RRM Radio Networks Radio Resource Management in Area Coverage Networks

Transcription

1 RRM Radio Networks Radio Resource Management in Area Coverage Networks Roberto Verdone Office Hours: Monday 4 5 pm A.Y Credits: 6

2 Mobile RAN Architecture: 2G Other Networks Service Area Core Network Cells Base Station BS Controller Mobile Station Radio Link PP Link

3 Mobile RAN Architecture: 2G MS BTS Other MSCs MSC PSTN HLR, VLR,... BSC MS BTS

4 Mobile RAN Architecture: 2G OMC MS BTS Other MSCs MSC PSTN HLR, VLR,... BSC MS BTS

5 Mobile RAN Architecture: 2.5G MS BTS MSC PSTN BSC Core Network MS BTS GSN IP

6 Mobile RAN Architecture: 2/3G MS BTS BSC PSTN MS BTS Core Network UE Node B UE Node B RNC IP Other RNCs

7 Mobile RAN Architecture: LTE PSTN UE enode B Core Network UE enode B IP

8 Radio Resource Management RRM techniques aim at optimising the use of radio resources while fulfilling the quality requirements of the largest possible number of users

9 Radio Resource Management Decisions to be taken by the RRM entities (C.S. Services) B A Release the call? How many base stations? If one, what base? Accept the call? What base, RU? How many RUs?

10 Radio Resource Management Decisions to be taken by the RRM entities (C.S. Services) At call set up: Admission control Initial base station assignment Initial channel assignment Initial bandwidth assignment (whether to accept a new call) (what base) (what RU) (how many RUs) During the call: Power control (what power) Base re-assignment (what base) Re-assignment of the number of bases (how many bases) Channel re-assignment (what RU) Bandwidth re-assignment (how many RUs) Call release (whether to release a call)

11 Radio Resource Management Decisions to be taken by the RRM entities (P.S. Services) At Packet Data Transfer (PDT) set up: Admission control Initial base station assignment (what base) Initial channel assignment (what RU) Initial bandwidth assignment (how many RUs) (whether to accept a new PDT) During the PDT: Power control (what power) Base re-assignment (what base) Re-assignment of the number of bases (how many bases) Channel re-assignment (what RU) Bandwidth re-assignment (how many RUs) Call release (whether to release a PDT)

12 Radio Resource Management Admission Control The process of determining whether a service request can be admitted to the system

13 Radio Resource Management: Admission Control The call could be rejected for reasons related to capacity, or interference levels Networks planned with reference to worst-case: Admission Control is normally absent (e.g. GSM)

14 Radio Resource Management Admission Control Directed Retry The process of determining whether a service request can be admitted to the system The process of re-directing a new user toward a base station different from the one providing the best link budget

15 Radio Resource Management: Directed Retry If one base cannot provide service, the call request is re-directed toward a different base (if within range). Networks planned with reference to worst-case: Directed Retry is normally present (e.g. GSM)

16 Radio Resource Management Admission Control Directed Retry Channel Assignment Distinction: The process of determining whether a service request can be admitted to the system The process of re-directing a new user toward a base station different from the one providing best link budget The process of choosing the RU (and its number) to be allocated to the user 1) assignment of RUs to the cells (Channel Allocation) 2) assignment of RUs to the users within cells (Ch. Assignment)

17 Radio Resource Management: Channel Allocation Channel Allocation Techniques Fixed (FCA): a predefined (sub-)set of channels is assigned to a base; the channel to be allocated to the user is selected among these pre-assigned channels Dynamic (DCA): channels are in a pool, and can be selected by every base for each link Hybrid (HCA): part of channels are allocated via FCA, part via DCA Channel Assignment Techniques Normally based on measurements performed on the field. Scheduling.

18 Radio Resource Management Admission Control Directed Retry Channel Allocation Power Control Distinction: The process of determining whether a service request can be admitted to the system The process of re-directing a new user toward a base station different from the one providing best link budget The process of choosing the channel (and the number of RUs) to be allocated to the user The process of setting the transmission power level fast PC and slow PC

19 Radio Resource Management Admission Control Directed Retry Channel Allocation Power Control Hard Handover The process of determining whether a service request can be admitted to the system The process of re-directing a new user toward a base station different from the one providing best link budget The process of choosing the channel (and the number of RUs) to be allocated to the user The process of setting the transmission power level The process of changing serving base and RU

20 Radio Resource Management: Hard Handover One base station at a time (Break Before Make) Not seamless Can have a serious impact on the signalling channels

21 Radio Resource Management Admission Control Directed Retry Channel Allocation Power Control Hard Handover Soft/Softer Handover The process of determining whether a service request can be admitted to the system The process of re-directing a new user toward a base station different from the one providing best link budget The process of choosing the channel (and the number of RUs) to be allocated to the user The process of setting the transmission power level The process of changing serving base and/or channel The process of modifying the set of serving bases

22 Radio Resource Management: Soft Handover More than one base station at a time (Make Before Break) Seamless Service Macrodiversity: reduced shadowing margin Microdiversity: MR Combining (downlink) or S Combining (uplink) Can have a serious impact on the network capacity Active set The set of serving base stations

23 Radio Resource Management: Softer Handover More than one base station within the same site at a time Maximal Ratio Combining both on uplink and downlink

24 Radio Resource Management Admission Control Directed Retry Channel Allocation Power Control Hard Handover Soft Handover Load Control The process of determining whether a service request can be admitted to the system The process of re-directing a new user toward a base station different from the one providing best link budget The process of choosing the channel (and the number of RUs) to be allocated to the user The process of setting the transmission power level The process of changing serving base and/or channel The process of modifying the set of serving bases The process of controlling the load of the network

25 Mobile RAN Architecture: 2/3G Power Control Load Control Scheduling Power Control Handover Admission Control Load Control Power Control MS BTS BSC PSTN MS BTS UE Node B Power Control UE Node B RNC IP

26 Mobile RAN Architecture: LTE Load Control Scheduling Power Control Handover Admission Control Load Control PSTN UE enode B Core Network Power Control UE enode B IP