In wireless networks we have high and time varying packet losses due to the effect of fading. One way to provide communication without effect of fading is to introduce channel coding and network coding in the system operation. Channel coding (redundant symbols/ bits at the physical layer) is to add redundant information into inside the packet to recover errors in the original information. Network coding (redundant packets at the network layer) is to add redundant information across multiple packets. The channel coding can be called as error correction and the latter network coding can be called as erasure correction. Specially, channel coding is a conventional error correction technique it can be used for point-to-point communication …show more content…
Conversely, erasure correction is always used as end-to-end communication. It can be operated on the packet level, and can be used at either link layer, network layer, or application layer. The traditional network coding allows the intermediate nodes along multiple interleaved paths to generate redundant network-coded packets without decoding all original packets in a distributed manner [1], [2], while the redundancy on network layer can also be used for error correction. Here we explain how to use joint network channel coding scheme based on LDPC codes for multiple access relay channel in section I and Section II. We proposed some preliminaries for our proposed schemes of Min-max relay selection algorithm on Section III. We proposed En masse relay selection schemes and detailed explanation about in Section IV. We shown that En masse relay selection schemes achieves significant performance gains compared to min-max selection criterion in Section V. II. NON-BINARY JOINT NETWORK CHANNEL …show more content…
R. Li, R. W. Yeung, and N. Cai, “Linear Network Coding,” IEEE Trans. Inf. Theory, vol. 49, no. 2, pp. 371–381, Feb. 2003. [2] C. Fragouli, J.-Y. L. Boudec, and J.Widmer, “Network coding: an instant primer,” ACM SIGCOMM Comput. Commun. Rev., no. 1, Jan. 2006. [3] J. Huang, S. Zhou, and P. Willett, “Near-Shannon-limit linear-time encodable Non binary irregular LDPC codes,” in Proc. 2009 IEEE GLOBECOM, pp. 867–872. [4] R. G. Gallager, Low Density Parity Check Codes. MIT Press, 1963. [5] A.Bennatan and D. Burshtein, “Design and analysis of non binary LDPC codes for arbitrary discrete memoryless channels,” IEEE Trans. Inf. Theory, vol. 52, Feb. 2006. [6] F.R.Kschischang, B. Frey, and H.-A. Loeliger, “Factor graphs and the sum-product algorithm, ”IEEE Trans.Inf. Theory, vol. 42, p. 498–519, Feb. 2001. [7] A. Chakrabarti, A. de Baynast, A. Sabharwal, and B. Aazhang. Ldpc code design for half-duplex decode-and-forward relaying. In Proc. 43rd Allerton Conf. on Communication, Control, and Computing, Sept. 2005. [8] X. Qin and R. Berry, “Opportunistic splitting algorithms for wireless networks,” in Proc. 2004 INFOCOM, pp.
When there is loss of packet, the sender doesn’t wait for the time out and resends the packets immediately using the mechanism of fast recovery and fast retransmit.
The sender encodes the information and selects the communication channel through which the message is sent, the receiver receives and decodes the message and
Furthermore, compression techniques that fall into two categories: lossless (reversible, no data loss) and lossy (irreversible, greater data reduction). Effective compression is best achieved with a combination of data reduction techniques such as bit rate reduction and compression. The difference is that bit rate reduction eliminates unnoticeable data, and compression removes unnecessary and excessive data through mathematical algorithms. Due to different forms of redundancy and the fact that the human visual system is unable to detect certain details, information can be altered or removed causing changes that are imperceptible to the human eye or brain.
Delay Tolerant Networking (DTN) is a new area of research in the field of networking that deals with extending existing protocols or inventing new ones in a coordinated, architecturally clean fashion, to improve network communication when connectivity is periodic, intermittent and/or prone to disruptions and when multiple heterogeneous underlying networks may need to be utilized to effect data transfers.
Johnson, D., Maltz, D. (1996). Dynamic Source Routing in Ad-hoc Wireless network. Print ISBN: 0 79239697 0
... in Wireless Sensor Networks: Current proposal and Future Development, IEEE Xplore, Hong Kong, Oct- 2007.
throughput by transmitting independent data streams on the different transmit branches simultaneously and at the same carrier frequency.
Cormen T. H, Leiserson C. E., Rivest R. L. and Stein C. [1990] (2001). “Introduction to Algorithms”, 2nd edition, MIT Press and McGraw-Hill, ISBN 0-262-03293-7, pp. 27–37. Section 2.3: Designing algorithms..
In recent years, network coding [1], [2] has been considered as an auspicious information network paradigm for augmenting the throughput of multiple unicast networks [5]. The pioneering researches of network coding were undertaken by R. Ahlswede, N. Cai, S.-Y.R. Li and R.W. Yeung. Their discovery, which was first introduced in [1][2], are considered to be the crucial breakthrough in modern information theory and the time of its appearance, is recognized as the beginning of a new theory-Network Coding theory. In these elegant, succinct articles, within the purview of rigorous mathematics, the glimmering of an optimal network protocol for multiple unicast network was introduced in which the key idea is considering digital information as wave [riis].
There was a time in our life when going wireless was a dream and was considered highly expensive but then started the era of WIFI. The first outcome of this wireless transmission was IEEE 802.11 standard for wireless data transmission and it progressed as a/b/n with the time. The last stand 802.11n was the real heavyweight and gained a lot of popularity based on its amazing performance. It gave almost 5 times increase in bandwidth using MIMO (Multiple Input Multiple Output) antenna technique. The user experience for 802.11n standard was so good that it was called “end of an Ethernet” at that time. AC standard operates in the 5GHz band with some enhanced physical layer set with the idea of better video communication. It comes with more antennas, wider channels and more spatial stream along with a number of new features to boost throughput and reliability. This new IEEE 802.11ac technology is in reality only an up gradation of physical layer wireless technique used in 802.11n by the use of multiple inputs multiple output (MIMO) antenna technique. Few improvements done in 802.11ac and modified parameters can be studied as following:
Devicenet utilizes the CAN standard on the information connection layer. The base overhead needed by the CAN convention on the information connection layer enhances the Devicenet work when managing messages. The Devicenet information casing uses one and only information edge sort from the CAN convention (among other existing ones). The convention utilizes a base band width to transmit CIP messages. The Devicenet information casing arrangement is demonstrated on figure 1.4.
The Ethernet and WiFi provided a mechanism that could allow computers and electronic appliances to communicate with each other at home without needing to use the existing electrical wiring. As the norm of accessing information across the Internet is done with protocol such as FTP and HTTP, hardware developers saw the opportunity to take advantage of these communications technologies in open source hardware devices. Whereas X10 had lack of confirmation message without expensive two way devices, web technologies provide a whole framework for returning error codes and messages.[1]
Potter, B. (2006, June). Wireless Hotspots: . Communications of the ACM, pp. 51-56. Retrieved from http://topics.info.com/Wireless-Network-Security_4870
Speech coding can be defined as the act of transforming the speech signal to a more compact form in smaller memory. The access to unlimited bandwidth is impossible. Thus, code and compressing of speech signal are needed. Since speech compression required in long-distance communication, high-quality speech storage, and message encryption, many users need to share the same frequency bandwidth in digital cellular technology. The solution is by utilizing speech compression makes it possible for more users to share the available system. Speech coding is a lossy type of coding. The output signal does not exactly sound like the input. Audio coding tries to code the audio in a perceptually lossless way. The sound at the output is the similar as the input even though the input and output signals are not mathematically equivalent. This type of coding is commonly used for audio storage, broadcasting as well as Internet streaming . There are several techniques of speech coding for example Linear Predictive Coding (LPC), waveform coding and subband coding (Abdul et.al ,2003).
However, mobile signals in these environments suffer from multipath fading, penetration and scattering effects and other losses. Many solutions