Download
1 / 7
70 likes | 188 Vues
IS-95 <=> IS-2000 Hand-off Analysis. Prepared by Dragan Nerandzic, Bell Mobility. The Purpose of the Presentation. To identify possible hand-off problems in configurations when IS-2000 and IS-95 networks are deployed in the same CDMA channel, but in adjacent geographic areas (markets).
E N D
IS-95 <=> IS-2000Hand-off Analysis Prepared by Dragan Nerandzic, Bell Mobility
The Purpose of the Presentation • To identify possible hand-off problems in configurations when IS-2000 and IS-95 networks are deployed in the same CDMA channel, but in adjacent geographic areas (markets). • Hand-off mechanisms were simulated by similar IS-95 configurations.
Network Configuration g D a • Handoff areas: • Green - softer • Blue - no handoffs • Yellow - softer/soft • Red - soft • Pink - soft/soft • Light blue- soft/softer • Gray - handoff between IS-2000 and IS-95 • a,b,g - orientations of sectors. • A,B,C,D,E are sites with deployed IS-2000 at channel N. • f,g,h,I,j,k are sites with deployed IS-95 at channel N. • black, blue and orange lines are major highways in the area. • Points 1,2,3,4,5,6,7,8,9 are characteristic point along the route. b Major HW E A F 5 B 1 g 2 6 C 7 h 3 8 j 4 i k 9 Major HW Major HW
Network Configuration and Design • It is assumed that in general case sites A,B,C,D,E do not have IS-95 functionality. • Soft handoffs are functional between sites A,B,C,D,E. • Soft handoffs are functional between sites f,g,h,i j. • Handoffs between (A,B,C,D,E) and (f,g,h,i,j) are only hard handoffs (as per IS-2000) capabilities. • Hard-Handoff between (A,B,C,D,E) and (f,g,h,i,j) is RTD based. • RTD values are optimized in such a way to perform HHO at the location that is equidistant from target and serving cell. • There are two relevant ways to perform HHO in this network configuration: • a) Configure sites (A,B,C,D,E) so that at least border sites have IS-95 functionality. In that case, HO B->h (IS-2000 -> IS-95) would be performed in two steps: first from IS-2000 from one sector to IS-95 of the same sector (B->b) and then SHO from b->h. • b) Perform HHO directly from B->h.
HHO Options - Open Issues • Problem with solution a) is that coverage are of IS-2000 network becomes effectively smaller than necessary. That smaller footprint is a consequence of a need for sufficient margin to perform HHO IS-2000 -> IS-95 at the same sector. • Problem with solution b) is that this type of HHO can be optimized only for one route. Consequence of that design is increase of dropped calls in HHO area - gray zone.
Summary • Target sector, prior to HHO behaves as an interferer. • Source sector, after HHO behaves as an interferer. • Successful in channel HHO are occurring when target and source sectors are directly pointing to each other, so that serving sector provides sufficient signal to achieve desired Eb/No. • When target and source sectors are not pointing to each other, or when propagation effect result in imbalance of signal strengths of those sectors, in channel HHO is not successful. This configuration is very typical for non-interleaving network configurations.
Conclusions • IS-95 mechanisms that support HHO in the same frequency channel can not be optimized in such a way to provide high level of success in the whole area of intended HHO. • Use of the same mechanisms to support IS-2000 to IS-95 HHO will result in the same effects. • Due to the fact that large percentage of cdmaOne networks are operating in soft handoff mode, inability to perform successful HHO in border area will result in area with low probability of success and high probability of call failures. • Recommendation is to proceed with alternative handoff mechanisms to support reliable IS-2000 <-> IS-95 handoffs in the same channel.
