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Content caching is an efficient technique to reduce delivery latency and system congestion during peak-traffic times by bringing data closer to end users. Existing works consider caching only at higher layers separated from physical layer. In this paper, we study wireless caching networks by taking into account cache capability when designing the signal transmission. In particular, we investigate...
Despite the promising benefits of the cloud-radio access network (C-RAN), the fronthaul (FH) imposes stringent requirements in terms of data rate, latency, jitter and synchronisation. In the classical C-RAN, the FH capacity scales linearly with the number of the transmitting antennas, which has posed severe demands on the FH capacity, especially due to emerging 5G technologies such as massive MIMO...
In this paper, we investigate the inter-cell interference mitigation through mode selection of coordinated multi-point (CoMP) techniques in downlink LTE-A networks. The proposed scheme selects the single-cell (SC) or coordinated beamforming (CB) or joint processing (JT) transmission mode according to interference level to maximize the sum rate. We propose a low complexity algorithm which takes full...
This paper proposes a space division multiplexing aided opportunistic spectrum access (SDM-OSA) scheme for cognitive radio networks by exploiting the spatial signal processing ability provided by multiple antennas. With the scheme, cognitive transmission could be carried out using SDM even though there is no idle spectrum resource available. We make further discussion about antenna requirements for...
Significant throughput gains can be achieved in a multi-user MIMO (MU-MIMO) wireless system by exploiting the combination of multi-user scheduling and multi-user diversity. Open-loop MU-MIMO (OL-MU-MIMO) is a codebook based precoding technique where precoders are fixed a priori at the base station (BS) in a known fashion and the user needs to feedback which precoding vector is to be chosen referred...
Traditional approaches in the analysis of downlink systems decouple the precoding and the channel estimation problems. However, in cellular systems with mobile users, these two problems are, in fact, tightly coupled. In this paper, this coupling is explicitly studied by accounting for the channel training overhead and estimation error while determining the overall system throughput. This paper studies...
The DFT-based beamforming weight-vector codebook is considered as an effective design for spatially correlated channels. In this paper, we demonstrate that when the antenna elements are uniformly spaced as well as linearly arranged, and the channels are spatially correlated, the codewords in a DFT-based beaforming weight-vector codebook approximately match the distribution of the optimal beamforming...
In this paper, we study low feedback user grouping in downlink cooperative transmission multi-antenna systems. Users in the same group are served on the same frequency and time resource by multiple cooperative BSs using the zero-forcing precoder. We first derive the user's average received signal to interference and noise ratio (SINR). It shows that each user's SINR is an increasing function of the...
We present field experiment results on multiple input multiple output (MIMO) precoding using orthogonal frequency division multiple access (OFDMA) in the E-UTRA downlink. We measured the throughput performance of 4??4 MIMO precoding with 1- to 4-stream transmission. Time variation characteristics of throughput, SINR, and antenna correlations are compared to evaluate the selection criteria for the...
This paper studies the downlink closed loop transmission in the 3G long term evolution (LTE) system. We propose a precoding matrix selection algorithm from a finite codebook. The precoding, antenna selection, adaptive modulation and coding (AMC) require the channel information fed back from receiver to optimize the system performance. We study the codebook design and precoding matrix selection in...
In a pre-coded Multi User Multiple Input Multiple Output (MU-MIMO) system, the channelization can be done either by using any of the two basic access techniques, namely Orthogonal Frequency Division Multiple Access (OFDMA) and Space Division Multiple Access (SDMA), or by combining them. From resource allocation point of view, choice of any technique will require different fairness conditions among...
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