performance of different error protection schemes using the H.264 and H.265 standards. The schemes were specifically designed for supporting varying resolutions and motions over the noisy channel. A gain of 3 dB was recorded for the persistent scheme using the H.265 video standard over the H.264. In [25], the effects of minimum Hamming distance (\(d_{H,\text{min}}\)) was investigated for the SBC based ISCD two-stage system. An improvement in the BER performance was observed with the increase in \(d_{H,\text{min}}\) value. To meet the requirements of higher data rate, spectral efficiency, low latency, and reliability in 5G networks, authors in [26] performed a detailed comparison of the low-density parity check (LDPC) and polar codes. An interesting strategy to mitigate the distortions in video transmission with the aid of dynamic algorithm is proposed in [27]. Moreover, a new parameter is introduced in [27] to gauge the distortions in video communication system due to video encoding. Authors in [28] presented a protocol deploying turbo and systematic network coding for satellite video communication using high efficiency video coding (HEVC). Different combinations of source and channel codes are investigated in [29] to find the optimal strategies for video communication over the lossy channels. An interesting characterization approach was presented in [30] to investigate the energy requirement for the H.265 standard. An efficient algorithm adjustable to variations in power and altering network environments was presented for the H.265 video streams in [31]. To boost the quality of service for the compressed H.265 multi-user stream, reinforcement learning techniques were adopted in [32]. Table 1 shows an overview of the methods and systems investigated recently related to wireless video communication. In this treatise, we aim to attain a combinational gain using the merits of V-BLAST, space-time codes (STCs) and beamforming. These techniques are simultaneously employed in order to enhance the reliability of compressed information at the destination with lower \(E_{b}/N_{0}\) requirements. The system is referred to as layered steered space-time code (LSSTC), as demonstrated in [7; 33]. We have utilized iterative decoding for enhancing the performance of our proposed three-stage LSSTC system.