Small (Cell) Steps to 5G Evolution Skyworks Solutions, Inc

Small (Cell) Steps to 5G Evolution Skyworks Solutions, Inc. Woburn, Mass.

hile playing a virtual real- band. The result is an increase in the overall ity (VR) game can be surpris- data rate. ingly entertaining, it has one Use of CA is fairly widespread. The cell major drawback: the multi- phone or tablet used to read this article Wtude of wires needed to operate the system. likely already supports CA. However, some Keeping those wires from getting tangled networks have not fully taken advantage of can be quite a challenge, often requiring the technology or even deployed it, due to several pauses during the game. Part of the its high cost. Another factor impeding its difficulty is the amount of data VR systems use is that multiple bands inside one small require. Data must be sent to the user’s gog- cell box requires additional power amplifi- gles to enable high resolution video and a ers (PA) to support the different frequency dynamic experience; the VR goggles must bands, which means increased power con- also stream real-time data regarding the sumption and, often, thermal issues. Highly user’s movements and positions back to the efficient small cells can overcome many of system. Because of this, high data capac- these limitations. Thanks to new innovative ity cables are needed to connect the user techniques, next-generation small cell box- to the VR system and transfer the data. VR es with two to three bands and a multiple- systems will eventually evolve into wireless input-multiple-output (MIMO) configuration devices. One way to eliminate the wires is for enabling multiple data streams are now with a high efficiency network capable of possible. They allow enormous amounts of streaming large amounts of data, e.g., one data to be streamed to a smartphone, tablet that employs small cells. Small cells are not or VR device (see Figure 1). just good for improving VR systems; they are A big chunk of the power budget in a also a key enabler of 5G. small cell is allocated to the PAs—the de- Today, small cells are often installed by vices responsible for transmitting data in an cell phone providers to help end users com- ever extending range—while maintaining bat connectivity issues. Generally, the pro- data purity. Close collaboration between PA viders use a single, narrowband small cell vendors and system-on-chip or transceiver system. However, to realize increased data vendors has led to highly efficient systems. rates for 5G, next-generation small cells One such family of high efficiency PAs hails must support ever wider bandwidths. This from Skyworks Solutions. Its SKY6629x fam- can be achieved by using wideband systems ily of small cell enterprise PAs offers power- and taking advantage of carrier aggregation added efficiency (PAE) of 30 to 40 percent (CA) technology. CA increases data capacity and covers the major 3GPP bands from 700 by streaming on a licensed anchor channel MHz to 6 GHz, including the new band 48 and using additional channels, either with- from 3.5 to 3.7 GHz—also known as the in the same frequency band or a different CBRS band—and band 46, the licensed as-

50 2110 MHz 2140 MHz 2170 MHz 40

VR 30 AP Router 20 Mobile Phone

CATV STB ( % ) A dded E f ciency 10 0

ower- 6 9 12 15 18 21 24 27 30 P Unlicensed Pout (dBm) (5 GHz) Small Cell High Speed Data s Fig. 2 Skyworks’ SKY66294-11 PA achieves a PAE of 36 percent at +28 dBm output, biased with a 5 V supply. the inside temperature can increase LTE Licensed LTE to between 85°C and 90°C. To cool LTE-U Anchor LAA (700 MHz to 3.8 GHz) the boxes, developers usually incor- Carrier Aggregation porate metal heat sinks and some- times fans. Lowering PA power con- Low Speed Data VR sumption with Skyworks’ SKY6629x AP Router family eliminates the need for addi- Mobile Phone CATV STB tional metal or fans, providing small cell developers with a viable solution to help minimize power dissipation s Fig. 1 Small cells will densify the wireless network and increase data rates to users. and solve heat problems. and higher-order While the obvious application for MIMO systems. these high efficiency PAs is in small For example, the cells, they have other uses. They SKY66294-11 band can be used in distributed antenna 66 PA achieves systems, vehicle to everything (V2X) 36 percent PAE at infrastructure for car-to-car commu- the rated output nication and self-driving vehicles and power of +28 dBm, consumer electronics products such biased with a 5 V as high definition wireless cameras supply (see Fig- and drones. Given their efficiency (a) ure 2). The output and ability to be linearized, the PAs of the PA has an in Skyworks’ SKY6629x family have uncorrected adja- been used as driver amplifiers for cent channel leak- higher power, outdoor small cell sys- age ratio (ACLR) tems and in the early development of −33 dBc with of massive MIMO systems for 5G. a 20 MHz, 8 dB Without a doubt, small cell de- peak-to-average ployment is moving toward 5G input signal (using and will help to enable a seam- crest factor reduc- less handover from large macro tion). By applying base stations to indoor small cells. low complexity Densification of heterogeneous (b) digital predistor- networks (HetNet) is critical to the s Fig. 3 The linearity of the SKY66294-11 PA before (a) and tion (DPD), the PA realization of 5G and will be aided after (b) DPD. can be linearized by next-generation small cells. For sisted access (LAA) or LTE-U band, to more than -50 the industry, these small cells will which operates from 5.15 to 5.925 dBc, a full 5 dB lower than the -45 deliver key benefits, including ease GHz. While traditional linear PAs dBc specified by the 3GPP standard of deployment and smaller, less have a typical efficiency of 10 per- (see Figure 3). This improvement in conspicuous base stations. Because cent, the SKY6629x PAs offer 3x effi- performance saves power, reduces higher efficiency PAs reduce power ciency improvement. The increased thermal effects on the overall sys- consumption, “green” technology efficiency enables small cell devel- tem and provides more than 5 dB small cells offer added benefits that opers to either design a box with margin for linearity. the cellular industry can leverage. very low power consumption or one Higher efficiency PAs reduce the with more channels (i.e., more fre- total cost of small cell development quency bands for CA). That means and deployment. Current small cell Skyworks Solutions, Inc. no more 1 × 1 systems, as the in- boxes are single band systems. Even Woburn, Mass. dustry has moved to 2 × 2, 4 × 4 with only one or two PAs per box, www.skyworksinc.com