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Researchers Submit Patent Application, "Remote Radio Head Unit System with Wideband Power Amplifier and Method", for Approval

August 28, 2014

By a News Reporter-Staff News Editor at Politics & Government Week -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors WANG, Chengxun (Shenzhen, CN); STAPLETON, Shawn Patrick (Burnaby, CA), filed on April 9, 2014, was made available online on August 14, 2014.

The patent's assignee is Dali Systems Co., Ltd.

News editors obtained the following quote from the background information supplied by the inventors: "Wireless and mobile network operators face the continuing challenge of building networks that effectively manage high data-traffic growth rates. Mobility and an increased level of multimedia content for end users require end-to-end network adaptations that support both new services and the increased demand for broadband and flat-rate Internet access. In addition, network operators must consider the most cost-effective solutions to expand network capacity and evolution towards 4G and beyond.

"Wireless and mobile technology standards are evolving towards higher bandwidth requirements for both peak rates and cell throughput growth. Thee latest standards supporting this are HSPA+, WiMAX, TD-SCDMA and LTE. The network upgrades required to deploy networks based on these standards must balance the limited availability of new spectrum, leverage existing spectrum, and ensure operation of all desired standards. This all must take place at the same time during the transition phase, which usually spans many years.

"Distributed open base station architecture concepts have evolved in parallel with the evolution of the standards to provide a flexible, cheaper, and more scalable modular environment for managing the radio access evolution. For example, the Open Base Station Architecture Initiative (OBSAI), the Common Public Radio Interface (CPRI), and the IR Interface standards introduced standardized interfaces separating the Base Station server and the remote radio head part of a base station by an optical fiber.

"The RRU concept is a fundamental part of a state-of-the-art base station architecture. 2G/3G/4G base stations are typically connected to RRUs over optical fibers. Either CPRI, OBSAI or IR Interfaces may be used to carry data to the RRH to cover a three-sector cell. The RRU incorporates a large number of digital interfacing and processing functions. Traditionally, a multi-channel RRU means that multiple antennas are used, typically with two power amplifiers for two distinct bands. A duplexer is used to combine the two power amplifier outputs. Switches are used to isolate the transmit signals from the received signals as occurs in a Time Division Synchronous Code Division Multiple Access (TD-SCDMA) modulation. To extent the prior art architecture to multiple bands (i.e., two or more bands) implementation would consist of adding additional channelized power amplifiers in parallel. The output of the additional power amplifiers is typically combined in an N by 1 duplexer and fed to a single antenna.

"While conventional RRU architecture offers some benefits, RRUs to date are power-inefficient, costly and inflexible. Further, their poor DC-to-RF power conversion insures that they will have a large mechanical housing. In addition, current RRU designs are inflexible. As standards evolve, there is a need for multi-band RRUs that can accommodate two or more operating channels using a single wideband power amplifier. This creates an isolation problem at the individual receivers because the wideband power amplifier is always turned on. Isolation between the wideband transmitter and receivers is a problem with any modulation standard (HSPA+, WiMAX, LTE, etc.) when multi-band RRUs are developed using a single power amplifier. This is a common problem for all communication systems that utilize a wideband power amplifier in a multi-band scenario."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "Accordingly, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a high performance and cost effective technique for implementing RRU systems that service multi-frequency bands. Further, the present disclosure enables a RRU to be field-reconfigurable, and supports multi-modulation schemes (modulation agnostic), multi-carriers, multi-frequency bands, and multi-channels. The present invention also serves multi-frequency bands within a single RRU to economize the cost of radio network deployment. In particular, the present invention resolves an isolation issue for a RRU with fewer power amplifiers than the number of operating frequency bands. Multi-mode radios capable of operating according to GSM, HSPA, LTE, TD-SCDMA and WiMAX standards and advanced software configurability are key features in the deployment of more flexible and energy-efficient radio networks.

"The present invention achieves the above objects using techniques generally based on methods and techniques for maximizing the isolation between the transmitted signal (Tx Signal) and the received signal (Rx Signal). The Tx Signal may comprise noise generated at the output of the power amplifier or it may comprise an unwanted transmitter band leaking into the receiver. With the use of the present invention, conventional RRU's can be extended to a multi-band and multi-channel configuration. Multi-band means that more than one frequency bands are used in the RRU and multi-channel means that more than one output antenna is used. Various embodiments of the invention are disclosed.

"An embodiment of the present invention utilizes duplexers, switches and circulators to maximize the isolation between the transmitter and receiver. Another embodiment of the present invention utilizes an interference Cancellation System (ICS) together with duplexers, switches and circulators.

"Applications of the present invention are suitable for use with all wireless base-stations, remote radio heads, distributed base stations, distributed antenna systems, access points, repeaters, mobile equipment and wireless terminals, portable wireless devices, and other wireless communication systems such as microwave and satellite communications. The present invention is also field upgradable through a link such as an Ethernet connection to a remote computing center.


"Further objects and advantages of the present invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which:

"FIG. 1 is a block diagram of a TD-SCDMA dual-band single PA configuration in a remote radio head unit system in accordance with the present invention.

"FIG. 2 is a block diagram of the TD-SCDMA dual-band single PA with a Interference Cancellation System (ICS) configuration in a remote radio head unit system in accordance with the present invention.

"FIG. 3 is a FDD Modulation Agnostic Dual-Band Remote Radio Head with an Interference Cancellation System.

"FIG. 4 is an Interference Cancellation System using Power Detection.

"FIG. 5 is a TDD Modulation Agnostic Dual-Band Remote Radio Head with an Interference Cancellation System.

"FIG. 6 is an Interference Cancellation System using Correlation."

For additional information on this patent application, see: WANG, Chengxun; STAPLETON, Shawn Patrick. Remote Radio Head Unit System with Wideband Power Amplifier and Method. Filed April 9, 2014 and posted August 14, 2014. Patent URL:

Keywords for this news article include: Dali Systems Co. Ltd.

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Source: Politics & Government Week

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