Optimized Irregular Low-Density Parity-Check Codes for Multicarrier Modulations over Frequency-Selective Channels

Mannoni, Valérian; Declercq, David; Gellé, Guillaume

doi:10.1155/s1110865704312199

Cited by 6 publications

(6 citation statements)

References 26 publications

(28 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Wired cable modem standards, such as Asymmetric Digital Subscriber Line (ADSL), High bit-rate DSL (HDSL), and Very high-speed DSL (VDSL) [44] adapt modulation and coding independently across OFDM subbands. Some prior theoretical or simulation studies have proposed a similar approach for wireless channels [27,13,7,22,30,54,32,33,34,11], and a few papers [53,48] have investigated the complexity of hardware implementations of such designs. Our work builds on this foundation but differs in two ways.…”

Section: Related Workmentioning

confidence: 99%

Frequency-aware rate adaptation and MAC protocols

Rahul

Edalat²,

Katabi

et al. 2009

Proceedings of the 15th Annual International Conference on Mobile Computing and Networking

150

View full text Add to dashboard Cite

There has been burgeoning interest in wireless technologies that can use wider frequency spectrum. Technology advances, such as 802.11n and ultra-wideband (UWB), are pushing toward wider frequency bands. The analog-to-digital TV transition has made 100-250 MHz of digital whitespace bandwidth available for unlicensed access. Also, recent work on WiFi networks has advocated discarding the notion of channelization and allowing all nodes to access the wide 802.11 spectrum in order to improve load balancing. This shift towards wider bands presents an opportunity to exploit frequency diversity. Specifically, frequencies that are far from each other in the spectrum have significantly different SNRs, and good frequencies differ across sender-receiver pairs.This paper presents FARA, a combined frequency-aware rate adaptation and MAC protocol. FARA makes three departures from conventional wireless network design: First, it presents a scheme to robustly compute per-frequency SNRs using normal data transmissions. Second, instead of using one bit rate per link, it enables a sender to adapt the bitrate independently across frequencies based on these per-frequency SNRs. Third, in contrast to traditional frequency-oblivious MAC protocols, it introduces a MAC protocol that allocates to a sender-receiver pair the frequencies that work best for that pair. We have implemented FARA in FPGA on a wideband 802.11-compatible radio platform. Our experiments reveal that FARA provides a 3.1× throughput improvement in comparison to frequency-oblivious systems that occupy the same spectrum.

show abstract

Section: Related Workmentioning

confidence: 99%

Frequency-aware rate adaptation and MAC protocols

Rahul

Edalat²,

Katabi

et al. 2009

Proceedings of the 15th Annual International Conference on Mobile Computing and Networking

150

View full text Add to dashboard Cite

show abstract

“…For simulation purposes we compared our irregularity profile optimization results with the works of Mannoni [14] also related to the optimization of irregular LDPC with respect to the frequency selective multicarrier channel. Hence in order to facilitate the comparisons, the same channel impulse response used in [14] was employed for our simulation purposes and which corresponds to a typical ADSL channel with the impulse response given as: Using the GCA algorithm the obtained irregularity profile along with the normalized BER for the above mentioned channel at an SNR of 5dB (same as used in [14]) is given in figure (1) where no cycle-avoidance was done .…”

Section: Simulation Resultsmentioning

confidence: 99%

“…Hence in order to facilitate the comparisons, the same channel impulse response used in [14] was employed for our simulation purposes and which corresponds to a typical ADSL channel with the impulse response given as: Using the GCA algorithm the obtained irregularity profile along with the normalized BER for the above mentioned channel at an SNR of 5dB (same as used in [14]) is given in figure (1) where no cycle-avoidance was done . The optimized irregularity profile using avoidance of cycles of length 4 is given in figure (2).…”

Section: Simulation Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Greedy Check Allocation for Irregular LDPC Codes Optimization in Multicarrier Systems

Mahmood

Jaffrot

2007

2007 IEEE Wireless Communications and Networking Conference

View full text Add to dashboard Cite

The capacity approaching performances [1] of different types of Low Density Parity Check (LDPC) codes have led them to undergo extensive research in recent years. Along with asymptotic performances analysis, the optimization of 'irregularity' profile for different channels and the performance analysis of practical finite-length codes has also been extensively explored. With multi-carrier communications becoming the physical layer choice for many emerging wireless systems, a feasible solution for optimizing the irregularity profile of irregular LDPC codes for a frequency selective channel is a problem of particular importance and interest. This paper proposes a simple-to-implement Greedy 'Check' Allocation (GCA) based method for the construction of BER-optimized irregular LDPC codes using the criterion of Gallager upper bound [2] for probabilistic decoding. A comparison of our GCA algorithm with some existing works [3] on the irregular LDPC codes optimization for multicarrier systems based on the classical gaussian approximation of the 'Density Evolution' approach, shows that the same irregularity behavior can be achieved with a much simpler method.

show abstract

“…We will show how density evolution can be used as a tool to evaluate and optimize these different mapping methods. Interestingly, a similar use of density evolution was done to optimize degree distributions of LDPC codes for OFDM in [3].…”

Section: Introductionmentioning

confidence: 99%

Optimized Mapping Schemes for LDPC Coded Higher Order Modulated QAM Transmission

Lunglmayr

Berkmann

Computer Aided Systems Theory – EUROCAST 2007

View full text Add to dashboard Cite

Abstract. Low Density Parity Check (LDPC) codes are considered to be used in many future communication systems. We will show in this work how the performance of a communication system is influenced when different bit to symbol mapping schemes of a higher order modulation (e.g.: 16-QAM) are combined with LDPC coding. To evaluate and optimize bit-to-symbol mapping methods, a modified version of density evolution is proposed. In addition, simulation results are shown which justify the use of density evolution as a method for qualitative analysis of different symbol mapping schemes in conjunction with LDPC coding. We propose novel mapping methods and show performance results in combination with LDPC coding.

show abstract

Optimized Irregular Low-Density Parity-Check Codes for Multicarrier Modulations over Frequency-Selective Channels

Cited by 6 publications

References 26 publications

Frequency-aware rate adaptation and MAC protocols

Frequency-aware rate adaptation and MAC protocols

Greedy Check Allocation for Irregular LDPC Codes Optimization in Multicarrier Systems

Optimized Mapping Schemes for LDPC Coded Higher Order Modulated QAM Transmission

Contact Info

Product

Resources

About