As LTE roll-outs continue to gather pace across the globe, the arguments over the deployments for small cells grow stronger. Few seem to doubt that small cells will form part of the solution in providing infill coverage where the macro cells fail to reach, densifying network coverage in hotspots and supplying backhaul options.
The discussion is now all about Wi-Fi integration, cost efficient deployment, operational issues, multi-vendor deployment and backhauling for small cells.
At MWC 2013, all the big Tier One equipment providers showed off a range of small cells to meet outdoor, indoor and backhaul demands. Ericsson did not unveil a new metro cell, despite its purchase of outdoor Wi-Fi manufacturer BelAir last year. Instead, it concentrated on augmenting its distributedbase stations with the launchof the AIR 32 (antenna integrated radio).
Nokia Siemens Networks was showcasing its Flexi Zone Micro and Pico cells, along with two FAPe-hsp 5620 (HSPA+) and 7610 (first LTE) femtocells.
The newest additions to the Alcatel-Lucent metro cell portfolio, the 9764 Metro Cell Outdoor and the 9768 Metro Radio Outdoor – both based on Alcatel-Lucent Bell Labs’ lightRadio cube technology – were on show. It also displayed its 9362 Enterprise Cell v1.5, supporting up to 8 users and the 9362 Enterprise Cell V2.2, supporting from 16 to 32 users. Indoor residential is covered by its 9361 Home Cell.
Huawei unveiled its AtomCell small cell design last year, but this year it was touting its LampSite solution for providing better indoor coverage using TD-LTE technology to offer Wi-Fi in subway stations, buildings and other indoor scenarios.
However, the specialist manufacturers were busy too. UK firm Ubiquisys worked with Intel to pioneer the integration of a computing platform into its intelligent small cells, along with the provision of a cloud-based management system and secure delivery of applications to the edge cloud. It offers a range of multi-mode LTE/3G/Wi-Fi products using silicon platforms from long-term partners Texas Instruments and Broadcom. Its main focus is indoor cells, although it does deploy outdoor small cells too.
The company announced a host of partnering arrangements at MWC, including: a small cell managed service for operators with Norway’s Cloudberry Mobile; an improved small cell LTE video streaming experience with Cygnus Broadband; increasing small cell performance using software from Japan’s Jin-Magic; content and application optimisation delivery system with Israel’s Saguna Networks; and it is working with Quortos to provide an all-mobile enterprise phone system that removes the need for desk phones.
UK firm ip.access has a range of small cells for consumers, SoHo, SME, enterprise and public access. It did not launch any new products at the show, but demonstrated dynamic integration between Wi-Fi and LTE small cells. The solution gives control to the carrier (as opposed to the mobile handset) enabling it to switch the handset to Wi-Fi from LTE or vice versa to provide the best user experience.
Small cells for backhaul
Network backhaul is a critical issue facing mobile operators, not least the need to backhaul huge amounts of traffic from small cells.
All the major equipment providers have their range of solutions, including ZTE, which unveiled a wide range of data transmission methods, including packet bearer network backhaul solution, fixed broadband backhaul solution through PON (passive optical network), xDSL and cable, microwave wireless backhaul solution, Wi-Fi non-line-of-sight (NLoS) wireless backhaul solution and TD-LTE backhaul solution.
Dimitris Mavrakis, analyst at Informa, says: ‘Operators will go for fibre first for backhaul. If theycannot get fibre they will look at a vendor who will provide the most solutions, as they won’t want to go to individual vendors for particular solutions.
‘There is a lot of hype around in the space: distributed antenna systems, point to point, point to multi-point; microwave, millimetre wave non-line of sight and so on. Operators will probably mix and match different solutions to meet particular needs and environments, but they’ll prefer one-stop shop providers,’ says Mavrakis.
Canada’s DragonWave launched its Avenue Link Lite backhaul solution at MWC. It is a sub-6GHz point to point microwave radio supporting both licensed and unlicensed spectrum and suited for NLoS deployments – it is also LTE ready. It features low power consumption (under 15W), Power over Ethernet compatibility, reduced cabling requirements and in-band synchronisation, which eliminates the need for an external synchronisation source.
Point to multi-point solutions
Two point to multipoint (PTMP) backhaul providers were in action at MWC. Bluwan was showcasing its LinkFusion products, the second generation version of its fibre through the air backhaul system, which operates in the 42GHz band. It delivers up to 10Gbps per transmission hub and up to 240Mbps throughput per terminal.
Two all-outdoor LinkFusion network terminating equipment products are available: a 120Mbps and a 240Mbps version. In addition to backhaul capability, the products can be used as a relay for line of sight unmasking and canyon in-filling between buildings to fill in coverage not-spots.
The system uses TDD architecture, which operators sometimes perceive as having latency and synchronisation issues associated with it. However, Shayan Sanyal, CCO at Bluwan, says: ‘We’ve worked with carriers on trials over the last year to get their feedback and we have solved all the operational challenges for TDD: latency is sub-3milliseconds, 2 usually, and we have sorted the synchronisation issues. Our PTMP solution is meeting carrier grades, so we can slot ourselves in nicely into the HetNet backhaul.’
Cambridge Broadband Networks unveiled its PTMP VectaStar Metro product, which delivers 300Mbps into each small sector and up to 2.4Gb per hub site and is compatible with the VectaStar Gigabit macro backhaul platform. John Naylon, CTO, says the product aggregates cell site traffic to improve spectral efficiency by 40% compared with point to point systems.
‘We’ve taken the core of our leading multipoint microwave backhaul technology and optimised it for street level development,’ says Naylon, who also revealed that a 750Mbps version is in the works and will be available next year.
NEC fielded a powerful line up of backhaul solutions with options for carriers including: high capacity millimetre wave and microwave; non-line-of-sight (NLoS) radio; wavelength division multiplex (WDM) optical access; full IP routing; and unified network management systems.
Key products include: iPASOLINK SX for urban street-level connectivity in the 60GHz (V-band); iPASOLINK EX for urban small cell traffic aggregation and distributed RAN ‘fronthaul’ – in the 70-80GHz (E-band) all-outdoor radio capable of delivering capacities in excess of 10Gbps; iPASOLINK AX all-outdoor radio and iPASOLINK split-mount series for remote small cell connectivity and urban aggregation – NEC’s core wireless backhaul products in 6-42GHz frequency ranges; and non-line of sight (NLoS) products for small cell connectivity in obstructed radio environments.
Tarana Wireless, based in California, was the new kid on the block this year. It showcased its AbsoluteAir small cell backhaul portfolio at MWC, which features the company’s concentrating multipoint (CMP) architecture. The product line consists of concentrator nodes (CNs), end nodes (ENs), and an element management system (EMS).
Each EN connects directly via Ethernet to a small cell providing it with a full 75Mbps dedicated backhaul capacity. The CN aggregates links for up to four ENs, providing 300Mbps capacity in a single 10MHz channel – delivering spectral efficiency of 30 bits per second per hertz. Both line of sight and non-line of sight modes are catered for.
E- and V-band solutions
Finally, an increasing number of E-band (60GHz) and V-band (70-80GHz) millimetre wave PTP products are becoming available. The UK’s Sub10, a pioneer in the space, added the Liberator V100 to its range. It includes its ‘Snapback’ innovation, which provides ultra fast synchronisation reliability if the link is disrupted.
Huawei unveiled an E-band millimetre wave transmission product, while Ericsson launched the PT3060 microwave small cell in 60GHz for backhauling small cells deployed in a HetNet. BridgeWave showcased its Flex4G millimetre wave backhaul solution – the latest product in its high-capacity, multi-gigabit portfolio.