This clause defines the scope of this standard and provides
\nrelated information including normative and informative references
\nand a glossary of terms.<\/p>\n
Scope of the Standard<\/strong><\/p>\n The reference point for the P25 two-slot TDMA CAI is The two-slot TDMA CAI is divided into a physical layer and a Above the FDMA CAI and two-slot TDMA CAI are common functions Another common function shown in Figure 1-1 is the trunking 1<\/sup> Future support by the P25 Phase 2 Two-Slot TDMA CAI Project 25 – Phase 2 Two-Slot TDMA Media Access Control Layer Description – Addendum 1<\/b><\/p>\n
\nUm2<\/sub>, and this is shown in Figure 1-1 for orientation to
\nthe other parts of the air interface protocols. Document [R6]
\nexplains that the Um2<\/sub> interface supports trunked voice
\nand control services between the Radio Frequency Sub-System (RFSS)
\nand the subscribers in the system.1<\/sup> In addition to the
\nUm2<\/sub> interface for the P25 Phase 2 two-slot TDMA CAI, a
\nP25 Phase 2 system also supports a Um interface for the P25 Phase 1
\nFDMA CAI, and this is also shown in Figure 1-1. While Um<\/sub>
\nand Um2<\/sub> both support trunked voice and control, the
\nUm2<\/sub> interface has twice the spectrum efficiency of the
\nUm<\/sub> interface when used as a VCH.<\/p>\n
\nmedia access control layer, and these are abbreviated as the PHY
\nand the MAC respectively. The PHY defines the modulation and other
\nfunctions (see [R3]) used to transport information through the
\nUm2<\/sub> interface. The MAC has functions defined in this
\nstandard to convey trunked voice and associated control information
\nthrough the PHY, and subsequently through the Um2<\/sub>
\ninterface. The PHY and MAC are shown in the diagram in Figure 1-1.
\nThe TDMA PHY and MAC protocols are complemented by their FDMA Phase
\n1 equivalent protocol that is indicated in Figure 1-1 as the FDMA
\nCAI.<\/p>\n
\nthat can operate using either air interface. The common functions
\nshown in Figure 1-1 include P25 digital voice, encryption, and
\ntrunking control. The P25 half-rate vocoder used in TDMA is defined
\nin [R4] and the full rate vocoder used in FDMA is defined in [R4].
\nThe full-rate vocoder operates on the FDMA CAI through the Um
\nreference point. The half-rate vocoder operates on the two-slot
\nTDMA CAI via the MAC and PHY. If the voice is encrypted, then the
\nP25 block encryption protocol (see [R5]) is applied to the relevant
\nvoice mode to provide encrypted voice service through either the
\nFDMA CAI or the two-slot TDMA CAI. The interconnection of the
\nvocoder and encryption functions to both FDMA CAI and two-slot TDMA
\nCAI indicates the interoperability of those functions with both
\nchannels. The voice information, either encrypted or unencrypted,
\nis conveyed through the TDMA CAI on a logical channel known as the
\ntwo-slot TDMA Traffic Channel (TCH). The remainder of this standard
\nabbreviates this term to TDMA TCH. The voice and encryption
\nfunctions for the TCH are typically present at the end points of a
\ncall, as represented by the protocol stacks in Figure 1-1 with
\nSubscriber labels.<\/p>\n
\ncontrol. Trunking control functions in the FDMA CAI are conveyed
\nthrough a Phase 1 FDMA control channel or through link control
\nwords embedded in voice messages. The FDMA control channel messages
\nare defined in [R2] and the procedural protocol is defined in [R1].
\nThe Phase 1 FDMA control channel is abbreviated in many instances
\nin this standard to FDMA CCH. All of the messages in [R2] that
\npertain to two-slot TDMA voice services in the MAC are functionally
\ndefined in this standard as MAC Protocol Data Units (PDUs) in
\nClause 8. The procedural protocol for voice messages is defined in
\nClause 7 with supporting examples provided in Annex C and Annex D.
\nThe trunking control MAC PDUs are conveyed through the two-slot
\nTDMA CAI in a logical channel associated with voice that is either
\na Slow Associated Control Channel (SACCH) or a Fast Associated
\nControl Channel (FACCH) defined in this standard. The
\ninterconnection of the trunking control function to both the FDMA
\nCAI and twoslot TDMA CAI indicates the interoperability of trunking
\ncontrol with both channels. The SACCH and FACCH permit the
\nsubscribers on a call to operate a trunking control protocol with
\nthe RFSS. This is why the subscriber stacks and the RFSS stack in
\nFigure 1-1 contain a trunking control function block.<\/p>\n
\nfor P25 packet data service is expected to involve extensions to
\nthis standard.<\/p>\n","protected":false},"excerpt":{"rendered":"\n\n
\n Published By<\/td>\n Publication Date<\/td>\n Number of Pages<\/td>\n<\/tr>\n \n TIA<\/b><\/a><\/td>\n 2013<\/td>\n 94<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"featured_media":690427,"template":"","meta":{"rank_math_lock_modified_date":false,"ep_exclude_from_search":false},"product_cat":[2646],"product_tag":[],"class_list":{"0":"post-690417","1":"product","2":"type-product","3":"status-publish","4":"has-post-thumbnail","6":"product_cat-tia","8":"first","9":"instock","10":"sold-individually","11":"shipping-taxable","12":"purchasable","13":"product-type-simple"},"_links":{"self":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product\/690417","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/types\/product"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media\/690427"}],"wp:attachment":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media?parent=690417"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_cat?post=690417"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_tag?post=690417"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}