4G LTE Network Architecture LTE, a 4G wireless technology which has been developed by 3GPP (Third Generation Partnership Project), an industry trade group. The 4G technology LTE that stands for Long Term Evolution has been named so because it represents an evolution from the very basic GSM technology (2G) to 3G standard (UMTS) and the next step comprises of LTE evolving from the third generation of wireless networks. In particular, the factors that led to the emergence of 4G technology are dedicated to the inefficiency of 3G network for supporting the demands of rapidly growing number of users and their expectations of [...]
LTE Broadcast One of the key technologies behind the LTE Broadcast is the Single Frequency Network. LTE BROADCAST LTE Broadcast uses the same base stations and radio frequency spectrum as normal LTE transmissions, except that during the broadcast event, a certain portion of radio resources in the cells covering the service area are dedicated to the broadcast service for the duration of the event. The reserved timeslots are used to broadcast the event and the remaining timeslots are used for normal LTE unicast transmissions. During the reserved broadcast timeslots, all participating base stations transmits exactly the same signals at [...]
Unicast Services in 4G LTE Media from content servers to end-user devices can be transmitted by unicast or broadcast methods. UNICAST SERVICES IN 4G LTE Unicast is an efficient mechanism to deliver services that require a bidirectional link, such as real-time voice and video communication, web, email or social media. Users are spread out sparsely over disjoint multiple radio cells, consuming different content at different times, such as on-demand video streaming. When multiple users are watching the same content, such content is transmitted multiple times within the transport network and on the radio interface, leading to very low efficiency.
Uplink CoMP in LTE Advanced The CoMP reception in the UL involves reception of the UE signal at more than one cell. Uplink CoMP in LTE Advanced One of the cells would be a “central” cell responsible for combining signals received at multiple cells. The CoMP cells in the “operating set” can participate in coordinated scheduling. The CoMP reception of the Physical Uplink Shared Channel at multiple cells may or may not be transparent to the UE. The CoMP reception resembles soft handover in the UL. The benefit of CoMP reception is higher cell-edge throughput. The cost is higher [...]
Downlink CoMP (Co-ordinated Multi-Point) in LTE Advanced The Coordinated Multipoint (CoMP) feature is available for the DL and the UL. In the DL, CoMP transmission occurs, while CoMP reception is allowed in the UL. At a high level, CoMP transmission resembles soft handover and fast cell switching. CoMP transmission supports two cases, namely, Joint Processing (JP) and Coordinated Scheduling and Beamforming (CS/CB). Downlink CoMP-LTE Advanced Joint Processing (JP) has two use cases. The first case is where more than one cell transmits the same information at the same time. The UE then combines these two signals similar to 3G [...]
Soft-Handover in LTE Advanced LTE-Advanced supports multiple cells to coordinate their transmissions for a single user, providing a capability very similar in nature to soft handover used in 3G networks. Through Co-ordinated Multi-Point (CoMP) operation, multiple cells transmit the same data at the same time and receive the user’s transmissions at multiple locations; this approach is known as Joint Processing. The user is able to have a higher success rate than would be possible with only one cell involved, which results in improved performance at cell edges through macro diversity.
From ICIC (Inter Cell Interference Cancellation) to Further Enhanced ICIC Further Enhanced ICIC in Release 11 aims at strengthening the eICIC concept and boosting the overall performance. Due to synchronization signal collision from macro and picocells, a UE may have difficulty to detect picocells. To assist cell detection, the serving cell provides the UE a list of picocells IDs so that the UE can skip cell ID detection and directly perform picocell reference signal measurements. In order to enhance reliability, additional options are defined such as sending SIB1 information in a RRC Reconfiguration message or applying interference cancellation at the UE [...]
There are two distinct frequency planning strategies for Heterogeneous Network (HetNet) deployments where macrocells and small cells are overlaid: 1. Co-channel deployment, where macro and small cells use the same frequency carriers, 2. Dedicated Carrier deployment where macro cells and small cells use different frequency carriers. The co-channel case can utilize the full system bandwidth at both macro and small cell layers but at a cost of higher inter-cell interference. Enhanced ICIC features were defined in 3GPP Release 10 to address interference issues in Co-Channel HetNet. The concept of Almost Blank Subframes was added in Release 10 to help protect transmissions [...]
Inter Cell Interference Coordination (ICIC) in 4G ICIC is a multi-cell Radio Resource Management (RRM) function that takes into account information from multiple cells (e.g., the resource usage status and traffic load situation) and manages radio resources such that inter-cell interference is minimized. ICIC is defined in LTE to support soft frequency reuse. Messages are exchanged in real time between eNBs over the X2 interface for the ICIC function. These messages are triggered by certain thresholds and broadcast to neighbor cells. The neighbor cells can do interference-aware scheduling to lower or avoid interference in the network near cell edge with that [...]
Carrier Aggregation Across Cell-Sites in 5G In heterogeneous site configurations, a Remote Radio Head can be used at the small cell with the macrocell eNB. In this case, the eNodeB may provide carrier aggregation functions for the carrier components from the macrocell and small cell. In such cases, one scheduler controls both the macrocell and small cell resources in the network.