Radio Stripes: Definition, Advantages, and Disadvantages

This page explores radio stripes, covering their basics, advantages, and disadvantages. It outlines the benefits and drawbacks of this technology.

What is a Radio Stripe?

Traditional cellular networks use individual Access Points (APs) for each cell, based on the regions they serve. This can lead to interference between neighboring APs.

In contrast, a cell-free architecture allows each user to be served by all APs within their area of significance. This approach follows a user-centric design.

A radio stripe consists of numerous antennas embedded in a cable or on adhesive tape, making it easy to install in various locations. Radio stripes are used both outdoors and indoors, in areas such as:

• Densely populated city squares
• Cultural sites
• Malls
• Stadiums
• Train stations
• Busy airports
• Factories
• Warehouses

Refer to Cell-free Massive MIMO architecture for more information on radio stripe usage.

Figure-1, Image Courtesy: Ericsson and Linköping University Sweden

The antennas used in radio stripes are very small, allowing them to be easily integrated into cables or tape. Actual radio stripes may have tape or adhesive glue on the backside, similar to LED strips.

For 3.5 GHz frequencies, antennas may protrude slightly from the cable (as shown in Figure 1). At 10 GHz and higher frequencies, they become more embedded within the cable itself due to their reduced size.

As shown in Figure 1, all the antennas are arranged sequentially, like a daisy chain. A single CPU (Central Processing Unit) is mounted or printed at the end of the tape.

Figure-2, Image Courtesy: Ericsson and Linköping University Sweden

Figure 2 illustrates two antenna elements connected to a single APU (Antenna Processing Unit). APUs are interfaced using connectors to provide power and clock signals. Each APU contains a DSP (Digital Signal Processor), ADC (A to D converter), DAC (D to A converter), filters, I/Q modulators, signal amplifiers, phase shifters, and attenuators, as per the design requirements.

All antenna elements and APUs are enclosed within a protective material. The figure shows a CPU at the end of the tape. Neighboring CPUs are connected to each other. A CPU is also known as a stripe station, as it connects with one or more radio stripes.

In some embodiments, additional sensors or actuators are added to the radio stripe, including temperature sensors, vibration sensors, miniature microphones, and speakers.

Benefits or Advantages of Radio Stripes

Here are the advantages of radio stripes:

• Improved Service: Provides better service to users due to its wide availability and proximity to users.
• Flexibility: The cell-free architecture supported by radio stripes is flexible and can accommodate various use cases.
• Easy Installation: Radio stripes are lightweight and can be easily installed like cables, on lamp posts, or on pillars.
• Scalability and Cost Reduction: Designed for scalability and reduced costs.
• Printed Electronics Manufacturing: Radio stripes use very small components, making it possible to manufacture them using printed electronics methods.
• Invisibility: Radio stripes are nearly invisible, offering a more aesthetically pleasing appearance compared to base station antennas on towers.
• Robustness: Due to the highly distributed architecture, the system is minimally impacted when one or a few stripes are defective.
• Omni-directional and Low Power: The signals transmitted from radio stripe antennas are omni-directional and require low power levels.

Drawbacks or Disadvantages of Radio Stripes

Like all new technologies, radio stripes have some challenges and drawbacks:

• Cell Phone Grade Components: Radio stripe design necessitates the use of cell phone grade components.
• Synchronization: Accurate synchronization and coordination among antennas and APUs are essential for the cell-free network.
• Susceptibility to Disturbances: Wireless technology at high frequencies (>10 GHz) is prone to disturbances. For example, the signal can be easily blocked by a hand.
• Symbol Level Synchronization: Crucial for enabling joint coherent transmission. Coherent combination at the receiver is required when two APs transmit to the same UE simultaneously. Clustering is necessary to minimize delay and synchronization errors.