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APPLICATION NOTE


Abstract Wireless broadband operators constantly face challenges of balancing the economics to deploy a robust and reliable wireless broadband service in suburban-rural areas or at cell-edges. Till to date, a large portion of these areas still remains hugely underserved or receiving unreliable coverage. Most available studies have shown that WiMAX is indeed an ideal technology candidate not only for a suburban-rural deployment, but as a wireless broadband technology on an overall, with most of the studies focusing on infrastructure performance. This paper in retrospect functions to further solidify the technological advantage of WiMAX, where we explore and proof the concept of suburban-rural deployment through the optimal pairing of a proper CPE strategy. We will show that the best solution for suburban-rural area and cell-edge performance can be extended four times through deployment via outdoor CPEs. This paper explores deep into the technical and implementation advantages of an outdoor CPE solution, including the concept of antenna gain, transmission power, integrated POE design and environment-proof enclosure; and the effective advantage of Line of Sight performance and decreased penetration loss amongst other features of an outdoor CPE. We will also explore the misconception behind the high incremental cost, difficulty of engineering installation and service challenges in operations with the implementation of an outdoor CPE which has been the lead culprit towards the low adoption of this CPE strategy. Greenpacket will share three reference cases where deployment through the OX series outdoor CPE has shown great success in Australia, Africa and Haiti, from a performance and business implementation perspective.

APPLICATION NOTE


Introduction One major challenge for wireless broadband operators is to successfully deploy in a suburban-rural morphology. This challenge is inherent with disregard of the type of wireless technologies implemented, be it through WiMAX, Satellite, 3G, CDMA and similarly in the future, with LTE. In our previous white paper “Improving Indoor Coverage: How WiMAX Modems can Play a Major Role in the Subsystem” (WPWIC10), we have described technologies to improve user experience when they are farther away from the base station, or in the cell-edge area. We can see that in general, cell-edge represents the area where poor consistency in connectivity is prevalent, with typical modulation being QPSK where cell-edge users generally experience low and in many cases, inconsistent throughput speeds.

Point A

Loss of uplink connection (1TX without MIMO and Beamforming)

Downlink

Point B 64-QAM

16-QAM

Loss of downlink connection (without MIMO and Beamforming)

QPSK A

B CD

Point C

Loss of downlink connection with MIMO A

64-QAM

16-QAM

QPSK

Point D

Loss of downlink connection with Beamforming

Uplink Legend

• uplink connection • downlink connection

Coverage cut off point

Figure 1 : UL and DL Modulation Relative to Cell Radius

The figure below represents a typical wireless cell that has a cell-center with radius ‘r’ and cell edge with a radius of ‘2r’. Tabulating the coverage area, the cell-edge would give us an area of coverage equivalent to 4πr², while the cell-center is only πr². Showing the distinct differences in coverage area achieved between the cell-edge and cell-center. This direct difference implies that the efficiency of spectrum utilization by the base station is not able to achieve its intended maximum coverage and capacity capability unless higher modulation scheme can be extended further into the cell-edge coverage area; without which, a decent robust connectivity is next to impossible by just relying on the base station itself. cell center

F1

cell edge

F

2r F F2

F

r

F3

APPLICATION NOTE

01


WiMAX As The Best Solution With Outdoor CPE Challenges For Rural Broadband Deployment Broadband penetration in rural areas across the world has lagged far behind than that in urban areas, both in developed countries as well as in developing countries. This is mainly due to multiple reasons which make providing coverage in these areas economically non-viable. The main reasons for this low penetration lie within the following TOP 3 roadblocks: • As population density in rural areas is relatively low, setting up and maintaining copper or fiber lines to provide broadband service across the “last mile” incurs high costs for Internet Service Providers (ISPs) • Capacity on the backhaul or the “middle mile” from the ISP to the Internet backbone is often very limited and expensive as it is provided over facilities designed for voice telephony or cable television • The difference in per capita income between rural areas and urban regions means that broadband services need to be offered at a lower-price point in the rural areas in order to gain customer adoption. This combination of high CAPEX/OPEX and low Average Revenue per User (ARPU) has traditionally made the rural broadband market less lucrative for service providers, but the advent of new high speed mobile broadband technologies such as WiMAX has rapidly changed the situation.

APPLICATION NOTE

02


WiMAX As The Ideal Solution For Rural Broadband Deployments As operators around the world evaluate multiple technologies for rural broadband deployments, WiMAX is emerging as the de-facto standard. The advantages offered by WiMAX have time and again proven its commercial viability, among others: • Infrastructure Effectiveness: WiMAX offers a highly cost effective solution to address the rural broadband conundrum as physical infrastructure need not be rolled out to individual customer premises on the last mile. This significantly reduces the overall cost and the time-to-market in deploying the network. • Flexible Network Deployment: WiMAX allows operators to surgically choose deployment options and focus on specific areas where there is strong demand. • High Data Throughput: 802.16e has reached a stage of technology and standards maturity with field proven results that shows data throughput of over 40Mbps (@10MHz channel bandwidth). • Spectrum Concerns: WiMAX spectrum has typically been less expensive worldwide as compared to 3G licenses. Additionally, with mobile WiMAX being on licensed band, operators can deploy rural broadband networks with no spectrum-related concerns. The largest challenge facing operators in deploying a suburban/rural service is to create a balanced business case that allows them to maximize the access infrastructure capability from a coverage and capacity perspective and at the same time to deliver a robust and reliable service with a positive revenue return. Greenpacket believes that this can be realized effectively if ‘Line Of Sight’ (LOS) can be achieved through the pairing of Outdoor CPE to the network, where we will investigate the technology, performance and reveal a detailed deep dive reference case study based on a suburban/rural environment profile.

APPLICATION NOTE

03


Advantages Of Outdoor CPE The right CPE strategy for cell-edge and suburban/rural area is to deploy Outdoor CPE, and from our experience, outdoor CPE have the following advantages. i. Improved Uplink Technologies ii. High Transmission Power And High Gain Directional Antenna iii. Zero Penetration Loss iv. Further Improvements Due To Line Of Sight v. When Compared To External Antenna Option, Minimal Cable Loss vi. Environmentally Robust vii. Easy Installation viii. Plug And Play

(i) Improved Uplink Technologies We have stated a comprehensive analysis of the importance of uplink technologies in our previous white paper “A Practical Approach to Improve WiMAX Indoor Coverage.” Here, we briefly describe the most important technology Dual transmitter (2TX) which is implemented in our OX series Outdoor CPE. Dual Transmitter (2Tx) (CDD) The simplest Dual Transmitter technology employs Cyclic Delay Diversity (CDD) algorithm and signals are transmitted via a single data stream through two antennas and two power amplifiers – hence, both antennas are switched on and used for transmission. The combined power from two PAs provides approximately an additional perceived 3dB gain with potentially lower power consumption (if PA’s are tuned to a lower power). This arrangement improves uplink performance and lengthens coverage through better signal strength; however, it increases the cost of the modem as more components are used. Dual Transmitter (2Tx) STC Matrix (Uplink MIMO A) The second generation Dual Transmitter technology further employs Space Time Coding signaling algorithm (Uplink MIMO A) instead of just (CDD) algorithm as previously mentioned. However, in order to support this new algorithm, base stations need to be upgraded to support WiMAX R1.5. The hardware implementation is the same as Dual Transmitter (CDD) where transmission is conducted through two antennas and two power amplifiers. The combined power from two PAs provides approximately an additional perceived 4dB gain, which is better than the Dual Transmitter (CDD).

Antenna 2 PA Baseband

RF PA Antenna 1

Figure 2: Dual Transmitter (2Tx) component arrangement for CDD or STC

APPLICATION NOTE

04


(ii) High Transmission Power And High Gain Directional Antenna Comparatively, Outdoor CPEs are designed with higher maximum transmit EIRP. Greenpacket OX series Outdoor CPE has a 14dBi antenna, Dual transmitters (2Tx) with a combined Tx power rated at 27dBm, thus a maximum transmit EIRP equivalent to 41dBm, making it the most powerful mobile WiMAX CPE in the market today. Directional antenna is conventionally implemented to optimize the antenna performance specifically aligned to face towards the base station. Different from an indoor or USB based device, operator will normally assign service engineers to the premise where installation is based on the optimum facing direction and upon locating it, the outdoor antenna is locked into place. Figure 3 shows a sample antenna pattern for the 2.5GHz model. The diagram shows a concentrated RF energy radiated in a single direction (+- 10 degrees within the pink line). This specific radiation pattern plays the highest role of effectively increasing the coverage area.

Figure 3: Antenna patterns for OX250 main antenna

5dB improvement

USB dongles Average 23dBm 2dBi Antenna

11dB improvement

Indoor CPE Average 25dBm 5dBi Antenna

Outdooe CPE (OX series) Average 27dBm (2Ti) 14dBi Antenna

Figure 4 : Improvements of Outdoor CPE over indoor CPE. We can see that OX series can have 16dB improvements from indoor USB dongles

APPLICATION NOTE

05


(iii) Zero Penetration Loss Throughout our deployment experience, depending on the depth and material of the building, Glass windows and concrete walls induces a 6dB and 12dB penetration loss respectively where the implementation through indoor CPEs will normally endure. An Outdoor CPE, being placed normally on the roof of a specific building has the advantage of being subjected to zero penetration loss, even without line-of-sight (LOS).

Figure 5: Frequency Vs Depth of penetration (Pd) for representative profiles of clay soils of pune at different soil moisture

conditions (weight %)

(iv) Further Improvements With Line Of Sight (LOS) The key advantage for Outdoor CPE is that it can easily achieve Line of Sight (LOS) with proper mounting. Having achieved Line of Sight (LOS), there is no longer a multi-path problem and we can ensure optimal RF path between the CPE and the base station. Figure 6 shows how Line of Sight can be achieved by moving the CPE above the roof with a pole.

LOS CPE (OutDoor)

NLOS CPE (InDoor) Figure 6: Improvement of LOS with o utdoor CPE

In addition, studies show that for a full featured base station. To achieve the same transmission data rate of 11Mbps, LOS cell radius can be as far as 30km, while Non Line of Sight (NLOS) cell radius is only limited to 4km. This accounts for five times the radius or about 25 times more coverage area for the same base station. LOS is a very critical factor that affects the performance of the network, where an Outdoor CPE is proven to be the ideal solutions to achieve LOS.

APPLICATION NOTE

06


Full Featured From To Cell radius (Km)

Maximum throghput per sector (Mbps) Maximum throghput per CPE at Cell Edge (Mbps)

LOS

30

50

NLOS ( Ereg-Flat)

4

9

Indoor self-install CPE

1

2

Download

11.3

8

uplink

11.3

8

Download

11.3

8

0.7

0.175

uplink

Maximum number of subscribers

More

Table 1: LOS and NLOS performance comparison using Full featured Base Station

LOS 30 to 50km NLOS 4 to 9km Indoor self-install 1 to 2km

Figure 7 : Coverage Distance Differerence for LOS and NLOS deployment

(v) Outdoor CPE VS Indoor CPE + External Antenna: Minimal Cable Loss Another common solution to achieve LOS performance is to use outdoor external antenna to connect to an indoor CPE. However, using external antenna introduces cable losses. For example, we can see in the below diagram, a typical cable used for external antenna is RG316, which introduces about 1.5dB loss per meter length. Therefore, for an outdoor extension of 10m, this contributes to 15dB loss, which has similar magnitude as the typical outdoor external Antenna gain. This limitation is not absolute, where external antenna solutions with super high gain (greater than 15dBi) and super low loss cable (less than 0.5dB/m) can be found, the question is however extended to economic sense of forming a realistic solution rather than the best solution.

APPLICATION NOTE

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(vi) Outdoor CPE VS Indoor CPE + External Antenna: Minimal Cable Loss Another common solution to achieve LOS performance is to use outdoor external antenna to connect to an indoor CPE. However, using external antenna introduces cable losses. For example, we can see in the below diagram, a typical cable used for external antenna is RG316, which introduces about 1.5dB loss per meter length. Therefore, for an outdoor extension of 10m, this contributes to 15dB loss, which has similar magnitude as the typical outdoor external Antenna gain. This limitation is not absolute, where external antenna solutions with super high gain (greater than 15dBi) and super low loss cable (less than 0.5dB/m) can be found, the question is however extended to economic sense of forming a realistic solution rather than the best solution. Coaxial Cable :RG_316_/U Matrix Of Attenuation and Power CW Coefficients: a=0.7727 , b=0.0972 , Fmax =3 , Pwt 1GHz = 135 Frequency (GHz)

Nom attenuation (dB/m) sea level 25˚ C amblent temperature

Nom attenuation

Max. CW power

sea level 25˚ C amblent temperature

sea level 40˚ C amblent temperature

2.1 2.3 2.4 2.6 2.7 2.9 3.0

1.32 1.40 1.43 1.50 1.53 1.60 1.63

0.402 0.427 0.436 0.457 0.466 0.488 0.497

93 89 87 84 82 82 78

(dB/ft)

(watt)

Table 2 : Typical cable loss for Coaxial RG316 cable which is used for external antenna

Indoor CPE

Indoor CPE with external Ant

Outdoor CPE

Antenna Gain

5dBi

Not used

Not used

Cable Loss (RG316) External antenna

0 None

-9dB 14dBi

0 None

Penetration Loss Total Ant gain

-6dB -1dB

None 5dB

None 14dB

Line of Sight Performance

NO Poor

YES OK

YES Best

Table 3 : Comparison between a 2.5GHz Indoor CPE with and without a 14dBi external antenna, and a 2.5GHz Outdoor CPE mounted on a pole 6m above the ground

APPLICATION NOTE

08


Uncover The Myth about Outdoor CPE There exist general misconceptions about outdoor CPE implementation in terms of cost, having extreme restriction on being heavy, performing unreliably under changing weather conditions, and extremely difficult to install and service. New advancement on design and architecture has changed all this, Greenpacket’s OX series outdoor CPE is an example where cost is effectively affordable, weighing in at less than 2kg, flexibly mountable on a wall or pole or roof edge and capable of enduring temperatures between - 40°C ~ 60°C while in operations. Most importantly, OX series enclosure is certified to be IP67 compliant which comes with a protection against the effects of immersion in water up to depth of 1 meter. POE (Power over Ethernet) cable is also an important feature which ensures that only a single cable (RJ45) is stretched from the outdoor unit (ODU) directly indoors to the end user, where both the power and data is carried.

(i) Environmentally Robust In addition, OX series outdoor CPE is equipped with a robust mounting kit which has been certified to withstand severe windward and crosswinds. Figure 8 show the test result for OX series outdoor CPE withstanding hurricane rated winds (windward/crosswind under 60m/s for 10 minutes, Beauford Wind Force Scale 17)

Figure 8 : Greenpacket OX series under Hurricane-force Winward Test

APPLICATION NOTE

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(ii) Easy Installation OX series outdoor CPE mounting kit provides complete flexibility for installation. The pole-mounting and wall-mounting brackets can be selected according to field needs. The multi-angle mounting kit can also be adjusted where the antenna can be positioned to face toward the base station, receiving Line-of-Sight (LOS) signals. Figure 8 illustrates the quick installation using the standard mounting kit, withal done within five minutes.

Screw (35mm) Screw (60mm) Split washer

Lockwasher

Flat washer Bracket with Tab Bracket W/L Tab

Split washer Flat washer Nut

Nut

X2 Needed

Figure 9 : Examples of Pole Mount (vertical or horizontal) installation

(iii) Plug And Play, Auto Provisioning, And On-Site Service Free Greenpacket ensures that operators are free from having to manage the provisioning of devices. The device comes pre-provisioned to allow end subscribers to plug and be automatically connected to the operator’s base stations for an immediate play.

APPLICATION NOTE

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The Rural Leapfrog – ENDING THE WAIT FOR RURAL CONNECTIVITY Verifying It On The Field Understanding the concept and technological advantage of mobile WiMAX coupled with the service offering via an Outdoor Modem validates it as a viable solution option for rural connectivity. The bigger question remains on the performance capability of the WiMAX outdoor modem when deployed in a commercial field that is subjected to subscriber loading and the environmental uncertainties knowing historically the inherent limitation of implementation via a wireless technology. Vivid Wireless, is the first WISP to launch a mobile WiMAX network in Australia has had a successful service uptake since its launch in April 2010 covering the urban and suburban areas in cities of Perth, Sydney and Melbourne via Indoor IADs and USB modem. Looking to extend its service coverage to the fringing suburban and semi-rural areas within the city, Vivid Wireless conducted a citywide evaluation to benchmark the performance of the OX outdoor modem. Vivid Wireless wanted the performance test to be conducted on its commercially live network to ensure that the end results obtained is strictly similar to the end user experience. Choosing to compare it against the current commercially offered Green Packet high gain DX Indoor IAD, Vivid Wireless has the objective:1. To ensuring that the OX meets the technical specification as stated in its product datasheet. 2. To record the additional gain in coverage, and 3. To record the throughput speeds experienced

DX 230-Indoor IAD

OX 230-Outdoor Modem

Frequency

2.3GHz

2.3GHz

Maximum RF Transmit Power

28dBm (Combined 2Tx)

27dBm (Combined 2Tx)

Antenna Type

Intergrated Omni with 5dBi gain

Dual polarized with 14dBi gain

Received sensitivity

Average 5dB higher than WiMAX Forum RCT specification

Average 5dB higher than WiMAX Forum RCT Specification

MIMO

Matrix A & B

Matrix A & B

Table 4 : Technical Specification between Indoor IAD and Outdoor Modem

DX230 was mounted inside the test drive vehicle on the passenger seat while the OX230 is mounted on the roof of the car. Both RSSI and CINR measurement were recorded in both line-of-sight (LOS) and non-line-of-sight (NLOS) positions. The test drive was performed at multiple locations that varied between 200 meters and 9.5 kilometers to the base station.

APPLICATION NOTE

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Purple shade represents existing network coverage area Green shade indicates increased coveage area when using OX230 modem

Figure 10 : Coverage planning comparison between Indoor IAD and Outdoor Modem

On completion, Vivid Wireless observed significant performance increase from the OX outdoor modem with the OX having an average 12dBm more coverage, reaching a radius of over 9.5 kilometer with LOS. Proving that OX meets the specification as stipulated even on the field. This significant coverage gained will allow Vivid access to an additional 72,000 new subscribers on its existing infrastructure, allowing it to maximize and monetize its infrastructure investment further. DX 230-Indoor IAD

OX 230-Outdoor Modem

Indoor / Outdoor (Delta)

LOS

Distance to Cell (m)

RSSI (dBm)

CINR (dBm)

RSSI (dBm)

CINR (dBm)

RSSI (dBm)

CINR (dBm)

Yes

250

-43

26.6

-32

26.4

11

-0.2

No

840

-60.5

24.4

-52.1

19.5

8.4

-4.9

No

1100

-64

10.9

-50.3

20.3

13.7

9.4

No

1900

-84

8.1

-74

7.6

10

-0.5

Yes

2870

-54.6

9.7

-37.1

14.7

17.5

5

Yes

6400

-51

11.1

-41

8.3

10

-2.8

Yes

9500

-80.6

6.2

-64.5

4.7

16.1

-1.5

Table 5 : Summary test result comparison between Indoor IAD and Outdoor Modem

Numerous operators globally have had commercially successful deployments through similar strategies. Greenpacket approaches most of its deployment together with the operator in a collaborative manner, seeing multiple successful deployments in suburban and rural scenarios.

APPLICATION NOTE

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Reaching Within Remote Africa Direct-on-PC, a the leading operator in Nigeria has been deploying mobile WiMAX under the service name of Unwired by extending its wireless broadband voice and data services covering sub-urban and rural developing communities in selective areas of Lagos, Abuja and Port-Harcourt as a complimentary broadband access network to their existing VSAT and fixed wireless networks. The flexibility of mobile WiMAX has allowed the operator to grow its service coverage area flexibly as service demand grows. The strategy of service implementation via outdoor based CPE creates the best service advantage as it allows maximization of coverage making the service robust and reliable, perfect to the harsh conditions of the West African nation. With mobile WiMAX having the capacity efficiency that is 10x higher with an upfront subscriber acquisition cost that is 1/5 of current satellite network, the business case of providing affordable voice and broadband service is achievable. This has created confidence that the 4G network plans is set to lay the foundation for growth, both for the company and to the development of the underserved market.

Bringing Broadband To The Remote Islands The islands of the Caribbean are a well known holiday destination with a developing community and economy. Providing broadband services in islands with harsh environmental terrain has always been a challenge to service providers. Digicel International has been the champion serving over 11 million customers across 32 markets mainly on the islands of the Caribbean and the Pacific. Having launched mobile WiMAX in Haiti, Digicel has had a great success with its pay-as-you surf mobile WiMAX services in suburban areas of Haiti currently providing robust fast broadband services through Greenpacket indoor and USB based devices. Looking to extend the services offering in rural and remote areas, with the service quality having similar robustness is something that Digicel insist to maintain, in order to achieve this while not having to incur huge incremental CAPEX investment by deploying additional infrastructure to these subscribers located mainly in fringing cell edge of the network. The outdoor modem was evaluated and results has proved to be the perfect solution extending the coverage within a healthy modulation scheme to achieve broadband speeds and consistent service. Even with a higher subscriber acquisition cost via the outdoor modem implementation, the huge CAPEX/OPEX savings from infrastructure spending allows Digicel to scale the deployment needs with the number of subscription growth.

APPLICATION NOTE

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Explore A Blue Ocean Of Opportunity In Rural Connectivity Today As a leading developer of Next Generation Mobile Broadband solutions, Greenpacket has both the experience and best in class 4G WiMAX devices specifically designed for operators looking to maximize their investment in delivering a robust, reliable and fast 4G broadband for RURAL CONNECTIVITY.

Free Consultation If you would like a free consultation on selecting WiMAX modems for your fixed broadband network, please contact us at marketing.gp@greenpacket.com (kindly quote the reference code, DAP0411 when you contact us).

APPLICATION NOTE

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References 1. IRIX123 User Manual, Greenpacket 2. WiMAX’s technology for LOS and NLOS environments, WiMAX Forum Release 3. OX Series User Manual, Greenpacket 4. OX250 Antenna report, Greenpacket 5. Datasheet for Coaxial cable RG316, Huber + Suhner 6. K.S.Rao, Girish Chandra and P.V.Narasimha Rao, Study on penetration depth and its dependence on frequency, soil moisture, texture and temperature in the context of microwave remote sensing 7. http://www.itu.int/newsarchive/press/WTDC98/Feature1.html 8. http://it.tmcnet.com/topics/it/articles/36595-internet-usage-gaps-developing-countries-challenges-solutions.htm

APPLICATION NOTE

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About Greenpacket Greenpacket is the international arm of the Green Packet Berhad group of companies which is listed on the Main Board of the Malaysian Bourse. Founded in San Francisco’s Silicon Valley in 2000 and now headquartered in Kuala Lumpur, Malaysia, Greenpacket has a presence in 9 countries and is continuously expanding to be near its customers and in readiness for new markets. We are a leading developer of Next Generation Mobile Broadband and Networking Solutions for Telecommunications Operators across the globe. Our mission is to provide seamless and unified platforms for the delivery of user-centric multimedia communications services regardless of the nature and availability of backbone infrastructures. At Greenpacket, we pride ourselves on being constantly at the forefront of technology. Our leading carrier-grade solutions and award-winning consumer devices help Telecommunications Operators open new avenues, meet new demands, and enrich the lifestyles of their subscribers, while forging new relationships. We see a future of limitless freedom in wireless communications and continuously commit to meeting the needs of our customers with leading edge solutions. With product development centers in USA, Shanghai, and Taiwan, we are on the cutting edge of new developments in 4G (particularly WiMAX and LTE), as well as in software advancement. Our leadership position in the Telco industry is further enhanced by our strategic alliances with leading industry players. Additionally, our award-winning WiMAX modems have successfully completed interoperability tests with major WiMAX players and are being used by the world’s largest WiMAX Operators. We are also the leading carrier solutions provider in APAC catering to both 4G and 3G networks and aim to be No. 1 globally by the end of 2010. For more information, visit: www.greenpacket.com.

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Wimax Outdoor CPE for Suburban or Rural Deployment - GreenPacket Wimax Modems