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Currently many classical detection and decoding algorithms receive new attention in mobile communications. Amongst those classics are low density parity check codes [1], concatenated codes [2], weighted decoding with log-likelihood values as well as soft-in/soft-out decoding as performed by the BCJR algorithm and its derivatives [4], [5]. All four classics show up as key elements in the so-called...
This contribution considers the basic relations between coding, spreading, multicarrier and singlecarrier transmission against the background of MIMO-OFDM. MIMO-OFDM is taken, because it can be regarded as a scheme which contains many others as special cases, and also because of its increasing relevance for future wireless communication. It is shown that spreading plays a central role: Spreading in...
The establishment of a typical 3G videotelephony (video calls) session is a process that lasts typically around 5 to 8 seconds between today's deployed 3G video-call enabled terminals. This delay is exclusive of call signalling, and is due to the need to complete several protocol procedures as prescribed by the ITU-T H.324 standard and its annex C, including mobile level detection and H.245 messaging...
This paper presents results demonstrating the capacity benefits of Node B Power Sharing, hereafter referred to a NBPS, in a UMTS network for sites that are sectored. It is clear that NBPS at a sectored site has the potential to offer substantial gains when the traffic distribution is non-uniform across those sectors, i.e. hot-spot situations; however, this paper will demonstrate that even when the...
3G mobile system are designed to provide multimedia services. To fulfill QoS requirements for video applications, a robust video codec should be employed. In this paper, a robust and effective algorithm for Group of Blocks (GOB) Intra refresh in H. 264/AVC is presented. The objective is to mitigate the error propagation and improve the perceptual video quality over the mobile networks. Experimental...
Mobile receivers can benefit from an increased spatial diversity through cooperation. Two relaying techniques are typically used: either Amplify and Forward (AF) or Decode and Forward (DF). This contribution presents a new technique which combines the main advantages of both AF and DF. This technique amounts to a DF scheme where all operations are performed in a soft-input soft-output fashion. The...
Mobile relays are network elements which are expected to be part of future generation cellular and wireless network deployments. They can be considered as an extension of fixed relays. Both the fixed and mobile relaying concepts are two flavours of the relaying concept, which is aiming to address coverage and capacity limitations of existing cellular systems. As part of the research for mobile relays,...
For indoor Wireless LAN systems planning, an accurate propagation modelling is required. Semi-empirical models represent an efficient approach to the coverage prediction. Based on measurement results, the model parameters are derived. In this paper we present the influence of the measurement point choice on the accuracy of the parameters estimation and thus on the model robustness.
Wireless sensor nodes run on small battery power and it is sometimes impossible to replace the batteries due to the environment and cost factors associated with them. Therefore, energy efficiency is a critical issue in the design and management of a wireless sensor network. In this paper, following the configuration and protocol implementation within a wireless sensor network, energy efficiencies...
Being one of the first 3G operators in the world with early UMTS experience, 3 were able to focus immediately on the UMTS opportunities and the challenges ahead, resulting in 3 being one of the early drivers for Multimedia Broadcast Multicast Service (or MBMS). This paper provides a brief history regarding the drivers for MBMS. The paper moves on to explain why the architecture is defined as it is...
A new semi-deterministic model with two deterministic clusters and stochastic arriving rays within each cluster, which fits UltRa Lab of university of Southern California indoor UWB measurements well, is proposed based on time-domain geometrical optics (GO) technique. With the additional knowledge of the specific environment geometry, the semi-deterministic model is more accurate in modelling small-scale...
With the operation of General Packet Radio Service (GPRS) and emergence of Third Generation (3G) networks, the demand for the broadband wireless service is massively increased. Standard value-added services such as voice mail, Short Message Service (SMS) have been extended to some richer data exchange services which include email access and Multimedia Message Service (MMS). With MMS which is an evolution...
Multiple-Input Multiple-Output (MIMO) systems have recently appeared as candidates for future high-bandwidth wireless communications. Extensive research in that area has shown that MIMO systems offer significant capacity enhancements, especially in non Line-of-Sight (nLOS) environments, where rich scattering is present. In environments with a strong LOS signal, the capacity enhancement is thought...
The correct identification of pairs of cells to be defined as 'adjacent' is of key importance in any cellular radio system. However, unlike in other radio access technologies, in Code Division Multiple Access (CDMA) the failure to define a pair of cells as 'adjacent' can significantly degrade the coverage and capacity of all the cells concerned, especially under conditions of sufficient cell overlap...
Stanford University Interim Channel Model serial was proposed to simulate the fixed broadband wireless access channel environments where IEEE802.16d is to be deployed. This channel model serial embraces 6 channel models that are grouped into 3 categories according to 3 typical different outdoor terrains. On the other hand, IEEE802.16d Wireless-MAN system demands for a robust synchronization mechanism...
Every user that joins a wireless access network to connect to the Internet expects to receive a secure and reliable service. The process of discovering other nodes on the same link as well as the recovery of routing information is known as Neighbour Discovery Protocol (NDP) [1] and until recently little attempt was made to protect it from misuse and attacks. The recently suggested protection methods...
Multiple-input, multiple-output (MIMO) wireless channels with multiple element antenna arrays can, in principle, offer spectral efficiencies far better than those of conventional single channel systems. In practice however, this improvement relies strongly upon the available wireless channel characteristics of the physical environment. A system with redundant antennas was analysed using measured indoor...
This paper is focused on the study of high coding rate irregular low-density parity-check (LDPC) coded Orthogonal Frequency Division Multiplexing (OFDM) Bell Laboratories Layered Space-Time (BLAST) [1] systems for high-speed wireless transmission. One modified LDPC-coded OFDM BLAST scheme is proposed. To generate high coding rate irregular LDPC codes, three construction rules are adopted to obtain...
Mobility management research is centered on solving problems related on seamless mobility and security. In this paper, we define a problem that has been overlooked in scientific literature. We call the problem suspend mode mobility. When a laptop computer is put on suspend mode and moved to another location, we wish to use the same services without manual reconfiguration. We argue that the Internet...
This paper addresses the topic of bit and power loading in coded MIMO-OFDM systems. Due to the need of designing communication systems with high spectral efficiencies, the combination of multiple antennas at transmitter and receiver with OFDM represents a promising approach. Moreover, channel knowledge at the transmitter can be exploited to adapt the transmission to the channel. While loading strategies...
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