LTE-advanced: next-generation wireless broadband technology [Invited Paper]
TL;DR: An overview of the techniques being considered for LTE Release 10 (aka LTEAdvanced) is discussed, which includes bandwidth extension via carrier aggregation to support deployment bandwidths up to 100 MHz, downlink spatial multiplexing including single-cell multi-user multiple-input multiple-output transmission and coordinated multi point transmission, and heterogeneous networks with emphasis on Type 1 and Type 2 relays.
Abstract: LTE Release 8 is one of the primary broadband technologies based on OFDM, which is currently being commercialized. LTE Release 8, which is mainly deployed in a macro/microcell layout, provides improved system capacity and coverage, high peak data rates, low latency, reduced operating costs, multi-antenna support, flexible bandwidth operation and seamless integration with existing systems. LTE-Advanced (also known as LTE Release 10) significantly enhances the existing LTE Release 8 and supports much higher peak rates, higher throughput and coverage, and lower latencies, resulting in a better user experience. Additionally, LTE Release 10 will support heterogeneous deployments where low-power nodes comprising picocells, femtocells, relays, remote radio heads, and so on are placed in a macrocell layout. The LTE-Advanced features enable one to meet or exceed IMT-Advanced requirements. It may also be noted that LTE Release 9 provides some minor enhancement to LTE Release 8 with respect to the air interface, and includes features like dual-layer beamforming and time-difference- of-arrival-based location techniques. In this article an overview of the techniques being considered for LTE Release 10 (aka LTEAdvanced) is discussed. This includes bandwidth extension via carrier aggregation to support deployment bandwidths up to 100 MHz, downlink spatial multiplexing including single-cell multi-user multiple-input multiple-output transmission and coordinated multi point transmission, uplink spatial multiplexing including extension to four-layer MIMO, and heterogeneous networks with emphasis on Type 1 and Type 2 relays. Finally, the performance of LTEAdvanced using IMT-A scenarios is presented and compared against IMT-A targets for full buffer and bursty traffic model.
Citations
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TL;DR: The role of renewable energy in the design of sustainable, eco-friendly, and cost-effective 5G mobile networks is discussed and a comprehensive survey on the state-of-art of renewableenergy management techniques aiming to promote the sustainability and cost reduction of the large-scale mobile wireless infrastructures is provided.
46 citations
01 Aug 2012
TL;DR: A low-latency baseband signal compression algorithm used in ALU is introduced, which can effectively reduce the amount of data transferred between BBU and RUU in LTE system, to facilitate the deployment of LTE in the CRan architecture.
Abstract: C-RAN is the next-generation clean wireless access network architecture, which is based on centralized processing, the Collaborative Radio and Real-time Cloud Infrastructure. In C-RAN architecture, different access technology (eg.GSM / TD-SCDMA / WCDMA / LTE) can be support on the same hardware platform in baseband pool system; C-RAN can be applied to reduce the consumption of operators. LTE (Long Term Evolution) and LTE-A, which are based on OFDM and MIMO technologies, are regarded as the main wireless access technology in the evolution from 3G to 4G. LTE introduces variety of novel technologies to improve the system performance, especially in C-RAN architecture, such as Multi antennas MIMO, Carrier Aggregation, CoMP. However, C -RAN architecture also brings about lager data transmission in the optical fiber. In this paper a low-latency baseband signal compression algorithm used in ALU is introduced to reduce the data rate. Based on the Characteristics of LTE signal data, the algorithm removal redundancies in the spectral domain firstly, and then the block scaling, which is combined with non-linear (nonuniform) quantizer, is designed to minimize quantization error. This algorithm can effectively reduce the amount of data transferred between BBU and RUU in LTE system, to facilitate the deployment of LTE in the CRan architecture. Simulation analysis is given out in the paper; meanwhile TD-LTE system demo verification is also implemented. The results indicate that the scheme introduced can get good performance under a certain compression rate in the real system. Further research is also in progress.
45 citations
TL;DR: An overview on LTE spectrum sharing technologies on three popular spectrums, including the TV white-space channels, the frequently unused service-dedicated 3.5-GHz citizens broadband radio service spectrum, and the 5-GHz unlicensed bands is presented.
Abstract: Long-Term Evolution (LTE) communication systems feature advanced frequency reuse and interference coordination techniques providing faster and more secured mobile services. However, the network capacity in licensed spectrum is still behind market demands. Dynamic spectrum access or spectrum sharing in other frequently vacant or unlicensed frequency bands is considered an effective means to boost system throughput. Different from operations in licensed spectrum with exclusive access, LTE deployment needs to take into account the distinct regulations on channel access to each shared frequency band, in order to avoid interference to incumbent users, and to maintain fair play with peer operators in heterogeneous networks. This paper presents an overview on LTE spectrum sharing technologies on three popular spectrums, including the TV white-space channels, the frequently unused service-dedicated 3.5-GHz citizens broadband radio service spectrums, and the 5-GHz unlicensed bands. Existing spectrum usage in these frequency bands is analyzed, and the proposed methodologies on compliant operations are discussed for the reference of potential solutions to more efficient spectrum sharing mechanisms in the next generation mobile networks.
44 citations
Cites background from "LTE-advanced: next-generation wirel..."
...Several proposed coexistence features, such as the Almost Blank Subframe/LTE muting [10], have been included in 3GPP Release 8/9 for enhanced inter-cell interference coordination (eICIC)....
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...A summary on the features of these bands is listed in Table II [4], [10], [12]....
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TL;DR: In this paper, an orthogonal frequency-division multiple access (OFDMA)/single-carrier frequency division multiple-access (SC-FDMA)-aided multiuser STSK scheme for frequency-selective channels is proposed.
Abstract: Motivated by the recent concept of space-time shift keying (STSK), which was developed for achieving a flexible diversity versus multiplexing gain tradeoff, we propose a novel orthogonal frequency-division multiple access (OFDMA)/single-carrier frequency-division multiple-access (SC-FDMA)-aided multiuser STSK scheme for frequency-selective channels The proposed OFDMA/SC-FDMA STSK scheme can provide an improved performance in dispersive channels while supporting multiple users in a multiple-antenna-aided wireless system Furthermore, the scheme has the inherent potential of benefitting from the low-complexity single-stream maximum-likelihood detector Both an uncoded and a sophisticated near-capacity-coded OFDMA/SC-FDMA STSK scheme were studied, and their performances were compared in multiuser wideband multiple-input-multiple-output (MIMO) scenarios Explicitly, OFDMA/SC-FDMA-aided STSK exhibits an excellent performance, even in the presence of channel impairments due to the frequency selectivity of wideband channels, and proves to be a beneficial choice for high-capacity multiuser MIMO systems
43 citations
Cites methods from "LTE-advanced: next-generation wirel..."
...Hence, OFDMA/SC-FDMA-assisted STSK systems are advocated in this paper, because OFDMA and SC-FDMA have been adopted for the downlink (DL) and the UL of the Long Term Evolution Advanced (LTE-Advanced) standard, respectively [10]....
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TL;DR: A blind interference alignment scheme for partially connected cellular networks that cancels both intracell and intercell interference by relying on receivers with one reconfigurable antenna and by allowing users at the cell edge to be served by all the base stations in their proximity is proposed.
Abstract: We propose a blind interference alignment scheme for partially connected cellular networks. The scheme cancels both intracell and intercell interference by relying on receivers with one reconfigurable antenna and by allowing users at the cell edge to be served by all the base stations in their proximity. An outer bound for the degrees of freedom is derived for general partially connected networks with single-antenna receivers when knowledge of the channel state information at the transmitter is not available. It is demonstrated that for symmetric scenarios, this outer bound is achieved by the proposed scheme. On the other hand, for asymmetric scenarios, the achievable degrees of freedom are not always equal to the outer bound. However, the penalty is typically small, and the proposed scheme outperforms other blind interference alignment schemes. Moreover, significant reduction of the supersymbol length is achieved compared with a standard blind interference alignment strategy designed for fully connected networks.
43 citations
Cites methods from "LTE-advanced: next-generation wirel..."
...Motivated by the provision of flexible bandwidth allocation in the latest-generation of mobile communication standards such as LTE or LTE-A [131, 132] and the development of reconfigurable antennas [82–87], we propose in [128] a cooperative BIA based on flexible bandwidth allocation, to which we refer as fbwBIA in the following....
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References
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01 Sep 2006
TL;DR: A preliminary look at the air interface for Evolved UTRA (E-UTRA) and associated key technologies required to reach its design objectives are provided.
Abstract: With the emergence of packet-based wireless broadband systems such as 802.16e, it is evident that a comprehensive evolution of the universal mobile telecommunications system specifications is required to remain competitive. As a result, work has begun on long term evolution (LTE) of the UMTS terrestrial radio access and radio access network aimed for commercial deployment in 2010. Goals for the evolved system include support for improved system capacity and coverage, high peak data rates, low latency, reduced operating costs, multi-antenna support, flexible bandwidth operations and seamless integration with existing systems. To reach these goals, a new design for the air interface is envisioned. This paper provides a preliminary look at the air interface for Evolved UTRA (E-UTRA) and associated key technologies required to reach its design objectives. Initial E-UTRA system performance results show a 2 to 3x improvement over a reference Rel-6 UMTS system configuration [1, 2] for both uplink and downlink.
30 citations
24 Oct 2008
TL;DR: The proposed channel estimation technique is shown to have significant gains in performance compared to other well known channel estimation techniques such as the maximum-likelihood (ML) and the inverse fast Fourier transform (IFFT) channel estimation methods.
Abstract: The performance of the uplink physical channel of the 3GPP LTE system is considered in this paper. Assuming a single user spatial division multiple access transmission scheme, where users' signals are transmitted over different subcarriers, a low complexity channel estimation technique is proposed for the physical uplink shared channel (PUSCH). The proposed channel estimation technique is shown to have significant gains in performance compared to other well known channel estimation techniques such as the maximum-likelihood (ML) and the inverse fast Fourier transform (IFFT) channel estimation methods [5]. Simulation results for different channel models and modulation and coding schemes (MCS) using incremental redundancy (IR) based hybrid automatic repeat request (HARQ) operation are also shown. Finally, a robust detection scheme is proposed for the physical uplink control channel (PUCCH) and simulation results are summarized.
10 citations
"LTE-advanced: next-generation wirel..." refers methods in this paper
...The DFT precoding operation is performed to reduce the cubic metric (CM) of the signal, leading to higher maximum transmit power [2]....
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