Performance Evaluation of Network Header Compression Schemes for UDP, RTP and TCP

Modern cellular networks utilising the Long–Term Evolution (LTE) set of standards face an ever–increasing demand for mobile data from connected devices. Header compression is employed to minimise the overhead for IP–based cellular network traffic.In this paper, we evaluate the three header compression implementations used by such networks with respect to their potential throughput increase and complexity for different mobile service scenarios. We compare RTP, UDP and TCP profile compressions regarding their compression gain and complexity. Specifically, we consider header compression as defined by (i) IP Header Compression (RFC 2507), (ii) Robust Header Compression version 1 (RFC 3095), and (iii) the recently updated Robust Header Compression version 2 (RFC 5225) with TCP/IP profile (RFC 6846).This paper presents the performance evaluation of these header compression schemes for UDP, RTP and TCP, for both IPv4 and IPv6 streams in error–free and error–prone scenarios. A comparison between the Robust Header Compression methods and IP Header Compression is also provided. Our results show that all implementations have great potential for saving bandwidth in IP–based wireless networks, even under varying channel conditions. We also present for the first time an analysis of certain RTP header fields which, depending on the transmission characteristics, could have high impact on the overall compression gain

Prediction of RoHCv1 and RoHCv2 compressor utilities for VoIP

Modern cellular networks utilising the long–term evolution (LTE) and the coming 5G set of standards face an ever–increasing demand for low–latency mobile data from connected devices. Header compression is employed to minimise the overhead for IP–based cellular network traffic, thereby decreasing the overall bandwidth usage and, subsequently, transmission delays. Here, we employ machine learning approaches for the prediction of Robust Header Compression version 1’s and version 2’s compression utility for VoIP transmissions, which allows the compression to dynamically adapt to varying channel conditions. We evaluate various regression models employing r2 and mean square error scores next to complexity (number of coefficients) based on an RTP specific training data set and separately captured live VoIP audio calls. We find that the proposed weighted Ridge regression model explains about at least 50 % of the observed results and the accuracy score may be as high as 94 % for some of the VoIP transmissions

18. századi magyar vonatkozású nyomtatott és illusztrált könyvek feltárása = Typographical research of 18th ct. Hungarian illustrated and printed books

A 18. századi magyar vonatkozású nyomtatott és illusztrált könyvek feltárása az 1701-1750 korszakra vonatkozóan -- a pályázat munkatervében szereplő célkitűzésnek megfelelően -- megtörtént. Elkészült a fenti időkörbe tartozó magyarországi betűtípus- és dísz-repertórium, teljes körű nyilvántartással és reprodukciókkal (23 nyomda 5160 kiadványából 858 betű-sorozat és 4 807 díszítőelem), és elkészült a magyar vonatkozású, külföldön készült metszetek leírása, képi megjelenítéssel együtt (1800 kiadványból kigyűjtött 2700 metszet) Ez utóbbiak leírása és képi megjelenítése egyrészt adatbázis formájában áll rendelkezésre, másrészt az Országos Széchényi Könyvtár honlapján a Digitális Képkönyvtárban: http://nektar-2oszk.hu/librivision.hun.html és www.kepkonyvtar.hu | The typographical research of 18th century printed and illustrated works covering the period 1701--1750 has been finished, according to the aims of the project. As a result of the researches, the complete repertory of the typographical elements, ornaments and illustrations produced in Hungary was collected with textual descriptions and reproductions (from the 5160 printings produced by 23 printing offices containing 858 letter-types and 4807 various ornamental elements), together with the wood-cuts, and engravings of events and personalities of Hungarian relevance (from 1800 publications 2700 engravings). The latter have been worked into a database, and they are also accessible on the website ""Digital Pictures"" of the National Széchényi Library: http://nektar-2oszk.hu/librivision.hun.html respectively www.kepkonyvtar.h