MAC-ehs PDU Structure with Example
There are two different types of MAC HSDPA PDU format depending upon the upper layer configuration. MAC-hs MAC-ehs In this tutorial only MAC-ehs is covered. In this case the MAC HSDPA PDU is consists of MAC-ehs header One or more reordering PDUs Each reordering PDU consists of one or more reordering SDU belonging to the same priority queue. Header Elements LCH-ID (Logical Channel Identifier): 4 bits The LCH-ID field provides identification of the logical channel at the receiver and the re-ordering buffer destination of a reordering SDU. LCH-ID Designation 0000 Logical Channel 1 0001 Logical Channel 2 . . . . . . . . . . . . . . . . . . . . . . . 1110 Logical Channel 15 1111 Logical Channel 16 TSN (Transmission Sequence Number): 6 bits The TSN field provides an identifier for the transmission sequence number on the HS-DSCH. The TSN [...]
MAC HSDPA PDU (MAC-hs)
There are two different types of MAC HSDPA PDU format depending upon the upper layer configuration. MAC-hs MAC-ehs In this tutorial only MAC-hs is covered. MAC-hs In this case the MAC HSDPA PDU is consists of MAC-hs header One or more MAC-hs SDU NOTE: A maximum of one HSDPA PDU is transmitted in on TTI Header Elements VF (Version Flag): 1 bit VF field is there to provide extension capabilities. This should be set to zero for now Queue ID (Queue Identifier): 3 bits The Queue ID field provides identification of the reordering queue in the receiver. TSN (Transmission Sequence Number): 6 bits or 9 bits The TSN field provides an identifier for the transmission sequence number on the HS-DSCH. The TSN field is used for reordering purposes to support in-sequence delivery to higher layers. NOTE: Only for TDD 1.28 Mcps configuration TSN can have a value of 6 bits [...]
Basics of data transmission in a UMTS system
In a UMTS system, the maximum supported downlink data rate is 2.048 Mbps. With other technologies such as HSPA, LTE, higher data rates are possible, but we look at data rates for UMTS only systems. Each application has a certain Quality of service (QOS) requirement. A user who wishes to run a application that demands high data rate informs the network of his throughput requirement in Quality Of Service (QOS) attributes during PDP context activation. It is from this message that the network becomes aware of the user’s data rate requirement. Apart from data rate, other parameters like application’s error resilience, time sensitivity etc is negotiated. If the network could fulfill the requirement, it informs the user by accepting and activating the PDP context and sets up a Radio Access Bearer (RAB). Network provides channel details that UE has to use in order to send and receive data in a [...]
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MAC PDU Structure for non-HSPA Transport Channels
This tutorial describes about the MAC PDU structure when HS-DSCH and E-DCH transport channel are not used. MAC PDUs are also called the MAC Transport Blocks (TB). MAC PDU is a bit string. The MAC PDU is consists of the MAC header and the MAC SDU (RLC PDU)
MAC (Medium Access Control) Architecture (25.321)
MAC is a layer 2 protocol in the UMTS Access Stratum. MAC has the input as logical channels and at the output it has transport channels. This tutorial covers only the MAC architecture. The following sections are covered
- MAC Architecture - UE Side
- MAC Architecture - UTRAN Side
UMTS Logical Channels and Transport Channels
Logical channels define ‘WHAT’ type of information is being transferred and transport channel defines ‘HOW’ the information is being transferred. In this tutorial different types of logical channels and transport channels and their mappings are described.
