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System Features

System Features. System Features. DL-UL Ratio. Defines the ratio of transmit (Down Link) time to receive (Up Link) time, in percents. The available values are: 1: 65-35 2: 60-40 3: 55-45 4: 50-50 (Default) 5: 45-55 6: 40-60 7: 35-65

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System Features

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  1. System Features

  2. System Features DL-UL Ratio • Defines the ratio of transmit (Down Link) time to receive (Up Link) time, in percents. • The available values are: • 1: 65-35 • 2: 60-40 • 3: 55-45 • 4: 50-50 (Default) • 5: 45-55 • 6: 40-60 • 7: 35-65 • The DL-UL Ratio of all Base Stations in the same coverage area (neighboring cells) must be set to the same value • The 1PPS clock which received from a GPS system, ensures inter-site and intra-site synchronization among all sectors and neighboring cells preventing cross interference and saturation problems

  3. Using subchannelization enables to Connect far or weak SUs Better utilization of the UL Power (dBm) +22 +19 3.5 MHz Frequency (Hz) 1.75 MHz System Features Sub-Channelization 2

  4. System Features Sub-Channelization • In version 4.0.2 only groups of 16/8/4 sub-channels are supported (16 is full bandwidth) • One Symbol Per SU + operating only in BPSK ½ is a non optimize implementation. SU that operate in sub-channel expect to have low throughput • The SU switch to “Sub Channel” only if: • Rate = 0 (BPSK ½) • RSSI is bellow the threshold • 3.5Mhz channel spacing • -97dBm for 8 sub-channels • -100dBm for 4 sub-channels • 5Mhz channel spacing • -94dBm for 8 sub-channels • -97dBm for 4 sub-channels • Sub Channels feature should be enable in the AU by selecting the minimum number of sub-channels. 16 = Sub channels is Disable • Additional rates added to the “Performance Monitoring” of the SU

  5. System Features TDD- Basic Air Frame Structure 1 subchannel (sub-ch.) f 16 Subcarriers 16 Subcarriers 16 Subcarriers 16 Subcarriers Symbol #37 / 50 16 Subcarriers Symbol #1 Symbol #2 Symbol #3 Symbol #4 16 Subcarriers 16 Subcarriers 16 Subcarriers 16 Subcarriers 16 Subcarriers 16 Subcarriers 16 Subcarriers UL = 37 symbols @ 3.5 MHz t (ms)

  6. BreezeMAX 2.x TDD ATPC • Automatic Transmit Power Control (ATPC) is required to minimize the interference caused by the strong signal of an SU from one sector to other SU in another sector • An ATPC algorithm will cause the SU to transmit a power level that minimizes the interference to other SU units, while maintaining a sufficient receiving power level • The ATPC algorithm is managed by the AU • The AU collects UL link quality information for each SU, performs an estimation and calculates of the ATPC correction (the required change in the SU Tx power) • The ATPC correction is then transferred to SU and is executed

  7. BreezeMAX 2.x TDD ATPC AU SU • SU transmits a burst (1) • AU measures the received signal level for that burst and calculates the ATPC correction (2) • AU transmits the ATPC correction to the SU (3) • SU receives the ATPC correction, adjusts the Tx power Burst Tx 1 2 ATPC Cor. 3 4

  8. BreezeMAX 2.x TDD ATPC and OFDMA – Noise Level • When several SUs transmit simultaneously – each of one increases the total level of noise • If Very strong SU transmits simultaneously with a very weak SU, the noise induced by the strong one will cause SNR of the weak SU to be too low • In order to avoid this, all SUs should not bee too strong – their RSSI should be not higher than a Nominal RSSI (-74 Dbm).

  9. BreezeMAX 2.x TDD ATPC and OFDMA – Noise Level • Changing an amount of subchannels may causes change in RSSI. • This may cause SNR reduction of weak SU. • In order to avoid this, reduction in amount of subchannels will be done together with reduction of 3 Dbm in SU TX power

  10. BreezeMAX 2.x TDD ATPC and OFDMA – Two Roles • Thus, ATPC in TDD system plays two roles: • It compensates the link quality changes • It compensates changes in the subchannels • Amount of subchannels may be done frequently – so the TX power of SU should be corrected frequently. • Moreover, these correction should be done exactly in the same frame when amount of subchannels is changed. • Dues to these reasons, ATPC corrections are provided in the UL MAP information elements. • Reminder – in FDD it was done with ranging-response message.

  11. BreezeMAX 2.x TDD ATPC and OFDMA – Play with Sub-Channels • Example: • In frame 1 SU was working on full bandwidth • In frame 2 AU decided to move it to 8 subchannels. In order not to pass the Nominal RSSI, SU needs to reduce its TX power in 3 Dbm. So, ATPC delta = -3 Dbm. • In frame 3 SU is moved from 8 to 1 subchannels. TX power is reduced in –9. • In frame 4 SU is moved to full BW. That means that RSSI will drop in 12 DBM below the nominal. To avoid that, AU sends ATPC correction of +12 Dbm. • So, the principle is: Keep the SU as close to Nominal as possible, without crossing the Nominal.

  12. BreezeMAX 2.x TDD ATPC and OFDMA – Possible Amount of Sub-Channels • AU allocates to SU subchannels in such a way that SU is capable to reach nominal RSSI. • For example – if SU is transmitting in the maximum power, it uses 8 subchannels and it is received at nominal RSSI. Then the legal amount of subchannels will be 8,1,2,4. Full BW will not be used • Weak SU (transmission on MAX TX power and RSSI is below nominal) – then this SU will always use single subchannel.

  13. System Features Multi Rate • Motivation - to optimize tradeoff between capacity and error rate: • Most of the links, most of the time use high order modulation  maximizes capacity • “Bad” links, use lower modulation  maximizes availability • Independent adaptation per SU • Independent adaptation for UL and DL, based on link quality information (Burst Error Rate, SNR) • Dynamic adaptation - modulation can be changed on a per burst basis • UL transmission rate - determined by the AU • DL transmission rate - determined by the SU

  14. System Features Multi Rate Downlink - Concept • Each SU uses the highest possible rate • Improves the ability to overcome changes • Fast response to performance degradation • Immunity to short-term link changes • Every SU collects DL link quality information, performs reliable link estimation and calculates the highest possible DL rate • The SU informs the AU about the Best-Rate via the Range-Request message • The SU defines the optimal rate according to the DL adaptation mechanism which is based on BuER monitoring and SNR estimation

  15. System Features Multi Rate Downlink - SU Thresholds • The DL Tx rate (AUSU) is determined by the SU according to 2 thresholds: • SNR • Minimum entry threshold for each DL Rate • Minimum required SNR in order to keep using this rate • Burst Error Rate (BuER) • The system DL rate should retain a BuER lower than this limit • For example, for BuER of 10-2 for each 100 successfully received bursts, only one burst can be with CRC error • In order to achieve a specific rate, the SNR value should be equal to (or higher) than the minimum required SNR of that rate and the BuER should be equal to (or lower) than the maximum BuER of that rate.

  16. BreezeMAX 2.x TDD Multi Rate Uplink - Concepts • Each SU transmits in optimal possible rate • Improves the ability to overcome changes • Fast response to performance degradation • Immunity to short-term link changes • The AU defines a UL rate for each SU, starting with two rates below the rate that is indicated by the SNR

  17. BreezeMAX 2.x TDD Multi Rate Uplink - AU Threshold • The UL Tx rate (SUAU) is determined by the AU according to the following threshold: • Burst Error Rate (BuER) • The system UL rate should retain a BuER lower than this limit • For example, for BuER of 10-2 for each 100 successfully received bursts, only one burst can be with CRC error

  18. BreezeMAX 2.x TDD Multi Rate Uplink - AU Threshold • In the FDD system the rate was selected as described above • One rate per row • But in TDD…

  19. BreezeMAX 2.x TDD Multi Rate Uplink - AU Threshold • In version 4.0.1 the sub-channelization will work only when the following the following conditions are met: • Working at row 0 • RSSI is less than -79 dBm

  20. System Features Fragmentation and Packing • Each of the MPDU payloads comprises one or more (or part of) MAC Service Data Unit (MSDU) • MSDU is the Ethernet frame (user data) that belongs to a certain CID • As the size of the user data (MSDU), which is usually different size than the size of the MPDU, fragmentation and packing is used to utilize the air resource • Packing can be used when MSDU size < MPDU size • Fragmentation can be used when MSDU size > MPDU size

  21. System Features Diversity 2nd Order Diversity • Multiple channel configuration with second order diversity allows coverage of one sector by a single AU-IDU and two ODUs connected to channels 1 and 2 • The same frequency and transmit power are set for both ODUs • Version 4.0.2 – No STC • Antenna 1 delay : - 2 symbols • Antenna 2 delay : + 2 symbols BS Outdoor Unit sector #1 BS Outdoor Unit sector #1

  22. System Features Diversity 4th Order Diversity • Multiple channel configuration with 4th order diversity allows a single sector coverage by a single AU-IDU with 4 ODUs • The channels are paired: channels 1 and 2 form one pair, channels 3 and 4 form the second pair • The two ODUs connected to each pair are connected to the same dual polarization antenna • The same frequency and transmit power are set for all 4 ODUs • Version 4.0.2 – No STC • Antenna 1 delay : - 2 symbols • Antenna 2 delay : + 2 symbols • Antenna 3 delay : - 2 symbols • Antenna 4 delay : + 2 symbols BS Outdoor Unit sector #1 BS Outdoor Unit BS Outdoor Unit sector #1 BS Outdoor Unit

  23. System Features Frequency Scanning • This feature allows for automatic scanning of the frequency by the SU. No need to configure the frequency in which the AU is working for each SU. • Under the SU menu the following parameters are available: • Start Rx Frequency – The scanned range will start with this frequency • End Rx Frequency - The scanned range will end with this frequency • Scanning Main Step – The steps in which the scanning algorithm jumps (125 KHz – 1750 KHz) • Scan Step Mask – higher resolution of steps in the scanning mode • 1 – Is the start frequency scanned • 2 – 125 KHz from the main step • 3 – 250 KHz from the main step • 4 – 375 KHz from the main step • 5 – 500 KHz from the main step • 6 – 625 KHz from the main step • 7 – 750 KHz from the main step • 8 – 875/1250 KHz from the main step (depends on 3.5 or 5 MHz channel spacing) • On the SU side it is also possible to configure discrete frequencies – THIS IS ONLY AVAILABLE ON SU SIDE

  24. System Features Best AU • The system allows an SU to find the best AU it should associate with after scanning the entire range as defined in the scanning frequency feature • When Disabled the SU will associate with the first AU it finds in the scanned range (with the correct BST ID) • When enabled the SU scans all AUs in a predefined range, in all frequencies and in all available antennas (in automatic antenna selection mode) • Each of the AUs with which the SU can communicate (perform initial phase of network entry), is given a quality mark based on the quality of the signal at which it is received by the SU, for each of the relevant antennas • At the end of the scanning process, the SU build a table of the AUs it found, the table includes: • Frequency used • AU ID • SNR • Antenna used (for SU Si) • The SU will associate with the AU that has the best SNR. If it can not associate to it, the SU will try the next AU in the list

  25. System Features Best AU • After link loss the SU will try to associate using the same frequency for 5 minutes. After this time it will go in to scanning mode again • After SU reset the SU will try to associate with the same frequency for 1 minute. After this time it will go in to scanning mode. • In both cases scanning mode is – • “Short Scan” only to the frequencies in the Best AU list are scanned • If non of the frequencies are available go to “Full Scan” (entire range scan) • When working with the SU Si the scan button allows the user to go in to scanning mode • Full scan (press on button more than 3 seconds) – start the scan process from the start by clearing the best AU list • Short scan (press on button less than 3 seconds) – Go over the AUs in the best AU list check again the SNR of each and associate to the best one

  26. System Features Best AU Preferred AU • When the best AU is enabled, the operator can still decide to use a specific AU (if available) • This is done using the preferred AU mechanism • Preferred BST/AU ID – Full ID or partial ID of the AU we want to associate with • Preferred BST/AU ID Mask – Defining a group of IDs we will allow association with • The SU will try to associate to AUs only if the AU ID and mask match the configuration in the preferred AU. If no AU is available, the SU will try to associate with AU ID and Base Station ID as define in the “MAC” menu • The default is • Preferred BST/AU ID – 186.190.0.0.0.0 • Preferred BST/AU ID Mask – 0.0.0.0.0.0 • Meaning we will associate with any AU on the best AU list

  27. DRAP System Features Dynamic Resource Allocation Protocol (DRAP) CPE(ODU) BMAX-CPE-IDU-NG-4D1W(indoor) VoIP Servers PSTN AU-IDU-2C AU-ODU sector #1 802.11g NPU 100 / 1000 Mbps Ethernet switch PC Router (R) Base Station Shelf(BMAX-BS-SH) PC PC PC Internet • The Dynamic Resource Allocation Protocol (DRAP) enables Registration of the Network Gateway (NG) and Voice Gateway (VG) with the NPU

  28. System Features Radius • There is the possibility to connect the NPU to a RADIUS server • The RADIUS server can be used for Authentication and Accounting • The NPU supports RFC-2866 (Accounting) and RFC-2865 (Authentication) • Up to two RADIUS servers can be connected to the NPU (for accounting purposes) one as primary and other one as secondary • Up to two RADIUS servers can be connected to the NPU (for authentication purposes) one as primary and other one as secondary • There is also the possibility to connect the same RADIUS server for Authentication and Accounting purposes

  29. System Features

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