IEEE International Symposium on Personal, Indoor and Mobile Radio Communications
13–16 September 2021 // Virtual Conference // By 6G Flagship

Integrated Access and Backhaul for 5G and Beyond


Dr. Mohamed-Slim Alouini
King Abdullah University of Science and Technology, Saudi-Arabia

Dr. Behrooz Makki
Ericsson AB, Sweden

Dr. Erik Dahlman
Ericsson AB, Sweden

Dr. Filip Barać
Ericsson AB, Sweden


To cope with the exponential growth of demand on wireless communications, 5G and beyond will densify the network with many base stations (BSs) of different types. The BSs, however, need to be connected to the operators’ core network via a transport network. On a global scale, fiber and wireless microwave technology are dominating media for backhauling. Fiber offers reliable connection with demonstrated Tbps data rates. However, fiber deployment may take long installation time, requires noteworthy initial investment, and may even be not allowed in, e.g., metropolitan areas. Wireless backhaul, on the other hand, comes with significantly lower cost and time-to-market as well as higher flexibility.

Traditionally, wireless backhaul hasbeen mainly based on proprietary technology operating in millimeter wave (mmw) spectrum and constrained to line-of-sight (LoS) propagation conditions. However, with 5G NR, cellular technology is extending into mmw spectrum; the spectrum historically used for backhauling. Also, with small-cells deployed on street level, the backhaul links need to operate also under NLoS (N:non) conditions. These, along with reducing the time-to-market/operation cost, are the main motivations for the integrated access and backhaul (IAB) concept. The aim of IAB is to provide flexible wireless backhaul using 3GPP NR technology, providing not only backhaul but also the existing cellular services in the same node.

The objective of the tutorial is to bring new insights to the analysis, design and standardization of IAB networks. Such networks guarantee the communication requirements in future smart cities and solve the ubiquitous connectivity problems in many challenging network environments, e.g., coverage/capacity enhancements in rural areas. The tutorial will 1) go through the recently finished Release 16 and ongoing Release 17 IAB work-items of 3GPP, as the world’s biggest 5G research program, 2) present proof-of-concept results for the usefulness of IAB, and 3) provide a vision for IAB-related research towards 6G.

Structure and content

  • Part 1. Integrated Access and Backhaul: An Enabler for Network Densification in 5G and Beyond (30 min)
    • Motivation of dense small-cell networks in 5G and beyond.
    • An overview of different backhaul technologies.
    • The introduction of IAB;a candidate backhauling technology in 5G.
    • Proof-of-concept simulations for IAB.
  • Part 2. IAB Standardization in 3GPP (90 min)
    • IAB in 3GPP Release 16
      1. IAB Architecture
      2. IAB node integration procedure
      3. Backhaul Adaptation Protocol and packet routingover the backhaul
      4. Spectrum for IAB
      5. The IAB radio link
      6. Timing alignment
    • IAB Enhancements in 3GPP Release 17
      1. Topology adaptation and topology redundancy for load balancing and robustness
      2. SimultaneousTx/Tx, Tx/Rx, Rx/Rx, Rx/Txoperation
      3. End-to-end performance, fairness, and spectral efficiency
      4. Congestion mitigation
  • Part3. IAB in the beyond 5G era; Open research problems (60 min)
    • Mobile IAB-Meshed IAB-IAB using network coding
    • Caching-based IAB
    • IAB using a combination of parallel technologies
    • Unmanned aerial vehicle(UAV)-assisted IAB Networks
    • IAB performance optimization using machine learning
    • Intelligent reflective surface (IRS)-assisted IAB