Research and Development

4G LTE Advanced


The Long Term Evolution (LTE) standard defined by 3GPP is a highly flexible radio interface that aims at bridging the gap between 3G and 4G standards. LTE Release 8 specification was completed in 2009 and triggered LTE service deployment by leading mobile network operators. It has set various target requirements to achieve higher system performance than HSPA in 3GPP Release 6. It has improved system capacity, cell edge user throughput and lower C/U plane latency, supported by introduction of new radio interface technologies, such as OFDM, frequency domain scheduling and MIMO. In the following year, LTE Release 9 has also been completed to extend various functionalities in LTE Rel.8. The area of enhancement includes closed subscriber group (CSG), self-organizing network (SON), and new functionalities such as location information service and MBMS (Multimedia Broadcast and Multicast Service).

LTE Advanced:

To keep up with the today's rapidly growing traffic, especially by the wide spread of smart phone devices, it became necessary to achieve much higher level of system performance, while keeping the backward compatibility. Accordingly, the radio access interface specifications for LTE-Advanced has been developed in 2011. LTE-Advanced (LTE Rel.10 and beyond) sets a major important milestone in standardization where meets and exceeds requirements set by IMT-Advanced for 4G (International Mobile Telecommunications). The new requirements include spectral efficiency, higher bandwidth, and lower latency. To meet these competitive requirements, a series of new technologies have been introduced into LTE-Advanced, such as Carrier Aggregation, Enhanced MIMO, and CoMP (Coordinated multi-point transmission/reception). LTE-Advanced will enable higher than 1Gbps downlink bandwidth in addition to the existing LTE service and open a new era of true wireless broadband services in the near future. LTE-Advanced services will become available from leading mobile network operators around 2014. Additional features include non-contiguous spectra usage to further enhance the current LTE services.

SAI Technology has been heavily engaged in LTE product development from the early stages of LTE standards. SAI has demonstrated complete end to end system solutions for eNodeB and UE for LTE-Release 8 and 9. SAI is developing LTE advancements to fulfill new and future generations of LTE products. SAI is committed to delivery of LTE Advanced (Release 10 and beyond) products by March 2012.

802.11 AC / AD / WiGiga


In 2009, 802.11n was ratified. It provides for up to 4x4 MIMO (Single user) along with wider bandwidths and a number of MAC layer improvements leading to a peak theoretical throughput in the order of 600 Mbps. Since the ratification of 802.11n, a new task group (TGac) has begun working on the next standard for even higher throughput within <6GHz spectrum. A closely coupled task group (TGad) is looking at very high throughput for spectrum >6Ghz (such as the 60 Ghz ISM band).

The IEEE 802.11ac Task Group (TG) has beendeveloping amendment to IEEE 802.11 having PHY (Physical layer) as well as MAC (Medium Access Control sub layer) enhancements.  These are the following goals for designing the IEEE 802.11ac amendment.

• Backward compatibility with IEEE 802.11a and IEEE 802.11n operated in 5GHz.

• Single STA throughput: 802.11ac STA shall be capable of getting throughput up to 500Mbps.

• Multi-STA throughput: The aggregate throughput when 802.11ac system has multiple STAs connected should be greater than or equal to 1Gbps.

New features in this standard are the bandwidths of 80 MHz and 160 MHz (11n offered only 40 MHz), 256QAM, up to eight antennas and multi-user MIMO.Gross data rates of 293 Mbit/s are possible with only 80 MHz bandwidth, one antenna and 64QAM 5/6; all 802.11ac devices must support this mode. Optional modes using 256QAM and eight antennas under optimal conditions permit gross data rates of 3.5 Gbit/s. 802.11ac is designed only for license-free 5 GHz bands and will no longer include the 2.4 GHz industrial scientific medical (ISM) band previously used primarily for WLANs.

For details on the exact extensions in the PHY layer, see our whitepaper on 802.11ac PHY extensions.

SAI is developing 802.11ac PHY and MAC layer stacks, as well as system solutions with particular emphasis on MU-MIMO high performance implementation. This work is in collaboration with leading silicon and SoC vendors for 802.11ac. 

04/01/13: SAI Eagle 4G LTE Cloud Wireless Broadband Router [Enterprise Class]

Concurrent with the802.11ac developments, a number of industry groups are looking at the ISM band at 60 Ghz (typically 57-66 Ghz) as the next frontier for WLANs. Clearly, such a high center frequency (mm wave) comes with a number of challenges including

  • Limited range, due to the proximity of the oxygen absorption band
  • Implementation cost and high power consumption

MIMO techniques are helping overcome at least some of the range issue, and a 32x32 antenna array can be easily implemented on a CMOS process. Thus, as these hurdles are overcome the 60 Ghzband promises even higher data rates – up to 7 Gbps.

The IEEE 802.11ad standard adds a mm wave operating mode to the 802.11n with a mmSTA being a station that is capable of mm wave operations. Although the base protocol is an extension of 802.11n and 802.11ac, a number of mmWave mode specific packets and formats have been defined in this standard(for e.g., mmWave CTS). In addition, upto 5 bits are reserved for defining the number of beams, thus permitting as many as 32 beams.

Due to the strong dependence on beamforming, considerable effort is going into refining the beam forming procedures and transactions within the 802.11ad standard. Similarly the large number of receive and transmit chains required for such a system are pushing the standards committee to refine the power management techniques used in 802.11n/ac. MIMO for reducing power consumption and turning off some of these chains when not required without affecting network latency and performance.

This standard is in draft and still being developed, although initial silicon is available from a select set of companies.

Besides the 802.11ad standard, a few other standards are being pursued for the 60 Ghz ISM band.

SAI is working with leading 60 GHz chip vendors for 802.11ad implementation on CMOS platforms. This work clearly leverages SAI’s work on 802.11ac with a focus on high performance and low power solutions.


The WiGig specification was contributed to the IEEE 802.11ad standardization process, and was confirmed in May 2010 as the basis for the 802.11ad draft standard.

Wireless Video


In parallel with the 802.11 stream of standards, there has been a steady march of Wireless personal area networks towards the 60 Ghz ISM band as well. In particular the requirements of being able to develop a wireless video area network for full HD resolution leads towards similarly high data rate requirements.

The latest Wireless HD 1.1 standard aims for

  • Stream uncompressed audio and video up to Quad Full HD (QFHD) resolution,
  • 48 bit color and 240 Hz refresh rates
  • Support for 3D video formats
  • Efficient data networking using IP
  • Flexible wireless connectivity using USB bridging
  • Simple, fast file transfer with OBEX.
  • Low rate PHY (2.5-40 Mb/s) for omni-directional control and discovery
  • Medium-rate PHY (0.5-2 Gb/s) for low power, mobile applications and lowcomplexityuniversal bi-directional data support
  • High-rate PHY (1-7 Gb/s) for high quality, full resolution video
  • Improved coverage and higher data rates (in excess of 28 Gb/s) through the use of
  • The spatial multiplexing high rate PHY (SM-HRP) option
  • Video coding to improve link robustness
  • HDCP 2.0 in addition to DTCP content protection support

SAI has completed significant work in video streaming on existing protocols – WiMax, LTE as well as 802.11 in their various forms (802.16e, 802.16d, 3G,LTE Rel 9 as well as 802.11g/n/ac). SAI is extending such video streaming work into the Wireless High Definition technologies and markets for high performance full resolution video.

White Papers

LTE Advanced

This paper addresses the performance targets and the technology components being studied by 3GPP for LTE Advanced. The high level targets of LTE-Advanced are to meet or exceed the IMT-Advanced requirements set by ITU-R. A short history of the LTE standard is offered, along with a discussion of its standards and performance. The technology components considered for LTE-Advanced include extended spectrum flexibility to support up to 100MHz bandwidth, enhanced multi-antenna solutions with up to eight layer transmission in the downlink and up to four layer transmission in the uplink, coordinated multi-point transmission/reception, the use of advanced relaying and heterogeneous network deployments.

Download LTE-Advanced White Paper PDF

Joint ITU-GISFI Workshop on

“Bridging the Standardization Gap: Workshop on Sustainable Rural Communications”

(Bangalore, India, 17-18 December 2012)

LTE Advanced eNB Small Cell System

Design Challenges Network Topologies and Applications

By: Dr Venkat Rayapati,

President &CEO,

Download LTE-Advanced Small Cell Systems Presentation PDF

LighReading Webinar

Scale Solutions Across Mobile Networks

Sponsored by Avago Technologies

June - 2014

By: Dr Venkat Rayapati,

President & CEO of SAI Technology Inc.


Raghu Kondapalli

Director of Technology,

Strategic Planning & Solution

Architecture, Network Solutions

Group, Avago Technologies

Download LTE-Advanced Small Cell Systems Presentation PDF

Just added--

Video: SAI Technology presents LTE Mobile Software Defined Networks and Applications


Video: SAI Techonology's CEO Dr. Venkat Rayapati presenting material at Mobile World Congress 2014, Barcelona, Spain.

SAI worked with LSI to showcase their AXXIA 5500 processor and demonstrate an architecture that will provide an optimized LTE and Wi-Fi solution for enterprise networks.

Video: Multi-threaded LTE UE Baseband Solution from MIPS and SAI Technologies.

Presentation Material based on a collaboration demo presented at Mobile World Congress 2013 in Barcelona, Spain.

This video shows SAI Technology's CEO Dr. Venkat Rayapati demonstrating LTE in the lab located at SAI Technology, Santa Clara, CA

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