Long Term Evolution most recent R&D papers

C. Spiegel, J. Berkmann, Zijian Bai, T. Scholand, C. Drewes, G.H. Bruck, B. Gunzelmann, and P. Jung. On mimo for utra LTE. Communications, Control and Signal Processing, 2008. ISCCSP 2008. 3rd International Symposium on, pages 1004-1008, March 2008.[ abstract ]

The long term evolution of UMTS (Universal Mobile Telecommunications System), UTRA LTE, is based on OFDM (orthogonal frequency division multiplexing) combined with MIMO (multiple-input multiple-output) techniques. In particular, the Alamouti and the V-BLAST (Vertical Bell Labs Layered Space Time) schemes are seen as interesting MIMO concepts. In this communication, the authors will compare these two MIMO schemes w.r.t. the achievable performance in the UTRA LTE downlink using up to two transmit and two receive antennas.

R. Bestak. Evolution of mobile networks. Systems, Signals and Image Processing, 2008. IWSSIP 2008. 15th International Conference on, pages 29-32, June 2008.[ abstract ]

3GPP is in the process of defining the long-term evolution (LTE) for 3G, in order to maintain the future competitiveness of 3G technology. The main targets for this evolution concern increased data rates, improved coverage, and reduced latency. Taken together these results in significantly improved service provisioning and reduced operator costs in a variety of traffic scenarios. This paper discusses main requirements of the LTE and provides basic features, including network architecture and channel concept.

T. Haustein, V. Venkatkumar, J. Eichinger, E. Schulz, T. Wirth, V. Jungnickel, A. Forck, S. Wahls, C. Juchems, F. Luhn, and R. Zavrtak. Measurements of multi-antenna gains using a 3GPP-LTE air interface in typical indoor and outdoor scenarios. Wireless Conference, 2008. EW 2008. 14th European, pages 1-6, June 2008.[ abstract ]

In this paper we report the first real-time measurements of a 3GPP-LTE multiple antenna system in typical indoor and outdoor scenarios. In a single cell, single user scenario we demonstrate throughput exceeding 100 Mbit/s with a 2times2 MIMO configuration. This throughput gain is significant as compared to existing single antenna systems. We describe the basic LTE system design and prototype ingredients which were implemented to achieve these results. The highlight of our MIMO-OFDM system design is frequency dependent link adaptation. In principle, we show that this parallel link adaptation provides robust gains in a cellular broadband system. The robustness is seen in both our indoor and outdoor measurement results. The key feature of our work is implementation of multiple antenna concepts in such a broadband system.

C. Spiegel, J. Berkmann, Zijian Bai, T. Scholand, and C. Drewes. Mimo schemes in utra LTE, a comparison. Vehicular Technology Conference, 2008. VTC Spring 2008. IEEE, pages 2228-2232, May 2008.[ abstract ]

The long term evolution of UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access, abbreviated as UTRA LTE, will be based on OFDM (orthogonal frequency division multiplexing). Furthermore, MIMO (multiple-input multiple-output) techniques have been considered as a means for the improvement of wireless connectivity. In wireless systems, high data rates in the downlink are desirable: Furthermore, with respect to an efficient implementation, the downlink requires a thorough assessment. In particular, the Alamouti and the V-BLAST (Vertical Bell Labs Layered Space Time) schemes are seen as interesting concepts. In this communication, the authors will compare these two MIMO schemes w.r.t. the achievable performance in the UTRA LTE downlink using up to two transmit and two receive antennas. Furthermore, the authors will discuss the deployment of spatial multiplexing in the UTRA LTE downlink and will show that the performance of successive interference cancellation (SIC) based data detection techniques for MIMO-OFDM is beneficial.

P. Kela, J. Puttonen, N. Kolehmainen, T. Ristaniemi, T. Henttonen, and M. Moisio. Dynamic packet scheduling performance in utra long term evolution downlink. Wireless Pervasive Computing, 2008. ISWPC 2008. 3rd International Symposium on, pages 308-313, May 2008.[ abstract ]

In this paper we evaluate the performance of dynamic Packet Scheduling (PS) of 3GPP UTRAN Long Term Evolution (LTE) Downlink. Packet scheduling is of utmost importance in 3G LTE, because all traffic types with different Quality of Service requirements are competing of the resources. We present a decoupled time and frequency domain packet scheduling framework for LTE downlink. Simulation results with three basic packet scheduler combinations with different amount of fairness are presented in four different 3GPP macro simulation cases to show the both extremes in tradeoff between fairness and spectral efficiency. In addition, the effect of multiuser diversity on packet scheduling performance is studied. It is shown that by dividing the packet scheduler into a time domain and a frequency domain and utilizing different algorithms in both domains, the throughput fairness between users can be effectively controlled.

Zihuai Lin, B. Vucetic, and Jian Mao. Ergodic capacity of LTE downlink multiuser mimo systems. Communications, 2008. ICC '08. IEEE International Conference on, pages 3345-3349, May 2008.[ abstract ]

This paper presents the analysis of the average channel capacity and the SINR distribution for multiuser Multiple Input Multiple Output (MIMO) systems in combination with the base station based packet scheduler. The packet scheduler is used to exploit the available multiuser diversity in the time, frequency and spatial domains. The analysis model is carried out for 3 GPP LTE downlink transmission. Two Spatial Division Multiplexing (SDM) multiuser MIMO schemes in the context of LTE downlink transmission are investigated. They are Single User (SU) and Multi-user (MU) MIMO schemes. In general, the outage probability for systems using SU-MIMO scheme is larger than the one with MU-MIMO scheme. Compared with the systems without preceding, linear preceding can improve the outage probability. The paper contributions are the derivation of a mathematical expression of the SINR distribution and the average channel capacity for multiuser MIMO systems with a frequency domain packet scheduler.

A. Nimbalker, Y. Blankenship, B. Classon, and T.K. Blankenship. Arp and qpp interleavers for LTE turbo coding. Wireless Communications and Networking Conference, 2008. WCNC 2008. IEEE, pages 1032-1037, 31 2008-April 3 2008.[ abstract ]

The Long Term Evolution (LTE) of the WCDMA standard requires turbo decoding throughputs of up to 100 Mbps. Unfortunately, the existing WCDMA turbo interleaver does not permit an efficient high throughput implementation. The almost regular permutation (ARP) and quadratic polynomial permutation (QPP) interleavers were proposed to rectify this situation with QPP selected for LTE. In this paper, the interleavers are compared and a full suite of LTE designs and performance results for both are presented.

J. Berkmann, C. Carbonelli, F. Dietrich, C. Drewes, and Wen Xu. On 3g LTE terminal implementation - standard, algorithms, complexities and challenges. Wireless Communications and Mobile Computing Conference, 2008. IWCMC '08. International, pages 970-975, Aug. 2008.[ abstract ]

Currently, 3GPP standardizes an evolved UTRAN (E-UTRAN) within the Release 8 Long Term Evolution (LTE) project. Targets include higher spectral efficiency, lower latency, higher peak data rate when compared to previous 3GPP air interfaces. The air interface of E-UTRAN is based on OFDMA and MIMO in downlink and on SCFDMA in uplink Main challenges for a terminal implementation include efficient realization of the inner receiver, especially for channel estimation and equalisation, and the outer receiver including a turbo decoder which needs to handle data rates of up to 75 Mbps per spatial MIMO stream. We show that the inner receiver can nicely and straightforwardly be parallelized due to frequency domain processing. In addition to the computational complexity of even a simple linear equaliser, one of the challenges is an efficient implementation considering necessary flexibility for different MIMO modes, power consumption and silicon area. This paper will briefly overview the current LTE standard, highlight a functional data flow through the single entities of an LTE terminal and elaborate more on possible first implementation details, including sample algorithms and first complexity estimates.

Che-Sheng Chiu and Chia-Chi Huang. Improving inter-sector handover user throughput by using partial reuse and softer handover in 3GPP LTE downlink. Advanced Communication Technology, 2008. ICACT 2008. 10th International Conference on, 1:463-467, Feb. 2008.[ abstract ]

"Increased cell edge bit-rate" is an important requirement for 3GPP LTE, and inter-cell interference problem is a key issue for improving the cell edge bit-rate. In this paper, we propose an inter-cell interference mitigation scheme for 3GPP LTE downlink, and particularly, we focus on intra-node-B scenario. The proposed scheme makes use of a combination of partial reuse and softer handover for inter-sector handover users. The simulation results were obtained using a dynamic system-level simulator. The simulation results show that, compared to the partial reuse scheme, the proposed scheme can provide significant throughput gains for inter-sector handover users and achieve almost the same average sector throughput.

A.-M. Bosneag, A. AbdulWakeel, and W. Leahy. A distributed mechanism for detecting cell data inconsistencies in LTE radio access networks. Wireless Communications and Networking Conference, 2008. WCNC 2008. IEEE, pages 2921-2926, 31 2008-April 3 2008.[ abstract ]

The evolution for the third generation (3G) wide area mobile networks (long term evolution LTE) is currently nearing completion in the third generation partnership program (3GPP). Fundamental changes to classical public mobile systems have been proposed. These architectural changes specify that the network architecture for the LTE radio access networks changes from the 3G hierarchical design towards a flat design. The new model greatly improves latency for data traffic setup, but also introduces challenges to the traditional telecom network management architecture that relies on a centralised model. Issues related to scalability and availability become critical, especially for management tasks that involve checks of properties over an entire (sub)network. This paper proposes a layered peer-to-peer architecture for the network management system of LTE radio access networks, and shows how the problem of checking the consistency of neighbouring cell relations for handover may be solved in a distributed manner. The algorithm was tested both on Ericsson's Mobile Switching Platform to demonstrate technical feasibility, and on a larger scale, on top of the Bamboo simulator, using real cell information provided by 3G operators that implemented the Ericsson solution. The experiments show that the distributed algorithm correctly checks the consistency of neighbouring cell relations with very high percentages of detecting inconsistencies in both static and dynamic networks of increasingly larger size.

Ji-Hoon Yun, Myoungwon Lee, and Suhan Choi. Comparison of handover schemes for 3GPP long term evolution and 3GPP2 ultra mobile broadband. Personal, Indoor and Mobile Radio Communications, 2008. PIMRC 2008. IEEE 19th International Symposium on, pages 1-5, Sept. 2008.[ abstract ]

As a radio access technology for next generation cellular networks, 3GPP and 3GPP2 are standardizing Long Term Evolution (LTE) and Ultra Mobile Broadband (UMB), respectively. In this paper, we compare the handover schemes of both technologies in three aspects, i.e., interruption time of a user plane, required wireless resources and the overhead for avoiding packet reordering. The comparison results show that UMB achieves shorter interruption time and less overhead for reordering avoidance while LTE incurs less resource waste.