In 5G (NR) networks RB (Resource Block- Resource Block) and PRB (Physical Resource Block- Physical Resource Block) are both resource allocation units on the radio interface; they are essential for efficient data transmission and reception, and play a key role in realizing the high data rates, low latency, and flexibility that 5G promises, with their respective characteristics and uses are as follows;
I. RB (Resource Block) in 5G (NR) its represents the unit of frequency and time resources that can be allocated to a user or service, and is also the basic building block for resource allocation in the time-frequency domain, where.
Frequency and time division:RBs are organized in both the frequency and time domains; RBs are continuous blocks of spectrum in the frequency domain, and RBs represent continuous time slots within a subframe in the time domain.
Size and Configuration:The RB size in the frequency domain is determined by the system bandwidth; typically 1 RB in a 5G(NR) system usually corresponds to 12 subcarriers in the frequency domain, while the number of allocations in the time domain depends on the time slot and subframe configuration.
Flexibility and Adaptability:RBs are flexible in terms of resource allocation, allowing network operators to adapt the allocation to the specific requirements of users, applications and network conditions. This adaptability is essential to achieve efficient spectrum utilization.
Downlink and uplink RB: In the downlink, the base station (gNodeB) allocates RBs to users (UEs) for data transmission; in the uplink, UEs transmit data to the gNodeB based on the allocated RBs.
Orthogonality:RBs are designed to be orthogonal so that interference is minimized when assigning RBs to different users or services. This orthogonality improves the overall spectral efficiency of the system.
MIMO and beamfitting: RBs play a critical role in supporting advanced technologies such as MIMO and beamfitting. The allocation of RBs can be optimized to take advantage of spatial diversity and enhance the overall performance of the wireless link.
II.PRB (Physical Resource Block) is a specific instance of a resource block in the physical layer of a wireless communication system; it refers to the actual set of subcarriers and time slots allocated for data transmission.
Subcarrier and Symbol Allocation:The PRB consists of a set of consecutive subcarriers in the frequency domain and represents a set of consecutive symbols or time slots in the time domain.The allocation of subcarriers and symbols within the PRB is determined by the system configuration and modulation scheme.
Mapping to the Physical Layer:The PRB is the entity that physically maps to the wireless signals transmitted over the air.The information carried by the PRB includes user data and control information required to manage the communication link.
Modulation and Coding:Subcarrier assignment within the PRB allows for the simultaneous transmission of multiple data streams using techniques such as QAM (Quadrature Amplitude Modulation). Modulation and coding schemes can be adapted to the channel conditions and specific characteristics of the PRB.
Dynamic Resource Allocation:PRBs support dynamic resource allocation, allowing the system to adapt to changing channel conditions and different data rate requirements. This adaptability is essential to achieve high spectral efficiency and to meet the diverse needs of different services.
Channel quality feedback: The channel quality associated with a particular PRB is continuously monitored. the UE provides channel quality feedback to the gNodeB, allowing dynamic adjustment of resource allocation to maintain reliable communications.
Scheduling and authorization: The scheduling and authorization of PRBs is a core function in the 5G system. gNodeB schedules PRBs to be allocated to UEs based on factors such as channel conditions, QoS (Quality of Service) requirements, and priority.
TDD and FDD operation:PRBs can be adapted to both time division duplex (TDD) and frequency division duplex (FDD) modes of operation. This flexibility enables 5G networks to operate efficiently in a variety of deployment scenarios.
Digits and timeslot configuration:The concept of digits in 5G refers to the combination of subcarrier spacing and timeslot duration. Different numbers are defined to accommodate different use cases.PRB allocation is closely related to the number and timeslot configurations, affecting the granularity of resource allocation.
Beam Management and Mobility:PRBs play a role in beam management and mobility management strategies. Beamforming and tracking of mobile users involves dynamic adaptation of PRB allocations to optimize the communication link.
Link Adaptation and Efficiency:PRBs support link adaptation techniques in which modulation and coding schemes are dynamically adapted to channel conditions. This adaptation helps to improve the efficiency and reliability of data transmission.
RB (Resource Blocks) and PRB (Physical Resource Blocks) as the basic units of 5G (NR) wireless networks provide the basis for dynamic allocation of resources in the time and frequency domains.RB provide flexibility, adaptability, and orthogonality, whereas PRB denote the physical entities that carry the user's data and control information through the air interface.Effective management of RB and PRB is essential to achieve the high-performance goals of 5G (high data rates, low latency, and efficient spectrum utilization). latency and efficient spectrum utilization).
