How do you use RAN interference management techniques to improve spectrum efficiency and quality of service?

1 Co-channel interference

Co-channel interference (CCI) occurs when multiple cells or users transmit on the same frequency channel, causing mutual interference and reducing the signal-to-interference-plus-noise ratio (SINR). CCI can be managed by using cell planning and optimization techniques, such as adjusting the transmit power, antenna tilt, and cell size of the base stations. Another technique is to use frequency reuse schemes, such as fractional frequency reuse (FFR) or soft frequency reuse (SFR), which divide the frequency band into different sub-bands and assign them to different cell regions or users based on their interference level and QoS requirements.

2 Adjacent channel interference

Adjacent channel interference (ACI) occurs when the signal from a neighboring channel leaks into the desired channel, causing interference and reducing the SINR. ACI can be managed by using proper filtering and guard bands to minimize the out-of-band emissions and the adjacent channel leakage ratio (ACLR). Another technique is to use interference cancellation or suppression algorithms, such as successive interference cancellation (SIC) or interference rejection combining (IRC), which can detect and remove the interfering signals from the desired signal using signal processing techniques.

3 Inter-cell interference coordination

Inter-cell interference coordination (ICIC) is a technique that aims to coordinate the interference management among different cells in a RAN, especially in heterogeneous networks (HetNets) that consist of macrocells and small cells. ICIC can be implemented by using centralized or distributed methods, such as network-assisted interference cancellation and suppression (NAICS) or almost blank subframes (ABS). ICIC can also use information exchange and signaling protocols, such as X2 interface or fast information network (FIN), to enable the coordination and cooperation among the base stations.

4 Multi-user MIMO

Multi-user MIMO (MU-MIMO) is a technique that enables multiple users to share the same time-frequency resource by using multiple antennas at the base station and the user equipment. MU-MIMO can use different precoding and beamforming techniques, such as zero-forcing (ZF) or dirty paper coding (DPC), to create spatial multiplexing and diversity gains and to reduce the inter-user interference. MU-MIMO can also use different user selection and scheduling algorithms, such as greedy or semi-orthogonal, to maximize the network throughput and QoS.

5 Cognitive radio

Cognitive radio (CR) is a technique that enables the RAN to dynamically access and use the spectrum resources based on the spectrum availability and the network demand. CR can use different spectrum sensing and sharing techniques, such as energy detection or cooperative sensing, to identify the spectrum holes and the spectrum opportunities in the licensed or unlicensed bands. CR can also use different spectrum access and allocation techniques, such as spectrum handoff or dynamic spectrum leasing, to adapt to the spectrum variations and to avoid or exploit the interference from the primary or secondary users.

6 Non-orthogonal multiple access

Non-orthogonal multiple access (NOMA) is a technique that enables multiple users to share the same time-frequency resource by using different power levels or code domains. NOMA can use different multiple access schemes, such as power-domain NOMA or code-domain NOMA, to create superposition coding and multi-user detection gains and to increase the spectral efficiency and the user fairness. NOMA can also use different interference management techniques, such as SIC or NOMA-ICIC, to mitigate or coordinate the intra-cell or inter-cell interference.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?