Congzhe Cao

Congzhe Cao
University of Alberta | UAlberta

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36
Publications
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262
Citations

Publications

Publications (36)
Article
Online fountain codes (OFC) have attracted much attention for their good intermediate performance, which is important for receivers with low-complexity requirement. However, low-complexity receivers generally have limited buffer size to store coded symbols that have not been fully decoded yet, as well as limited power budget for feedback transmissi...
Conference Paper
Full-text available
Polar codes used with successive cancellation decoders (SCDs) provide a hardware-friendly low-complexity solution for a variety of applications. However, SCDs suffer from high latency. A set of fast SCDs has been proposed in the literature to reduce this latency. Irregular polar codes can reduce the decoding complexity and improve the error rate co...
Article
Full-text available
We study the ability of recently developed variable-length constrained sequence codes to determine codeword boundaries in the received sequence upon initial receipt of the sequence and if errors in the received sequence cause synchronization to be lost.We first investigate construction of these codes based on the finite state machine description of...
Article
In this paper, we study wireless broadcast schemes based on online fountain codes. We first propose and analyze an online fountain code based-broadcast scheme, where the coded symbol degree is updated based on the decoding states of all receivers. Then we propose and analyze an improved broadcast scheme by taking advantage of the received coded sym...
Article
For the benefit of improved intermediate performance, recently online fountain codes attract much research attention. However, there is a trade-off between the intermediate performance and the full recovery overhead for online fountain codes, which prevents them to be improved simultaneously. We analyze this trade-off, and propose to improve both o...
Preprint
For the benefit of improved intermediate performance, recently online fountain codes attract much research attention. However, there is a trade-off between the intermediate performance and the full recovery overhead for online fountain codes, which prevents them to be improved simultaneously. We analyze this trade-off, and propose to improve both o...
Article
Full-text available
In this paper, we propose a novel polar coding scheme for blind detection in 5G systems. In the proposed scheme, the codewords for different aggregation levels (ALs) are constructed in a nested fashion, and a low-latency detection scheme is proposed. The nested construction is exploited to help locate the target physical downlink control channel (P...
Article
Contention-based access is a promising technology for massive and sporadic transmissions. In this paper, we propose a novel contention-based multiple access scheme, named irregular repetition spatially-coupled slotted ALOHA (IRSC-SA), motivated by the spatial coupling and irregular repetition techniques. There are different classes of users and slo...
Preprint
Full-text available
Constrained sequence (CS) codes, including fixed-length CS codes and variable-length CS codes, have been widely used in modern wireless communication and data storage systems. Sequences encoded with constrained sequence codes satisfy constraints imposed by the physical channel to enable efficient and reliable transmission of coded symbols. In this...
Article
Full-text available
Polar codes have been applied in many applications due to the excellent decoding performance as well as relatively low encoding and decoding complexity. In the cell search procedure for the fifth generation (5G) systems, part of the common information bits are transmitted in successive transmission blocks. In this paper, multipleblock combined deco...
Article
Full-text available
We consider the construction of capacity-approaching variable-length constrained sequence codes based on multi-state encoders that permit state-independent decoding. Based on the finite state machine description of the constraint, we first select the principal states and establish the minimal sets. By performing partial extensions and normalized ge...
Article
Full-text available
Polar codes have become the channel coding scheme for control channel of enhanced mobile broadband in the fifth generation (5G) communication systems. Belief propagation (BP) decoding of polar codes has the advantage of low decoding latency and high parallelism but suffers from high complexity. In this paper, a low complexity BP decoder is proposed...
Conference Paper
Full-text available
Constrained sequence codes have been widely used in modern communication and data storage systems. Sequences encoded with constrained sequence codes satisfy constraints imposed by the physical channel, hence enabling efficient and reliable transmission of coded symbols. Traditional encoding and decoding of constrained sequence codes rely on table l...
Article
In this paper, we propose a novel approach to enhance the performance of frameless slotted ALOHA (SA) protocol. We employ signature codes to help the receiver identify the packets contained in collisions, and use successive interference cancellation (SIC) for packet recovery. We model the proposed scheme as a two-state Markov model represented by a...
Article
Full-text available
The use of constrained sequence (CS) codes is important for the robust operation of transmission and data storage systems. While most analysis and development of CS codes has focused on fixedlength codes, recent research has demonstrated advantages of variable-length CS codes. In our design of capacity-approaching variable-length CS codes, the cons...
Preprint
Full-text available
Constrained sequence codes have been widely used in modern communication and data storage systems. Sequences encoded with constrained sequence codes satisfy constraints imposed by the physical channel, hence enabling efficient and reliable transmission of coded symbols. Traditional encoding and decoding of constrained sequence codes rely on table l...
Article
The online property of fountain codes enables the encoder to efficiently find the optimal encoding strategy that minimizes the encoding overhead based on the instantaneous decoding state. Therefore, the receiver is able to optimally recover data from losses that differ significantly from the initial expectation. In this paper, we propose a framewor...
Article
Full-text available
This paper considers the use of polar codes to enable secure transmission over parallel relay channels. By exploiting the properties of polar codes over parallel channels, a polar encoding algorithm is designed based on Channel State Information (CSI) between the legitimate transmitter (Alice) and the legitimate receiver (Bob). Different from exist...
Conference Paper
Full-text available
Ultra-reliable forward error correction (FEC) codes approaching the Shannon limit have played an important role in increasing spectral efficiency of wireless communications. In addition to the error correction performance, both low-power and low-latency decoding are demanded for the fifth generation (5G) wireless applications. In this paper, we int...
Article
Full-text available
Sequences encoded with Pearson codes are immune to channel gain and offset mismatch that cause performance loss in communication systems. In this paper, we introduce an efficient method of constructing capacity-approaching variable-length Pearson codes. We introduce a finite state machine (FSM) description of Pearson codes, and present a variable-l...
Conference Paper
Full-text available
We propose polar turbo product code (TPC) to enable parallel/pipeline decoding, for high-throughput transmission. With irregular polar codes, the computational complexity and latency can be significantly reduced, yet outperforming BCH-constituent TPC by 0.5dB.
Article
Full-text available
The next-generation fiber-optic communications call for ultra-reliable forward error correction (FEC) codes which are also capable of low-power and low-latency decoding. In this paper, we propose a new class of polar codes, whose polarization units are irregularly pruned to reduce the computational complexity and decoding latency without sacrificin...
Article
A new encoding scheme for on-line fountain codes is proposed to provide unequal error protection (UEP) for source symbols. Both the weighted-selection strategy and the expanding-window strategy are used to achieve the UEP property. We analyze the bound of overhead to demonstrate the performance. We also make comparisons with on-line fountain codes...
Conference Paper
A novel approach to design capacity-approaching variable-length constrained sequence codes has recently been developed. A critical step in this design process is the construction of minimal sets based on a finite state machine description of the encoders. In this paper we propose three generalized criteria to select the state that will result in co...
Article
We propose using variable-length constrained sequence codes to mitigate inter-cell interference (ICI) in all-bitline flash memory with multi-page programming for single-level cell (SLC), multi-level cell (MLC), and triple-level cell (TLC) flash memory structures. We outline constraints that mitigate ICI in these systems based on an observation of t...
Article
We study improved degree distribution for Luby Transform (LT) codes which exhibits improved bit error rate performance particularly in low overhead regions. We construct the degree distribution by modifying Robust Soliton distribution. The performance of our proposed LT codes is evaluated and compared to the conventional LT codes via And-Or tree an...
Article
Full-text available
We propose a low complexity list successive cancellation (LCLSC) decoding algorithm to reduce complexity of traditional list successive cancellation (LSC) decoding of polar codes while trying to maintain the LSC decoding performance at the same time. By defining two thresholds, namely "likelihood ratio (LR) threshold" and "Bhattacharyya parameter t...
Article
We propose an extended packetization-aware mapping algorithm based on fountain codes to enhance video stream performance which is vulnerable to packet losses. By properly utilizing the proposed algorithm in finite-length cases, the edges connecting to a source symbol are scattered over multiple encoding packets so that the decoding probabilities ar...
Conference Paper
This paper proposes a multicast transmission scheme with Hybrid Automatic Repeat reQuest (HARQ) based on Network Coding (NC) and Adaptive Modulation and Coding (AMC). We analyze the system throughput theoretically and derive the optimal number of retransmissions with multi-retransmission consideration. Numerical results show that under specific Qua...

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Project (1)
Project
Develop constrained sequence codes that are used for modern communication and data storage systems, including hard drives, flash memories, DNA-based storage, wireless visible light communications, etc. Work on new code design and detection/decoding methods.