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A Guide to Processors for Wireless Base Stations

Fourth Edition

Published December 2016

Authors: Jag Bolaria and Tom R. Halfhill

Single License: $4,495 (single copy, one user)
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As smartphone users consume ever-increasing amounts of wireless data, operators are upgrading their networks to support LTE and LTE-Advanced. They are also deploying small-cell base stations to increase network capacity in congested areas and to extend coverage in sparsely covered areas.

Revenues are not necessarily increasing commensurately with bandwidth demand, however. The budget pressure on operators is in turn squeezing base-station OEMs. Fortunately, the onward march of Moore’s Law and the trend toward smaller base stations are enabling semiconductor suppliers to integrate major baseband-processing functions in a single SoC.

In an effort to improve their return on investments, operators are looking at offloading cellular traffic to unlicensed spectrum. Chip vendors are taking different approaches to using this spectrum. At the same time, software-defined technologies and virtualization are changing traditional infrastructure equipment. The approach for base stations by each vendor differs in important ways. In some cases, vendors have made strategic decisions on the level of investment by the specific wireless infrastructure market segment. A Guide to Processors for Wireless Base Stations brings clarity to this evolving landscape by analyzing trends, describing the base-station processors, and drawing conclusions about the chip vendors and their products.

The report begins with an overview of 3G (UMTS) and 4G (LTE) technology, highlighting the aspects of the cellular network, the underlying communication technology, and relevant semiconductor technologies. We examine various options for using unlicensed spectrum to augment cellular communications. Another chapter discusses the major technology and business trends affecting the market for base-station processors, providing insight into the market's evolution. We examine new 5G technologies and make forecasts for residential, enterprise, and macro base stations. We also break down shipments of integrated base-station processors by vendor and project the potential revenue of this segment through 2020.

Following these introductory chapters, the report covers the major suppliers of base-station processors: Broadcom, Cavium, Intel, NXP (which acquired Freescale), Qualcomm, and Texas Instruments. We provide a synopsis of their business, explain their products’ key features, and draw conclusions about their competitive standing and the types of designs for which their offerings are best suited. We also discuss the internal architecture of their processors, system-design considerations, and their likely product roadmaps.

We then dedicate a chapter to detailed head-to-head comparisons of some popular base-station processors. The report concludes with our outlook for the leading vendors.

As the leading analysts covering high-performance communications chips, The Linley Group has the expertise to deliver a comprehensive look at integrated base-station processors. Coauthors Jag Bolaria and Tom R. Halfhill use their broad experience in communications semiconductors and embedded processors to deliver the technical and strategic information you need to make informed business decisions.

This report is written for:

  • Engineers who need to select processors to design 3G and 4G (LTE) base stations
  • Marketing and engineering staff at companies that sell base-station processors, design services, or software that runs on base stations
  • Technology professionals who want an introduction to cellular base-station technology
  • Financial analysts who desire a detailed analysis and comparison of base-station processor vendors and their chances of success
  • Press and public-relations professionals who need to get up to speed on base-station technology

What's New in This Edition

  • Broadcom’s new direction in small-cell processors
  • Cavium rolls out new Octeon Fusion M processors
  • NXP's direction after acquiring Freescale’s QorIQ Qonverge family
  • Qualcomm's pending acquisition of NXP
  • Intel’s focus on small-cell processors and Cloud RAN
  • Qualcomm’s residential wins at T-Mobile and pending merger with NXP's QorIQ Qonverge family
  • Texas Instruments' revised strategy for KeyStone processors
  • Market forecasts through 2020
  • 2015 market shares for integrated base-station processors
  • Evolving 5G technologies and early market movers
  • New cellular standards for unlicensed spectrum and their market implications
  • Updated head-to-head comparisons of processors for 4G small cells

Mobile infrastructure continues to grow, but at a slower rate than in recent years, paralleling the slower sales of tablets and smartphones. Even so, network operators are struggling to keep up with bandwidth demand. Worse, from a business standpoint, operators are still having trouble increasing their average revenue per user. To add capacity, they must use the available radio-frequency spectrum more efficiently or find new RF spectrum.

Small-cell base stations are one solution. The smallest examples are residential base stations, sometimes deployed by operators to address customer complaints about poor cellular coverage. Small cells also include enterprise base stations that cover a workplace, outdoor cells that cover a campus, and cells that cover a large venue (such as a sports stadium). These base stations cost much less to build and deploy than the large macrocells that form the cellular network’s backbone. A cellular network that combines macrocells with small cells is called a heterogeneous network (hetnet). Although hetnets provide better coverage, cost-conscious operators are increasingly reluctant to deploy small cells in the vast numbers once predicted.

To make small base stations easier and less expensive to build, chip vendors have introduced integrated base-station processors that consolidate most of the system’s vital functions in a single chip. These functions include radio-baseband processing, which is performed by digital signal processors (DSPs), and user scheduling, which is performed by general-purpose CPU cores. By adding various accelerators, I/O interfaces, and memory controllers, such an integrated processor is almost a base station on a chip. A few of these products are powerful enough for even macro-cells, especially in multiprocessor configurations. The newest chips implement LTE and LTE-Advanced, capitalizing on the global deployments of 4G networks.

Several vendors have introduced these processors in recent years, but the number of vendors is now dwindling. Lower-than-expected demand and corporate acquisitions are taking their toll. In early 2016, Avago acquired Broadcom (while keeping the Broadcom name) and immediately began major cutbacks. Among the casualties were Broadcom’s integrated base-station processors, which are still available to existing customers but are no longer marketed for new designs. After acquiring Mindspeed’s wireless business, Intel eventually terminated its development projects.

Most other base-station processors have killed 4G product development, although a few new 4G variants have shipped in the past year. These vendors are focusing their development efforts on the upcoming 5G transition, which will debut new technologies. The 5G standard is still in flux, however, and commercial base-station deployments aren’t expected to begin until 2019 or later, although a few operators plan to deploy pre-standard devices sooner.

One new technology stirring controversy involves offloading some cellular traffic onto unlicensed RF spectrum that is currently used for Wi-Fi networking, Bluetooth links, and numerous other consumer applications ranging from garage-door openers to baby monitors. Adding cellular traffic could interfere with those signals. Cellular operators and chip vendors are promising peaceful coexistence, but so far, none have deployed such a service commercially. Any such deployments would boost sales of new base stations that support this technology.

The most powerful integrated base-station processor is Cavium’s Octeon Fusion-M CNF7500, which can handle up to 3,600 LTE users in a 12-sector macrocell. NXP’s QorIQ Qonverge B4860 can handle up to 1,200 LTE users, enough for a smaller macrocell (or a larger cell when operating in a multiprocessor configuration). All other integrated base-station processors are designed for small cells that serve from about a dozen to a few hundred users. Almost all 3G-only processors have left the market, given operators’ emphasis on 4G deployments. Most existing processors are dual-mode 3G/4G products.

Chip architectures vary widely, so base-station software isn’t portable from one chip vendor to another. Each company uses a different combination of CPU and DSP cores. This incompatibility discourages customers from switching vendors. Over time, we expect more vendors to use ARM CPUs, but the industry is unlikely to standardize on a DSP architecture, so vital baseband software will remain incompatible.

Intel is more interested in selling general-purpose Xeon x86 processors for cloud radio access networks (C-RANs) and other new elements of the wireless infrastructure. Qualcomm offers the industry’s most complete hardware/software solution, especially since Broadcom’s withdrawal. Its pending acquisition of NXP will widen its product line and create an opportunity to establish leadership in this market. We expect TI’s product line to remain relatively static; unrelated analog products are becoming its main focus. Cavium has strong base-station processors and an opportunity to exploit niches left vacant by other vendors, but it’s a relatively small company with several product families to support. If industry consolidation continues, it’s one of the few remaining takeover targets.

In summary, integrated base-station processors, small cells, hetnets, 4G networks, and future 5G technologies are rapidly changing wireless networks and are realigning the market players. We expect to see few new 4G products as the surviving vendors focus on emerging 5G technology for their next-generation products.

List of Figures
List of Tables
About the Authors
About the Publisher
Executive Summary
1 Cellular Networks
Cellular Standards
3G Cellular Networks
LTE Cellular Networks
Base Stations
Types of Cellular Base Stations
Base-Station Anatomy
2 Cellular Technology
Cellular Protocols
3G Technologies
3.5G Technologies
4G Technologies
3GPP Release 11
3GPP Release 12
3GPP Release 13
Future 5G Standard
Layer 2 and Above
Physical Layer
LTE Downlink
LTE Uplink
3 Base-Station Processors
What Is a Base-Station Processor?
What Is Not a Base-Station Processor
Common Characteristics
DSP Accelerators
Packet-Processing Accelerators
RF Interfaces
Backhaul Interfaces
System Interfaces
Base-Station System Design
4 Market and Technology Trends
Technology Trends
Network Capacity
Heterogeneous Networks
Distributed Antenna Systems (DASs)
Wi-Fi Offload and Unlicensed Spectrum
Wireless Backhaul
Cloud RAN
5G Technology
Expanding 5G Spectrum
5G Enabling New Applications
Transition to 5G
Market Trends
Macro Base Stations
Small Cells
Wireless-Base-Station Market Share
5 Broadcom
Company Background
Product Roadmap
6 Cavium
Company Background
Key Features and Performance
Internal Architecture
CPU Architecture
DSP Architecture
System Design
Developer Tools
Product Roadmap
7 Intel
Company Background
Key Features and Performance
Transcede Processors
PC3008 Processor
Internal Architecture
Transcede Processors
PC3008 Processor
System Design
Developer Tools
Product Roadmap
Company Background
Key Features and Performance
QorIQ Qonverge BSC913x Processors
QorIQ Qonverge B4860 and B4420 Processors
Internal Architecture
System Design
Developer Tools
Product Roadmap
9 Qualcomm
Company Background
Key Features and Performance
Internal Architecture
Cellular Modems
ARM-Compatible CPUs
ARM Cortex-A7
Hexagon DSP
System Design
Developer Tools
Product Roadmap
10 Texas Instruments
Company Background
Key Features and Performance
KeyStone I Processors
KeyStone II Processors
Internal Architecture
System Design
Developer Tools
Product Roadmap
11 Processor Comparisons
Processors for 4G Metrocells and Macrocells
Processors for 4G Picocells
Processors for 4G Femtocells
12 Conclusions
Vendor Outlook
Other Vendors
Closing Thoughts
Appendix: Further Reading
Figure 1‑1. 3G cellular network topology.
Figure 1‑2. LTE cellular network topology.
Figure 1‑3. Simplified block diagram of a base station.
Figure 2‑1. Dual connectivity enables heterogeneous networks.
Figure 2‑2. Downlink map of LTE logical, transport, and physical channels.
Figure 2‑3. Layer 2 downlink architecture for LTE.
Figure 2‑4. OFDM subcarriers.
Figure 2‑5. Resource blocks in an LTE data stream.
Figure 2‑6. Block diagram of LTE downlink signal chain (transmitter side).
Figure 2‑7. Block diagram of WCDMA downlink signal chain. (transmitter side)
Figure 3‑1. Two contrasting designs for LTE base stations.
Figure 4‑1. Heterogeneous cellular network.
Figure 4‑2. Forecast of mobile subscriptions by radio technology, 2012-2022.
Figure 4‑3. Forecast of macrocell-base-station shipments, 2014–2020.
Figure 4‑4. Forecast of small-cell base-station shipments, 2014–2020.
Figure 4‑5. Forecast of base-station revenue, 2015–2020.
Figure 4‑6. Worldwide revenue market share of the top four vendors of integrated base-station processors, 2014 and 2015.
Figure 6‑1. Block diagram of Cavium Fusion-M CNF7500.
Figure 6‑2. Memory architecture of Octeon Fusion-M’s DSP subsystem.
Figure 6‑3. Base station using Cavium Octeon Fusion-M.
Figure 7‑1. Block diagram of Intel Transcede T21xx.
Figure 7‑2. Block diagram of MAP vector unit.
Figure 7‑3. Block diagram of Intel PC3008.
Figure 8‑1. Block diagram of NXP QorIQ Qonverge B4860.
Figure 8‑2. Block diagram of an LTE macrocell base station using Qonverge B4860.
Figure 9‑1. Block diagram of Qualcomm Krait CPU.
Figure 9‑2. Block diagram of Qualcomm Hexagon DSP.
Figure 9‑3. Block diagram of Qualcomm FSM9955 in a 2x2 MIMO enterprise base station.
Figure 10‑1. Block diagram of Texas Instruments KeyStone II TCI6636.
Figure 10‑2. Block diagram of a base-station design using a TI KeyStone II processor.
Table 2‑1. Cellular technologies and data rates.
Table 2‑2. LTE and LTE-A user-equipment (UE) categories.
Table 2‑3. Summary of 3GPP releases.
Table 2‑4. 3GPP Release 11 carrier aggregation.
Table 2‑5. Comparison of 5GHz protocol features.
Table 6‑1. Key parameters for Cavium Octeon Fusion-M processors.
Table 7‑1. Key parameters for Intel Transcede processors.
Table 7‑2. Key parameters for Intel PC3008 processor.
Table 8‑1. Key parameters for NXP Qonverge BSC913x processors.
Table 8‑2. Key parameters for NXP Qonverge B4860 and B4420 processors.
Table 9‑1. Key parameters for selected Qualcomm FSM processors.
Table 10‑1. Key parameters for TI KeyStone TCI6614 processor.
Table 10‑2. Key parameters for TI KeyStone II processors.
Table 11‑1. Comparison of processors for 4G macrocells and metrocells.
Table 11‑2. Comparison of processors for 4G picocells.
Table 11‑3. Comparison of processors for 4G enterprise femtocells.


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