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Application Experiment Ground Station Guidelines

November 27, 2006

Application Experiment Ground Station Guidelines (Nov. 27, 2006) i

Introduction These "Application Experiment Ground Station Guidelines" provide information on

the requirements of the earth station equipment for WINDS and may help in the preparation of experiment proposals. [Note] ABOUT UPDATES TO THIS PAPER

Some of the WINDS specifications are presented here as a reference only, and are subject to change as the WINDS design matures in the future. Any updates will be incorporated as necessary.

Application Experiment Ground Station Guidelines (Nov. 27, 2006) ii

Table of contents 1. Outline of WINDS 1

2. Network configuration using WINDS 2

2.1 ATM baseband switching mode 2

2.2 Bent-pipe TDMA mode 3

3. Terminal types and examples of link budget 5

3.1 Types of user terminals 5

3.2 Examples of link budget 6

4. Hardware requirement of user terminal 11

4.1 Functions of user terminal 11

4.2 Performance of RF equipment 13

4.3 Performance of baseband equipment [TBD] *

5. Outline of protocols 16

5.1 ATM baseband switching mode 16

5.2 Bent-pipe TDMA mode [TBD] *

6. Additional information 20

6.1 Examples of improvement of TCP performance 20

6.2 Issues of international frequency coordination 20

6.3 Requirements for common frequency usage with Fixed Wireless Access (FWA) systems 20

7. Example of development of prototype earth station 22

[Terminology] 24

* To be added in the revised edition.

Application Experiment Ground Station Guidelines (Nov. 27, 2006) 1

1. Outline of WINDS WINDS (Wideband InterNetworking engineering test and Demonstration Satellite) is an experimental

satellite enables communications at significantly higher data rates. The satellite employs very

advanced technologies described below in order to realize both very high data rate transmissions and

advanced broadband satellite networking.

1) Fixed multi-beam antenna (MBA) and Ka-band multi-port amplifier (MPA)

Japan and several areas in Southeast Asia are covered by MBA spot-beams. The MBA can

generate a narrow beam width (spot beam) to concentrate the energy of the transmitted and

received radio wave, and provide a required functions for high data rate satellite communications.

The MPA, used with MBA, amplifies the transmitting power of several channels (maximum 8ch)

simultaneously, and can allocate power for each channel arbitrarily. For the Ka band, it enables the

allocation of power to areas specified in the experiment plan to compensate for a significant

attenuation that may be caused by rainfall.

2) Ka-band active-phased array antenna (APAA)

The APAA antenna can steer beams electronically within +/-7 degrees in the north-south direction or

+/-8 degrees in the east-west direction from the sub-satellite point with a beam, and generate two

beams simultaneously. Areas not covered by MBA can access WINDS using the APAA. The

performance (EIRP, G/T) of the APAA is less than that of the MBA, so larger earth stations are

required for APAA access than for MBA access.

3) Onboard Switching Router(ABS : ATM Baseband Switch)

The ABS receives the data bursts sent by users, demodulates them, redirects them by destination

address attached in a header of the ATM cell, and transmits them to the destination user. Because

the ATM cells to be sent to the same beam are multiplexed in a downlink, the transmission power of

the satellite transponder can be used efficiently and layer 2 routing is performed at the same time.

4) Very Wide Bandwidth Transponder

The ABS can be bypassed in the WINDS transponder, which is called the "Bent-pipe TDMA Mode".

In this case, the full bandwidth transponder of 1.1GHz can be utilized. The users' data bursts are not

be demodulated onboard, but satellite switching can be performed by switching the IF-Switch in

satellite switched time division multiple access manner. (SS-TDMA)

Due to the advanced technologies described above, WINDS provides superb communications

capability in a variety of networking configurations, such as:

- Mesh type networking connecting many sites at high data rates (max. 1.5-155Mbps) and carrying

multimedia contents.

- Mesh or star type networking connecting several sites at very high data rates (1.2Gbps).


* Remarks

Although WINDS provides very high data transmission rates, high throughput is not achieved in some

cases of Internet use. It degrades Transmission Control Protocol (TCP) performance, but the

degradation can be avoided by using TCP extension or Performance Enhancing Proxy (PEP)

technology. Information regarding this issue is described in section 6.1 (2).

2. Network Configuration with WINDS 2.1 ATM baseband switching mode 2.1.1 Topology of connection

Figure.2-1 shows the connection topology in when the ATM baseband switching mode is used.

Here, each user terminal is logically connected to the ABS onboard the WINDS. The ABS

demodulates signals from user terminals, identifies the header of cells, and transfers association

cells and traffic data cells to the Network Management Center (NMC) and to destination user

terminals, respectively.

When user stations communicate with one another, first they are given an assignment of time slots

on a traffic link (data link) between them by means of a signaling link, and then transfer data

between them on the assigned time slots.

The signaling slot is pre-assigned for area, so the user terminal should use the assigned slot in the

area where the terminal is located. The association data must employ ATM layer protocol which the

ABS can treat, and SAAL protocol which the NMC employs.

Traffic data should be formatted as ATM cells which the ABS can treat, but upper layer protocols

are not specified by the WINDS network itself.

2.1.2 Information transmission capacity

In the ATM baseband switching mode, the information transmission capacity depends on the

performance of an ABS modulator/demodulator installed in WINDS, the transmission/reception

performance of a transponder in WINDS, and the transmission/reception performance of an earth

station. In the case of communication within Japan, the scale of an earth station to accommodate

the maximum information transmission rates of an uplink and a downlink will be described below:

a) Uplink

1.5 / 6 Mbps: Compact small terminal which can be installed at home (USAT)

24 / 51 Mbps: VSAT which can be installed in schools and SOHOs (1~2mø:HDR-VSAT), or

larger terminals (2~3mø: SDR-VSAT，≥5mø:LET)

155 Mbps: HDR-VSAT, SDR-VSAT or LET which can transmit three 51 Mbps signals.

b) Downlink

155 Mbps: All user terminals described in the uplink section.


Figure.2-1 Topology of connection in the ATM baseband switching mode

2.2 Bent-pipe TDMA mode

The bent-pipe mode enables TDMA or CW (continuous-wave) operations. The topology of

connection and the information transmission capacity by means of TDMA will be described below:

2.2.1 Topology of connection

Fig.2-2 shows the topology of connection in the bent-pipe mode. Each user terminal connects to

the destination user terminals through WINDS in this mode.

In this mode, unlike the ATM baseband switching mode, the physical link (time slot) is assigned by

the pre-assignment system by which each user station is given an assignment of time slots used

for data transmission in advance in the planning stage of experiment. Each user station acquires

information on its slot assignment and timing of transmission/reception by receiving and

demodulating notifications distributed from the NMC via WINDS.

2.2.2 Information transmission capacity

Data transmission capacity in this mode depends on the performance of the WINDS transponder

and the performance of earth terminals. The WINDS project aims at realizing higher data rates via

satellite than existing satellite communications systems. Therefore, 622Mbps is a basic

transmission rate in the WINDS network in the bent-pipe mode, and is achieved when a physical

link is established by one earth terminal. Double linking achieves transmission rate of 1.2Gbps.

ABS

WINDS

NMC ODU

IDU Terminal

ODU

IDU External

network

Connecting to other AS

TDMA slot assignment and other link control

(NMC: Network Management Center) User in the WINDS network

Traffic link

Signaling link

Router


(The technical challenge of achieving 1.2Gbps with single channel is now under study.) The

information necessary for setting a link is distributed as a notification to each user at a transmission

rate of 155Mbps. It is necessary to demodulate the notification information for TDMA

communication by means of the bent-pipe mode.

To achieve the above-mentioned transmission rate, basically an earth station (SDR-VSAT or LET)

of a scale of at least 2-3mø is necessary within Japan.

Figure. 2-2 Topology of connection in the bent-pipe TDMA mode

SW Matrix

WINDS

NMC ODU

IDU Terminal

ODU

IDU External

network

Connecting to another AS

TDMA slot assignment and another link control

(NMC: Network Management Center) User in the WINDS network

Traffic link

Signaling link

Router

Application Experiment Ground Station Guidelines (Nov. 27, 2006)

5

3. Terminal types and examples of link budget

3.1 Types of user terminals

The following table shows specified user terminal types for WINDS experiments.

Table 3-1 User terminal types for WINDS experiments

Type Description Applicable

operation mode

Maximum information rate

in uplink *1

Maximum information

rate in downlink

MBA1

MBA2

*2

APAA

*3

USAT ・Mini earth station that can be installed home

ATM baseband switching 1.5/6Mbps 155Mbps ○ △ ×

HDR-VSAT ・Small earth station that can be installed in schools, SOHO, etc.

ATM baseband switching

1.5/6/24/51/ 155(51 x 3ch)Mbps *4 155Mbps ○ △ △

ATM baseband

switching

1.5/6/24/51Mbps

155(51 x 3ch)Mbps *4 155Mbps ○ ○ ○

SDR-VSAT ・Medium size terminal for corporate

use Bent-pipe 622Mbps 622Mbps ○ △ △

ATM baseband

switching

1.5/6/24/51Mbps

155(51 x 3ch)Mbps *4 155 Mbps ○ ○ ○

LET

・Large scale terminal for installation

in large enterprises and research

organizations. Bent-pipe 622Mbps

1.2Gbps(622M x 2ch)

622Mbps

1.2Gbps (622M x 2ch) ○ △ △

△： This can be used subject to conditions. *1 In the case of ATM baseband switching, 1.5Mbps is needed for a signaling link, and, for a traffic link, any one of 1.5, 6, 24, 51 and 51 x 3 Mbps is used. *2 Assumed link availability is 98 %. Higher link availability requires a higher EIRP and G/T for the user terminal. *3 Because APAA's EIRP and G/T are smaller than those of MBAs, the G/T and EIRP of the user terminal should have a larger than those of MBAs. In

addition, the required EIRP and G/T differ slightly by area and location of earth terminal. *4 155Mbps (Uplink) requires 3 channels use of 51Mbps.


3.2 Examples of link budget

Typical link budget calculations are shown in this section. Because rain attenuation depends on

the location of the earth station, these calculations are based on a clear sky condition. When

downlink rain attenuation occurs, increased noise temperature affecting the earth stations must be

considered for correct calculations. 1) ATM baseband switching link for USAT in MBA1 coverage（1.5／155Mbps）

Area Hokkaido East Beam (Nemuro)

Item unit uplink downlink

Freq. GHz 28.05 18.25

EIRP dBW 41.8 USAT 64.4 MBA1

Pointing Loss dB Included in EIRP

Free Space Loss dB -212.9 -209.2

Polarization Loss dB -0.2 -0.2

Absorption Loss dB -0.4 -0.2

Rain attenuation dB

Pointing Loss dB Included in G/T

G/T dB/K 17.7 MBA1 11.5 USAT

Rx C/No dB･Hz 74.6 94.9

Total C/No dB･Hz 74.6 94.9

Required C/No dB･Hz 73.6 93.9

Margin dB 1.0 1.0

Modulation QPSK QPSK

Required Eb/No dB 7.3 BER：5×10-4 7.3 BER：5×10-4

Transmission

Degradation dB -2.7 -3.5

Bit rate * dB･Hz 63.6 2.3Mbps 83.1 204Mbps


* Actual bit rate becomes larger than the information bit rate because preamble, error correction code

and other redundant parts are added to the information bits to form a burst format.


2) ATM baseband switching link for HDR-VSAT in MBA1 coverage（51／155Mbps）



Freq. GHz 28.05 18.25

EIRP dBW 57.4* VSAT 57.5 MBA1

Pointing Loss dB -0.5 Included in EIRP




Rain attenuation dB

Pointing Loss dB Included in G/T -0.5

G/T dB/K 17.7 MBA1 19.0 VSAT

Rx C/No dB･Hz 89.7 94.9



Margin dB 1.0 1.0



Transmission


Bit rate dB･Hz 78.7 74Mbps 83.1 204Mbps

Required C/No* dB･Hz 88.7 93.9

* In case of 51Mbps×3（＝155Mbps）uplink, 4.8dB should be added.


3) ATM baseband switching link for HDR-VSAT in MBA2 coverage (51／155Mbps)

Area Manila


Freq. GHz 28.05 18.25

EIRP dBW 55.7* VSAT 57.1 MBA2

Pointing Loss dB -0.5 Included in EIRP




Rain attenuation dB

Pointing Loss dB Included in G/T -0.5

G/T dB/K 19.0 MBA2 19.0 VSAT

Rx C/No dB･Hz 89.7 94.9



Margin dB 1.0 1.0



Transmission


Bit rate* dB･Hz 78.7 74Mbps 83.1 204Mbps

Required C/No* dB･Hz 88.7 93.9* In case of 51Mbps×3（＝155Mbps）uplink, 4.8dB should be added.


4) Bent-pipe link for SDR-VSAT in MBA1 coverage (622 Mbps)


Item unit Uplink downlink

Freq. GHz 28.05 18.25

EIRP dBW 72.6 SDR-VSAT 65.2 MBA1

Power Allocation Loss dB

Pointing Loss dB -0.5




Rain Attenuation dB

Pointing Loss dB -0.5

G/T dB/K 17.7 MBA1 24.5 SDR-VSAT

Rx C/No dB･Hz 104.9 Included in MBA 108.1

Total C/No dB･Hz 103.2

Required C/No dB･Hz 100.2

Margin dB 3.0

Modulation QPSK

Required Eb/No dB 7.3 BER：5 x 10-4

Transmission

Degradation dB -4.0

Bit Rate dB･Hz 88.9 782Mbps



5) Bent-pipe link for LET in APAA coverage (622 Mbps)

Area Sydney (1 beam operation)


Freq. GHz 28.05 18.25

EIRP dBW 80.1 LET 55.3 APAA

Pointing Loss dB -0.5 -0.9




Rain Attenuation dB

Pointing Loss dB -0.9 -0.5

G/T dB/K 8.7 APAA 34.1 LET

Rx C/No dB･Hz 102.7 107.1

Total C/No dB･Hz 101.4


Margin dB 1.1

Modulation QPSK

Required Eb/No dB 7.3 BER：5×10-4

Transmission

degradation dB -4.0

Bit Rate dB･Hz 88.9 782Mbps



4. Requirements for user terminal The following sections describe requirements for user terminals used in the WINDS experiments. 4.1 Functions of user terminal 4.1.1 TDMA synchronization function

All user terminals should have a TDMA synchronization function by receiving reference burst sent

from WINDS. See section 5 for TDMA format and synchronization method.

4.1.2 Signaling functions

The user terminals needs to have the function of receiving a response as information on available

traffic slots to an association request by sending the request on signaling slots and receiving

reference busts from the MNC to acquire traffic slots for data transmission when it starts

communication. (Demand-assignment system)

For the bent-pipe mode, the pre-assignment system is used where slots are assigned in advance.

4.1.3 RF signal transmission functions

The user terminal should send a burst signal in a signaling slot or assigned traffic slots of assigned

frequency channel in the Ka-band.

For the uplink frequency for an association request, any frequency in the frequency channel

assigned to a beam for the earth station should be used; and for traffic bursts, the frequency

assigned in a response to an association request should be used. (Both in the 27GHz band)

The earth station should have the functions of coding, modulating and transmitting an association

request on signaling slots and transmission data on traffic slots.

1) Burst format

See section 5.

2) Transmission scheme

a) Modulation: QPSK

（not specified for traffic burst in bent-pipe TDMA mode)

b) Error correction: Reed-Solomon Code RS(255, 223)


3) Transmission power control function (TPC function)

The user terminal should have the functions of estimating rain attenuation from the level of

reception of reference burst signals transmitted from WINDS and automatically controlling the

transmission power according to the estimates. For the bent-pipe mode, these functions are

preferable. For the estimation of rain attenuation on downlink, signals for a Ka band telemetry

link, described in 4.1.5, can be used.


4) Automatic Frequency Control (AFC) Function

The user terminal should provide control of the assigned transmitting frequency.

4.1.4 RF Signal reception function

The user terminal should receive, demodulate and decode reference bursts transmitted on

signaling slots, and traffic burst signals for its area. It should also identify an ATM cell header in the

decoded signals to extract the data addressed to it. Down link frequency is 18GHz band.

1) Burst format

See section 5.

2) Transmission scheme

a) Modulation： QPSK


b) Error correction： Reed-Solomon Code RS(255, 223)


4.1.5 Satellite tracking function (this applies only to SDR-VSAT and LET)

The earth station should be capable of tracking the WINDS satellite by using the residual carrier of

signals for a Ka band telemetry link transmitted from the satellite. (The Ka band telemetry link is a

separate link provided for the monitoring of the state of mission equipment onboard satellite.)

The specifications for signals for the Ka band telemetry link (downlink) are as follows.

a) Frequency: 18.9GHz band

b) Transmission EIRP: 17.2dBW (θ < 6deg.), 15.7dBW (θ < 8deg.)

*θ is an angle of the earth station to the subsatellite point as zero

degree (a half of the vertex angle at the satellite).

c) Polarization: RHCP

d) Modulation: PCM (NRZ-L)/PSK/PM

e) Sub-carrier frequency: 40 KHz

f) Modulation depth : 1.1rad ± 10％ or less

g) Data rate of information: 10kbps

4.1.6 Base-band interface function

The user terminal needs to have a base-band interface with the equipment, such as data terminals

and routers, that the user uses. This function depends on the equipment that the user uses, so the

user is required to confirm the specifications and performance by itself.


4.2 Specifications of RF equipment

Table 4-1 shows the specifications of the RF part of the earth station. Fig. 4-1 shows the

transmission and reception frequencies (provisionally specified).

UPLINK27.537

27.592527.648 27.722

27.777527.833 27.907

27.962528.018

28.33 BCN28.75

PIL28.8

NIL28.9

275MHz 270MHz37MHz

55.5MHz

55.5MHz

74MHz

55.5MHz

55.5MHz

74MHz

55.5MHz

55.5MHz

37MHz

11.5625MHz

11.5625MHz

32.375MHz

2.3125MHz

NIL18.917.7925 17.9775 18.1625 18.53

270MHz

367.5MHz

92.5MHz

185MHz

185MHz

DOWNLINK

1.5Mbps再生中継回線

6、24、51Mbps再生中継回線

155Mbps再生中継回線

622Mbps非再生中継回線

Figure. 4-1 Transmission/reception frequencies (provisionally specified)

Ka telecommand

1.5 Mbps ATM baseband switching link

6, 24 or 51 Mbps ATM baseband switching link

155 Mbps ATM baseband switching link

622 Mbps bent-pipe TDMA link

Ka telemetry


14

Table 4-1 Specifications of RF User Terminal Equipment

USAT HDR-VSAT SDR-VSAT LET

Transmitting frequency 27GHz band (tentative)

Stability of transmitting frequency ≤1×10-7 ≤1×10-7 ≤1×10-7 ≤1×10-7

Receiving frequency 18GHz band (tentative)

EIRP (linear operation) ≥ 48.8dBW *1 ≥ 66.9dBW *2 ≥ 75.4dBW ≥ 80.2dBW

G/T ≥ 11.5dB/K ≥ 19.0dB/K ≥ 24.5dB/K ≥ 32.0dB/K

Dynamic range of receiving signal ≥ 10.0dB ≥ 10.0dB TBD TBD Polarization Vertical or Horizontal (Linear)

Separation of polarization ≥ 20dB ≥25dB TBD TBD Side lobe To meet ITU-Rrec. S580-5

Off-axis emission To meet ITU-Rrec. S524-8

RF frequency-amplitude characteristics TX: ≤ ±0.7dB/6.4MHz TX: ≤ ±1.0dB/51.8MHz ≤ 0.75dB/500MHz ≤ 0.75dB/500MHz

RF frequency-phase characteristics TX: ≤ ±0.1dB/6.4MHz TX: ≤ ±0.2dB/51.8MHz ≤ 1nsec/300MHz ≤ 1nsec/300MHz

RF phase noise characteristics TX: ≤ 3deg.rms

(less than 20kHz-4.6MHz)

TX: ≤ 3deg.rms

(less than 20kHz-37MHz) ≤ -60 dBc at 1kHz from center frequency

≤ -70 dBc at 10 kHz from center

* 1: In the case of up-link maximum information transmission rates (6Mbps), * 2: In the case of up-link maximum information transmission rates (51x3Mbps)

[Attention]

ITU-R specifies off-axis emission power density of earth station in order to avoid interference between satellite networks. User terminal should reflect this

recommendation, especially the antenna diameter is very small.

Refer to the attached information on ITU-R recommendations regarding off-axis EIRP of earth station (S.524-8)


Excerpts of RECOMMENDATION ITU-R S.524-8

Recommends 4-That earth stations operating in GSO networks in the FSS operating in the

27.5-30 GHz frequency band be designed in such a manner that at any angle, ϕ, which is 2° or more

off the main lobe axis of an earth station antenna, the e.i.r.p. density in any direction within 3° of the

GSO should not exceed the following values:

Angle off-axis Maximum e.i.r.p. per 40 kHz

2° ≤ ϕ ≤7° (19 – 25 log ϕ) dB(W/40 kHz)

0 7° < ϕ ≤9.2° –2 dB (W/40 kHz)

0 9.2°< ϕ ≤48° (22 – 25 log ϕ) dB(W/40 kHz)

48° < ϕ ≤180° –10 dB (W/40 kHz).

For any direction in the region outside 3° of the GSO, the above limits may be exceeded by no more

than 3 dB;

NOTE 21 – In the frequency range 27.5-29.0 GHz for earth stations whose antenna diameter is less

than 65 cm, the off-axis e.i.r.p. density levels given in recommends 4 may be exceeded by up to 3 dB

provided that the maximum off-axis e.i.r.p. density does not exceed the following values:

Angle off-axis Maximum e.i.r.p. per 2 MHz

2° ≤ ϕ ≤7° (37 – 25 log ϕ − 10 log M) dB(W/2 MHz)

7° < ϕ ≤9.2° (16 − 10 log M) dB(W/2 MHz)

9.2°< ϕ ≤48° (40 – 25 log ϕ − 10 log M) dB(W/2 MHz)

48° < ϕ ≤180° (7 − 10 log M) dB(W/2 MHz).

Where M is the number of earth stations which are in the receive beam of the satellite to which these

earth stations are communicating and which are expected to transmit simultaneously in the same 2

MHz band and in the same polarization. It should be noted that for these cases a reduction in e.i.r.p.

density, or additional orbital separation, would be required in order to arrive at the same adjacent

satellite interference in the Earth-to-space direction as would result from the off-axis e.i.r.p., values as

specified in recommends 4.


5. Outline of protocols 5.1 ATM baseband switching mode

In this mode, all user terminals should be synchronized to the ABS onboard WINDS, and a user

terminal can transmit signal in assigned signaling slot and assigned traffic slots. The following

section outlines processing procedure.

5.1.1 Synchronization method

1) TDMA Frame

In the ATM baseband switching mode, the TDMA frame structure shown in Figure.5.1-1 is

employed for all of frequency channels. The basic frame consists of 20 time slots whose duration

is constantly 2msec. The first slot of the basic frame, the "Signaling Slot (SS)" is used to send the

Association Request burst from users in uplink and to send the Reference Burst to provide notice

of slot assignment control and ABS status in downlink. The 19 other time slots, called “Traffic

Slots” and assigned to users according to user' requirement are used for data transmission

between users.

A Super Frame consists of the 16 basic frames described above. Each signaling slot in the 16

frames of a Super Frame is pre-assigned to 16 areas on the Earth. In other words, the WINDS

network can provide communications services to 16 areas, and users in the 16 areas can send an

association request once in a Super Frame, and then send data in the assigned Traffic Slots.

Super Frame = 16 Frames (640 msec)

Frame = 20 Slots (40 msec)

• • • • •

• • • • • • •Frame#1 Frame#2 Frame#3 Frame#4 Frame#16

SS TS#1 TS#2 TS#3 TS#4 TS#19 SS : Signaling SlotTS : Traffic Slot 2 msec

SS in Frame#n isassigned to Area#n. TSs in a Super Frame are assigned to user data traffic

dianmically.フレーム#nの SS は

エリア#nに割り当

てられている．

スーパーフレーム中のTS はダイナミックにユーザ間

データ転送用に割り当てられる．

2 msec

2) Outline of synchronization

The WINDS network requires that all user terminals be synchronized to the WINDS network. The

Reference Burst (RB) is used to synchronize user terminals. As mentioned in the previous section,

the RB is sent to define users once in a Super Frame. The first part of the RB contains a 32 bit

Figure. 5.1-1 TDMA Frame Structure (ATM baseband switching Mode)


code (Unique Word) for timing detection, and a user terminal can detect the Super Frame using

this bit sequence. Because each user terminal should know the order of the receiving RB in a

Super Frame, the user terminal can determine the starting point of the receiving Super Frame.

The frame timing can be obtained by dividing the Super Frame by 16. In addition, the slot timing

can be obtained by dividing the Frame timing by 20. Once the receiving timing is obtained,

transmitting timing can be obtained using satellite orbit information and physical allocation of the

user terminal. The orbit information of the WINDS satellite is also contained in every RB.

The user terminal must not be used to transmit a signal if it receives RBs. (Inter-locking function)

5.1.2 Connection control method

1) Association burst

When a user starts communication, the user terminal sends an association burst including

connection request information to the signaling slot assigned to the user’s area. When more than

one earth station sends requests for association at the same time, there can be competition for

association. So the earth station needs to be capable of retransmitting an association request

after a random wait time.

2) Assignment of traffic slots

The connection request from users included in the association bursts is transmitted to the

network management center (NMC) in the Tsukuba Space Center via ABS. The NMC assigns

traffic slots to users based on the request, current assignment status, satellite power allocation

situation, and other parameters. The determined slot assignment information is delivered by RB

to user terminals.

The user terminal should recognize the assigned user traffic slots from the assignment

information in RB, after which the user terminal is permitted to send data bursts to the destination

user terminal using only the assigned traffic slots.

3) Connection termination

When a user terminal ends communication with a destination user terminal, its terminal should

send an Association termination request burst using ATM cell (VPI/VCI to NMC) toward the NMC.

The NMC should terminate the connection based on the Association termination request, and

release the assigned traffic slots for connection.

5.1.3 Burst format

Figure. 5.1-2 shows the burst format. Both the association burst, RB and traffic burst employ this

format which enables transmitting in the 2msec time slot.


HDR TRL

Info#n RS#n

HDR : Header ヘッダ PA : Preamble プリアンブル CR : Carrier Recovery 搬送波再生部

BTR : Bit Timing Recovery ビットタイミング再生部

UW : Unique Word ユニークワード DB #n : n-th Data Block 第nデータブロック

TRL : Trailer トレイラ GT : Guard Time ガードタイム

DB#1 DB#NDB#n

Cell1 Cell2 Cell3 Cell4 Pad

GT

Info#n : n-th Information 第n情報RS #n : n-th Reed-Solomon Code

第nリードソロモン符号Cell : ATM Cell Pad : Padding パディングビット

223 Bytes

32 Bytes

2 msec

PA UW

CR BTR

BTR

Uplink

Downlink

CR = all ‘0’ BTR = “0011- - - “

BTR = “00101101- - - “50 Bytes

Figure.5.1-2 Burst Format

A header and trailer are added to the main body of a burst in order to cancel the transient response

of the circuit. The bit sequence for these parts is all "0s" for the uplink and the same sequence as

BTR for the downlink. The number of data block varies according to transmission rate. Each data

block consists of an information field of 223Bytes and 32Bytes Reed-Solomon code. The addition of

a header, trailer, Reed-Solomon code and guard time makes the actual transmission rate higher

than the information rate. The "symbol rate" is defined as the half rate of this actual transmission

rate because QPSK is used as the modulation scheme. These parameters are shown in table 5.1-1.

Table 5.1-1 Burst transmission Parameters

Up / Down Information rate Nh*1 Nt*2 N*3 Symbol rate

Uplink 1.5 Mbps 2 2 2 1.15625Msps

6Mbps 2 2 8 4.625Msps

24Mbps 4 4 30 18.5Msps

51Mbps 8 8 60 37Msps

Downlink 155Mbps 144 656 180 101.75Mbps

*1 : Number of header bits，*2 : Number of trailer bits，*3 : Number of data blocks

Pre-amble for uplink burst consists of 200 bits of carrier recovery (CR) and 200 bits of bit timing

recovery (BTR). Pre-amble for downlink burst consists of 400 bits of BTR only. Bit sequence of

these pre-amble are shown in Figure. 5.1-2.

Unique words (UW) for reference burst (RB) are distinguished from other burst in order to identify


the RB, because the UW in RB is used to detect super frame timing. The bit sequence of those UWs

is shown in table 5.1-2.

Table 5.1-2 Bit Sequence of Unique Words

Type of Burst I-channel Q-channel

Reference Burst 1100101111000100 (0xCBC4) 0011010000111011 (0x343B)

Traffic Burst 1011011100000110 (0xB706) 0100100011111001 (0x48F9)

Association Burst same as traffic burst same as traffic burst


6. Additional information 6.1 Examples of improvement of TCP performance

It is known that the throughput of Transport Control Protocol (TCP) is markedly degraded much

over a satellite link with a long delay or a very high speed fiber optic link (so called "long fat pipe")..A

few solutions, described below, have been developed to solve this problem.

1) TCP Extension

The Internet Engineering Task Force (IETF) has developed TCP Extension technique to overcome

the degradation of TCP throughput. This technique is opened as RFC-1323, RFC-2018 and

RFC-2488, and many workstations employ these RFCs. TCP throughput can be improved by

making these TCP extensions active before beginning experiments.

2) Using special protocol for satellite link

The TCP extension described above, however, cannot eliminate degradation by "slow start"

process or "congestion control" mechanism. To solve this issue, another technique using a

different protocol dedicated to the satellite links has been developed. Here, protocol conversion

between common TCP/IP and the dedicated protocol should be done at the edge of the satellite

links. The equipment for protocol conversion is called "Performance Enhancing Proxy (PEP)". One

such popular dedicated protocol is "express transport protocol (XTP)", and PEP using XTP is

commercially available. This technique still raises a few issues however such as:

- when an error occurs in satellite links, the reliability of information transmission between

terminals at both ends is not guaranteed,

- protocol conversion is not possible if IPSec is employed.

6.2 Issues of international frequency coordination

Satellite network utilizing WINDS is under international coordination. For this purpose, earth

stations listed below are submitted.

Type of earth

stations

Antenna pattern Maximum

transmitting

power(dBW)

Maximum transmitting

power density at antenna

input (dBW/Hz)

USAT 29-25logθ 12.5 -48.1

HDR-VSAT 29-25logθ 19.3 -41.3

SDR-VSAT 29-25logθ 23.2 -37.4

LET 29-25logθ 23.2 -37.4

6.3 Requirements for common frequency usage with Fixed Wireless Access (FWA) systems

Note that care is necessary with regard to interference between the WINDS satellite network and


FWA. It is recommended that you check the laws and recommendations concerning requirements

for common frequency usage with the FWA in your location.


22

7 Example of development of a prototype earth station Table 7-1 shows the specifications for an earth station in the experimental WINDS system that JAXA and NICT refer to as a base of design. Fig. 7-1 shows

diagrams and views of USAT and VSAT under development in WINDS.

Table 7-1 Baseline of Specifications of Earth Stations for WINDS Experiments

USAT HDR-VSAT SDR-VSAT LET Transmission frequency range 27GHz band Receiving frequency range 18GHz band Antenna diameter 0.45m 1.2m 2.4m 5m equivalency Required G/T ≥ +11.5dB/K ≥ +19.0dB/K ≥ +24.5dB/K ≥ +32.0dB/K Required EIRP (linear operation) ≥ +48.8dBW ≥ +66.9dBW ≥ +76.0dBW ≥ +82.0dBW Polarization Linear ( V/H depends on the area where the earth station is locating) Transmission signals Data transmission (traffic), signaling Information rate

Uplink: 1.5/6Mbps (traffic) 1.5Mbps (signaling)

Downlink: 155Mbps

Uplink: 6/24/51/155Mbps (traffic)*1.5Mbps (signaling)

Downlink: 155Mbps

622Mbp (traffic), 155Mbps (reference burst)

Error correction code Reed-Solomon code RS(255,223) for traffic and signaling Traffic: N/A Reference burst: reed-Solomon code RS(255,223)

Modulation scheme Uplink: QPSK (burst format) Uplink: N/A

Downlink: QPSK Multiple access schemes Uplink: MF-TDMA Downlink: MF-TDMA TDMA Transmission power control Required Expected installation case Transportable Transportable by vehicle

(half -day installation) Transportable by vehicle Fixed model

Automatic satellite tracking Not required (manual tracking by monitoring residual carrier of network monitoring signal)

Required (using residual carrier of network monitoring signal)

* 155Mbps (Uplink) requires 3 channels use of 51Mbps


23

Fig. 7-1 Configuration of USAT for WINDS developed by JAXA

全面差し替え

PC etc.

PC etc.

PC etc.

Figure. 7-1 Configuration of USAT for WINDS developed by JAXA

fixed

fixed


[Terminology]

ABS ATM Baseband Switch : high speed ATM switch on-board WINDS

APAA

Active Phased Array Antenna : Electronically steerable beam antenna which

has antenna array with amplifiers and phase shifters

AS

Autonomous System：An Internet unit network in independently controlled by

a single administrator.

Association

request

Information with which the user station notifies a reference station of a

connection request

ATM

Asynchronous Transfer Mode：Layer-2 protocol commonly used in

broadband networks. Featuring advanced QoS control or friendliness to

multi-media communication.

EIRP Equivalent Isotropic Radiated Power

G/T Gain to noise temperature ratio

HDR-VSAT High Data Rate Very Small Aperture Terminal

IETF

Internet Engineering Task Force: A group researching Internet technology to

be used as standards.

IF Switch

Onboard switch to change the path inside WINDS in down converted

intermediate frequency (not regenerative)

IP Internet Protocol

LET Large-scale Earth Terminal

MPA Multi-Port Amplifier: An amplifier with several input and output ports.

QPSK Quadrature Phase Shift Keying (modulation scheme)

SAAL Signaling ATM Adaptation Layer

SDR-VSAT Super high Data Rate Very Small Aperture Terminal

TCP Transport Control Protocol

TPC Transmission Power Control

USAT Ultra Small Aperture Terminal

WINDS Wideband InterNetworking engineering test and Demonstration Satellite

Signaling slot

Time slot dedicated to sending association request burst or reference burst

located at the first part of each TDMA frame.

Association

request burst

A burst which a user sends to the network control station (NMC) to notify it of

connection request.

Uplink Link from earth station to the WINDS

Area Physical area on the earth surface covered by a WINDS antenna beam.

Link availability

Percentage of communication link that can be used. (time which the link

suffers from rain attenuation or other reason is eliminated)


Network Management Center (NMC)

An earth station dedicated to control of the WINDS network, which it is

planned will be located at the Tsukuba Space Center of JAXA.

Signaling Connection control between user terminals such as connect, release, etc.

Information rate

Transmission rate of user information. Physical bit rate becomes larger

than information rate because redundant bits such as error correction code

are added to user information.

Throughput Efficiency of link usage.

Slot A unit of time sliced. WINDS defines a slot as 2 msec duration.

Cell

Data transmission block in ATM protocol. A cell consists of 5 Bytes (octet)

of header and a 48 Bytes(octet) data field.

Downlink Link from the WINDS to earth stations

Long fat pipe Communication link with a large delay-bandwidth product.

Traffic Exchange of data between users.

Traffic burst A burst which carries data between users.

Traffic data Information transmitted between users.

Beam

A number of radio wave sent from an antenna. (Multi-beam antenna has

multiple beams.)

Protocol

Rules of communication. Procedure of data transmission, modulation

scheme, error recovery and other rules are specified in a protocol.

Baseband Digital bit stream not modulated.

Header Information added to the beginning of a data block for control.

Reference burst

A burst sent from the NMC or ABS to the user terminal which contains the

sync-code, slot assignment information, operation status of network, satellite

orbit information, and so on.

Routing Selection or setting up of path of communication.

Layer 2 Link layer of Open System Interconnection (OSI) model specified by ISO.

Signaling slot

For uplink, time slot on which the user transmits an association request; and

for downlink, time slot on which reference bursts are transmitted


Application Experiment Ground Station Guidelines

The First Edition December 10, 2003 The Second Edition November 27, 2006

Secretariat Space Communications Research Office

Information and Communications Policy Bureau Ministry of Internal Affairs and Communications

Central Common Government Office, No. 2 Bldg., 11th floor

2-1-2 Kasumigaseki, Chiyoda-ku, Tokyo 100-8926, Japan

Email [email protected]

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