Note:
Changing a Service Class while in use can cause the Service Flow to be
in the wrong ‘state’ – to overcome this, a re-provision of the SS is required
and in some instances a re-provision of the BS TRx Channel maybe needed. Note:
Changing a Service Class while in use can cause the Service Flow to be
in the wrong ‘state’ – to overcome this, a re-provision of the SS is required
and in some instances a re-provision of the BS TRx Channel maybe needed.
The following screen is used to specify a set of Quality of Service (QoS) parameters which will be associated with a Service Flow to a Subscriber.
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Name: Length 2 to 64 characters. Allowed characters 0 to 9, A to Z, a to z, ., #, -, _
Scheduling is for UPLINK traffic ONLY (as defined in the 802.16-2004 standard)
Best Effort - BE
non real Time Polling Service - nrtPS
real time Polling Service - rtPS
Unsolicited Grant Service - UGS
All Downlink traffic is treated the same but is subject to Packet Classifier and Service Class Priority.
Further reading on this subject can be found on pages 138 to 142 of the 802.16-2004 Standard
Scheduling Type: A scheduling service is configurable, for requesting and provisioning data transmission on the uplink. This specifies the upstream scheduling service used for upstream service flow. If the referenced parameter is not present in the corresponding 802.16 QOS Parameter Set of an upstream service flow, the default value of this object is Best Effort. Possible scheduling services are available:
Best Effort: Best Effort is a method of requesting uplink bandwidth for a service flow. The bandwidth is requested by transmitting a bandwidth request from the ST to the BS TRx in a contended access bandwidth slot in the UL sub-frame. There exists the possibility that two (or more) STs will attempt to transmit a bandwidth request at the same time and that neither request will be decoded successfully by the BS TRx; each ST initiates a random back-off timer before attempting to retransmit the bandwidth request. On successfully receiving the bandwidth request the BS TRx will schedule bandwidth for use by the ST; the ST may or may not use the bandwidth slot for the correct service flow.
Non-real-time Polling: Non real time polling is similar to real time polling as it is configured on a service flow to allow that service flow to request uplink bandwidth. However in the case of non-real-time polling the interval at which bandwidth is made available occurs over much longer periods. Bandwidth is then provided by the BS TRx for use by the ST; the ST may or may not use the bandwidth slot for the correct service flow.
Real-time Polling: Real time polling is configured on an SF to allow that a service flow to request uplink bandwidth at regular intervals. Bandwidth is then provided by the BS TRx for use by the ST; the ST may or may not use the bandwidth slot for the correct a service flow.
Unsolicited Grant Service: The unsolicited grant service provides fixed size data grants on a regular basis. Uplink latency depends on regularity of data grants, which in turn depends on how the specific UGS is provisioned.
UGS allows grants of a specific size at the poll period. With a rate of 64000 bps (Max Sustained and Min Reserved) this is a grant of 8000 Bytes per second. If the Scheduling Poll Period is set to 100 ms this will allow a grant of 800 Bytes at each scheduled poll period. So the Max Packet Size to pass at these settings would be 800 Bytes- less various overheads. If you test this with a ping –l xxx you will find the result is about 601Bytes with headers this equates to 743 Bytes “on the wire”.
Undefined (custom)
Traffic Priority: The value of this parameter specifies the priority assigned to a service flow. For uplink service flows, the BS TRx should use this parameter when determining precedence in request service and grant generation, and the SS shall preferentially select contention Request opportunities for Priority Request CIDs based on this priority. Range = 0 to 7 [0= lowest Priority 7 = highest priority]. A secondary management channel automatically has priority '8', the primary management channel has '9' and the basic channel has '10'
Request/transmission Policy: Defines extra properties of a Service Flow used to maximize the efficiency of the air-interface. The value of this parameter provides the capability to specify certain attributes for the associated service flow. Select items by clicking with the mouse. More than one item may be selected by clicking with the mouse with the Ctrl key pressed.
Broadcast BW Req. Note: This should always be selected (activated)
Piggyback Req
Fragmentation
PHS
SDU Packing
CRC
Max Sustained Rate (bps): The peak information rate associated with a Service Flow. The minimum rate will be around 32kbps with the maximum only limited by the capacity of the radio channel. The granularity associated with the maximum sustainable rate will depend on the packet size. This parameter defines the peak information rate of the service. The rate is expressed in bits per second and pertains to the SDUs at the input to the system.
Max Traffic Burst (Byte): The maximum burst size that must be accommodated within a Service Flow. The minimum and maximum can be any number which the operator must implement to ensure a subscriber does not overtly utilize system capacity whilst maintaining a reasonable user experience. This parameter defines the maximum burst size that must be accommodated for the service.
Min Reserved Rate (bps): The committed information rate that is guaranteed but which can be overbooked. The minimum rate is zero bps with the maximum limited by the capacity of the radio channel. The granularity associated with the maximum sustainable rate will depend on the packet size. This parameter specifies the minimum rate reserved for this service flow.
Min Tolerable Rate (bps): The minimum committed information rate that is required, below this level service will not be offered. The minimum rate is zero bps with the maximum limited by the capacity of the radio channel. The granularity associated with the maximum sustainable rate will depend on the packet size. This parameter specifies the minimum tolerable rate for this service flow.
Minimum Tolerable Traffic Rate: Minimum Tolerable Traffic Rate =R (bits/sec) with time base T(sec) means the following. Let S denote additional demand accumulated at the MAC SAP of the transmitter during an arbitrary time interval of the length T. Then the amount of data forwarded at the receiver to CS (in bits) during this interval should be not less than min {S, R * T}.
Tolerated Jitter (ms): Defines the maximum variation in packet delay associated with a Service Flow. The maximum and minimum tolerable jitter can be any number but will depend upon application requirements using the service flow. For example, VoIP services will require a tighter specification of jitter than web browsing. This parameter defines the Maximum delay variation (jitter) for the connection.
Max Latency (ms): Defines the maximum delay through the BS TRx from a packet arriving through to transmission. This is the max time the buffer will hold onto the packet before it gets discarded. If you set the max latency to less than the Scheduling Poll Period then it depends on when exactly the packet gets received as to whether it gets discarded. The maximum and minimum latency can be any number but will depend upon application requirements using the service flow. For example, VoIP services will require a tighter specification of latency than web browsing. The value of this parameter specifies the maximum latency between the reception of a packet by the BS TRx or SS on its network interface and the forwarding of the packet to its RF Interface.
SDU Length Indicator: The Service Data Unit (SDU) is the payload of the packet . The value of this parameter specifies whether the SDUs on the service flow are variable-length or fixed-length. The parameter is used only if packing is on for the service flow. The default value is variable-length SDUs.
Variable-length
Fixed-length
SDU Size (Byte): The value of this parameter specifies the length of the SDU for a fixed-length SDU service flow. This parameter is used only if packing is on and the service flow is indicated as carrying fixed-length SDUs. It specifies the SDU size in bytes. The default value is 49 bytes, i.e., VC-switched ATM cells with PHS. The parameter is relevant for both ATM and Packet Convergence Sublayers.
Scheduling Poll Period (custom): Sets the polling period for RTP, nRTP and UGS.
A message lists hardware that does not support ARQ.
Enable: ARQ enabling is requested for the connection.
Not Requested
Requested
Window Size Byte: Indicates the maximum number of unacknowledged fragments at any time. Range 0 to 1024. Default = Not Specified.
Block Lifetime (10 us): The maximum time interval an ARQ fragment will be managed by the transmitter ARQ machine, once initial transmission of the fragment has occurred. If transmission or re-transmission of the fragment is not acknowledged by the receiver before the time limit is reached, the fragment is discarded. A value of 0 means Infinite.
Sync Loss Timeout (10 us): The maximum interval before declaring a loss of synchronization of the sender and receiver state machines. A value of 0 means Infinite.
Delivery Order: Indicates whether or not data is to be delivered by the receiving MAC to its client application in the order in which data was handed off to the originating MAC.
Not Preserved
Preserved
Rx Purge Timeout (10 us): Indicates the time interval the ARQ window is advanced after a fragment is received. A value of 0 means Infinite.
Block Size Byte: This value of this parameter specifies the size of an RQ block. Values may be selected from a drop down list.
See Action Buttons
