Long Term Evolution (LTE)-based 4G technology is reshaping the wireless infrastructure landscape, and that brings a new set of opportunities for IP core licensor CEVA Inc. and its DSP offerings for multi-mode LTE base stations.
LTE devices—both handsets and radio base stations—are haunted by power constraints, mainly due to the requirement of complying to multiple network technologies: GSM/GPRS, EDGE, W-CDMA, TD-SCDMA, HSPA+, FDD and TDD modes of LTE and LTE-Advanced, and Wi-Fi. That puts a significantly larger burden on radio base stations that are bound to adapt to changing traffic patterns across the 4G network.
Moreover, LTE-centric 4G infrastructure is gradually shifting from macro-cells for wide open spaces and metro-cells for high population areas toward heterogeneous network architecture or HetNet—a multilayer system of overlapping big and small cells that pump out cheap bandwidth. However, while HetNet turns big-tower cellular into dense, multilayer high-capacity network, it also demands greater adaptability and flexibility within base stations to carry out bandwidth engineering effectively.
As a result of these shifts in base station market, infrastructure vendors are moving away from off-the-shelf chips supplied by ASSP vendors like Freescale and TI. And they are moving toward system-on-chips (SoCs) for multi-mode LTE base stations. Here, CEVA’s XC family of DSP cores promises to overcome power consumption, time-to-market and cost challenges regarding adoption of SoCs for multi-mode LTE base stations.
CEVA-XC supports multiple wireless standards in software
The IP platform licensor has been positioning its CEVA-XC4500 family of special-purpose DSPs especially for LTE infrastructure needs through software-based modems that can serve intense demands related to multi-mode wireless baseband, smart wireless backhaul and Wi-Fi offloading. The CEVA-XC4500 builds on the strengths of the CEVA-XC4000 family and optimizes structure, performance, and low power necessary for wireless OEMs deploying new base stations into the HetNet.
The fourth generation of the CEVA-XC architecture, CEVA-XC4500 DSP cores offer powerful fixed point and floating point vector capabilities, supplying the performance and flexibility demanded by LTE wireless infrastructure applications. They allow multi-mode LTE base station SoCs to adapt to different types of traffic and varying loads through multicore arrangement built on DSP clusters. Each core can handle multiple queues to avoid any network stalls or deadlocks.
The XC4500 DSP core can also perform digital front-end tasks, providing pre-distortion, sampling filters, up- and down-conversion, and other radio management functions. Moreover, it can support wireless backhaul with up to 4096 QAM, OFDM or single-carrier support, wideband spectrum, and support of both TDD and FDD.
The CEVA-XC DSP core evolution
LTE Base Station SoCs
The Chinese wireless infrastructure vendor ZTE Corp. has licensed CEVA-XC DSP core to design FDD/TDD multi-mode SoCs for LTE base stations. ZTE, like other wireless infrastructure OEMs, clearly sees mobile networks heading toward small cells and is readying small cell base stations by using SoC platforms built around Ceva’s DSP cores.
In July 2014, CEVA beefed up its Wi-Fi capabilities for 4G networks by acquiring RivieraWaves, a privately-held Bluetooth and Wi-Fi connectivity IP vendor based in Sophia-Antipolis, France. RivieraWaves has brought software-based Wi-Fi algorithms to CEVA’s LTE processing portfolio, a much-needed product in the context of small cells and access points within LTE networks.
The DSP technology has expanded to almost every tenet of communication systems. At the same time, however, general-purpose DSPs are generally falling short in the next-generation networking applications like LTE and LTE-Advanced. For instance, take Multiple Input and Multiple Output (MIMO) system, one of the leading tools for improving data rates in LTE networks. The MIMO technology increases spectral efficiency of the channel and improves the data rates for channel bandwidth by using multiple receive and transmit antennas.
MIMO, which creates multiple network streams, is a fundamental element in the LTE system and presents a classical case study for the implementation of special-purpose DSPs such as CEVA-XC. For optimizing MIMO in LTE networks, CEVA is proposing Maximum Likelihood Detector (MLD) technique that is a non-linear MIMO receiver implementation and is fundamentally based on an exhaustive constellation search.
MIMO is a fundamental element in the LTE system design
The above example shows that the complexity of LTE components like MIMO will make it imperative for LTE chip suppliers to augment advanced DSP cores. And, that LTE technology marks an important turning point in the evolution of SoC signal processing. That bodes well for CEVA’s product roadmaps and its efforts to take its wireless baseband DSP horsepower inside LTE and LTE-Advanced infrastructure chips.
The LTE build-out could pick greater momentum during 2015 and so could CEVA’s DSP core shipments for the LTE market. “This could be a good year for Ceva,” said Will Strauss, President & Principal Analyst, Forward Concepts, in a recent company newsletter.
Image credit: CEVA Inc.
Majeed Ahmad is author of books Age of Mobile Data: The Wireless Journey To All Data 4G Networksand Essential 4G Guide: Learn 4G Wireless In One Day.