Term Evolution Standards Research Articles

Upper bounds on the minimum distance for turbo codes using CPP interleavers

Analysis of error correction performance for error correcting codes is very important when using such codes in digital communication systems. At medium-to-high signal-to-noise ratios, the distance spectrum of the error correcting code represents a good indicator for the error correction performance of the code. It is desired that the minimum distance of the code is as large as possible and that the corresponding multiplicity (i.e. the number of codewords having the weight equal to the minimum distance) is as small as possible. If we know an upper bound of the minimum distance of the code, then we have a good indication about the capabilities and the limitations of the code. One of the classes of the error correcting codes with the best performance is that of turbo codes. For such codes, establishing upper bounds on the minimum distance is challenging because it depends on the interleaver component of the turbo code. In this paper we consider turbo codes with component convolutional codes as in the Long Term Evolution standard. The interleaver lengths are of the form $$16 \varPsi $$ or $$48 \varPsi $$ , with $$ \varPsi $$ a product of different prime numbers greater than three. The first achievement in the paper is that for these interleaver lengths, we show that cubic permutation polynomials (CPP), with some constraints on the coefficients, when $$3 \not \mid (p_i-1)$$ for a prime $$p_i > 3$$ , always have a true inverse CPP. The most accurate upper bounds on the minimum distance for turbo codes are achieved by identifying bit information sequences leading to a certain weight of the corresponding turbo-codeword. In this paper we have indentified such bit information sequences by means of the full range dual impulse method to estimate the weight of the turbo-codewords. For the previously mentioned turbo codes and CPP interleavers, we show that the minimum distance is upper bounded by the values of 38, 36, and 28, for three different classes of coefficients. Previously, it was shown that for the same interleaver lengths and for quadratic PP (QPP) interleavers, the upper bound of the minimum distance is equal to 38. Several examples show that $$d_{min}$$ -optimal CPP interleavers are better than $$d_{min}$$ -optimal QPP interleavers because the multiplicities corresponding to the minimum distances for CPPs are about a half of those for QPPs. A theoretical explanation in terms of nonlinearity degrees for this result is given for all considered interleaver lengths and for the class of CPPs for which the upper bound is equal to 38.

Patenting strategies and characteristics of declared inventions in the long term evolution standard

This study provides an empirical analysis of patent declarations at the European Telecommunications Standards Institute concerning the core releases of the Long Term Evolution standard for mobile communications. The analysis of the declared Standard Essential Patents suggests that the distribution of essential inventions across firms is less concentrated than in previous mobile standard generations [Global System for Mobile communications and Universal Mobile Telecommunications System in 1991 and 1999], mainly due to the entry of new global players. We investigated the characteristics of the declared patents and their value as proxied by the number of citations received before and after the declaration. We distinguish between entrant and incumbent firms. The declared patents receive on average more citations than a control sample of nondeclared. However, such citation premium is higher for incumbent firms than entrants. Overall evidence suggests that new global players in the field are more likely to declare patents with a narrower technological scope and that have a relatively lower technological merit as captured by citations.

R‐11‐based power control approach for overlaid femtocell networks

SummaryShort range, low power, plug‐and‐play femtocell has carved a niche for itself because of its potential for higher rate indoor voice and data service, coverage enhancement over cell edges, high network capacity, and negligible greenhouse gas emission. The frequency reuse phenomenon in two‐tier cellular network subjects the cell‐edge macrouser to severe downlink interference from co‐channel deployed femtocells in the same province. Downlink power control approach is a recommended remedy to overcome such type of interferences. This paper proposes release‐11‐based maximum downlink power control (R‐11‐based MDPC) approach to protect macrouser's service from co‐channel interference. The feedback strategy incorporated in this paper is formulated by R‐11 of 3rd Generation Partnership Program for Long Term Evolution standard. Implementation of new R‐11‐based feedback strategy between femto‐base station and macro‐base station with MDPC approach ensures instantaneous power control with minimal feedback delay, higher signal‐to‐interference‐plus‐noise ratio (SINR), simple receiver module design, and better service availability. Simulation results of R‐11‐based MDPC approach clearly indicate reduced feedback delay, better power control with minimal interference, improved SINR, and negligible outage probability. Copyright © 2015 John Wiley & Sons, Ltd.

On the Role of Overlapping Factor in FBMC-SMT Systems

The overlapping factor has a vital role in determining the optimum bandwidth utilization and the desired side band suppression. In this paper, we review one of the filter bank multicarrier technique-staggered multi tone modulation, discuss its efficient implementation in polyphase form and compare between several performance parameters of the same. We also discuss the role of overlapping factor in staggered multi tone modulation systems. We describe a low complexity procedure for generation of the required overlapping factors based on frequency sampling method. Our simulations describe the effectiveness of the optimum value selection for overlapping factor in a staggered multi tone modulation system. The proposed system is theoretically found to be compatible with the Long Term Evolution standards. The performance evaluation of the proposed system in ideal conditions emphasizes about the reduction in spectrum leakage in sidebands of the staggered multi tone modulation system, along with a little increase in system complexity.

MIMO multiband antenna system with nonresonant elements

ABSTRACTMulti‐input multi‐output (MIMO) technology will enable high‐data rates in wireless devices to allow speech and video calls to streaming media and web browsing all over a common platform. MIMO technology needs M antennas both in transmission and reception. As the space in a wireless device is limited, including M antennas is a challenge. To face such challenge, a MIMO antenna system is proposed which comprises two small nonresonant elements operating in the frequency region 824–960 MHz and two identical elements operating at 1710–2170 MHz. The size of each of the nonresonant elements is only 5 × 5 × 5 mm3. The proposed MIMO system is analyzed in terms of bandwidth, efficiency, correlation, and multiplexing efficiency. MIMO capacity is measured in a reverberation chamber considering a free‐space Rayleigh scenario and also including the effect of a phantom head and hand. The results reveal that the proposed MIMO system provides capacity close to the ideal bound while having a small size and able to operate at several 2G, 3G, and 4G long term evolution standards. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:183–190, 2015

A joint resource optimization and adaptive modulation framework for uplink single‐carrier frequency‐division multiple access systems

SummaryIn this paper, we study joint resource allocation and adaptive modulation in single‐carrier frequency‐division multiple access systems, which is adopted as the multiple access scheme for the uplink in the 3GPP Long Term Evolution standard. We formulate an adaptive modulation and sum‐cost minimization (JAMSCmin) problem. Unlike orthogonal frequency‐division multiple access, in addition to the restriction of allocating a subchannel to one user at most, the multiple subchannels allocated to a user in single‐carrier frequency‐division multiple access systems should be consecutive as well. This renders the resource allocation problem prohibitively difficult and the standard optimization tools (e.g., Lagrange dual approach widely used for orthogonal frequency‐division multiple access, etc.) cannot help towards its optimal solution. We propose a novel optimization framework for the solution of this problem that is inspired from the recently developed canonical duality theory. We first formulate the optimization problem as binary‐integer programming (BIP) problem and then transform this BIP problem into continuous space canonical dual problem that is the concave maximization problem. Based on the solution of the canonical dual problem, we derive joint resource allocation and adaptive modulation algorithm, which has polynomial time complexity. We provide conditions under which the proposed algorithm is optimal. We compare the proposed algorithm with the existing algorithms in the literature. The results show a tremendous performance gain. Copyright © 2013 John Wiley & Sons, Ltd.

Evolution of 3GPP LTE in Release 11 and beyond [Guest Editorial

The articles in this special section focus on the topic of third generation networking Long Term Evolution standards and protocols.

Evolved multimedia broadcast/multicast service (eMBMS) in LTE-advanced: overview and Rel-11 enhancements

The Third Generation Partnership Project defined multimedia broadcast/multicast service in 2005 to optimize the distribution of video traffic. This standard covers the terminal, radio, core network, and user service aspects. This MBMS standard has evolved into enhanced MBMS (eMBMS) that builds on top of the 3GPP Long Term Evolution standard. eMBMS evolution brings improved performance thanks to higher and more flexible LTE bit rates, single frequency network operations, and carrier configuration flexibility. 3GPP Rel-11 also brings improvements in the areas of service layer with, for example, video codec for higher resolutions and frame rate, and forward error correction. eMBMS allows offloading of the LTE network and backhaul. It enables the possibility to deliver premium content to many users with secured quality of service in defined areas. Other important use cases are pushed content via user equipment caching and machine-to-machine services. This article describes the relevant use cases for eMBMS in terms of service. It then gives a tutorial on eMBMS, in particular highlighting the evolution over MBMS. The scope comprises the radio access, core network, and service layer.

Orthogonal frequency division multiple access in WiMAX and LTE: a comparison

Orthogonal frequency-division multiple access has been adopted by both the WiMAX and Long Term Evolution standards, which are the two main contenders in the 4G wireless scenario. In this article, we do a detailed comparison of the implementation of OFDMA in LTE and WiMAX. The multiuser diversity advantage of OFDMA is well used in LTE, whereas the frequency diversity advantage is nicely exploited in WiMAX. The physical layer overhead in LTE is significantly better than in WiMAX. The network entry process of an LTE mobile is simpler than in a WiMAX mobile. In addition, LTE systems are expected to react faster to changes in the traffic and channel conditions due to the smaller frame times. However, the OFDMA design in WiMAX will cater for more extreme channel conditions, which is perhaps more than what is expected in practice as our investigation reveals.

Reconfigurable Turbo Decoder With Parallel Architecture for 3GPP LTE System

This brief presents a parallel architecture for the turbo decoder using the quadratic permutation polynomial interleaver. The supported block size ranges from 40 to 6144 with an increment of 8, and thus, it includes 188 sizes in the 3rd Generation Partnership Project Long Term Evolution standard. The proposed design can allow one, two, four, or eight soft-in/soft-out decoders to process each block with configurable iterations. To support all data transmissions in the parallel design, a multistage network with low complexity is also utilized. Moreover, a robust path metric initialization is given to improve the performance loss in small blocks and high parallelism. After fabrication in the 90-nm process, the 2.1-mm2 chip can achieve 130 Mb/s with 219 mW for the size-6144 block and eight iterations.