Local Home Network

Description

The Local Home Network (LHN) is a 3GPP concept introduced in Release 12 to support Selected IP Traffic Offload (SIPTO) at the Local Network. It defines a set of access nodes—specifically Home NodeBs (HNBs), Home eNodeBs (HeNBs), or Radio Network Controllers (RNCs)—and Local Gateways (L-GWs) that are interconnected in a standalone gateway architecture. The primary purpose is to allow user traffic to be offloaded locally, meaning it does not have to traverse the mobile core network to reach local services or the internet. This is particularly beneficial for residential, enterprise, and hotspot deployments where a large portion of traffic is local or destined for the internet, and backhaul to the core is costly or inefficient.

The architecture of a Local Home Network is based on the standalone GW (SGW) architecture, which separates the control plane and user plane for local offloading. The (H)NBs or RNCs provide radio access and have IP connectivity to the L-GWs. The L-GWs act as gateways for local traffic, performing functions such as IP address allocation, packet routing, and policy enforcement. The LHN is defined by the set of these nodes that are managed together and share a common local network configuration. The HNB-GW or RNC can connect to multiple L-GWs to provide redundancy or load balancing. The L-GWs are typically located close to the access nodes, often in the same physical location, to minimize latency and backhaul costs.

When a UE attaches to a cell belonging to an LHN, the network can decide to route specific traffic flows via the L-GW instead of the central gateway (e.g., GGSN/PGW). This decision is based on SIPTO policies, which can be configured per APN, per subscriber, or per service. The L-GW may perform NAT and firewall functions to protect the local network. The LHN is identified by a specific identifier that is used during session establishment to select the appropriate L-GW. The 3GPP specifications TS 23.060 (GPRS), TS 23.401 (EPS), and TS 25.413 (UTRAN Iu interface) define the procedures for SIPTO at the Local Network and the role of the LHN.

The Local Home Network concept was introduced to address the growing demand for local IP access (LIPA) and SIPTO in femtocell and enterprise deployments. LIPA allows a UE to access a local home network directly without going through the mobile core, while SIPTO offloads selected traffic to the internet or a local network at a point closer to the user. The LHN provides a standardized framework for these capabilities, ensuring interoperability between different vendors' equipment. It also enables operators to offer new services, such as enterprise-specific applications hosted locally, without impacting the mobile core.

The definition of Local Home Network has remained stable across releases from Rel-12 to Rel-19, with only minor formatting differences in the specification text. This indicates that the fundamental concept and architecture have not required revision. The feature continues to be relevant as networks evolve towards 5G, where local offloading remains an important capability for supporting ultra-low latency and high-bandwidth applications in enterprise and industrial settings. In 5G, similar concepts are realized through Edge Computing and Local Area Data Networks (LADN), but the LHN remains a foundational element for 4G and legacy deployments.

Purpose & Motivation

The Local Home Network was created to solve the problem of inefficient backhaul and high latency for local traffic in mobile networks. In traditional cellular architectures, all user traffic, even if destined for a local server or the internet, must traverse the mobile core network. This is costly for operators, consumes backhaul capacity, and introduces latency. For residential and enterprise users, a significant portion of traffic is local (e.g., file sharing, local servers) or internet-bound, and offloading this traffic at the edge can yield substantial savings and performance improvements.

The motivation for LHN came from the success of femtocells and the need to integrate them better with local networks. Home NodeBs and Home eNodeBs were deployed to improve indoor coverage, but they still relied on the core network for all traffic. By introducing L-GWs and the standalone GW architecture, 3GPP enabled local breakout, which allows traffic to be routed directly to the local network or the internet without going through the core. The LHN defines a set of access nodes and gateways that work together to provide this capability in a standardized way.

The LHN also addresses the need for a scalable and manageable architecture for local offloading. It provides a clear separation between access nodes and local gateways, allowing operators to deploy L-GWs in a distributed manner and manage them as a group. This is particularly important for enterprise deployments where multiple access points and gateways need to be coordinated. The concept has been further enhanced in later releases with features like SIPTO and LIPA, and it continues to be a building block for edge computing and 5G local area networks.