Boost Wireless Performance with Cost-Effective Interleaved MIMO DAS Solutions

In the quest for high-performance cellular infrastructure, many organizations are turning to advanced deployment methodologies, including Multiple-Input Multiple-Output (MIMO) technology. This approach employs multiple antennas at both the transmitter and receiver ends of a Distributed Antenna System (DAS) to enhance communication performance. However, the cost associated with full MIMO implementations often leads organizations to seek more cost-effective alternatives. Enter interleaved MIMO, a solution that delivers MIMO-like performance without the significant expense.

Why Consider MIMO?

Organizations are increasingly recognizing the benefits of MIMO technology for their wireless networks:

Increased Capacity and Throughput

MIMO enables multiple data streams to be transmitted simultaneously, significantly boosting data capacity and throughput. This is particularly beneficial in high-density environments such as stadiums, airports, and large corporate buildings, where data traffic is heavy.

Enhanced Signal Quality

With improved signal strength and reliability, users enjoy fewer dropped calls and higher data speeds, leading to a more satisfying wireless experience.

Better User Experience

With improved signal strength and reliability, users enjoy fewer dropped calls and higher data speeds, leading to a more satisfying wireless experience.

Efficient Spectrum Utilization

With the increasing demand for wireless bandwidth, it is crucial to utilize the available spectrum efficiently. MIMO technology allows for more data to be transmitted without needing additional frequency allocation.

Future-Ready Infrastructure

As wireless technology evolves - especially with the rollout of 5G - MIMO is becoming a standard feature. Integrating MIMO into DAS ensures compatibility with current and future wireless standards, helping to avoid obsolescence.

Support for Multiple Operators and Technologies

MIMO-enabled DAS can accommodate various wireless operators and technologies, including 4G and 5G. This versatility makes it an ideal solution for organizations needing to meet diverse wireless demands.

Reduced Interference

MIMO systems effectively manage interference, which is critical in environments where many wireless signals coexist.

Cost-Effectiveness

While incorporating MIMO into a DAS requires an initial investment, the long-term benefits - such as increased capacity and improved service quality - can lead to significant cost savings. It also reduces the need for extra infrastructure to manage increased data traffic.

Despite these advantages, why aren't all DAS installations equipped with MIMO?

Part of the reason is that some organizations may not need higher performance levels. However, the primary obstacle is often the significant cost associated with traditional MIMO systems. These setups require multiple antennas for both transmission and reception, leading stakeholders to carefully consider the trade-offs.

Introducing Interleaved MIMO

A promising solution gaining traction is interleaved MIMO, where the DAS design incorporates alternating transmitters and receivers to provide MIMO-level performance in critical coverage areas without the expense of deploying multiple antennas at each access point.

With interleaved MIMO, access points are spaced apart, and the signals from each access point are interleaved—mixed alternatively—across the coverage area. This approach significantly enhances radio coverage and minimizes power imbalances among the Remote Antenna Units (RAUs), resulting in reduced fading, increased capacity, and markedly improved data rates.

In contrast to traditional MIMO, which necessitates antennas for each data stream, interleaved MIMO requires fewer cables and antennas, making implementation costs significantly lower. The result is performance equivalent to MIMO, meeting the needs of many organizations that find a traditional MIMO deployment financially unfeasible.

Configuring Interleaved MIMO

Traditional MIMO employs multiple parallel paths. For instance, in a standard 2×2 MIMO setup, there are two parallel paths, each equipped with a transmitting and receiving antenna. However, in interleaved MIMO, only one path is available at each antenna point, with the design alternating between the two parallel paths at each point. The advantage is that the overlapping coverage area can utilize both paths—similar to traditional MIMO—without incurring typical MIMO costs.

In a 2×2 MIMO scenario, there are six antenna points, each transmitting and receiving on two paths, referred to as path A and path B. In interleaved MIMO, path A operates from three locations, while path B also functions from three locations, staggered to ensure that the overlapping antenna points benefit from access to both paths.

This setup results in an approximate 80% coverage area experiencing a data rate increase through interleaving (~30% enhancement), provided that the paths remain within 12 dB of each other.

Successfully Implementing Interleaved MIMO

While the design and spacing requirements for an interleaved MIMO network are specific to each building, two critical factors must be considered:

1. The Signal-to-Interference-Plus-Noise Ratio (SINR) must exceed 20 dB to support higher data rates. Any design meeting typical key performance indicators (KPIs) should fulfill this requirement.

2. In a 2×2 MIMO configuration, the two paths should stay within 12 dB of each other for balanced performance.

Interleaved MIMO presents numerous advantages over traditional MIMO - beyond just cost considerations, including:

• Improved Signal Robustness: Interleaving distributes data across multiple antennas and time intervals, reducing signal fading and interference, particularly in environments with high reflection or obstruction.

• Enhanced Error Correction: By spreading data across multiple paths, interleaved MIMO enhances error correction capabilities, allowing accurate reconstruction of data even if one path encounters interference.

• Increased Spectral Efficiency: Interleaved MIMO can achieve higher spectral efficiency, optimizing the use of available spectrum for increased data throughput without needing additional bandwidth.

• Better Handling of Multipath Propagation: Interleaved MIMO effectively manages multipath effects, turning potential drawbacks into advantages by enhancing signal diversity and strength.

• Enhanced Capacity in High-Interference Environments: In high-interference situations, interleaved MIMO maintains higher data transmission capacity by reducing the impact of interference across the signal.

These benefits make interleaved MIMO an attractive option for advanced wireless communication systems, especially in environments where reliability and efficient bandwidth usage are paramount.

Interleaved MIMO with Zinwave Active DAS

Bolton Technical offers interleaved MIMO with the Zinwave Active DAS, specifically engineered for large facilities exceeding 25,000 square meters. Zinwave Active DAS is perfect for locations where reliable communication and advanced connectivity are crucial for safety, security, and digital transformation. It delivers top-quality signals and superior mobile experiences in hospitals, airports, government buildings, universities, and other public spaces.

Our Zinwave DAS aggregates all signal sources to a single point of interface that connects to a primary hub. This hub transports optical signals via fiber to secondary hubs and remote radio units, optimizing frequencies from 150 MHz to 5 GHz.

Designed for energy efficiency, scalability, and ease of installation, Zinwave Active DAS occupies less space than competing solutions and allows for the reuse of existing fiber networks. Built-in real-time remote monitoring capabilities facilitate troubleshooting and maintenance.

Implementing interleaved MIMO requires careful design, planning, and some additional equipment. For only about 10% more than a Single Input Single Output (SISO) solution, you can achieve an interleaved MIMO system that significantly enhances performance.