| 1. |
- Fonseca, Maria Nilma, et al.
(författare)
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DCT-based compression scheme for OFDM baseband signals
- 2018
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Ingår i: 2018 Wireless Days, WD 2018. - 9781538656327 ; 2018-April, s. 92-97
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Konferensbidrag (refereegranskat)abstract
- The requirements on the data rates of communication systems increase roughly an order of a magnitude at each new generation. This increase can be especially noticeable for the new centralized radio access networks (C-RAN) scenarios, considered for meeting the requirements of the fifth generation (5G) wireless systems. The general C-RAN architecture normally assumes data transmission in the form of digitized baseband, i.e. I/Q samples. This paper proposes a relatively low-complexity compression scheme for LTE OFDM baseband samples based on transform coding, using the discrete cosine transform (DCT). The compression method is evaluated in both downlink and uplink. The results show that this process can be configured to achieve compression ratio according with the load, for example, in the range of 5:1 to 31:1, with error vector magnitudes (EVMs) lower than 2.8%.
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| 2. |
- Huang, Yezi, et al.
(författare)
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Functional Split of Zero-Forcing Based Massive MIMO for Fronthaul Load Reduction
- 2018
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Ingår i: IEEE Access. - 2169-3536. ; 6, s. 6350-6359
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Tidskriftsartikel (refereegranskat)abstract
- The evolution towards centralized radio access network (C-RAN) for 5G is driven by the need for improved network performance and reduced total-cost-of-ownership (TCO). In CRAN, physically separated remote radio units (RRUs) and baseband units (BBUs) are connected via fronthaul (FH) links, which are capacity constrained. When base-station antennas are upgraded to support massive MIMO techniques, an intra PHY split between RRU and BBU becomes favorable to avoid the dramatic rate growth on the FH links. In this paper, we present a new uplink functional split alternative that decomposes the massive MIMO processing, on the basis of zero-forcing (ZF) equalization, into two phases: dimension-reduction phase and interference cancellation phase, which are implemented in RRU and BBU respectively. Compared with the traditional C-RAN architecture having all baseband processing in the BBU, the new scheme largely alleviates the FH load by reducing the number of FH streams to be equal to the number of MIMO user layers. Compared with an existing split that places all MIMO processing in RRU, the new scheme reduces the RRU complexity without compromising the post-processing performances.
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