ZTE's ZXSDR 8000 Family

Current Perspective

ZTE’s LTE base stations portfolio is threatening to the competition. Across its family of products, ZTE can point to strong capacity performance, good scalability, and a multi-standard solution that includes not only GSM and WCDMA, but also CDMA2000.

ZTE’s current LTE solution set consists of three base stations, the ZXSDR BS8700, BS8800 and BS8906. The BS8700 is a distributed base station consisting of a base band unit (BBU) B8200 and a remote radio unit (RRU) R8882. The BS8800 is a full sized integrated macro base station consisting of BBU B8200 and radio system unit RSU82. ZTE positions these two base stations as its high-capacity solutions. The BS8906, ZTE’s low-capacity LTE base station is a micro compact base station consisting of a BBU B8200 and RSU82. Both the BS8700 and BS8906 can scale with the addition of up to 17 RRUs.

ZTE’s overall LTE solution has many notable features that help make the vendor a strong player in the LTE space. Both the BS8700 and BS8800 can support an impressive number of LTE carriers―18 and 12 at 20MHz, respectively. While the practicality of that capacity can be debated, it does provide operators with investment future-proofing if such capacity is needed. The BS8800 delivers 12 LTE carriers in a 0.27-square meter footprint, with a nearly best-in-class of 44.4 carriers per square meter footprint. Thanks to CDMA2000 support, ZTE can deliver multi-standard solutions to operators coming from both 3GPP and 3GPP2 technology families.

In the highly competitive wireless infrastructure space, maintaining one’s market position is a constant challenge. For ZTE to maintain its position, the vendor needs to deliver on its promise of 2010 commercial availability for the BS8800 and BS8906. Wins at the likes of operators such as Telstra CSL and Telenor, while lacking the same high profile as competitors’ wins at A&T and Verizon Wireless, will give the vendor plenty of opportunities to prove its infrastructure performance claims in actual commercial settings. This deployment experiences will give ZTE the credibility it needs as more, and larger, operator opportunities become available.

Buying/Selecting Criteria

Base station capacity

■    High-capacity base station (LTE carriers): ZTE’s ZXSDR BS8700 and BS8800 support up to 18 and 12 carriers at 20MHz, respectively (higher number of carriers available with smaller spectrum channels). The BS8700 uses 18 RRUs to reach its maximum capacity, a configuration the vendor says it does not recommend, as most operators do not have the spectrum to support it. Carrier capacity translates directly into the number of users a base can support, and the data available to those users.

■    Low-capacity base station (LTE carriers): ZTE’s ZXSDR BS8906 delivers one carrier at 20MHz. This is the smallest capacity reported by vendors with a low-capacity solution. Extra carriers can be added through lower sized spectrum channels. While extra radio units can be added for increased capacity, the vendor says that would negate it from being a low-capacity base station. Low-capacity solutions provide operators with a cost-effective option to extend capacity into hard-to-reach areas: inside buildings, along highways, valleys, etc. Likewise, in emerging markets, low-capacity solutions are important for cost-effective coverage of rural areas.

■    GSM TRX: ZTE’s two high-capacity base stations deliver capacity of 60 GSM TRX, a figure only bested by Nokia Siemens Networks and Huawei. ZTE claims its low-capacity base station can support a market-leading figure of 60TRX as well. The ability to support a large number of users with a single base station, thanks to strong capacity support, helps operators control their CAPEX.

■    WCDMA carriers: ZTE’s BS8800 delivers 24 carriers of WCDMA and the BS8900 delivers 30 carriers (thanks to the use of a secondary cabinet). The low-capacity ZXSDR BS8906 supports 24 WCDMA carriers. With all three base stations, ZTE has the ability to deliver the capacity levels needed to remain competitive.

■    Capacity scalability: ZTE’s three LTE base stations, ZXSDR BS8700, BS8800, and BS8906, have the ability to scale their capacity. Both the BS8700 and BS8906 can support the addition of 17 RRUs for increased capacity, giving each the ability to grow from one carrier up to 18 carriers. The BS8800 has a secondary cabinet that allows the doubling of carrier capacity, reaching 12 carriers at 20MHz.

Base station coverage

■    Output power: ZTE reports 2×40W output power for all three of its LTE base stations. This power level can be scaled back if necessary. However, scaling back is not the same as offering multiple options. In scaling, the operator pays for the top-end power, even though it is using something less. Power output represents a base station’s ability to “push” RF signals out to users. High output power enhances coverage by extending cell reach or penetrating deeper into structures.

■    Radio receive sensitivity: ZTE reports its LTE base station family has radio receive sensitivity in a range of -108.8dBm to -103.5dBm, based on channel size. Though RF power output is important for getting RF signals out to users, strong receive sensitivity allows a BTS to “hear” signals from low-power devices (e.g., handsets).

■    Spectrum support: ZTE’s ZXSDR BS8700, BS880, and BS8960 all support the major spectrum bands. The more spectrum bands available with a base station, the more deployment scenarios it can support.

■    MIMO support: Multiple-input multiple-output (MIMO) antenna support is a critical feature of LTE, allowing for better coverage and/or better capacity. ZTE’s high-capacity solutions support both 2×2 and 4×4 MIMO. Its low-capacity base station, BS8906, supports both 2×2 and 2×4 MIMO. MIMO support beyond 4×4 is not needed. Both of ZTE’s base stations support single-input single-output (SISO).

Site deployment flexibility

■    Space efficiency (high capacity): ZTE’s BS8800 delivers 12 LTE carriers in a 0.27-square meter footprint, with a nearly best-in-class efficiency of 44.4 carriers in a square meter footprint. Capacity density represents the number of carriers supported by a base station in a given amount of floor space. Since base station real estate is at a premium, LTE base stations that can support a high number of sector-carriers in a small space provide OPEX savings.

■    Space efficiency (low capacity): On the low end, vendors report space efficiency metrics that are not easily compared, given zero-footprint architectures and in-building deployment purposes. Regardless, the ZXSDR BS8906 delivers 6.6 carriers in a square meter. This performance can be increased with the addition of extra RRUs. In a low-capacity solution, footprint is not as important, because solutions are often wall or ceiling-mounted. However, it is still critical that these products provide the necessary capacity without harm to interior design aesthetics.

■    Outdoor adjuncts: All three of ZTE’s LTE base stations (BS8700/BS8800/BS8906) can be deployed either indoors or outdoors. While most deployments favor indoor base station placement, the availability of an outdoor adjunct allows the vendor to address a greater range of deployment scenarios. The availability of outdoor adjuncts is fairly common across infrastructure vendors.

■    Mass (high capacity): ZTE’s BS8700 comes with a weight of 22.5 kg, a very light figure reflective of its distributed architecture. The BS8800, however, is not so light, with 12 LTE carrier support weighing in at 250 kg, making it the heaviest base station for this class. Even the one-cabinet configuration remains one of the heaviest solutions on the market at 135 kg. Lower-mass base stations benefit from greater ease of installation.

■    Remote radio support: ZTE, like all of its major competitors, offers remote radio support. Both ZXSDR BS8700 and BS8906 come with remote radio support. Power output for both is 2×40W. Distributed base station solutions allows for network coverage/capacity in areas that cannot support a full base station deployment. It is good for hard-to-reach areas.

■    Transport options: ZTE claims all three of its LTE base stations support Fast Ethernet/Gigabit Ethernet and 16 T1s for circuit transport and ATM, ATM IMA, and Ethernet for packet transport. Notably, ZTE is the only vendor not to report STM-1/OC3 support for circuit transport. A wide range of transmission and backhaul options enables mobile operators to leverage multiple transport network architectures and assets, ensuring the backhaul will support new data services, aggregate traffic onto higher-capacity links for cost savings, etc.

Technology evolution

■    GSM/WCDMA support (high-capacity base station): ZTE’s two high-capacity LTE base stations support both GSM and WCDMA. Multi-standard base station solutions are becoming an increasingly important vendor tool. Operators, with an eye to the future, want 2G and 3G solutions that can also support LTE. Infrastructure vendors are also eyeing their multi-standard solutions as a way of selling a network refresh at the time of LTE deployment.

■    GSM/WCDMA support (low-capacity base station): ZTE’s low-capacity LTE base station, ZXSDR BS8906, supports both GSM and WCDMA communications. This allows ZTE to take advantage of benefits coming from multi-standard support across its entire LTE base station portfolio.

■         CDMA2000 support: While not as common as GSM/WCDMA, some infrastructure vendors have multi-standard solutions that support CDMA2000 alongside LTE. The benefits of this multi-standard support are the same as with GSM and WCDMA.