MulteFire operates 4G LTE technology standalone in licence exempt (unlicensed or shared) spectrum, avoiding the need to acquire and pay for spectrum. Businesses and property owners can buy, install and operate their own MulteFire network in the same way as they do for Wi-Fi. It incorporates LTE functionalitysupporting voice and data, either independently as a private network and/or interworking with existing mobile networks to provide secure, seamless service through a neutral host. Cellular subscribers from any network can roam and make use of MulteFire networks where commercially and technically supported.
MulteFire is suitable for any spectrum band that require over-the-air contention, such as the global 5 GHz unlicensed spectrum band or shared spectrum in the upcoming 3.5 GHz CBRS band in the U.S. It builds on elements of the 3GPP Release 13/14 standards for Licensed Assisted Access (LAA/eLAA) which modifies standard LTE to operate in global unlicensed spectrum. Enhancements including Listen-Before-Talk have been designed to efficiently co-exist with other spectrum users, such as Wi-Fi.
The full range of LTE services are available through MulteFire, including VoLTE (Voice), high speed Mobile Broadband (data), LTE Broadcast and IoT optimizations. It promises LTE-like performance with the simplicity of Wi-Fi-like deployments.
As with mobile networks, there will be fully transparent and seamless mobility as you walk around a building, handing over between small cells as required. MulteFire can interwork with external mobile networks to provide service continuity.
Since MulteFire is based on LTE, it will operate in 20MHz TDD sub-bands, capable of peak data rates up to 400Mbps (using 4x4 MIMO with 256 QAM). Furthermore, the standard allows multiple sub-bands to be aggregated to achieve even higher speeds.
MulteFire can operate anywhere worldwide, without further regulatory approval, costly spectrum or specialist expertise. It uses many of the sophisticated features designed into LTE to deliver high performance, seamless mobility and resilience, even in highly congested environments. As with Wi-Fi, multiple MulteFire networks can co-exist, overlap or be friendly neighbours in the same physical space.
MulteFire unleashes enormous potential for small cells to become more widely adopted, and could form a useful multi-operator solution for building owners at lower cost than today’s DAS by acting as a neutral host or single-operator enterprise solutions.
Realisation and compatibility
MulteFire is most appropriately implemented using Small Cells due to the low transmit power typically imposed on unlicensed or shared spectrum bands. The smaller footprint of each cell leads to greater spectrum reuse, delivering high capacity in dense environments such as stadiums, malls, airports and train stations.
Listen-Before-Talk and dynamic sub-band selection simplify and avoid the need for specialist RF planning. Like LAA and eLAA, MulteFire can dynamically detect and select the least used sub-bands to avoid other users such as Wi-Fi. It will also use Listen-Before-Talk to ensure fair co-existence when sub-bands have to be shared with other users.
MulteFire has been specified to comply with global regulatory requirements, such as Listen-Before-Talk (LBT), ensuring the same mass-market products will be equally applicable for use anywhere and fully compatible with other deployments worldwide.
Compatible devices could include data-only dongles, smartphones, tablets and computers. These will require new hardware and chipsets, but will share many of the same enhancements required for LAA and eLAA.
LTE inherently incorporates strong security mechanisms, ensuring authentication of devices, networks and encrypting data traffic. MulteFire devices could either have physical SIM cards or virtual eSIMs to support service continuity from external mobile networks.
Alternatively, any MulteFire network could issue its own SIM cards or eSIMs for use with its own services. It is also possible for standalone networks to allow open access from devices without or regardless of a SIM card, automatically self-provisioning a local identity.
MulteFire can also support IoT use cases through optimizations such as eMTC (defined in 3GPP R13), which reduces device complexity and extends battery life and range.
Co-existence with Wi-Fi
There is much industry debate and concern about the impact on existing use of unlicensed spectrum, principally occupied today by Wi-Fi. There are regional variations on regulatory requirements, with concerns raised that unmodified LTE in unlicensed bands would swamp other users and cause havoc to Wi-Fi installations.
MulteFire is based on LAA and eLAA for downlink and uplink respectively. These modify LTE transmissions to behave co-operatively with known and unknown users sharing the same band using over-the-air contention based techniques including Listen-Before-Talk. This is designed to meet regulatory requirements worldwide and would comply with those even in regions where this is not required. This enables harmonious co-existence between MulteFire and other unlicensed technologies such as Wi-Fi. With these techniques, MulteFire is suitable for any band that requires over-the-air contention for fair sharing of spectrum, and one example is the upcoming three tiered 3.5 GHz CBRS spectrum in the U.S. with the General Authorized Access (GAA) tier that benefits from over-the-air contention as deployments expand.
As an example, European Regulations mandate that any RF transmission equipment using the 5 GHz band must comply with ETSI standard EN 300 893, which specifies spectrum sharing mechanisms and RF output power limits. These specifications are expected to be refined in 2016 to ensure that all technologies, including as Wi-Fi, LAA and MulteFire behave co-operatively, such as stating the same energy detect level required to back-off for other users.
Timescale and Dependencies
The MulteFire Alliance plans to publish its Release 1 specification in Q4 2016. This will be heavily based on the LAA 3GPP Release 13 specifications ready and frozen in March 2016, and under development for Release 14 primarily adding uplink support (eLAA).
Demonstrations of both LAA, eLAA and MulteFire have already been made, and the technology is well understood. Multiple MulteFire Alliance members showed co-existence with Wi-Fi and enhanced performance during Mobile World Congress 2016. There have been many simulations to establish performance under heavy load. The Alliance is confident that the specifications can be easily implemented and deployed.
LTE small cell as well as enterprise Wi-Fi vendors are likely to incorporate MulteFire into their portfolio and we should expect to see products become available once the specification has been ratified.
The MulteFire Alliance plans to establish a certification program similar to that of the Wi-Fi Alliance, whereby product vendors can complete independent testing and market their products as MulteFire capable.
Devices such as dongles, smartphones, tablets and computers will require a MulteFire capable chipset. It is expected that chipsets being developed for LAA/eLAA will also inherently support MulteFire, and will become mass market and mainstream. It may take a little time to seed the market with a critical mass of MulteFire capable devices, but specific private network applications could accelerate initial take-up.
For more information, including alternative system architectures, business drivers and likely commercial inter-relationships, read our White Paper sponsored by the MulteFire Alliance.